LM2596T-ADJ

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LM2596T中文资料

LM2596T中文资料元器件交易网/doc/a66360844.html,3.0A, 150Khz, Step-Down Switching RegulatorFEATURES3.3V, 5.0V, 12V, 15V, and Adjustable Output Versions Adjustable Version Output Voltage Range, 1.23 to 37V +/- 4%. Maximum Over Line and Load Conditions Guaranteed 3.0A Output Current Wide Input Voltage Range Requires Only 4 External Components 150Khz Fixed Frequency Internal Oscillator TTL Shutdown Capability, Low Power Standby Mode High Efficiency Uses Readily Available Standard Inductors Thermal Shutdown and Current Limit Protection Moisture Sensitivity Level(MSL) Equals1 TO-263(D2) TO-220V TO-220LM2596ApplicationsSimple High-Efficiency Step-Down(Buck) Regulator Efficient Pre-Regulator for Linear Regulators On-Card Switching Regulators Positive to Negative Converter(Buck-Boost) Negative Step-Up Converters Power Supply for Battery Chargers1. 2. 3. 4. 5. Vin Output Ground Feedback On/OffDESCRIPTIONThe LM2596 series of regulators are monolithic integrated circuits ideally suited for easy and convenient design of a step-down switching regualtor(buck converter). All circuits of this series are capable of driving a 3.0A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5.0V,12V, 15V, and an adjustable output version.ORDERING INFORMATIONDevice LM2596T-X.X LM2596TV-X.X LM2596R MarkingLM2596T-X.X LM2596T-X.X LM2596R-X.X Package TO-220 TO-220V TO-263These regulatiors were designed to minimize the number of externalcomponents to simplify the power supply design. Standard series of inductors optimized for use with the LM2576 are offered by several different inductor manufacturers. Since the LM2596 converter is a switch-mode power supply, its efficiency is significantly higher in comparison with popular three-terminal limear reguators, especially with higher input voltages. In many cases, the power dissipated is so low that no heatsink is required or its size could be reduced dramatically. A standard series of inductors optimized for use with the LM2596 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies. The LM2596 features include a guaranteed +/- 4% tolerance on output voltage within specified input voltages and output load conditions, and +/-15% on the oscillator frequency (+/- 2% over 0oC to 125 oC). External shutdown is included, featuring 80 uA(typical) standby current. The output switch includes cycle-bycycle current limiting, as well as thermal shutdown for full protection under fault conditions.HTC1Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorTypical Application (Fixed Output Voltage Versions)LM2596LM2596-5.033 uH680 uF1N5824220 uFFigure 1. Block Diagram and Typical ApplicationABSOLUTE MAXIMUM RATINGS(Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.)Power DissipationTO-220, 5-LeadThermal Resistance, Junction-to-Ambient Thermal Resistance, Junction-to-caseTO-263Thermal Resistance, Junction-to-Ambient Thermal Resistance, Junction-to-caseHTC2Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorLM2596OPERATING RATINGS (Operating Ratings indicate conditions for which the device is intended to befunctional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.)ELECTRICAL CHARACTERISTICS / SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 2) (Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500mA. For typical values TJ = 25°C, for min/max values TJ is the operating junction temperature range that applies [Note 2], unless otherwise noted.)LM2596-3.3 ([ Note 1]. Test Circuit Figure 2 )73 LM2596-5.0 ([ Note 1]. Test Circuit Figure 2 ) 180 LM2596-12 ([ Note 1]. Test Circuit Figure 2 )90 LM2596-15 ([ Note 1]. Test Circuit Figure 2 )98 LM2596-ADJ ([ Note 1]. Test Circuit Figure 2 )73HTC3Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorELECTRICAL CHARACTERISTICS / Device ParametersLM2596(Unless otherwise specified, Vin = 12 V for the 3.3 V, 5.0 V, and Adjustable version, Vin = 25 V for the 12 V version, and Vin = 30 V for the 15 V version. ILoad = 500 mA. For typical values Tj = 25°C, for min/max values Tj is the operating junction temperature range that applies [Note 2], unless otherwise noted.)10 0 127 110 15050 100 173 1731.16 01.4 1.53.6 3.4100 4.5 6.9 7.5 50 30 102 5 00 2 0 2.0 2.0 2 V LOGIC = 2.5V (Regulator OFF) V LOGIC = 0.5V (Regulator ON) 5 0.02 1.3 1.32500.6 0.6 15 5.01. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2596 is used as shown in the Figure 1 test circuit, system performance will be as shown in system parameters section .2. Tested junction temperature range for the LM2596 : TLOW = –0°C THIGH = +125°C3. The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which causes the regulated output voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to output pin.5. Feedback (Pin 4) removed from output and connected to 0 V.6. Feedback (Pin 4) removed from output and connected to +12 V for the Adjustable, 3.3 V, and 5.0V ersions, and +25 V for the 12 V and15 V versions, to force the output transistor “off”.7. Vin = 40 V.HTC4Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorTYPICAL PERFORMANCE CHARACTERISTICS (Circuit ofFigure 2)LM2596HTC5Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorTYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 2)Feedback Pin Bias CurrentLM2596HTC6Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorTest Circuit and Layout GuidelinesLM2596Figure 2. Typical Test Circuits and Layout GuideAs in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance can generate voltage transients which can cause problems. For minimal inductance and ground loops, the wires indicated by heavy lines should be wide printed circuit traces and should be kept as short as possible. For best results, external components should be located as close to the switcher lC as possible using ground plane construction or single point grounding. If open core inductors are used, special care must be taken as to thelocation and positioning of this type of inductor. Allowing the inductor flux to intersect sensitive feedback, lC groundpath and COUT wiring can cause problems. When using the adjustable version, special care must be taken as to the location of the feedback resistors and the associated wiring. Physically locate both resistors near the IC, and route the wiring away from the inductor, especially an open core type of inductor.HTC7Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorLM2596PIN FUNCTION DESCRIPTION Symbol 1VinDescription This pin is the positive input supply for the LM2596 step–down switching23 45regulator.In order to minimize voltage transients and to supply the switching currents needed by the regulator, a suitable input bypass capacitor must be present .(Cin in Figure 1). Output This is the emitter of the internal switch. The saturation voltage Vsat of this output switch is typically 1.5 V. It should be kept in mind that the PCB area connected to this pin should be kept to a minimum in order to minimize coupling to sensitive circuitry. Circuit ground pin. See the information about the printed circuit board layout. Gnd Feedback This pin senses regulated outputvoltage to complete the feedback loop. The signal is divided by the internal resistor divider network R2, R1 and applied to the non–inverting input of the internal error amplifier. In the Adjustable version of the LM2596 switching regulator this pin is the direct input of the error amplifier and the resistor network R2, R1 is connected externally to allow programming of the output voltage. ON/OFF It allows the switching regulator circuit to be shut down using logic level signals, thus dropping the total input supply current to approximately 80 mA. The threshold voltage is typically 1.4 V. Applying a voltage above this value (up to +Vin) shuts the regulator off. If the voltage applied to this pin is lower than 1.4V or if this pin is left open, the regulator will be in the "on" conditionHTC8Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorLM2596PACKAGES DIMENSION : TO220-5LHTC9Oct 2004 - Rev 0元器件交易网/doc/a66360844.html,3.0A, 15V, Step-Down Switching RegulatorPACKAGES DIMENSION : TO220V-5LLM2596HTC10Oct 2004 - Rev 0元器件交易网/doc/a66360844.html, 3.0A, 15V, Step-Down Switching RegulatorLM2596PACKAGES DIMENSION : TO263-5LHTC11Oct 2004 - Rev 0。

