MP1484互换的同步降压型DC-DC稳压器MXT2484

ABSOLUTE MAXIMUM RATINGS (1)

Supply Voltage (VIN).......................-0.3V to 26V Switch Voltage (VSW)............. –1V to VIN + 0.3V Bootstrap Voltage (VBS) ...Vsw-0.3V to VSW + 6V Enable/UVLO Voltage (VEN)...........–0.3V to +6V Comp Voltage (VCOMP) ...................–0.3V to +6V Feedback Voltage (VFB) ................–0.3V to +6V Junction Temperature ........................... +150°C Lead Temperature ................................. +260°C Storage Temperature.............. –55°C to +150°C

Recommended Operating Conditions(2)

Input Voltage (VIN) ......................... 4.75V to 23V Output Voltage (VSW) ....................... 0.925 to 20V Operating Temperature...............–20°C to +85°C Thermal Resistance(3) θJA θJC

SOIC8N ................................ 50...... 10... °C/W

Notes:

1) Exceeding these ratings may damage the device. 2) The device is not guaranteed to function outside of its operating conditions.

3) Measured on approximately 1” square of 1 oz copper.

3A, 23V, 340 – 450 kHz Synchronous Rectified Step-Down Converter

DESCRIPTION

The MXT2484SX is a monolithic synchronous buck regulator. The device integrates 100m Ω MOSFETS that provide 3A continuous load cur-rent over a wide operating input voltage of 4.75V to 23V. Current mode control provides fast transient response and cycle-by-cycle cur-rent limit. An adjustable soft-start prevents inrush current at turn-on. In shutdown mode, the supply cur-rent drops below 1μA. This device, available in an 8-pin SOIC pack-age, provides a very compact system solution with minimal reliance on external components.

FEATURES

• 3A Output Current

• Wide 4.75V to 23V Operating Input Range • Integrated 100m Ω Power MOSFET Switches • Output Adjustable from 0.925V to 20V • Up to 95% Efficiency • Programmable Soft-Start • Stable with Low ESR Ceramic Output Capacitors • Fixed 340KHz Frequency

• Cycle-by-Cycle Over Current Protection • Input Under Voltage Lockout • Thermally Enhanced 8-Pin SOIC Package APPLICATIONS

• Distributed Power Systems • Networking Systems • FPGA, DSP, ASIC Power Supplies • Green Electronics/ Appliances

• Notebook Computers

MXT2484SX MXT2484SX

ELECTRICAL CHARACTERISTICS

V IN = 12V, T A = +25°C, unless otherwise noted.

Parameter

Condition

Min

Typ Max Units Shutdown Supply Current V EN ≤ 0.3V

0.3 3.0 µA Supply Current V EN ≥ 2.6V, V FB =

1.0V

1.4 1.5 mA Feedback Voltage

4.75V ≤ V IN ≤ 23V

900

925 950

mV Feedback Over voltage Threshold 1.1 V Error Amplifier Voltage

480 V/V Error Amplifier Tran conductance ΔI C = ±10μA

800 µA/V High-Side Switch-On Resistance 100 m Ω Low-Side Switch-On Resistance

100

m Ω High-Side Switch Leakage V EN = 0V, V SW = 0V

9 10 µA Upper Switch Current Limit 4.0 6.5 A Lower Switch Current Limit

0.9

A COMP to Current Sense Transconduc-tance 5.2 А/V 300

340

380

KHz

Oscillator Frequency MXT2484SXA

MXT2484SXB

400 405 500 KHz

110 KHz Short Circuit Frequency MXT2484SXA MXT2484SXB V FB = 0V

150 KHz Maximum Duty Cycle V FB = 0.8V

90

% Minimum On Time

220 nS EN Shutdown Threshold Voltage V EN Rising

1.1 1.3 1.5 V EN Shutdown Threshold Voltage Hysterics

200 mV EN Lockout Threshold Voltage 2.2

2.5 2.7

V EN Lockout Hysterics

210

mV Input UVLO Threshold Rising V IN Rising

3.80

4.05 4.40

V Input UVLO Threshold Hysteretic

210 mV Soft-start Current V SS = 0V 12 µA Soft-start Period C SS = 0.1μF

10 ms Thermal Shutdown 4

160

°C

MXT2484SX