L4957A
Up to 5A ULDO linear regulator
General features
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■
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1.5V, 1.8V, 2.5V and 3.3V fixed output voltage
3V to 14V input voltage range
3
1
200mΩ R
DS(on)
typical @ t
J
= 125°C
■
0.6V max. drop-out at 2A
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■
■
■
Excellent load regulation
0.6mA quiescent current at any load
Short circuit protection
Thermal shutdown
D
2
PAK
Description
Applications
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The L4957AD devices are
Ultra Low Drop Output
linear regulators with an internal N-channel
MOSFET of 200mΩ particulary suitable for low
voltage/low dropout applications.
Operating with a input voltage from 3V to 14V
they are capable to deliver up to 5A.
Mother boards
Processor I/O & supplies
Low voltage memory & chip set supplies
Graphic & sound cards
Low voltage logic supplies
Post regulator for SMPS
so
codes
Order
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The devices are ideal for use as one of the
suppliesrequired by processor, for example they
are the cost effective and efficient solution for
conversion from 3.3V (rail bus) to 2.5V @ 2.5A or
to 1.5V with high current rating.
Fast response transient minimise the output
capacitor value. A minimum of 22µF assures the
stability in all load conditions.
The on-chip trimming technique offers a tighter
voltage reference tolerance (with ± 2% including
line and load variation) beside to ensure a
controlled short circuit current. Thermal shutdown
provides protection against overload conditions
that creates excessive junction temperature
.
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Part number
Tube
L4957AD1.5
L4957AD1.8
L4957AD2.5
L4957AD3.3
Tape and Reel
L4957AD1.5TR
L4957AD1.8TR
L4957AD2.5TR
L4957AD3.3TR
Rev 6
1/12
www.st.com
12
April 2006
Contents
L4957A
Contents
1
2
Block diagram and typical application . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1
2.2
Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1
3.2
Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4
5
6
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
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Pin description
L4957A
2
2.1
Pin description
Pin connection
Figure 3.
Pin connection
(top view)
3
2
1
GND
OUT
IN
D98IN933A
D
2
PAK
2.2
Pin description
Table 1. Pin description
Name
1
2
3
Pin N°
IN
GND
OUT
Description
Unregulated input voltage; this pin must be bypassed with a capacitor larger
than 10µF.
To connect to Ground to get 1.5V, 1.8V, 2.5V or 3.3V output.
Regulated output voltage. A minimum bypass capacitor of 22µF is required to
insure stability.
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