UM0613 Datasheet, PDF (1/11 Pages) STMicroelectronics – Dual DC-DC converter for powering an AMOLED display

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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November 2010
Doc ID 15186 Rev 1
1/11
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