Detailed description

STP2CMP

10/23

DocID022734 Rev 2

5

Detailed description

The STP2CMP is a charge-pump-based 2-channel LED driver designed for mobile phone

display backlighting, using constant current topology. Each of the 2 channels can be

controlled independently. When ONx is pulled high, a constant current is sunk into the

LEDx pin when one LED is connected. This constant current is defined or programmed by

5.1

Enable pin (EN)

The active high enable input pin is used to shut down the whole device. When this pin is

pulled low, the device enters into shutdown mode with only 5 µA max. current

consumption. An internal pull-d

own of 300 kΩ is present on this pin.

5.2

LED turn-on pin (ONx)

When the EN pin is pulled high, the STP2CMP provides the flexibility to control the turning

on/off on the 2 channels independently through the 2 active high ON pins. To control the

brightness of each LED channel, it is possible to drive the selected ON pin with a PWM

is present on these pins.

5.3

Programmable output current

The LED currents at the 2 channels are programmed individually through a resistor

5.4

Charge pump

The STP2CMP charge pump can be disabled or enabled according to the CP_SEL pin.

When enabled (CP_SEL is high), the charge pump provides a clamping voltage of typ. 5.0

V to ensure enough headroom to drive the LEDs. An internal pull-

down of 300 kΩ is

present on this pin. The charge pump can be disabled by pulling low the CP_SEL pin,

< 3.1 V so that the charge pump maintains the regulation at 5 V, the total current drawn

5.5

Thermal protection

The thermal protection circuit ensures device shutdown when it is overheated (for example,

due to an output short-circuit) to typ. 150 °C.The device resumes normal operation when

the temperature drops by 15 °C from the thermal shutdown threshold.