500mA SmartLDO With Power Up
Signal Sequencing
PRELIMINARY - January 17, 2000
TM
SC1545
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1545 was designed for instantly available moth-
erboard applications. As part of the Semtech family of
SmartLDO’s it provides additional control functions not
available in a standard LDO.
The device provides the capability to control three sep-
arate supplies. There is an on-board 500mA, 2.5V
LDO with current limit protection, and drive pins for an
N-channel MOSFET and a P-channel MOSFET. Inter-
nal logic circuitry ensures that the system starts up in a
controlled manner, and that the correct outputs are en-
abled during specific sequences of BF_CUT and SLP.
The LDO draws its power from the 5V standby supply,
and the N-channel MOSFET drive is derived from the
12V supply.
The SC1545 is available in the surface mount SO-8
package.
FEATURES
•
•
•
500mA LDO with Over Current Protection (OCP)
±2.5% LDO regulation over line, load and
temperature
Power sequencing for three supplies
APPLICATIONS
•
•
•
Instantly available motherboards
Embedded systems
Desktop computers
ORDERING INFORMATION
Part Number
SC1545CS
(1)
Package
SO-8
Note:
(1) Add suffix ‘TR’ for tape and reel packaging.
TYPICAL APPLICATION CIRCUIT
2.5V IN
Q1
2.5V OUT
Si4410
C1
2 x 100uF
C2
100uF
3.3V IN
Q2
3.3V OUT
IRLMS6802
C3
2 x 100uF
C4
100uF
U1
1
2.5V OUT
2
3
4
C5
10uF
VO
GND
PDR
NDR
SC1545
5VSTBY
12VIN
BF_CUT
SLP
8
7
6
5
C6
1uF
C7
0.1uF
5V STANDBY
12V IN
BF_CUT
SLP
1
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
SEMTECH [ SEMTECH CORPORATION ]
