We're currently using an MSP430 with an integrated LCD controller that only has a 1/3 bias mode. The LCD display has a 2-mux configuration and the data sheet specifies "drive method: 1/2 duty, 1/2 bias." While everything appears to work fine in the prototype and the active segments are clearly visible, we were wondering what are the drawbacks by using a different bias? Is there any potential for damage?

We were advised that we could provide an external 1/2 bias resistor network and feed that to both the 1/3 and 2/3 voltage inputs with the internal charge pump disabled and that this would be safe. I assume it would result in the modified waveforms below. The overall RMS voltage for an active segment should be less, but if the segments still are still visible when turned "on," it seems like it should be okay? Is the logic here correct/incorrect, or are we missing some important details?

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  • \$\begingroup\$ "The LCD Display"...You want us to comment on the operation of an LCD with no datasheet to look at? \$\endgroup\$ – Voltage Spike Jul 16 at 20:38

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