42.6.1.11 Reference Refresh and Power Refresh

There are two refresh signals for SLCD:

• Reference refresh, which is used to periodically sample the bias current and target VLCD voltage.
• Power refresh, which is used to charge the external VLCD capacitor to the target VLCD level. This is usually due to the fact that the LCD panel driving waveform will need to charge the panel segment capacitors.

The reference refreshment rate is defined by the leakage of the circuit. The bias current and reference voltage start to drift slowly due to parasitic effects. A high frequency refresh rate can tolerate higher leakage at cost of higher power consumption. User can configure the reference refresh rate by writing the Reference Refresh Frequency bits in the Control A register (CTRLA.RRF).

The power refreshment rate is defined by the leakage of the circuit. High frequency could result in bit higher power but can tolerate higher load current on VLCD, which means driving a bigger panel at higher frequency. User can configure the power refresh rate by writing the Power Refresh Frequency bits in the Control A register (CTRLA.PRF)