The TPS65165 is a Compact LCD Bias IC with 3 high-speed operational amplifiers for gamma correction and/or VCOM supply. The device generates all 3 voltage rails for TFT-LCD displays (Vs, VGL and VGH). The device incorporates a high-voltage switch that can be controlled by a logic signal from the timing controller (TCON) to provide the gate-voltage modulation for VGH. If this function is not required, the CTRL pin can be tied high.
The device also features a high-voltage stress test, where the output voltage of VGH is typically set to 30 V, and the output voltage of Vs is programmable to any higher voltage. The high-voltage stress test is enabled by pulling the HVS pin high. Adjustable sequencing is implemented, and can be programmed by selecting the capacitor values connected to ADLY and GDLY. The device consists of a boost converter to provide the source voltage Vs operating at a fixed switching frequency of 600 kHz. A fully integrated positive charge pump, switching automatically between doubler and tripler mode provides an adjustable regulated TFT gate on voltage VGH. A negative charge pump driver provides adjustable regulated output voltage VGL. To minimize external components the charge pumps for VGH and VGL operate at a fixed switching frequency of 1.2 MHz. The device includes safety features like overvoltage protection of the boost converter, short circuit protection of VGH and VGL as well as thermal shutdown.
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