AMOLED Power Supply Use Case: AMOLED Smartphone Displays

USE CASE

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Active-matrix organic light-emitting diode (AMOLED) displays are becoming increasingly popular in smartphones, thanks to the vivid contrasts in graphics. Smartphones with AMOLED displays are a hit with consumers, who enjoy the resulting high contrast ratio and wide viewing angles.

The use of the MP5611 in AMOLED smartphone displays can provide a number of benefits, including reduced size and complexity of the power supply, improved power efficiency, improved image quality, and longer battery life.

Compared to their predecessors, AMOLED displays also have higher power consumption rates . From a design perspective, maximizing efficiency has meant rethinking how the power rails are used, as AMOLED displays use multiple power rails. It is important to regulate the different voltages for each rail to maintain proper operation.

Multiple separate buck converters are traditionally used to regulate power rails. This approach takes up valuable space and results in efficiency losses for each buck converter. Another challenge is sufficiently regulating the different power rails. Failing to regulate the power rails can result in distortions and poor overall image quality.

The use of the MP5611 in AMOLED smartphone displays can provide a number of benefits, including reduced size and complexity of the power supply, improved power efficiency, improved image quality, and longer battery life. Its solution is elegant: the MP5611 integrates a boost converter for the positive driving voltage to the electroluminescent (EL) (ELVDD ), an inverting buck-boost (IBB) converter for the negative driving voltage to the EL (ELVSS ), and another boost converter for the output to the display driver IC (AVDD) into a single package. The single-wire digital control pin (CTRL) can configure the ELVSS, ELVDD, and AVDD voltages following digital protocol, which reduces the overall size and complexity of the power supply.

In addition, the MP5611 AMOLED power supply features power-saving features that further reduce the power consumption of AMOLED smartphone displays. This includes a soft start (SS) feature to gradually ramp up the converter’s output voltage (VOUT), which reduces the inrush current. An active fast discharge function helps to quickly discharge the output capacitors (COUT) when the converter is turned off. The MP5611 also provides a cycle-by-cycle current limit that protects the converter from over-current (OC) conditions that can damage the AMOLED display. Under-voltage lockout (UVLO) prevents the converter from operating if the input voltage (VIN) drops below a certain level.

Additional features include:

• 2.9V to 5.2V Input Voltage (V_IN) Range
• Triple Output (AVDD, ELVDD, ELVSS)
• High Accuracy for Output Voltage (V_OUT)
• Good Line and Load Regulation
• 4.6V to 5.2V Configurable ELVDD Voltage (V_ELVDD), Default 4.6V
• -1.4V to -6.4V Configurable EVLSS Voltage (V_ELVSS), Default -4V
• 500mA Output Current (I_OUT) for ELVDD and ELVSS
• 5V to 7.7V Configurable AVDD Voltage (V_AVDD), Default 5.8V
• 100mA I_OUT for AVDD
• Respective Enable for AVDD and ELVDD
• AVDD Output Over-Current Protection (OCP) (90mA to 270mA)
• ELVDD Output OCP (80mA to 650mA)
• Output Short to Ground Protection
• Over-Temperature Protection (OTP)
• Available in a TQFN-16 (3mmx3mm) Package

The MP5611 is a versatile and powerful triple-output converter that can be used to address the issue of power consumption in AMOLED smartphones. For more information, explore MPS’s wide selection of display power and control solutions.