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The RT9921 includes a high-performance boost regulator, a low dropout linear regulator (LDO), a gate pulse modulator (GPM), a voltage detector, a VCOM buffer (unity-gain OPA), and a VGH charge pump controller for active-matrix thin-film transistor (TFT) liquid-crystal displays (LCDs). <p align="justify">The boost converter provides the regulated supply voltage for the panel source driver ICs. The converter is a high switching frequency (640kHz or 1.2MHz) current-mode regulator with an integrated 16V N-Channel 0.2W MOSFET that allows the use of ultra-small inductors and ceramic capacitors. It provides fast transient response to pulsed loading while achieving efficiency over 90%. The device can produce output voltage as high as 15V from an input as low as 2.5V. Soft-Start is programmed by external capacitor, which sets the input-current ramp-rate. </p><p align="justify">The low-dropout (LDO) linear regulator can supply up to 350mA current while input voltage is 3.3V. It uses an internal P-MOSFET as the pass device. It is suitable for the supply voltage of the timing controller. </p><p align="justify">The GPM is controlled by frame signals from timing controller to modulate the Gate-On voltage, VGHM, which acts a flicker compensation circuit to reduce the coupling effect between gate lines and pixels. It also can delay the Gate-On voltage while power-on for achieving a corrected power-on sequence for gate driver ICs. Both of power-on delay time and the falling time of the Gate-On voltage are programmable by external capacitor and resistor. </p><p align="justify">The voltage detector monitors the supply voltage to issue a reset signal while the detected voltage is too low. The detecting level is decided by an external resistor divider and the delay time is programmable by an external capacitor. </p><p align="justify">The VCOM buffer can drive the LCD VCOM voltage that features high short-circuit current (140mA), fast slew rate (12V/&mu;s), wide bandwidth (12MHz) and rail-to-rail inputs and outputs. </p><p align="justify">The VGH charge pump controller provides regulated TFT Gate-On voltage. The regulation of the positive charge pump is generated by the internal comparator that senses the output voltage and compares it with an internal reference. </p>
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  • 输入电压范围:2.5V~5.5V
  • 640kHz/1.2MHz电流模式Boost转换器
    ►脉冲负载快速响应能力
    ►输出电压可调(精度±1%)
    ►内建16V, 2A, 0.2Ω N-MOSFET
    ►效率高达90%以上
    ►可调软启动
    ►过流保护
    ►输出欠压保护
  • 低压差线性稳压器
    ►可调输出电压范围:1.5V~VIN-0.5V(±1.5%)
    ►最大负载能力:350mA
  • GPM控制器
    ►下降时间和上电延时可调
    ►可调闪烁补偿
    ►可调上电时序
  • 电压检测器
    ►检测电压阈值可调(±2%精度),时延可调
  • 使用单位增益运算放大器作为VCOM缓冲器
  • 使用电荷泵电路实现VGH调节
  • 过热保护
  • 24引脚VQFN封装
  • 符合RoHS规范,不含卤素
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