Simplified Block Diagram
Click any title below to view the detail page where available.
- 18 Reference Voltages
- 7-Bit Digital Variable Resistor (DVR)
- Independent DACs with 8-Bit Resolution
- 20V (max) Operating Voltage
- Startup Protection for Column Drivers
- Output Swing within 150mV of Rails
- TFT LCDs
The 14 programmable reference voltages are divided evenly into seven upper and seven lower voltages for the upper and lower gamma curves of LCD column drivers. Each channel has a static 8-bit digital-to-analog converter (DAC) and an isolation buffer to ensure stable reference voltages. This architecture reduces the effects of power-supply noise and kickback current from the source driver chips. Each buffer provides a high peak current to reduce the recovery time of the output voltages when critical levels and patterns are displayed.
The MAX9694 has two features to protect the column drivers during startup. First, the gamma outputs remain in a high-impedance state until the registers are loaded. Second, the four reference buffers ramp up proportionally with the analog supply, which ensures that OUT_REFL_H is always at a lower voltage than OUT_REFU_L.