
L4955
5A ULDO LINEAR REGULATORS FAMILY
UP TO 5A OUTPUT CURRENT
±
2% PRECISEOUTPUT VOLTAGES
FASTTRANSIENT RESPONSE
0.75V TYP. DROP OUT VOLTAGEAT 5A
OPERATINGINPUT VOLTAGEFROM 4.5V
ADJUSTABLE VERSION:
V
O
= 1.26V
INHIBIT (I
Q
= 120
μ
A TYP.)
POWERGOOD
PROGRAMMABLECURRENT LIMIT
HEPTAWATT PACKAGE
FIXED VERSION:
3.3V,5.1V OUTPUTS
VERSAWATTPACKAGE
VERYLOW QUIESCENT CURRENT
SHORT CIRCUIT PROTECTION (Foldback
function)
THERMALSHUTDOWN
APPLICATIONS
PENTIUM
ANDPOWER PC
SUPPLIES
POSTREGULATOR FOR SMPS
LOW COST SOLUTION FOR 5V TO 3.3V
CONVERSION
LOW COST BATTERYCHARGER
CONSTANT CURRENT REGULATOR
SUITABLE
FOR
STANDBY FEATURE
APPLICATION
WITH
DESCRIPTION
The L4955 is a family of monolithicultra very low
drop linear regulators designed to supply the
most recent microprocessors.
The dropout voltageis only0.75V (Typ.) at 5A, di-
rectly dependenton the output current conditions.
Realized in BCDII technology, it has on board a
charge pump to properly drive an N-channel
power mos Transistor with 150m
of R
DSON
.
It operates from a 4.5V minimum supply, with a
very low quiescent current irrespective of the
load; a minimum of 22
μ
F output capacitor is re-
quired for stability.
The on-chip trimming techniques improve the pre-
cisionof the available outputvoltages to
±
2%.
Ancillary functions like power good, inhibit with
low power consumption, programmable output
voltage and current limiting make the flexible
heptawatt version usable in applications where
power management, stand-by, features, post
regulation and adjustable current generators for
batterychargers are important.
February 1999
TYPICALAPPLICATIONS
HEPTAWATT
VERSAWATT
(TO-220)
MULTIPOWER BCD TECHNOLOGY
ORDERING
NUMBERS
L4955
L4955V3.3
L4955V5.1
OUTPUT
VOLTAGE
1.26V ADJ
3.3V
5.1V
PACKAGE
HEPTAWATT
VERSAWATT
VERSAWATT
L4955
CL
GND
ADJ
OUT
IN
INH
PG
7
5
2
4
6
3
1
C1
V
IN
R1
R2
C2
V
OUT
D97IN589
L4955VXXX
GND
OUT
IN
3
2
1
C1
V
IN
C2
V
OUT
D97IN590
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