A8498资料
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Package: 8-Lead SOIC with exposed thermal pad (suffix LJ)
Description
The A8498 is a step down regulator that will handle a wide input operating voltage range. The A8498 is supplied in a low-profile 8-lead SOIC with exposed pad (package LJ). Applications include: ▪ Applications with 8 to 50 V input voltage range needing
Wide Input Voltage 3.0 A Step Down Regulator
Functional Description
The A8498 is a fixed off-time, current-mode–controlled buck switching regulator. The regulator requires an external clamping diode, inductor, and filter capacitor, and operates in both continuous and discontinuous modes. An internal blanking circuit is used to filter out transients resulting from the reverse recovery of the external clamp diode. Typical blanking time is 200 ns.
Part Numbera
Packingb
A8498SLJTR-T
13 in. reel, 3000 pieces/reel
A8498SLJ-T
98 pieces/tube
aLeadframe plating 100% matte tin. bContact Allegro for additional packing options.
TJTSD
Temperature increasing
–
Thermal Shutdown Hysteresis
TJTSD(hys) Recovery = TJTSD – TJTSD(hys)
–
1Negative current is defined as coming out of (sourcing) the specified device pin. 2Specifications over the junction temperature range of 0ºC to 125ºC are assured by design and characterization.
R2 2 k7
VOUT 3.3 V / 3 A
ESR
COUT 220 μF 25 V
Efficiency %
90.0 88.0 86.0 84.0 82.0 80.0 78.0 76.0 74.0 72.0 70.0
0
Efficiency vs. Output Current
VOUT (V) 5 3.3
Package Thermal Characteristics*
Package
RθJA (°C/W)
PCB
LJ
35
4-layer
* Additional information is available on the Allegro website.
Ordering Information Use the following complete part numbers when ordering:
Load Supply Voltage, VIN pin
VIN
–
–
50
V
Input Voltage, VBIAS pin
VBIAS
–0.3
–
7
V
Switching Voltage
VS
–1
–
–
V
Input Voltage Range, ENB pin
VENB
Operating Ambient Temperature Range
tss
5
Buck Switch Current Limit
ICL
VFB > 0.4 V VFB < 0.4 V
3.5 0.5
ENB Open Circuit Voltage
VOC
Output disabled
2.0
ENB Input Voltage Threshold
VENB(0) LOW level input (Logic 0), output enabled
Characteristics
Symbol
Test Conditions
Min.
VENB = LOW, VIN = 42 V, VBIAS = 3.2 V, VFB = 1.5 V (not switching)
–
VIN Quiescent Current
IVIN(Q)
VENB = LOW, VIN = 42 V, VBIAS < 3 V, VFB = 1.5 V
元器件交易网
A8498
Wide Input Voltage 3.0 A Step Down Regulator
Functional Block Diagram
BOOT VIN
ENB μC
TSET
GND VBB UVLO TSD
Boot Charge
–
ENB Input Current
IENB(0)
VENB = 0 V
–10
VIN Undervoltage Threshold
VUVLO
VIN rising
6.6
VIN Undervoltage Hysteresis
VUVLO(hys) VIN falling
0.7
Thermal Shutdown Temperature
–
+
Switch Disable
Switch PWM Control
+
I_Peak
Clamp
–
I_Demand
–
Error
COMP
+
VIN
LX L1
D1
VOUT ESR COUT
FB
Bias Supply
VBIAS
VBIAS is connected to VOUT
when VOUT target is between 3.3 and 5 V
500 1000 1500 2000 2500 3000 IOUT (mA)
Circuit for 42 V step down to 3.3 V at 3 A. Efficiency data from circuit shown in left panel. Data is for reference only.
–
VENB = HIGH
–
VBIAS Input Current
IBIAS
VBIAS = VOUT
–
Buck Switch On Resistance
RDS(on)
TA = 25°C, IOUT = 3 A TA = 125°C, IOUT = 3 A
– –
Fixed Off-Time Proportion
Approximate Scale 1:1
CBOOT 0.01 μF
BOOT
VIN
ENB
LX
A8498
RTSET 63.4 k7
TSET GND
VBIAS FB D1
Typical Application
+42 V
CIN2 220 μF
50 V
CIN1 0.22 μF
L1 68 μH
R1 6.34 k7
Based on calculated value
–15
Feedback Voltage
VFB
0.784
Output Voltage Regulation
VOUT
IOUT = 0 mA to 3 A
–3
Feedback Input Bias Current
IFB
–400
Soft Start Time
voltage protection ▪ 12 V lighter-powered applications (portable DVD, etc.) ▪ Point of Sale (POS) applications ▪ Industrial applications with 24 or 36 V bus
Description
LJ package, SOIC surface mount with exposed thermal pad
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Typ.
