2.1.1 Bias Voltage Selection Example

The LCD charge pump output voltage selected when programming the BIAS<2:0> bits should correspond to the drive/operating voltage supplied by the manufacturer of the LCD panel. Table 2-4 shows some of the key electrical specifications for the custom LCD panel manufactured by Varitronix used on the PIC16F19197 Low-Power Touch Enabled LCD Demonstration. The manufacturer of this LCD panel specifies that the drive voltage (VLCD) required for the display is 4.3V. For an application using this particular glass, EN5V should be set (EN5V = 1) to operate within the 5.0V voltage range, and the BIAS<2:0> bits should be set to provide an output voltage of 4.31V (BIAS<2:0> = 011). Depending upon the specifications of the particular LCD glass being used in an application, the BIAS<2:0> bits can be configured accordingly to satisfy the drive requirements. An example code snippet demonstrating the initialization of the LCD module on the PIC16F19197 to drive a display using the built in LCD charge pump is included in LCD Module Configuration Example.