LM2596中文资料

PCB 的另一面覆盖有面积约为 16 平方英寸铜箔。注14： LM2596T-3.3, LM2596T-5.0, LM2596T-12， LM2596T-ADJ为TO-220封装（DIP）；
LM2596S-3.3, LM2596S-5.0,LM2596S-12， LM2596S-ADJ为TO-263封装（SMT）。
η
效率
VIN=12V，ILOAD=3A
73
LM2596□—5.0 （见注 14）
VOUT
输出电压
5.0 7V≤VIN≤40V， 0.2A≤ILOAD≤3A
η
效率
VIN=12V，ILOAD=3A
80
3.168/3.135 3.432/3.465
V V（min） V（max） %
4.800/4.750 5.200/5.250
2 30
A A(min) A(max) μA(max) mA mA(max)
IQ
静电流
见注 9
5 10
mA mA(max)
ISTBY
待机静电流
ON/OFF 脚=5V（OFF）（9）
80
μA
200/250
μA(max) ３
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LM2596 开关电压调节器 SEPTEMBER， 2004
ILOAD=500mA。（见注 14）
361 符号
参量
cu 器件参数
.m Ib
反馈偏置电流
wwwfO
振荡器频率
条件
LM2596□—XX
典型值（2）极限值（3）
单位
只适用于输出可调节的情况，VFB=1.3V

LM2596全中文资料

LM2596 开关电压调节器LM2596开关电压调节器是降压型电源管理单片集成电路，能够输出3A的驱动电流，同时具有很好的线性和负载调节特性。

固定输出版本有3.3V、5V、12V，可调版本可以输出小于37V的各种电压。

该器件内部集成频率补偿和固定频率发生器，开关频率为150KHz，与低频开关调节器相比较，可以使用更小规格的滤波元件。

由于该器件只需4个外接元件，可以使用通用的标准电感，这更优化了LM2596的使用，极大地简化了开关电源电路的设计。

其封装形式包括标准的5脚TO-220封装（DIP）和5脚TO-263表贴封装（SMD）。

该器件还有其他一些特点：在特定的输入电压和输出负载的条件下，输出电压的误差可以保证在±4%的范围内，振荡频率误差在±15%的范围内；可以用仅80μA的待机电流，实现外部断电；具有自我保护电路（一个两级降频限流保护和一个在异常情况下断电的过温完全保护电路）特点※ 3.3V、5V、12V的固定电压输出和可调电压输出※可调输出电压范围1.2V～37V±4%※输出线性好且负载可调节※输出电流可高达3A※输入电压可高达40V※采用150KHz的内部振荡频率，属于第二代开关电压调节器，功耗小、效率高※低功耗待机模式，I Q的典型值为80μA※TTL断电能力※具有过热保护和限流保护功能※封装形式：TO-220（T）和TO-263（S）※外围电路简单，仅需4个外接元件，且使用容易购买的标准电感应用领域※高效率降压调节器※单片开关电压调节器※正、负电压转换器典型应用（固定输出）LM2596□-5.0管脚图极限参数名称范围单位最大电源电压 45 V脚输入电压-0.3～25 V“反馈”脚电压 -0.3～25 V到地的输出电压（静态） -1 V功耗由内部限定 --储存温度 -65～150℃静电释放（人体放电1） 2000 V气流焊（60秒） 215 ℃ TO-263红外线焊接（10秒） 245 ℃ 焊接时的管脚温度TO-220 波峰焊/电烙铁焊接（10秒）260℃最高结温 150 ℃温度范围 -40～125℃工作条件电源电压 4.5～40 V注1：人体放电模式相当于一个100PF 的电容通过一个1.5K 的电阻向每个管脚放电。

LM2596主回路

LM2596 开关电压调节器LM2596-ADJ 是3A 电流输出降压开关型集成稳压芯片，它内含固定频率振荡器（150KHZ ），和基准稳压器（1.23v ），并具有完善的保护电路：电流限制、热关断电路等。

利用该器件只需极少的外围器件便可构成高效稳压电路。

该器件还有其他一些特点：在特定的输入电压和输出负载的条件下，输出电压的误差可以保证在±4%的范围内，振荡频率误差在±15%的范围内；可以用仅 80μA 的待机电流，实现外部断电；具有自我保护电路（一个两级降频限流保护和一个在异常情况下断电的过温完全保护电路）可调输出调节器的设计步骤条件：VOUT 为可调节的输出电压，VIN （max ）为最大直流输入电压，ILOAD （max ）为最大负载电流，F=开关频率（为固定值 150KHz ）步骤：1．输出电压值的计算（即选择图 1中的 R1和 R2）利用以下的公式来选择适当的电阻值，V out= Vref ( +1 )这里的 VREF=1.23V ，在 240Ω和 1.5KΩ之间为 R1 选择一个适当的阻值。

低阻值使敏感的反馈脚的噪声容限降到最小（选用精度为 1%金属膜电阻，可以使温度系数降低，随时间的稳定度最好）。

R2 = R1 ( — 1 )2. 电感的选择（L1）A. 可以通过以下的公式计算电感电压与微秒的乘积 E·T其中 VSAT 为内部开关饱和电压，且 VSAT=1.16VVD 为二极管正向压降，VD=0.5V 。

B. 用前面公式中所得的 E·T 的值，从图 7的纵坐标上找一个相匹配的电感序号。

在横坐标上选一个最大的负载电流。

C. 由 E·T 值和最大的负载电流值的交叉处确定一个电感区域，每个区域都由一个电感值和一个电感序号（LXX ）表征。

D. 从图 8所列的 4个生产厂家的元件号中选一个适当的电感，最好使用磁屏蔽结构的电感器。

3. 输出电容的选择（COUT ）A. 在大多数的使用中，使用 82μF ～820μF 之间的低等效电阻（Low ESR ）的电解电容或固态钽电容效果最好，电容要靠近 IC ，管脚要短，连接的铜线要短。

lm2596中文资料

VIN=25V，VOUT =3V， ILOAD=3A
η
效率
VIN=25V，VOUT =15V，ILOAD=3A
电气特性（所有输出）
典型值（2）极限值（3）
单位
12.0
88 1.230
73 90
11.52/11.40 12.48/12.60
V V（min） V（max） %
1.193/1.180 1.267/1.280
2000
V
气流焊（60 秒）
215
℃
焊接时的管脚
TO-263
温度
红外线焊接（10 秒）
245
℃
TO-220
波峰焊/电烙铁焊接（10 秒）
260
℃
最高结温
150
℃
工作条件
温度范围电源电压
-40～125
℃
4.5～40
V
注 1：人体放电模式相当于一个 100PF 的电容通过一个 1.5K 的电阻向每个管脚放电。
电气特性
说明：标准字体对应的项目适合于 TJ=25℃时，带下划线的粗斜体字对应的项目适合于整个温度范围；系统参量(4) 测试电路见图 1
符号
参量
条件
典型值（2）
极限值（3）
单位
LM2596□—3.3 （见注 14）
VOUT
输出电压
3.3 4.75V≤VIN≤40V，
0.2A≤ILOAD≤3A
η
效率
A(max)
50
μA(max)
2 30
mA mA(max)
5 10
mA mA(max)
80
μA
200/250
μA(max) ˏ

LM2576-ADJ及其应用

单片式开关稳压器LM2576-ADJ及其应用摘要:利用单片式开关稳压器LM25762-ADJ 构成Buck 变换器,不稳定直流电压仍采用线性电源方法获得,输出直流电压既保持了线性电源宽范围连续可调的特点,又具有开关电源高效率的优点,电路简单,实用性强。

