The AAT1267 offers a compact power supply solution to provide all voltages required by a thin-film-transistor (TFT) liquid-crystal display (LCD) panel for TV applications running from a 12V supply rail. It includes a boost and a buck regulator, a positive and a negative regulated charge-pump, a high voltage switch with gate pulse modulation, an operational amplifier, a high accuracy LDO for gamma reference and one open drain RESET output.
The current mode boost regulator provides a fast transient response supply voltage for the source drivers. It provides an output voltage up to 20V from input voltages ranging from 8V to 14V. The boost regulator integrates a low RDSON (0.1Ω) N-MOSFET, and operates at a selectable switching frequency of either 500kHz or 750kHz, thereby minimizing board space while providing good efficiency. An externally programmed soft start minimizes inrush current and output overshoot. In addition, the AAT1267 integrates a control block that can drive an external P-Channel MOSFET to sequence power to source drivers.
The current mode buck regulator operates at either 500kHz or 750kHz and typically supplies system logic power (T-CON). It provides fast load transient response to pulsed loads while producing efficiencies over 90%. This buck regulator integrates a 16.5V, 3.2A, 0.1Ω, power MOSFET that allows the use of ultra-small inductors and ceramic capacitors. A built-in 7-bit digital soft-start function controls startup inrush currents.
The positive and negative charge pump regulators provide supply voltages for the TFT LCD’s gate drivers. Both output voltages can be adjusted with external resistive voltage dividers. For improving TFT LCD image quality, a gate pulse modulation (GPM) circuit shapes the gate-on signal. The slope of the gate-on voltage and GPM power on delay time can be set by external resistor and capacitor.
The operational amplifier drives the LCD backplane (VCOM). This unity-gain buffer is capable of rail-to-rail input and output, ±200mA output short-circuit current, and a 45V/μs slew rate.
A high accuracy low dropout linear regulator is used as an adjustable reference voltage for gamma correction. The LDO guarantees a minimum 60mA output current, and has an internal high accuracy reference of +/–0.5%. The LDO output is set via external feedback resistors.
The 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 AAT1267 device includes various protection features such as UVLO, OCP, OVP, SCP, UVP and thermal shutdown.
The AAT1267 is available in a small 7 x 7 x 0.75mm, ultra-thin, 48 pin QFN package 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.