LOW VOLTAGE/ BOOST DC-DC CONTROLLER - Semtech Corporation
Description
LOW VOLTAGE, BOOST DC-DC CONTROLLER
August 22, 2000
SC1408
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.
semtech.
com
DESCRIPTION
The SC1408 is a low voltage boost controller that operates from a 1.
8V to 16.
5V input range.
A shutdown pin allows the user to turn the controller off reducing supply current to less than 2µA typical.
Output voltage can be preset to 5V or is adjustable from 3V to 16.
5V with a resistor divider.
The controller changes frequency in low load conditions to improve efficiency.
The SC1408 was designed for two cell Alkaline or single cell Lithium Ion battery applications.
With the proper external components it can be used as a boost converter or a buck/boost converter.
A current sense is implemented with an external resistor that is not in the load current path.
The SC1408 operates in “bootstrapped” mode.
When the input voltage to the device is less than 2.
5V during startup, a low voltage 50% fixed duty cycle oscillator is switched in to initiate boost action.
FEATURES •= 1.
8V to 16.
5V input range •= Up to 10W output power •= Preset 5V or adjustable output •= Up to 300kHz switching frequency •= 10µA max shutdown current •= Industrial temperature range •= SO-8 or MSOP-8 package APPLICATIONS •= PDA Power supplies •= Battery powered applications •= Positive LCD Bias generator •= Portable communications (cellular phones) •= Peripheral card supplies •= Industrial power supplies ORDERING INFORMATION
Part Number
(1)
Package SO-8 MSOP-8
Temp.
Range (TA) -40° to +85°C
SC1408IS.
TR SC1408IMS.
TR
Note: (1) Only available in tape and reel packaging.
A reel contains 2500 devices.
TYPICAL APPLICATION - BOOST CONFIGURATION
Vin (1.
8V to 16.
5V)
L1
D1
Vout (3V to 16.
5V)
U1 2 4 + 5 C2 7
BST GATE
Q1 1 8
R3
SHDN ISENSE REF GND FB AGND
+ 3 6 R2 R4
C3
SC1408IS C5
1 © 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
LOW VOLTAGE, BOOST DC-DC CONTROLLER
August 22, 2000
SC1408
ABSOLUTE MAXIMUM RATINGS
Parameter Input Voltage Small Signal G...
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