关键词:开关电源;开关稳压器1 引言开关电源以其体积小、重量轻、变换效率高被广泛应用于电子设备中。

其电路拓扑有多种形式,无工频变压器的开关电源最具吸引力,但这种电源只适用于输出电压固定或变化范围不大的场合,而不适和要求输出电压幅度变化很大或连续可调的场合。

利用单片式开关稳压器LM2576-ADJ 替代线性稳压器构成串联开关式稳压电源,在电路中只需增加续流二极管和储能电感等几只元器件,使电路更加简洁,除具有线性电源宽范围连续可调的优点外,同时使电源效率得到了大幅度提高,在负载较轻时,不加散热器也能正常工作,又使整机的重量和体积有所减少。

2 LM2576-ADJ 简介LM2576-ADJ 美国NS 公司生产的单片降压式开关稳压器,由振荡器、取样放大器、比较器、PWM 调制器、功率开关等部分组成。

采用TO-220 封装,仅有5只管脚,外形和塑封晶体管差不多。

其功能框图及引脚排列如图1、图2 所示。

图1 LM2576 功能框图图2 LM2576 引脚排列时间：2010-05-26 13:46:51 来源：电子设计信息网作者：杨智敏侯传教刘霞图3 LM2576-ADJ 典型应用电路3 LM2576-ADJ 构成单片开关电源3. 1 工作原理交流电经电源变压器隔离降压再经桥式整流滤波后,加到LM2576-ADJ 输入端1 脚。

稳压器控制端4 脚接于电位器W和电阻R 组成的分压电路上,改变W即可改变分压比,就能调节其输出电压大小。

Vo = UREF(1 +W/R) ,其中UREF为稳压器取样电路基准电压为1. 23V。

C1 输入端滤波电容, C2 、C3 输出端滤波电容如图4 所示。

lm2596-3.3 LM2596-ADJ LM2596-12 LV2596-3.3 中文资料

LM2596 开关电压调节器
LM2596 开关电压调节器是降压型电源管理单片集成电路，能够输出 3A 的驱动电流，同时具有很好的线性和负载调节特性。固定输出版本有 3.3V、5V、12V，可调版本可以输出小于 37V 的各种电压。
该器件内部集成频率补偿和固定频率发生器，开关频率为 150KHz，与低频开关调节器相比较，可以使用更小规格的滤波元件。由于该器件只需 4 个外接元件，可以使用通用的标准电感，这更优化了 LM2596 的使用，极大地简化了开关电源电路的设计。

５
TO-263 封装（S）尺寸图
单位：英寸/毫米
TO-220 封装（T）尺寸图
单位：英寸/毫米

６
设计步骤及实例
固定输出调节器的设计步骤
条件：VOUT=3.3（或 5 、或 12）V , VIN（max）为最大直流输入电压, ILOAD（max）为最大负载电流步骤： 1. 电感的选择（L1） A．要根据图 4、图 5 和图 6 所示的数据选择电感的适当值（分别对应输出电压为 3.3V、5V 和 12V），对于所有的
R1----1K，1%
D1----5A/40V IN5825 L1---68μH
CFF----参照有关的应用信息
图 1 标准测试电路
在开关调节器中，PCB 版面布局图非常重要，开关电流与环线电感密切相关，由这种环线电感所产生的暂态电压往往会引起许多问题。要使这种感应最小、地线形成回路，图中所示的粗线部分在 PCB 板上要印制得宽一点，且要尽可能地短。为了取得最好的效果，外接元器件要尽可能地靠近开关型集成电路，最好用地线屏蔽或单点接地。最好使用磁屏蔽结构的电感器，如果所用电感是磁芯开放式的，那么，对它的位置必须格外小心。如果电感通量和敏感的反馈线相交叉，则集成电路的地线及输出端的电容 COUT 的连线可能会引起一些问题。在输出可调的方案中，必须特别注意反馈电阻及其相关导线的位置。在物理上，一方面电阻要靠近 IC，另一方面相关的连线要远离电感，如果所用电感是磁芯开放式的，那么，这一点就显得更加重要。

lm2596中文资料

VFB
反馈电压
0.2A≤ILOAD≤3A
VOUT 调为 3V，电路图见图 1
η
效率
VIN=25V，VOUT =3V， ILOAD=3A
VIN=25V，VOUT =15V，ILOAD=3A
电气特性（所有输出）
典型值（2）极限值（3）
单位
12.0
88 1.230
73 90
11.52/11.40 12.48/12.60
特点
※ 3.3V、5V、12V 的固定电压输出和可调电压输出 ※ 可调输出电压范围 1.2V～37V±4% ※ 输出线性好且负载可调节 ※ 输出电流可高达 3A ※ 输入电压可高达 40V ※ 采用 150KHz 的内部振荡频率，属于第二代开关电压调节器，功耗小、效率高 ※ 低功耗待机模式，IQ 的典型值为 80μA ※ TTL 断电能力 ※ 具有过热保护和限流保护功能 ※ 封装形式：TO-220（T）和 TO-263（S） ※ 外围电路简单，仅需 4 个外接元件，且使用容易购买的标准电感
５
TO-263 封装（S）尺寸图
单位：英寸/毫米
TO-220 封装（T）尺寸图
单位：英寸/毫米
６
设计步骤及实例
固定输出调节器的设计步骤
条件：VOUT=3.3（或 5 、或 12）V , VIN（max）为最大直流输入电压, ILOAD（max）为最大负载电流步骤： 1. 电感的选择（L1） A．要根据图 4、图 5 和图 6 所示的数据选择电感的适当值（分别对应输出电压为 3.3V、5V 和 12V），对于所有的
符号
参量
器件参数
Ib
反馈偏置电流
fO
振荡器频率
VSAT

lm2596-3.3__LM2596-ADJ_LM2596-12_LV2596-3.3_中文资料

见注 9
5 10
mA mA(max)
ISTBY
待机静电流
ON/OFF 脚=5V（OFF）（9）
80
μA
200/250
μA(max)

３
符号
参量
条件
θJC
θJA
θJA
热阻
θJA
θJA
ON/OFF 控制（测试电路见图 1）
TO-220 或 TO-263 TO-263（10） TO-263（11） TO-263（12） TO-263（13）
V V(max)
最大工作周期（ON） DC
最小工作周期(OFF）
见注 7 见注 8
100
%
0
%
ICL
极限电流
峰值电流（6，7）
4.5 3.6/3.4
A A(min)
6.9/7.5
A(max)
输出为 0V（6，8）
50
μA(max)
IL
输出漏电流
输出为-1V（9）
2 30
mA mA(max)
IQ
静电流
特点
※ 3.3V、5V、12V 的固定电压输出和可调电压输出 ※ 可调输出电压范围 1.2V～37V±4% ※ 输出线性好且负载可调节 ※ 输出电流可高达 3A ※ 输入电压可高达 40V ※ 采用 150KHz 的内部振荡频率，属于第二代开关电压调节器，功耗小、效率高 ※ 低功耗待机模式，IQ 的典型值为 80μA ※ TTL 断电能力 ※ 具有过热保护和限流保护功能 ※ 封装形式：TO-220（T）和 TO-263（S） ※ 外围电路简单，仅需 4 个外接元件，且使用容易购买的标准电感
ON/OFF 脚逻辑输入

