400mA/200mA Dual 3.3V Smart
Power Switch
PRELIMINARY - October 9, 2000
SC1543
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1543 provides a glitch free 3.3V output when
one of two 3.3V input sources is present. It does not
require external logic to sequence from one input
source to the other. Whenever VIN1 exceeds a
predetermined threshold value the internal MOSFET
connects it鈥檚 source voltage to the output. If the input at
VIN1 is below the threshold another internal MOSFET
connects VIN2 to the output. If both inputs are at 3.3V
then VIN1 will be connected to the output.
The SC1543 is designed to provide 400mA from the
main input (VIN1) and 200mA from the secondary input
(VIN2). A very low quiescent current of 10碌A(chǔ) in
shutdown mode reduces power dissipation.
The internal logic and control circuit detects the voltage
levels of VIN1 and VIN2, and compares them to an
input reference voltage of 2.9V. An internally controlled
period of switch overlap ensures that the transition
between supplies is as glitch-free as possible.
The SC1543 is available in an MSOP-8 surface mount
package.
FEATURES
鈥?
鈥?
鈥?
鈥?
鈥?
Glitch free transitions between inputs
Internal logic selects appropriate input
400mA load current capability from main input
Low power shutdown mode
Industrial temperature range
APPLICATIONS
鈥?
Mini PCI cards
鈥?
Peripheral cards
鈥?
Instantly available personal computers (IAPCs)
ORDERING INFORMATION
Part Number
(1)
Package
MSOP-8
SC1543IMSTR
Note:
(1) Only available in tape and reel packaging. A reel
contains 2500 devices.
APPLICATION CIRCUIT
SHUTDOWN
U1
3.3V IN
1
2
3
3.3VAUX IN
4
VIN1
VIN1
VIN2
VIN2
SC1543
CIN1
1uF
CIN2
1uF
COUT
10uF
SHDN
VOUT
VOUT
GND
8
7
6
5
3.3V OUT
1
漏 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
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