November 2010

Doc ID 15186 Rev 1

1/11

UM0613

User manual

Dual DC-DC converter for powering an AMOLED display

based on the STOD02

Introduction

The STOD02 demonstration board is dedicated to showing the performance of the STOD02

dual DC-DC device, which is used to power AMOLED displays up to 3.0" with an input

voltage range from 2.5 to 4.5 V.

It integrates a step-up and inverting DC-DC converter, able to deliver the positive and

negative voltages needed for the AMOLED panel to operate. Due to the high switching

frequency and to the full integration of the synchronous switches, the STOD02 needs very

few and small external components, therefore reducing the BOM cost and the PCB area.

At the same time, this small size solution does not penalize the overall performance:

efficiency stays above 85 % in the most used range of output current and input voltage while

very good line and load transients allow the maintaining of a stable output voltage when the

input voltage changes rapidly due to series resistance of the battery.

The STOD02 works in pulse-skipping mode during low load condition and in PWM mode (at

1.6 MHz) for medium/high load conditions. The Enable pin allows the turning off of the

device, therefore reducing the current consumption to less that 1 µA. The negative output

voltage can be programmed by an MCU through a dedicated pin which implements S-wire

protocol. Soft-start with controlled inrush current limit and thermal shutdown are integrated

functions of the device.

Figure 1.

Typical application schematic

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