CAT4137

Features:

` Drives up to 5 White LEDs from 3V
` Power Efficiency up to 87%
` Low Quiescent Ground Current 0.1mA
` Adjustable Output Current (up to 30mA)
` High Frequency 1MHz Operation
` "Zero" current shutdown mode
` Operates down to 2V (from two AA batteries)
` Soft start power-up
` Open LED low power mode
` Automatic shutdown at 1.9V (UVLO)
` Thermal shutdown protection
` Thin SOT23 5-Lead (1mm max height)


Application

· LCD Backlighting
· Cellular Phones
· Handheld Devices
· Digital Cameras


Pinout




Specifications

Parameter	Rating	Unit
VIN, FB voltage	-0.3 to +7	V
SHDN* voltage	-0.3 to +7	V
SW voltage	-0.3 to 40	V
Storage Temperature Range	-65 to +160	°C
Junction Temperature Range	-40 to +125	°C
Lead Temperature	300	°C

Description

The CAT4137 is a DC/DC step-up converter that delivers a regulated output current. Operation at a constant switching frequency of 1MHz allows the device to be used with small value external ceramic capacitors and inductor.

CAT4137 drives a string of white LEDs connected in series and provides the regulated current to control the LEDs with inherent uniform brightness and matching. An external resistor R1 sets the output current and allows up to 30mA current to be supported over a wide range of input supply voltages from 2.2V to 5.5V, making the device ideal for battery-powered applications.

LED dimming can be done by using a DC voltage, a logic signal, or a pulse width modulation (PWM) signal. The shutdown control pin allows CAT4137 to be placed in power-down mode with "zero" quiescent current.

In addition to thermal protection and overload current limiting, the device also enters a very low power operating mode during "Open LED" fault conditions. CAT4137 is housed in a low profile (1mm max height) 5-lead thin SOT23 package for space critical applications.