PMIC for LCD TV / Monitor


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The RT9955 generates all the supply rails for thin-film transistor (TFT) liquid-crystal display (LCD) panels in TVs and monitors. It includes boost and buck regulators, VGH and VGL charge pump regulators, gate pulse modulator (GPM) , HV LDO, voltage detector (XAO) and VCOM OP. The RT9955 supports input voltage from 8V to 14V and is optimized for LCD TV panel and LCD monitor applications running directly from 12V supply.

The boost and buck regulators feature internal power MOSFETs and high frequency operation, allowing the use of small inductors and capacitors, for in a compact solution. Both switching regulators use fixed frequency, current mode control architectures, providing fast load-transient response and easy compensation.

The VGH and VGL charge pump regulators provide supply voltages for the TFT gate driver. Both output voltages can be adjusted with external resistive voltage dividers.

The GPM is controlled by frame signals from the timing controller to modulate the Gate-On voltage (VGHM), which acts as a flicker compensation to reduce the coupling effect between gate lines and pixels. It can also delay VGHM while power on to achieve a correct power on sequence for gate driver ICs. The VGHM power on delay time, the falling time and falling stop voltage can all be programmed by an external capacitor, an external resistor and an resistive voltage divider.

The voltage detector (XAO) monitors VIN voltage to issue a reset signal when the VIN voltage is too low. The detecting level is determined by an external resistive voltage divider.

The HV LDO can provide a highly accurate voltage (0.5%) for gamma reference voltage. It has fast transient response and also a wide operation input range.

The VCOM OP can drive the LCD VCOM voltage that features high short circuit current (300mA), fast slew rate (45V/μs), wide bandwidth (20MHz) and rail-to-rail inputs and outputs.

The RT9955 is available in a small WQFN-48L 7x7 package.


Key Spec.
Status Active
Vin (min) (V) 8
Vin (max) (V) 14
Number of LDO Regulators 1
Application TV
Features Adjustable Soft-Start
Package Type WQFN7x7-48
  • 8V to 14V Supply Input Voltage Range
  • Current Mode Boost Regulator
    ► 20V 3A 0.1Ω Internal N-MOSFET
    ► Programmable Over Current Protection
    ► Programmable Soft-Start
  • Current Mode Buck Regulator
    ► 16.5V 3.2A 0.15Ω Internal N-MOSFET
    ► Over Current Protection
    ► Adjustable Output Voltage from 1.8V to 3.3V
  • Adjustable VGH Charge Pump
    ► Continuous Output Current 50mA
  • Adjustable VGL Charge Pump
    ► Continuous Output Current 50mA
  • Gate Pulse Modulator
    ► 18V to 35V Positive Supply Input
    ► Power On/Off Sequence Control
    ► On-Chip GPM Controller with Adjustable Falling Time and Falling Stop Voltage
  • Voltage Detector (XAO)
    ► Adjustable Detecting Voltage (±1%)
    ► N-CH Open-Drain Output
    ► 5V to 20V Input Supply Voltage
    ► ±300mA Output Short-Circuit Current for 1ms
    ► 45V/μs Slew Rate
    ► 20MHz, -3dB Bandwidth
  • HV LDO
    ► 5V to 20V Input Supply Voltage
    ► Adjustable Output Voltage (±0.5%)
    ► Over Current Protection (60mA)
    ► Low Dropout Voltage 0.5V (60mA)
  • Selectable Frequency (500kHz/750KHz)
  • External PMOS Isolation Switch Controlled by Gate Drive Signal
  • Under Voltage Protection
  • Short Circuit Protection
  • Over Temperature Protection
  • Power On Sequence Control
  • Thin 48-Lead WQFN Package
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
PMIC for LCD TV / Monitor2010/03/31
Technical Documents
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Richtek Selection Guide [Oct., 2020]2020/12/30