New DC/DC converter to power AMOLED display drivers

The step-up converter circuit compares a built-in reference voltage of 1.0V to the FBP voltage (accuracy ±1.5%) and a positive output voltage can be set freely with the external components up to 18V. The inverting DC/DC converter compares the difference between the reference voltage and the FBN voltage (accuracy ±1.5%) to GND, then a negative output voltage can be set up to -15V with the external components.

Operating from an input voltage between 2.7V ~ 5.5V the XC9519 utilises a 1.2MHz switching frequency allowing the use of small inductors and ceramic capacitors, it operates in either fixed frequency PWM mode or with automatic PFM/PWM control to maximise efficiency during light loads. The choice of control method is user programmable via the MODE pin and the soft start and current control functions are internally optimized.

During stand-by, all circuits in the IC are shutdown to reduce current consumption to as low as 1.0μA or  less. The XC9519 also includes a gate control pin for use with an external P-channel MOSFET to implement a load disconnection function which prevents the battery charge from leaking to the output while the IC is not operating.

The GAINP and GAINN pins are used for loop compensation in order to optimize load transient response. With the built-in UVLO (Under Voltage Lock Out) function, the internal driver transistor is forced OFF when input voltage becomes 2.2V or lower.

The XC9519 is available in a thermally enhanced QFN-24 package for applications that require both a small form factor and a good amount of power dissipation.

Torex Semiconductor

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