0.90
4.4
– 3.5 450 650 – 0.8 – –100 10 – – – – – 6.9 – 165 15
Max.
1.35
6.35
100 5 – – 15
0.816 3
100 15 5 1.2 7 1.0 –1 7.2 1.1 – –
Units
mA
mA
μA mA mΩ mΩ % V % nA ms A A V V μA V V °C °C
Allegro MicroSystems, Inc.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
元器件交易网
A8498
buck regulator for 3.0 A output current ▪ Consumer equipment power ▪ Uninterruptible power supplies (lead acid battery
charger) ▪ Automotive telematics: 9 to 16 V input, with higher
A8498-DS, Rev. 2
元器件交易网
A8498
Wide InRegulator
Absolute Maximum Ratings
Characteristic
Symbol
Conditions
Min.
Typ.
Max. Units
TA
–20
–
85
°C
Junction Temperature
TJ(max)
–
–
150
°C
Storage Temperature
TS
–55
–
150
°C
*Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current ratings, or a junction temperature, TJ, of 150°C.
元器件交易网
A8498
Wide Input Voltage 3.0 A Step Down Regulator
ELECTRICAL CHARACTERISTICS1,2 at TA = 25°C, VIN = 8 to 50 V (unless noted otherwise)
Soft Start Ramp Generation
0.8 V
Allegro MicroSystems, Inc.
3
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
元器件交易网
A8498
Wide Input Voltage 3.0 A Step Down Regulator
Features and Benefits
▪ 8 to 50 V input range ▪ Integrated DMOS switch ▪ Adjustable fixed off-time ▪ Highly efficient ▪ Adjustable 0.8 to 24 V output
Description
The A8498 is a step down regulator that will handle a wide input operating voltage range. The A8498 is supplied in a low-profile 8-lead SOIC with exposed pad (package LJ). Applications include: ▪ Applications with 8 to 50 V input voltage range needing
Wide Input Voltage 3.0 A Step Down Regulator
Functional Description
The A8498 is a fixed off-time, current-mode–controlled buck switching regulator. The regulator requires an external clamping diode, inductor, and filter capacitor, and operates in both continuous and discontinuous modes. An internal blanking circuit is used to filter out transients resulting from the reverse recovery of the external clamp diode. Typical blanking time is 200 ns.
Part Numbera
Packingb
A8498SLJTR-T
13 in. reel, 3000 pieces/reel
A8498SLJ-T
98 pieces/tube
aLeadframe plating 100% matte tin. bContact Allegro for additional packing options.
TJTSD
Temperature increasing
–
Thermal Shutdown Hysteresis
TJTSD(hys) Recovery = TJTSD – TJTSD(hys)
–
1Negative current is defined as coming out of (sourcing) the specified device pin. 2Specifications over the junction temperature range of 0ºC to 125ºC are assured by design and characterization.
R2 2 k7
VOUT 3.3 V / 3 A
ESR
COUT 220 μF 25 V
Efficiency %
90.0 88.0 86.0 84.0 82.0 80.0 78.0 76.0 74.0 72.0 70.0
0
Efficiency vs. Output Current
VOUT (V) 5 3.3
Package Thermal Characteristics*
Package
RθJA (°C/W)
PCB
LJ
35
4-layer
* Additional information is available on the Allegro website.
Ordering Information Use the following complete part numbers when ordering:
Load Supply Voltage, VIN pin
VIN
–
–
50
V
Input Voltage, VBIAS pin
VBIAS
–0.3
–
7
V
Switching Voltage
VS
–1
–
–
V
Input Voltage Range, ENB pin
VENB
Operating Ambient Temperature Range
tss
5
Buck Switch Current Limit
ICL
VFB > 0.4 V VFB < 0.4 V
3.5 0.5
ENB Open Circuit Voltage
VOC
Output disabled
2.0
ENB Input Voltage Threshold
VENB(0) LOW level input (Logic 0), output enabled
Characteristics
Symbol
Test Conditions
Min.
