Boost regulator with integrated 3A switch for LED backlight strings
The Texas Instruments TPS61500PWPR is a current-mode step-up (boost) DC-DC regulator designed to drive LED backlight strings in LCD panels. It integrates a 3A switch, supports both analog and PWM dimming, and delivers a regulated output from 2.9V up to 38V from a supply input as low as 2.9V.
Switching frequency range and inductor sizing
The oscillator can be programmed from 200 kHz to 2.2 MHz via a single resistor. A higher frequency shrinks the inductor footprint but increases switching losses and may push the EMI peak above 1 MHz for CISPR 22 compliance. For a typical 10-LED string at 100 mA, a 22 µH inductor at 600 kHz balances efficiency and board area. The 3A switch current rating sets the practical output power ceiling. At 24 V output and 85% efficiency, the converter can deliver roughly 6 W continuous before the switch current limit is reached, which covers most medium-size LCD backlight applications.
Dimming options: analog and PWM
Both analog (DC voltage on the ADIM pin) and PWM dimming are supported. PWM dimming achieves a wider contrast ratio because the LED current is switched at full amplitude, while analog dimming avoids audible noise from the PWM frequency coupling into the output capacitor.