STP4CMP: Quad LED Driver Solution with Charge Pump

ST’s STP4CMP is a charge pump-based quad LED driver designed for RGB lighting or LCD Display backlighting. It supports LEDs with a forward voltage of up to 3.8V, an operating voltage of 2.7V~5.5V, four currents can be programmed individually, the maximum current is 30mA, the output current accuracy is ±7%, and the current matching between channels is within ±4%. Mainly used in mobile phone Display backlight and RGB LED indicator driver.

The STP4CMP is a charge pump based on a 4-channel LED driver (for RGB lighting or LCD backlighting). The STP4CMP is powered by a battery with an input voltage of 2.7V~5.5V. The device generates a regulated current sink with high channel-to-channel accuracy that can drive up to 4 LEDs. It supports LED forward voltage up to 3.8V, and the current sink for each channel can be set by 4 independent external resistors. Each channel is independently controlled. PWM control can be used directly on the 4 EN (switch) pins to provide brightness control. When enabled, this charge pump (with a small ceramic bucket capacitor between C1P and C1N) starts working, controlling VOUT with a clamp voltage.

Figure 1 STP4CMP block diagram

Figure 2 STP4CMP application block diagram

Main features of STP4CMP

• Operating voltage range: VCC(OPR)=2.7V~5.5V

• Full RGB function support

• 4-channel LED driver with separate ON/OFF control from input pins

• 4 channels individually programmable output current through 4 external resistors, max 30mA

• Maximum absolute output current accuracy ±7% and channel-to-channel, maximum mismatch ±4%

• Selectable charge pump on/off

•Thermal Protection

• Small QFN20 (1.8mm×3.2mm) package for STP4CMP application

• Mobile phone display backlight

• RGB LED indicator driver

Figure 3 STP4CMP evaluation board circuit diagram

STEVAL-TLL012V1 Demo Board

The STEVAL-TLL012V1 demo board demonstrates the performance of STP4CMP, a 4-channel LED driver based charge pump for RGB lighting or LCD backlighting. Using a battery with an input voltage of 2.7V to 5.5V, the device generates a regulated current sink with high channel-to-channel accuracy and can drive up to 4 LEDs. The device can support LEDs with forward voltages up to 3.8V. The current sink for each channel can be programmed using 4 independent external resistors. Each channel is independently controlled. PWM control that can be applied directly to the 4 EN (switch) inputs to provide brightness control.

Table 1 Application circuit external components

STEVAL-TLL012V1 Demo Board Main Features

• Operating voltage range: 2.7V~5.5V

• Full RGB function support

• Individual ON/OFF control of 4-channel LED driver and input pins

• 4 channels individually programmable output current (via 4 external resistors), 30mA max

• Absolute output current accuracy ±7%; maximum channel-to-channel mismatch ±4%

• Selectable charge pump on, off

•Thermal Protection

• RoHS Compliant