Chapter 14 LCD Functions
XIV - 14
Operation
2 times, 3 times boosting
2 times, 3 times boosting is used when LCD panel is used with 1/3 bias.
To operate 2 or 3 times voltage boosting, input reference voltage to the VLC3 pin, and connect capacity to
VLC1 and VLC2 pins to be connected to VSS. Connect capacity between C1 and C2 pin, as well.
3 times of VLC3 reference voltage is applied to the VLC1 pin, and 2 times of VLC3 reference voltage is
applied to VLC2 pin.
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Chapter 14 14-3-3 Voltage supply when using internal voltage booster circuit ]
2/3 times, 1/2 times boosting
2/3 times, 1/2 times boosting is useed when LCD panel is used with 1/3 bias.
To operate 2/3 or 1/2 times voltage boosting, input reference voltage to the VLC2 pin, and connect capac-
ity VLC1 and VLC3 pins to be connected to VSS. Connect capacity between C1 and C2 pin, as well.
3/2 times of VLC2 reference voltage is applied to the VLC1 pin, and 1/2 times of VLC2 reference voltage is
applied to VLC3 pin.
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Chapter 14 14-3-3 Voltage supply when using internal voltage booster circuit ]
2 times boosting
2 times boosting is used when LCD panel is used with 1/2 bias.
To operate 2 times voltage boosting, input reference voltage to VLC2 and VLC3 pins, which need to be
short-circuited in advance. Connect capacity between VLC1 and VSS pins. Connect capacity between C1
and C2 pin, as well.
2 times of VLC2 (VLC3) reference voltage is applied to VLC1 pin.
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Chapter 14 14-3-3 Voltage supply when using internal voltage booster circuit ]
When voltage booster circuit is active, internal voltage divider resistors cannot be used.
For 2 times, 3 times voltage boosting, input reference voltage VLC3 to voltage booster circuit
in the range of 1/3 VDD
≤ VLC3 ≤ 1.8 V.
For 3/2 times, 1/2 times voltage boosting, input reference voltage VLC2 to voltage booster
circuit in the range of 2/3 VDD
≤ VLC2 ≤ 3.6 V.
For 2 times voltage boosting, input reference voltage VLC2(= VLC3) to voltage booster circuit in
the range of 1/2 VDD
≤ VLC2 ≤ 2.7 V.
To generate LCD power supply (VLC1) using LCD voltage booster circuit, start the LCD volt-
age booster circuit and supply voltage right after reset. For transition to STOP mode, disable
(set 0 to) the start flag of the LCD driver circuit, and stop (set 0 to) the voltage booster start
flag in advance. After voltage booster circuit is switched to STOP mode, power from
microcontroller (VDD) is supplied to the LCD power supply (VLC1) by this procedure.