芯片lm2576-adj

引言开关电源以其体积小、重量轻、变换效率高被广泛应用于电子设备中。

2 LM2576-ADJ 简介LM2576-ADJ 美国NS 公司生产的单片降压式开关稳压器,由振荡器、取样放大器、比较器、PWM 调制器、功率开关等部分组成。

采用TO-220 封装,仅有5只管脚,外形和塑封晶体管差不多。

其功能框图及引脚排列如图1、图2 所示。

图1 LM2576 功能框图图2 LM2576 引脚排列LM2576-ADJ 是输出电压可调型,其技术参数为:输入电压3. 5～40V ;输出电压1. 23～37V ;输出电流3A ;振荡器固定频率52kHz ;TTL 关闭能力及低功率备用状态;具有热关闭和限流保护功能。

其典型应用电路如图 3 所示(输出电压连续可调) ,当直流输出端直接接于控制端 4 脚时,可输出固定电压。

LM2576系列产品是现流行的三端线性调整器的替代品。

图3 LM2576-ADJ 典型应用电路3 LM2576-ADJ 构成单片开关电源3. 1 工作原理交流电经电源变压器隔离降压再经桥式整流滤波后,加到LM2576-ADJ 输入端1 脚。

稳压器控制端4 脚接于电位器W和电阻R 组成的分压电路上,改变W即可改变分压比,就能调节其输出电压大小。

Vo = U REF(1 +W/R) ,其中U REF为稳压器取样电路基准电压为1. 23V。

C1输入端滤波电容, C2、C3输出端滤波电容如图4 所示。

降压型功率变换器LM2596的原理及应用

第十四届全国电源撞术年会论文集降压型功率变换器LM2596的原理及应用蒋玉萍中国运载火箭技术研究院(100076)摘要：本文介绍降压型功率变换器I．M2596的原理和应用。

叙词弋竖璺兰銮i姆开关电源ADJ。

LM2596控制芯片的工作频率为1501Cttz，其最大电流驱动I引言能力为3A，只需极少量的外围元件就可以实现辟压变换，大大LM7．596系列控制器是美国国家半导体公司推出的降压型开简化了小型开关电源的设计步骤，鳙短了开发周期。

关电源控制芯片，适用于简易高频降压变换器、扳上开关变换2特点和引脚说明器以及正负输出变换器。

该芯片具有四种不同的型号，输出电LM2596采用5脚TO一220(r)和5脚TO一263(s)封装，压分别为3．3v、5．OV、12V和可调输出四种，对应型号分别为：U心孵6T一3．3、删9耵一．5．0、u伫596T—12和U嘶T—如图I所示。

引坤50N，0FF引囊4Feed ma ck引朋3舒锄-d引箨201ln P at}胂l n_图l LM2596引脚封装2．1特点电压信号影响周围的敏感电路，线路板爱锕区需直接与该脚相LM2596系列控制芯片具有以下特点：连。

(1)具有四种不同的输出电压可供选择：3．3V、5．0V、(3)Gnxa,cl(引脚3)：信号地。

12V、可调：(4)Feedback(引脚4)：输出电压拉测端，构成反馈回路。

(2)可词输出电压范围为1．2v一37V±4％；(5)ON／OFF(引脚5)：通过该脚可以控制芯片的工作状(3)最大输出负载驱动电流3A；态。

当滚脚上的电压低于1．3V时，菩片进入工作状态；当该(4)输入电压最高可达40V；脚上的电压高于1．3v时(最高可达到25V)，芯片进人睡眠状(5)只需4个外国元件即可实现降压变换；态。