VENB = LOW, VIN = 42 V, VBIAS = 3.2 V, VFB = 1.5 V (not switching)
–
VIN Quiescent Current
IVIN(Q)
VENB = LOW, VIN = 42 V, VBIAS < 3 V, VFB = 1.5 V
元器件交易网
A8498
Wide Input Voltage 3.0 A Step Down Regulator
Functional Block Diagram
BOOT VIN
ENB μC
TSET
GND VBB UVLO TSD
Boot Charge
–
ENB Input Current
IENB(0)
VENB = 0 V
–10
VIN Undervoltage Threshold
VUVLO
VIN rising
6.6
VIN Undervoltage Hysteresis
VUVLO(hys) VIN falling
0.7
Thermal Shutdown Temperature
–
+
Switch Disable
Switch PWM Control
+
I_Peak
Clamp
–
I_Demand
–
Error
COMP
+
VIN
LX L1
D1
VOUT ESR COUT
FB
Bias Supply
VBIAS
VBIAS is connected to VOUT
when VOUT target is between 3.3 and 5 V
500 1000 1500 2000 2500 3000 IOUT (mA)
Circuit for 42 V step down to 3.3 V at 3 A. Efficiency data from circuit shown in left panel. Data is for reference only.
–
VENB = HIGH
–
VBIAS Input Current
IBIAS
VBIAS = VOUT
–
Buck Switch On Resistance
RDS(on)
TA = 25°C, IOUT = 3 A TA = 125°C, IOUT = 3 A
– –
Fixed Off-Time Proportion
Approximate Scale 1:1
CBOOT 0.01 μF
BOOT
VIN
ENB
LX
A8498
RTSET 63.4 k7
TSET GND
VBIAS FB D1
Typical Application
+42 V
CIN2 220 μF
50 V
CIN1 0.22 μF
L1 68 μH
R1 6.34 k7
Based on calculated value
–15
Feedback Voltage
VFB
0.784
Output Voltage Regulation
VOUT
IOUT = 0 mA to 3 A
–3
Feedback Input Bias Current
IFB
–400
Soft Start Time
voltage protection ▪ 12 V lighter-powered applications (portable DVD, etc.) ▪ Point of Sale (POS) applications ▪ Industrial applications with 24 or 36 V bus
Description
LJ package, SOIC surface mount with exposed thermal pad
Allegro MicroSystems, Inc.
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Typ.
0.90
4.4
– 3.5 450 650 – 0.8 – –100 10 – – – – – 6.9 – 165 15
Max.
1.35
6.35
100 5 – – 15
0.816 3
100 15 5 1.2 7 1.0 –1 7.2 1.1 – –
Units
mA
mA
μA mA mΩ mΩ % V % nA ms A A V V μA V V °C °C
Allegro MicroSystems, Inc.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
元器件交易网
A8498
buck regulator for 3.0 A output current ▪ Consumer equipment power ▪ Uninterruptible power supplies (lead acid battery
charger) ▪ Automotive telematics: 9 to 16 V input, with higher
A8498-DS, Rev. 2
元器件交易网
A8498
Wide InRegulator
Absolute Maximum Ratings
Characteristic
Symbol
Conditions
Min.
Typ.
Max. Units
TA
–20
–
85
°C
Junction Temperature
TJ(max)
–
–
150
°C
Storage Temperature
TS
–55
–
150
°C
*Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current ratings, or a junction temperature, TJ, of 150°C.
元器件交易网
A8498
Wide Input Voltage 3.0 A Step Down Regulator
ELECTRICAL CHARACTERISTICS1,2 at TA = 25°C, VIN = 8 to 50 V (unless noted otherwise)
Soft Start Ramp Generation
0.8 V
Allegro MicroSystems, Inc.
3
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
元器件交易网
A8498
Wide Input Voltage 3.0 A Step Down Regulator
Features and Benefits
▪ 8 to 50 V input range ▪ Integrated DMOS switch ▪ Adjustable fixed off-time ▪ Highly efficient ▪ Adjustable 0.8 to 24 V output