CS5257A-1
CS5257A-1
7 LDO 5-Pin Adjustable Linear Regulator
A
Description
This new very low dropout regula-
tor is designed to power the next
generation of advanced micropro-
cessors. To achieve very low
dropout, the internal pass transistor
is powered separately from the con-
trol circuitry. Furthermore, with the
control and power inputs tied
together, this device can be used in
single supply configuration and
still offer a better dropout voltage
than conventional PNP-NPN based
LDO regulators. In this mode the
dropout is determined by the mini-
mum control voltage.
It is supplied in five-terminal
TO-220 and D
2
PAK packages,
allowing for the implementation of
a remote-sense pin permitting very
accurate regulation of output volt-
age directly at the load, where it
counts, rather than at the regulator.
This remote sensing feature virtual-
ly eliminates output voltage varia-
tions due to load changes and resis-
tive voltage drops. Typical load
regulation measured at the sense
pin is 1mV for an output voltage of
2.5V with a load step of 10mA to
7A.
The very fast transient loop
response easily meets the needs of
the latest microprocessors. In addi-
tion, a small capacitor on the Adjust
pin will further improve the tran-
sient capabilities.
Internal protection circuitry pro-
vides for Òbust-proofÓ operation,
similar to three-terminal regulators.
This circuitry, which includes over-
current, short circuit, supply
sequencing and overtemperature
protection will self protect the regu-
lator under all fault conditions.
The CS5257A-1 is ideal for generat-
ing a secondary 2-2.5V low voltage
supply on a motherboard where
both 5V and 3.3V are already avail-
able.
Features
s
1.25V to 5V V
OUT
at 7A
s
V
POWER
Dropout < 0.35V @ 7A
s
V
CONTROL
Dropout < 1.10V @
7A
s
1.5% Trimmed Reference
s
Fast Transient Response
s
Remote Voltage Sensing
s
Thermal Shutdown
s
Current Limit
s
Short Circuit Protection
s
Drop-In Replacement for
LT1580
s
Backwards Compatible with
3-pin Regulators
Package Options
5 Lead D
2
PAK
5 Lead TO-220
Applications Diagram
5.0V
V
CONTROL
V
OUT
2.5V @ 7A
1
CS5257A-1
3.3V
V
POWER
V
SENSE
Adjust
100mF
5V
0.1mF
5V
124
1%
124 Load
1%
300mF
5V
1. V
SENSE
1
2. Adjust
3. V
OUT
4. V
CONTROL
5. V
POWER
Tab = V
OUT
10mF
10V
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
Rev. 4/5/99
1
A
¨
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