芯片进^睡眠状态后，所需供电电流仅为80,t工A。

如果该引(6)内置150Ⅺb定频振荡器；脚接地或悬空，则睡眠状态被屏蔽，芯片将始终处于工作状态。

LM2596TADJG中文资料

LM2596Product Preview3.0 A, Step-Down Switching RegulatorThe LM2596 regulator is monolithic integrated circuit ideally suited for easy and convenient design of a step−down switching regulator (buck converter). It is capable of driving a 3.0 A load with excellent line and load regulation. This device is available in adjustable output version and it is internally compensated to minimize the number of external components to simplify the power supply design.Since LM2596 converter is a switch−mode power supply, its efficiency is significantly higher in comparison with popular three−terminal linear regulators, especially with higher input voltages. The LM2596 operates at a switching frequency of 150 kHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Available in a standard 5−lead TO−220 package with several different lead bend options, and D2PAK surface mount package.The other features include a guaranteed $4% tolerance on output voltage within specified input voltages and output load conditions, and $15% on the oscillator frequency. External shutdown is included, featuring 80 m A (typical) standby current. Self protection features include switch cycle−by−cycle current limit for the output switch, as well as thermal shutdown for complete protection under fault conditions.Features•Adjustable Output Versions 1.23 V − 37 V •Guaranteed 3.0 A Output Load Current•Wide Input V oltage Range up to 40 V•150 kHz Fixed Frequency Internal Oscillator•TTL Shutdown Capability•Low Power Standby Mode, typ 80 m A•Thermal Shutdown and Current Limit Protection •Internal Loop Compensation•Moisture Sensitivity Level (MSL) Equals 1•Pb−Free Packages are AvailableApplications•Simple High−Efficiency Step−Down (Buck) Regulator •Efficient Pre−Regulator for Linear Regulators•On−Card Switching Regulators•Positive to Negative Converter (Buck−Boost)•Negative Step−Up Converters•Power Supply for Battery ChargersThis document contains information on a product under development. ON Semiconductor reserves the right to change or discontinue this product without notice.See detailed ordering and shipping information in the package dimensions section on page 11 of this data sheet.ORDERING INFORMATIONTO−220TV SUFFIXCASE 314BHeatsink surface connected to Pin 3TO−220T SUFFIXCASE 314DPin 1.V in2.Output3.Ground4.Feedback5.ON/OFFD2PAKD2T SUFFIXCASE 936A Heatsink surface (shown as terminal 6 incase outline drawing) is connected to Pin 35See general marking information in the device marking section on page 11 of this data sheet.DEVICE MARKING INFORMATIONFigure 1. Block Diagram and Typical Application8.0 V - 40 V Unregulated DC InputTypical Application (Adjustable Output Voltage Versions)Representative Block Diagram and Typical ApplicationMAXIMUM RATINGSRatingSymbol Value Unit Maximum Supply Voltage V in 45V ON/OFF Pin Input Voltage−−0.3 V ≤ V ≤ +V inV Output Voltage to Ground (Steady −State)−−1.0VPower DissipationCase 314B and 314D (TO −220, 5−Lead)P D Internally LimitedW Thermal Resistance, Junction −to −Ambient R q JA 65°C/W Thermal Resistance, Junction −to −Case R q JC 5.0°C/W Case 936A (D 2PAK)P D Internally LimitedW Thermal Resistance, Junction −to −Ambient R q JA 70°C/W Thermal Resistance, Junction −to −Case R q JC 5.0°C/W Storage Temperature RangeT stg −65 to +150°C Minimum ESD Rating (Human Body Model: C = 100 pF, R = 1.5 k W )− 2.0kV Lead Temperature (Soldering, 10 seconds)−260°C Maximum Junction TemperatureT J150°CStresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability.PIN FUNCTION DESCRIPTIONPin Symbol Description (Refer to Figure 1)1V in This pin is the positive input supply for the LM2596 step−down switching regulator. In order to minimize voltage tran-sients and to supply the switching currents needed by the regulator, a suitable input bypass capacitor must bepresent (C in in Figure 1).2Output This is the emitter of the internal switch. The saturation voltage V sat of this output switch is typically 1.5 V. It should be kept in mind that the PCB area connected to this pin should be kept to a minimum in order to minimize coupling tosensitive circuitry.3GND Circuit ground pin. See the information about the printed circuit board layout.4Feedback This pin is the direct input of the error amplifier and the resistor network R2, R1 is connected externally to allow pro-gramming of the output voltage.5ON/OFF It allows the switching regulator circuit to be shut down using logic level signals, thus dropping the total input supply current to approximately 80 m A. The threshold voltage is typically 1.4 V. Applying a voltage above this value (up to+V in) shuts the regulator off. If the voltage applied to this pin is lower than 1.4 V or if this pin is left open, the regulatorwill be in the “on” condition.OPERATING RATINGS (Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.)Rating Symbol Value Unit Operating Junction Temperature Range T J−40 to +125°C Supply Voltage V in 4.5 to 40VSYSTEM PARAMETERSELECTRICAL CHARACTERISTICS Specifications with standard type face are for T J = 25°C, and those with boldface type apply over full Operating Temperature Range −40°C to +125°CCharacteristics Symbol Min Typ Max Unit LM2596 (Note 1, Test Circuit Figure )Feedback Voltage (V in= 12 V, I Load = 0.5 A, V out = 5.0 V, )V FB 1.217 1.23 1.243VFeedback Voltage (8.0 V ≤ V in≤ 40 V, 0.5 A ≤ I Load≤ 3.0 A, V out = 5.0 V)V FB 1.1931.181.2671.28VEfficiency (V in= 12 V, I Load = 3.0 A, V out = 5.0 V)η−73−% Characteristics Symbol Min Typ Max Unit Feedback Bias Current (V out = 5.0 V)I b25100200nAOscillator Frequency( Note 2)f osc135120150165180kHzSaturation Voltage (I out = 3.0 A, Notes 3 and 4)V sat 1.5 1.82.0V Max Duty Cycle (ON) Note 4DC95%Current Limit (Peak Current Notes 2 and 3)I CL 4.23.55.6 6.97.5AOutput Leakage Current (Notes 5 and 6) Output = 0 VOutput = −1.0 V I L0.56.02.020mAQuiescent Current (Note 5)I Q 5.010mAStandby Quiescent Current (ON/OFF Pin = 5.0 V (“off”)) (Note 6)I stby50200250m AON/OFF PIN LOGIC INPUTThreshold Voltage 1.6VV out = 0 V (Regulator OFF)V IH 2.22.4VV out = Nominal Output Voltage (Regulator ON)V IL 1.00.8V ON/OFF Pin Input CurrentON/OFF Pin = 5.0 V (Regulator OFF)I IH−1530m A ON/OFF Pin = 0 V (regulator ON)I IL−0.01 5.0m A 1.External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.When the LM2596 is used as shown in the Figure 15test circuit, system performance will be as shown in system parameters section.2.The oscillator frequency reduces to approximately 30 kHz in the event of an output short or an overload which causes the regulated outputvoltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.3.No diode, inductor or capacitor connected to output pin.4.Feedback (Pin 4) removed from output and connected to 0 V.5.Feedback (Pin 4) removed from output and connected to +12 V to force the output transistor “off”.6.V in = 40 V.I Q , Q U I E S C E N T C U R R E N T (m A )V o u t , O U T P U T V O L T A G E C H A N G E (%)V o u t , O U T P U T V O L T A G E C H A N G E (%), S T A N D B Y Q U I E S C E N T C U R R E N T (T J , JUNCTION TEMPERATURE (°C)I O , O U T P U T C U R R E N T (A )T J , JUNCTION TEMPERATURE (°C)V in , INPUT VOLTAGE (V)V in , INPUT VOLTAGE (V)I N P U T - O U T P U T D I F F E R E N T I A L (V )T J , JUNCTION TEMPERATURE (°C)Figure 2. Normalized Output Voltage T J , JUNCTION TEMPERATURE (°C)Figure 3. Line RegulationFigure 4. Dropout Voltage