SLAZ100AA October 2012 – May 2021 CC430F6127
LCDB Module
Functional
VLCDEXT bit not working properly
When the VLCDEXT bit is set an external voltage applied to the LCDCAP/R33 pin should serve as the LCD voltage. This works as expected when the V2 to V4 voltages are generated externally (LCDEXTBIAS = 1) and external resistors are connected on the R03 to R33 resistor ladder. If internal V2 to V4 bias voltage generation is selected (LCDEXTBIAS = 0), applying an external LCD voltage on LCDCAP VLCDEXT has no effect.
The expected behavior for the VLCDEXT bit can be achieved by setting the VLCDx bits to a non-zero value and leaving the charge pump disabled (LCDCPEN = 0). The VLCDx bits are don't care when the charge pump is disabled so this does not result in any additional or unexpected current consumption.