2.5V to 5.5V Input Supply Voltage Range
640kHz/1.2MHz Selectable Frequency
Current Mode Boost Regulator
▪Built-in 16V, 2A, 0.2Ω N-MOSFET
▪Fast Load Transient Response
▪Adjustable Soft Start
Low Dropout Linear Regulator
▪1.5V to VIN Adjustable Output Voltage Range
▪350mA Minimum Output Current
▪±1.5% Accurate Output
Positive Charge Pump Regulator
High Voltage Switch with Gate Pulse Modulation
▪Adjustable Power On Delay Time
Unity-Gain Operational Amplifier
▪±250mA Short-Circuit Current
▪12V/μs Slew Rate
▪Adjustable Detecting Voltage and Delay Time
▪N-Channel Open-Drain Output
▪Input Under-Voltage Lockout (UVLO)
▪Overload Protection (Fault Protection)
▪Thermal Shutdown (OTP)
VQFN 24-4 x 4 x 0.9 Package Available
General Description
The AAT1187A is a highly integrated power management IC for TFT LCD panels. The device consists of a boost regulator, a positive charge pump regulator, a low dropout linear regulator, a unity-gain operational amplifier, a high voltage switch with gate pulse modulation and one open drain RESET  output.
The current mode boost regulator provides a fast transient response supply voltage for the source driver ICs. It provides an output voltage up to 16V from input voltages ranging from 2.5V to 5.5V. The boost regulator integrates a low RDSON (0.2Ω) N-MOSFET, and operates at a selectable switching frequency of either 640kHz or 1.2MHz, thereby minimizing board space while providing good efficiency. An externally programmed soft start minimizes inrush current and output overshoot.
The low dropout linear regulator typically supplies system logic power (T-CON). The LDO guarantees a minimum 350mA output current, and its output is set via external feedback resistors.
The positive charge pump regulator generates an adjustable regulated output voltage (VGH) for the gate-on driver. For improving TFT LCD image quality, a gate pulse modulation (GPM) circuit shapes the gate high signal (VGH). The slope of the gate high voltage (VGH) and GPM power on delay time can be set by external resistor and capacitor.
The unity-gain operational amplifier (buffer) drives the LCD backplane (VCOM). This buffer is capable of rail-to-rail input and output, ±250mA output short-circuit current, and a 12V/μs slew rate.
A RESET function is used to monitor the device supply voltage. A reset signal is issued via an open drain NMOS when the supply is below a programmable threshold. The threshold is set by external resistors and the delay time is set by an external capacitor.
The AAT1187A device includes various protection features such as input under-voltage lockout (UVLO) and over temperature shutdown. Regulator outputs include overload fault protection.
The AAT1187A is available in a small VQFN 24 pin 4X4X0.9 with a bottom side exposed thermal pad to provide optimal heat dissipation. The device is rated to operate from –40°C to +85°C ambient temperature range.
Smart Panel
Notebook Panel