The AAT1269 is a highly integrated power management IC for TFT LCD panels. The device provides a boost regulator, a synchronous buck regulator, a high voltage switch with gate pulse modulation, an I2C programmable VCOM operational amplifier, and one open drain reset output for input voltage monitoring.
The current mode boost regulator provides a fast transient response supply voltage for the source drivers. It provides an output voltage up to 16V from input voltages ranging from 2.2V to 6V. The boost regulator integrates a low RDSON (0.15Ω) N-MOSFET, and operates at a switching frequency that can be adjusted between 400kHz and 1.2MHz, thereby minimizing board space while providing good efficiency. An externally programmed soft start minimizes inrush current and output overshoot.
The current mode buck regulator provides fast load transient response to pulsed loads and typically supplies system logic power (TCON). It operates at a switching frequency that can be adjusted between 1.6MHz and 4.8MHz, allowing the use of ultra-small inductors and ceramic capacitors. The buck regulator also integrates a 5V, 1A, 0.15Ω power MOSFET, and produces efficiencies of over 90% during nominal load. A built-in 7-bit digital soft start function controls startup inrush currents.
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 programmable 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 35V/μs slew rate. It’s programmed by I2C interface with 7-bit, 128 step adjustable sink current output that can replace mechanical potentiometers to reduce labor cost.
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 the UVLO threshold.
The AAT1269 device includes various protection features such as input under voltage lockout (UVLO) and over temperature Protection (OTP). Regulator outputs include over voltage protection (OVP), under voltage protection (UVP) and short circuit protection (SCP).
The AAT1269 is available in a small WQFN 28 pin 4 x 5 x 0.75mm with a bottom side exposed thermal pad to provide optimal heat dissipation. The device is rated to operate from –40°C to +85°C temperature range.