STMicroelectronics Inductor Switch Boost Controller, 37V Output, 20mA PWM

STLD40D is a boost converter that operates from 3.0 V to 5.5 V. It can provide an output voltage as high as 37 V and can drive up to 10 white LEDs in series. The converter is a PFM (pulse frequency modulation) inductor switch that can work in discontinuous (DCM) mode operation. A minimum OFF time of the embedded boost switch TSWis fixed internally and allows limiting the switching frequency. The output current capability is 20 mA with an output voltage of 37 V. The regulation is done by sensing the LED current through the resistor RLED. The device can be turned ON/OFF through the logic enable signal pin EN. By applying a low frequency PWM signal the LEDs can be dimmed. The maximum Peak inductor current can be programmed by connected a resistor RSETto the pin RSET.

• Inductor switches boost controller
• PFM mode control
• High efficiency over wide range of input voltage from 3.0 V to 5.5 V
• Over voltage protection with automatic restart
• Adjustable Peak current limit
• Enable pin with possibility of PWM dimming control
• Low shutdown current < 1 μA
• Small external component
• Good load and line regulation
• QFN8 3 x 3 mm
• Applications
• White LED supply for LCD backlight
• Mobile phone
• PDA and organizers
• Any handsets powered form 3.0 V to 5.5 V