Figure 5. Current LimitFigure 6. Quiescent Current Figure 7. Standby Quiescent CurrentμA )1.00.60.20-0.2-0.4-1.0 1.41.21.00.80.60.40.20-0.2-0.4-0.66.56.05.55.04.54.02018161412108.06.04.0-0.8-0.60.40.8I s t b yV s a t , S A T U R A T I O N V O L T A G E (V )2.02.53.04.0I b , F E E D B A C K P I N C U R R E N T (n A ), S T A N D B Y Q U I E S C E N T C U R R E N T (μA )I s t b y , I N P U T V O L T A G E (V )T J , JUNCTION TEMPERATURE (°C)SWITCH CURRENT (A)N O R M A L I Z E D F R E Q U E N C Y (%)T J , JUNCTION TEMPERATURE (°C)Figure 8. Standby Quiescent Current V in , INPUT VOLTAGE (V)Figure 9. Switch Saturation VoltageFigure 10. Oscillator FrequencyFigure 11. Minimum Operating VoltageFigure 12. Feedback Pin Current2001801401201008060402001.61.41.21.00.80.60.40.205.04.53.51.51.00.50-50T J , JUNCTION TEMPERATURE (°C)100806040200-20-40-60-80-100125100755025-25-50160V i n −9.0−8.0−7.0−6.0−5.0−4.0−3.0−2.0−1.00.01.0−2.0 A 00ABC 100 m s/DIV2 m s/DIVFigure 13. Switching WaveformsFigure 14. Load Transient ResponseVout = 15 VA: Output Pin Voltage, 10 V/DIV B: Inductor Current, 2.0 A/DIVC: Inductor Current, 2.0 A/DIV, AC −CoupledD: Output Ripple Voltage, 50 mV/dDIV, AC −Coupled Horizontal Time Base: 5.0 m s/DIV50 V 04.0 A 2.0 A 100 mV OutputVoltageChange03.0 A2.0 A 1.0 A4.0 A - 100 mVLoad CurrentDFigure 15. Typical Test CircuitAdjustable Output Voltage Versionsout ref R2R1ǓR2+R1ǒV out V ref 1.0ǓWhere V ref = 1.23 V, R1 between 1.0 k and 5.0 kPCB LAYOUT GUIDELINESAs in any switching regulator, the layout of the printed circuit board is very important. Rapidly switching currents associated with wiring inductance, stray capacitance and parasitic inductance of the printed circuit board traces can generate voltage transients which can generate electromagnetic interferences (EMI) and affect the desired operation. As indicated in the Figure 15, to minimize inductance and ground loops, the length of the leads indicated by heavy lines should be kept as short as possible.For best results, single −point grounding (as indicated) or ground plane construction should be used.On the other hand, the PCB area connected to the Pin 2(emitter of the internal switch) of the LM2596 should be kept to a minimum in order to minimize coupling to sensitive circuitry.Another sensitive part of the circuit is the feedback. It is important to keep the sensitive feedback wiring short. To assure this, physically locate the programming resistors near to the regulator, when using the adjustable version of the LM2596 regulator.DESIGN PROCEDUREBuck Converter BasicsThe LM2596 is a “Buck” or Step −Down Converter which is the most elementary forward −mode converter. Its basic schematic can be seen in Figure 16.The operation of this regulator topology has two distinct time periods. The first one occurs when the series switch is on, the input voltage is connected to the input of the inductor.The output of the inductor is the output voltage, and the rectifier (or catch diode) is reverse biased. During this period, since there is a constant voltage source connected across the inductor, the inductor current begins to linearly ramp upwards, as described by the following equation:I L(on)+ǒV IN *V OUT Ǔt onLDuring this “on” period, energy is stored within the core material in the form of magnetic flux. If the inductor is properly designed, there is sufficient energy stored to carry the requirements of the load during the “off” period.Figure 16. Basic Buck ConverterR LoadPower The next period is the “off” period of the power switch.When the power switch turns off, the voltage across the inductor reverses its polarity and is clamped at one diode voltage drop below ground by the catch diode. The current now flows through the catch diode thus maintaining the load current loop. This removes the stored energy from the inductor. The inductor current during this time is:I L(off)+ǒV OUT *V D Ǔt offLThis period ends when the power switch is once again turned on. Regulation of the converter is accomplished by varying the duty cycle of the power switch. It is possible to describe the duty cycle as follows:d +ton T, where T is the period of switching.For the buck converter with ideal components, the duty cycle can also be described as:d +V outV inFigure 17 shows the buck converter, idealized waveforms of the catch diode voltage and the inductor current.Figure 17. Buck Converter Idealized WaveformsPROCEDURE (ADJUSTABLE OUTPUT VERSION:LM2596)PROCEDURE (ADJUSTABLE OUTPUT VERSION:LM2596) (CONTINUED)ORDERING INFORMATIONDevicePackage Shipping †LM2596TADJG TO −220(Pb −Free)50 Units / Rail LM2596TVADJG TO −220 (F)(Pb −Free)50 Units / Rail LM2596DSADJG D 2PAK (Pb −Free)50 Units / Rail LM2596DSADJR4GD 2PAK (Pb −Free)2500 / Tape & Reel†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D.A = Assembly Location WL = Wafer Lot Y = YearWW = Work WeekG= Pb −Free PackageTO −220TV SUFFIX CASE 314B1MARKING DIAGRAMS5TO −220T SUFFIX CASE 314DD 2PAK D2T SUFFIX CASE 936ALM2596T −ADJ AWLYWWGLM2596T −ADJ AWLYWWGLM2596D2T −ADJ AWLYWWG1515LM2596−ADJ AWLYWWG 15TO −220TV SUFFIX CASE 314B −05ISSUE LM0.10 (0.254)PMT NOTES:1.DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.2.CONTROLLING DIMENSION: INCH.3.DIMENSION D DOES NOT INCLUDEINTERCONNECT BAR (DAMBAR) PROTRUSION.DIMENSION D INCLUDING PROTRUSION SHALL NOT EXCEED 0.043 (1.092) MAXIMUM.DIM MIN MAX MIN MAX MILLIMETERSINCHES A 0.5720.61314.52915.570B 0.3900.4159.90610.541C 0.1700.180 4.318 4.572D 0.0250.0380.6350.965E 0.0480.055 1.219 1.397F 0.8500.93521.59023.749G 0.067 BSC 1.702 BSC H 0.166 BSC 4.216 BSC J 0.0150.0250.3810.635K 0.900 1.10022.86027.940L 0.3200.3658.1289.271N 0.320 BSC 8.128 BSC Q 0.1400.153 3.556 3.886S ---0.620---15.748U 0.4680.50511.88812.827V ---0.735---18.669W0.0900.1102.286 2.794TO −220T SUFFIX CASE 314D −04ISSUE FMQM0.356 (0.014)T SEATING PLANEDIM MIN MAX MIN MAX MILLIMETERSINCHES A 0.5720.61314.52915.570B 0.3900.4159.90610.541C 0.1700.180 4.318 4.572D 0.0250.0380.6350.965E 0.0480.055 1.219 1.397G 0.067 BSC 1.702 BSC H 0.0870.112 2.210 2.845J 0.0150.0250.3810.635K 0.977 1.04524.81026.543L 0.3200.3658.1289.271Q 0.1400.153 3.556 3.886U0.1050.1172.667 2.972NOTES:1.DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.2.CONTROLLING DIMENSION: INCH.3.DIMENSION D DOES NOT INCLUDEINTERCONNECT BAR (DAMBAR) PROTRUSION.DIMENSION D INCLUDING PROTRUSION SHALL NOT EXCEED 10.92 (0.043) MAXIMUM.B10.3750.4159.52510.541DETAIL A −AD 2PAK D2T SUFFIX CASE 936A −02ISSUE C5 REF NOTES:1.DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982.2.CONTROLLING DIMENSION: INCH.3.TAB CONTOUR OPTIONAL WITHIN DIMENSIONS A AND K.4.DIMENSIONS U AND V ESTABLISH A MINIMUM MOUNTING SURFACE FOR TERMINAL 6.5.DIMENSIONS A AND B DO NOT INCLUDE MOLD FLASH OR GATE PROTRUSIONS. MOLD FLASH AND GATE PROTRUSIONS NOT TO EXCEED 0.025(0.635) MAXIMUM.DIM A MIN MAX MIN MAX MILLIMETERS 0.3860.4039.80410.236INCHES B 0.3560.3689.0429.347C 0.1700.180 4.318 4.572D 0.0260.0360.6600.914E 0.0450.055 1.143 1.397G 0.067 BSC 1.702 BSC H 0.5390.57913.69114.707K 0.050 REF 1.270 REF L 0.0000.0100.0000.254M 0.0880.102 2.235 2.591N 0.0180.0260.4570.660P 0.0580.0781.473 1.981R 5 REF S 0.116 REF 2.946 REF U 0.200 MIN 5.080 MIN V0.250 MIN6.350 MIN__SCALE 3:1ǒmm inchesǓ*For additional information on our Pb −Free strategy and solderingdetails, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D.ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. 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lm2596中文资料

