Simplified Block Diagram
Click any title below to view the detail page where available.
- +1.8V to +6V Input Range
- Output Voltages
- +8V Output at 300mA (+2.2V Input Step-Up Switching Regulator)
- +21V Output at 20mA (Positive Charge Pump)
- -13V Output at 20mA (Negative Charge Pump)
- ±150mA High-Current Op-Amp Output
- Resistor-Adjustable Switching Regulator and Op-Amp Output Range
- Digitally Programmable Op-Amp Output Voltage
- +35V to -25V High-Voltage Level-Shifting Drivers
- Greater than 85% Efficiency (Step-Up Switching Regulator)
- 1.2MHz Step-Up Switching Frequency
- SMBus-Compatible Interface
- Windows 2000/XP/Vista (32-Bit)-Compatible Software
- 1.2mm Low-Profile Surface-Mount Components
- Lead-Free and RoHS Compliant
- Fully Assembled and Tested
- LCD Monitor Panels
- Notebook Computer Display
The MAX8798 EV kit (MAX8798EVKIT+) is a fully assembled and tested surface-mount printed-circuit board (PCB) that provides the features required for active-matrix, thin-film transistor (TFT) liquid-crystal displays (LCDs). The EV kit contains a step-up switching regulator, positive two-stage charge pump, negative two-stage charge pump, digitally adjustable VCOM calibration device with nonvolatile memory, SMBus™-compatible interface, high-speed operational amplifier (op amp), and high-voltage, level-shifting scan driver for thin TFT-LCD applications.
The EV kit operates from a DC supply voltage from +1.8V to +6V. The step-up switching regulator is configured for a +8V output providing at least 300mA from a +2.2V input. The positive charge pump is configured for a +21V output providing at least 20mA. The negative charge pump is configured for a -13V output providing at least 20mA. The op amp is capable of providing up to ±150mA peak and features a programmable output voltage initially configured for +3.2V. The high-voltage level-shifting scan driver buffers inputs from STV, CPV, and OE pads and shifts them to a desired level to drive TFT-LCD row logic.
The MAX8798 EV kit demonstrates low quiescent current and high efficiency (> 85%) for maximum battery time per charge. Operation at 1.2MHz allows the use of tiny surface-mount components. The MAX8798 thin QFN package (0.8mm max height), with low-profile external components, allows this circuit to be less than 1.2mm high.
The Maxim CMAXQUSB command module provides the SMBus-compatible interface and is connected to a PC through the universal serial bus (USB) port. The MAX8798 EV kit software provides a graphical user interface (GUI) for exercising the MAX8798 features.