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The L4977A is a stepdown monolithic power switching regulator delivering 7A at a voltage variable from 5.1 to 40V.
Realized with BCD mixed technology, the device uses a DMOSoutput transistor to obtain very high efficiency and very fast switching times. Features of the L4977A include reset and power fail for microprocessors,feed forward line regulation, soft start, limiting current and thermal protection. The device is mounted in a 15-lead multiwatt plastic power package and requires few external components. Efficient operation at switching frequencies up to 500KHz allows reduction in the size and cost of external filter components.
L4977A Maximum Ratings
Symbol
Parameter
Value
Unit
V9
Input Voltage
55
V
V9
Input Operating Voltage
50
V
V7
Output DC Voltage Output Peak Voltage at t = 0.1s f = 200KHz
-1 -7
V
I7
Maximum Output Current
Internally Limited
V6
Bootstrap Voltage Bootstrap Operating Voltage
65 V9 + 15
V V
V3,V12
Input Voltage at Pins 3, 12
12
V
V4
Reset Output Voltage
50
V
I4
Reset Output Sink Current
50
mA
V5,V10,V11,V13
Input Voltage at Pin 5, 10, 11, 13
7
V
I5
Reset Delay Sink Current
30
mA
I10
Error Amplifier Output Sink Current
1
A
I12
Soft Start Sink Current
30
mA
Ptot
Total Power Dissipation at Tcase < 120
30
W
Tj, Tstg
Junction and Storage Temperature
-40 to 150
L4977A Features
· 7A OUTPUT CURRENT · 5.1V TO 40V OUTPUT VOLTAGE RANGE · 0 TO 90% DUTY CYCLE RANGE · INTERNAL FEED-FORWARD LINE REGULATION · INTERNAL CURRENT LIMITING · PRECISE 5.1V ± 2% ON CHIP REFERENCE · RESETAND POWER FAIL FUNCTIONS · SOFT START · INPUT/OUTPUT SYNC PIN · UNDER VOLTAGE LOCK OUT WITH HYSTERETIC TURN-ON · PWM LATCH FOR SINGLE PULSE PER PERIOD · VERY HIGH EFFICIENCY · SWITCHING FREQUENCY UP TO 500KHz · THERMAL SHUTDOWN · CONTINUOUS MODE OPERATION