MAX8784 Evaluation Kit (MAX8784EVKIT) (MAX8784EVKIT)
The MAX8784 evaluation kit (EV kit) is a fully assembled and tested surface-mount PCB that provides the voltages and features required for active-matrix, thin-film transistor (TFT) liquid-crystal display (LCD) panels in LCD monitors and LCD TVs. The EV kit contains a step-up switching regulator, a two-stage positive charge pump for the TFT gate-on supply, a single-stage negative charge pump for the TFT gate-off supply, and three high-current op amps. Two capacitor-control delays are available: one to control the initial startup of the step-up, and the other to control the delay between the negative and positive charge pumps. Also included is a logic-controlled, high-voltage switch for the positive gate-driver supply. A high-voltage stress (HVS) mode is provided to increase the step-up and the positive charge-pump output voltages for stress testing the display panel during production. A capacitive dummy load is provided at the high-voltage switch output for ease of testing without a panel attached.
The EV kit operates from a DC supply voltage of +4.5V to +5.5V, as configured. The step-up switching regulator is configured for a +14V output providing at least 700mA. The positive charge pump is configured for a +28V output providing at least 50mA. The negative charge pump is configured for a -9V output providing at least 50mA. The three high-current op amps are each configured for a +7V output that can source or sink 180mA. The high-voltage switch can be controlled by external logic. The EV kit's input voltage range can be lowered to +4V at slightly lower load currents.
The MAX8784 step-up switching regulator operates at 1.2MHz, allowing the use of tiny surface-mount components. The MAX8784 thin QFN package (0.8mm max height), with low-profile external components, allows this circuit to be less than 3mm high.
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