lm2596中文资料1. 概述lm2596是一款高效率开关电源稳压器芯片，广泛应用于电子设备中对直流电压进行稳定调整的场合。

本文档将详细介绍lm2596的特性、工作原理、应用场景以及使用注意事项。

2. 特性•宽输入电压范围：4V-40V•可调输出电压范围：1.23V-37V•高效率：可达到92%•最大输出电流：3A•过热保护功能3. 工作原理lm2596采用了开关稳压器的工作原理，通过周期性地开关和断开电流流通路径，将输入电压转换为稳定的输出电压。

其主要原理如下：1.输入电压通过电感和开关管传导到输出端，同时电容储存能量。

2.控制器检测输出电压，如果低于设定值，则控制开关管开启，使电流通过电感传输到输出端，提供稳定的输出电压。

3.如果输出电压高于设定值，则控制开关管关闭，切断电流流动。

这种周期性的开关和断开电路，可以通过控制开关管的开启时间和关闭时间，来调整输出电压的稳定性和精确度。

4. 应用场景lm2596广泛应用于各种需要稳定直流电压的场合，以下是lm2596常见的应用场景：4.1 电子设备稳压电源lm2596可以根据需要调整输出电压，可以在电子设备中作为稳压电源芯片使用。

它可以将输入电压调整为稳定的输出电压，以供电子设备正常运行。

4.2 LED照明由于lm2596具有高效率和可调输出电压的特性，非常适合用于LED照明应用。

lm2596可以将输入电压调整为适合LED灯的电压，提供稳定的电源以驱动LED照明。

4.3 高频电源lm2596的高效率和宽输入电压范围，使其非常适合用于高频电源应用。

lm2596可以将输入电压转换为稳定的高频输出，满足高频电源的需求。

5. 使用注意事项在使用lm2596时，请注意以下事项：1.输入电压不要超过40V，否则可能导致芯片过载损坏。

2.充分考虑散热问题，尽量避免芯片过热，建议在芯片周围预留散热空间。

3.在使用lm2596时，应按照芯片的使用说明进行正确的电路设计和连接。

LM2596开关电压调节

2.0
V(min)
5
μA
15
μA(max)
0.02
μA
5
μA(max)
注 2：典型值是指在 25℃下的数值，代表最常见的情况。注 3：所有的极限参数都必须适合于室温（用正常字体表示）和极限温度（用带下划线的粗斜体字表示），所有室
温下的极限参数都是经过测试得出的，所有的极限温度下的极限参数都可以通过使用相关的标准静态质量控制方法来加以保证。注 4：二极管、电感、输入和输出端的电容以及调节输出电压的电阻等外接元件可能会影响开关调节器的系统性能。当 LM2596 用在如图 1 所示测试电路中时，其系统性能如电气特性中系统参量所示。注 5：当第二级电流极限功能启动时，开关频率会有所下降，下降的程度取决于过电流的严重程度。注 6：输出管脚不连接电感、电容或二极管。注 7：把反馈管脚和输出管脚断开，把反馈管脚连到 0V，以强制输出开关晶体管导通。注 8：把反馈管脚和输出管脚断开，把反馈管脚连到 12V（当 VOUT=3.3V、5V 或 ADJ 时）或 15V（当 VOUT=12V 时），以强制输出开关晶体管截止。注 9：VIN=40V 注 10：环境热阻（不外加散热片）是指 TO-220 封装的 LM2596 垂直焊接在覆盖有面积约为 1 平方英寸铜箔的 PCB 上所对应的值。注 11：TO-263 封装的 LM2596 垂直焊接在覆盖有面积约为 0.5 平方英寸铜箔的单面 PCB 上所对应的环境热阻。注 12：TO-263 封装的 LM2596 垂直焊接在覆盖有面积约为 2.5 平方英寸铜箔的单面 PCB 上所对应的环境热阻。注 13：TO-263 封装的 LM2596 垂直焊接在覆盖有面积约为 3 平方英寸铜箔的双面 PCB 上所对应的环境热阻，而 PCB 的另一面覆盖有面积约为 16 平方英寸铜箔。注14： LM2596T-3.3, LM2596T-5.0, LM2596T-12， LM2596T-ADJ为TO-220封装（DIP）； LM2596S-3.3, LM2596S-5.0,LM2596S-12， LM2596S-ADJ为TO-263封装（SMT）。

中文资料 LM2596电源降压调整器

LM2596电源降压调整器（150KHz，3A）英文文章名：LM2596 SIMPLE SWITCHER® Power Converter 150 kHz3A Step-Down Voltage Regulator文章出处：版本号：DS012583 日期：2002年5月摘录人：黄明强摘录日期：2007年5月3日是否好买估计：生产中心正在使用价格：概述：LM2596系列开关电压调节器是降压型电源管理单片集成电路，能够输出3A的驱动电流，同时具有很好的线性和负载调节特性。

固定输出版本有3.3V、5V、12V，还有一个输出可调版本。

添加少量的外部元件就可以使用该电压调节器。

该器件内部集成有频率补偿和固定频率发生器。

开关频率为150KHz，与低频开关调节器相比较，可以使用更小规格的滤波元件。

其封装形式包括标准的5脚TO-220封装和5脚TO-263表贴封装。

由于该器件可以使用通用的标准电感，这更优化了LM2596的使用，极大地简化了开关电源电路的设计。

该器件还有其他一些特点：在特定的输入电压和输出负载的条件下，输出电压的误差可以保证在±4%的范围内，振荡频率误差在±15%的范围内；可以用仅80μA的待机电流，实现外部断电；具有自我保护电路（一个两级降频限流保护和一个在异常情况下断电的过温完全保护电路）。

特征：※ 3.3V、5V、12V的固定电压输出和可调电压输出※可调输出电压范围1.2V～37V，±4%※封装形式：TO-220（T）和TO-263（S）※保证输出负载电流3A※输入电压可高达40V※仅需4个外接元件※很好的线性和负载调节特性※150KHz固定频率的内部振荡器※TTL关断能力※低功耗待机模式，I Q的典型值为80μA※高转换效率※使用容易购买的标准电感※具有过热保护和限流保护功能应用：※简易高效率降压调节器※在卡上的开关电压调节器※正到负电压转换器专利号：5382918典型电路（固定输出电压版本）：封装和型号：※弯曲交叉的引脚，通孔封装，5脚TO-220 (T)订货型号：LM2596T-3.3, LM2596T-5.0,LM2596T-12 or LM2596T-ADJ ※表面贴封装，5脚TO-263 (S)订货型号：LM2596S-3.3, LM2596S-5.0, LM2596S-12 or LM2596S-ADJ 极限条件：最大供电电压45VON /OFF 管脚输入电压-0.3≤V≤+25V反馈脚电压-0.3≤V≤+25V输出电压到地（稳态）-1V功率消耗内部限定储存温度-65°C 到+150°CESD易感性（人体模式）2KV焊接温度T封装(锡焊, 10秒) +260°C最大结温+150°C运行条件：温度范围－40°C≤T J≤+125°C供电电压 4.5V 到40VLM2596-3.3电参数说明：标准字体对应的项目适合于TJ=25℃时，粗体字对应的项目适合于全温度范围LM2596-5.0电参数说明：标准字体对应的项目适合于TJ=25℃时，粗体字对应的项目适合于全温度范围LM2596-12电参数所有输出电压版本电参数说明：标准字体对应的项目适合于TJ=25℃时，带下划线的粗斜体字对应的项目适合于整个温度范围。

lm2596-3.3 LM2596-ADJ LM2596-12 LV2596-3.3 中文资料

LM2596S-ADJ程控电压源

LM2596S-ADJ程控电压源⽅案1计算过程：流过电阻R3的电流I3 ，流过电阻R2的电流I2 ，流过电阻R1的电流I1FB引脚反馈电压VFB，单⽚机DAC输出电压VG，⼆极管压降VD,通过下⾯推导：I3=(VG-VD-VFB)/R3I2=(VOUT-VFB)/R2I1=VFB/R1VD为⼆极管导通电压0.4V VFB=1.23(VG-1.23-0.4)/R3+(VOUT-1.23)/R2=1.23/R1(VG-1.63)/R3+(VOUT-1.23)/R2=1.23/R1VG<=1.63V时，I3=0,VOUT=1.23*(1+R2/R1)=23.78VVG>1.63V时，VOUT=1.23*(1+R2/R1)-(VG-1.63)*R2/R3VG=3.25V时输出最⼩ VOUT=23.78-35.64/R3=23.78-23.78=0V所以可以实现0-23.78V可调输出电压计算公式:VOUT=1.23*(1+R2/R1)-(VG-1.63)*R2/R3按图中参数,如果程控电压变化1mV输出电压变化等于 22K/1.5K * 1mV =14.667 mV对程控电压的精度要求较⾼⽅案2这⾥的反馈回路串⼊了⼀个运放，该运放组成⼀个⽐较电路，把电阻R1、R2的分压反馈信号与设定电压Vset进⾏⽐较，然后运放输出的调整电压通过⼀个⼆极管反馈到LM2596的FB脚。

由于反馈信号加在运放的同相输⼊端，到达FB引脚的反馈信号极性没有改变，在整体来看还是负反馈，所以输出电压同样可以稳定。

再根据运放的虚短虚断，运放的输⼊电压V+ = V- ，也就是说输出电压：Vout = Vset(1+R2/R1)。

相对于图1，输出电压公式中芯⽚内部的Vref变成了外部可控的Vset，相当于把芯⽚的内部基准电压移到了外部，通过DAC可以很⽅便地调节Vset。

电路中运放电源加⼊了-5V负电压，⽬的是使运放可以输出达到Vref(1.235V)+ VD1(0.7V)左右，使得输出电压可以稳定，D1和R5是为了确保不让运放输出的负电压反馈⾄FB引脚。

lm2596(中文)

η
效率
VIN=12V，ILOAD=3A
80
3.168/3.135 3.432/3.465
V V（min） V（max） %
4.800/4.750 5.200/5.250
V V（min） V（max） %
２
电子发烧友电子技术论坛
４
电子发烧友电子技术论坛
LM2596 开关电压调节器 SEPTEMBER， 2004
测试电路及其布线方案（固定输出）
注：反馈线要远离电感，电路中的粗线一定要短，最好用地线屏蔽。
CIN---470μF/50V COUT----220μF/25V D1----5A/40V IN5825 L1---68μH，L38
VLOGIC=2.5V（调节器关） VLOGIC=0.5V（调节器开）
LM2596□—XX
典型值（2）极限值（3）
单位
2
℃/W
50
℃/W
50
℃/W
30
℃/W
20
℃/W
1.3
V
0.6
V(max)
ቤተ መጻሕፍቲ ባይዱ
2.0
V(min)
5
μA
15
μA(max)
0.02
μA
5
μA(max)
注 2：典型值是指在 25℃下的数值，代表最常见的情况。注 3：所有的极限参数都必须适合于室温（用正常字体表示）和极限温度（用带下划线的粗斜体字表示），所有室
LM2596 开关电压调节器 SEPTEMBER， 2004
符号
参量
条件
LM2596□—12 （见注 14）
VOUT
输出电压
15V≤VIN≤40V， 0.2A≤ILOAD≤3A

基于LM2596-ADJ-DCDC稳压器的高效率恒流稳压电源设计

基于LM2596-ADJ DC/DC稳压器的高效率恒流稳压电源设计开关恒流稳压电源LED DC/DC当前全球能源紧缺日益加剧，制约着经济的发展，节能成为人类面临的重要课题。

在照明领域，被称为第4 代照明光源或绿色光源的LED 照明产品以节能、环保、寿命长、体积小、坚固耐用等特点吸引着世人的目光。

由于LED 的伏安特性呈现非线性且伏安特性具有负温度系数的特点，以及生产工艺和生产水平的差异，不同生产厂家生产的同样功率等级的大功率LED 伏安特性存在差异，即使是同一厂家生产的同一批次的LED，个体间的正向压降也存在一定差异等原因，为了减少LED 的光衰，延长LED 的使用寿命，LED 的驱动电源采用低压直流恒流电源。

目前，安森美、TI 等世界知名半导体器件公司均推出了适合LED 驱动的DC/DC 专用恒流控制集成电路，如NCP3066、TPS40211DG 等，该类集成电路具有较高的转换效率，但该类集成电路价格相对较高，市面上不易购买。

针对该问题，本文阐述了基于市面常用的DC/DC 开关稳压器的恒流稳压电源的通用设计方法，并给出相关设计实例以及相关测试数据。

1 基于DC/DC 稳压器的恒流稳压电源设计DC/DC 开关稳压器自问世以来，广泛应用于各种电子设备中，用作恒压源，当负载电流在额定范围内变化时，其输出电压保持不变。

DC/DC 开关稳压器的原理框图如图1 所示。

图1 DC/DC 开关稳压器原理框图DC/DC 开关稳压器输出电压：其中Vref为DC/DC 开关稳压器内部自带的基准电压或者用户外接的基准电压，R1、R2构成输出电压采样电路，用于设置输出电压的大小。

当输出电压Vout因负载变化而变化时，反馈电压Vf也随着变化，DC/DC 稳压器内部的控制电路根据反馈电压Vf（采样电压）与Vref差值的大小来适当调整功率变换电路的控制参数（如PWM 的占空比等），使输出电压稳定在一个固定的值，达到稳压的目的。

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LM2596 SIMPLE SWITCHER Power Converter 150 kHz 3A Step-Down Voltage Regulator
May 2002
LM2596
SIMPLE SWITCHER® Power Converter 150 kHz
3A Step-Down Voltage Regulator
© 2002 National Semiconductor Corporation DS012583

LM2596
Connection Diagrams and Ordering Information
Bent and Staggered Leads, Through Hole Package
5-Lead TO-220 (T)
Surface Mount Package 5-Lead TO-263 (S)
01258302
Order Number LM2596T-3.3, LM2596T-5.0, LM2596T-12 or LM2596T-ADJ See NS Package Number T05D
Symbol
Parameter
Conditions
LM2596-5.0
Typ
Limit
(Note 3)
(Note 4)
Units (Limits)
SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1
VOUT
Output Voltage
7V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A
Symbol
Parameter
Conditions
LM2596-12
Typ (Note 3)
Limit (Note 4)
Units (Limits)
SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1
VOUT
Output Voltage
15V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A
Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation†, and a fixed-frequency oscillator.
Features
n 3.3V, 5V, 12V, and adjustable output versions n Adjustable version output voltage range, 1.2V to 37V
±4% max over line and load conditions n Available in TO-220 and TO-263 packages n Guaranteed 3A output load current n Input voltage range up to 40V n Requires only 4 external components n Excellent line and load regulation specifications n 150 kHz fixed frequency internal oscillator n TTL shutdown capability n Low power standby mode, IQ typically 80 µA n High efficiency n Uses readily available standard inductors n Thermal shutdown and current limit protection
Other features include a guaranteed ±4% tolerance on output voltage under specified input voltage and output load conditions, and ±15% on the oscillator frequency. External shutdown is included, featuring typically 80 µA standby current. Self protection features include a two stage frequency reducing current limit for the output switch and an over temperature shutdown for complete protection under fault conditions.
3.3
V
3.168/3.135
V(min)
3.432/3.465
V(max)
η
Efficiency
VIN = 12V, ILOAD = 3A
73
%
LM2596-5.0 Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Temperature Range
2 kV
+215˚C +245˚C +260˚C +150˚C
Operating Conditions
Temperature Range Supply Voltage
−40˚C ≤ TJ ≤ +125˚C 4.5V to 40V
LM2596-3.3 Electrical Characteristics
5.0
V
4.800/4.750
V(min)
5.200/5.250
V(max)
η
Efficiency
VIN = 12V, ILOAD = 3A
80
%
LM2596-12 Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Temperature Range
General Description
The LM2596 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 3A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, and an adjustable output version.
The LM2596 series operates at a switching frequency of 150 kHz thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Available in a standard 5-lead TO-220 package with several different lead bend options, and a 5-lead TO-263 surface mount package.
Maximum Supply Voltage ON /OFF Pin Input Voltage Feedback Pin Voltage Output Voltage to Ground
(Steady State) Power Dissipation Storage Temperature Range ESD Susceptibility
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Temperature Range
Symbol
Parameter
Conditions
45V −0.3 ≤ V ≤ +25V −0.3 ≤ V ≤+25V
−1V Internally limited −65˚C to +150˚C
Human Body Model (Note 2) Lead Temperature S Package
Vapor Phase (60 sec.) Infrared (10 sec.) T Package (Soldering, 10 sec.) Maximum Junction Temperature
01258303
Order Number LM2596S-3.3, LM2596S-5.0, LM2596S-12 or LM2596S-ADJ See NS Package Number TS5B

2
LM2596
Absolute Maximum Ratings (Note 1)
Typical Application (Fixed Output Voltage