TMP89FW24AFG Datasheet, PDF (407/548 Pages) Toshiba Semiconductor – 8 Bit Microcontroller TLCS-870/C1 Series

TMP89FW24A
23.5 LCD Display Operation
The LCD drive voltage V_LCD is given by the potential difference between the VLC and VSS pins (V_LC −
V_SS). The LCD lights up when the potential difference between segment and common outputs is ±VL_CD. At other
times, the LCD is turned off.
Power supply connections should be made to satisfy the condition VLC ≤ VDD. Connection examples are
shown in Figure 23-4.
COM
LCD Panel
COM
SEG
VDD
MCU
VLC
LV2
LV1
VSS
VDD
Contrast
adjustment
Can also be used as
port pins or segment
output
LCD Panel
SEG
VDD
MCU
VLC
LV21
LV12
VSS
VDD
Can also be used as
port pins or segment
output
(a) VDD > VLC
(b) VDD = VLC
When internal bleeder resistance is used (LCDCR2<BRSEL>=”1”)
COM
LCD Panel
SEG
VDD
MCU
VLC
LV2
LV1
VSS
VDD
Contrast
adjustment
COM
LCD Panel
SEG
VDD
MCU
VLC
LV21
LV12
VSS
VDD
(a) VDD > VLC
*1
*2
*3
(b) VDD = VLC
*1
*2
*3
When external bleeder resistance is used (LCDCR2<BRSEL>=”0”)
*1 : 1/3 bias
*2 : 1/2 bias
*3 : Static
Figure 23-4 Connection Examples
Note 1: When the CPU operating voltage is the same as the LCD drive voltage, the VLC pin should be connected to the VDD
pin.
Note 2: At reset, the common output pins become low. However, the multiplexed pins (input/output port or segment output)
are configured as port input pins (high impedance). Therefore, if the multiplexed pins (input/output port or segment out-
put) are used as segment output pins and an external reset signal is input for a prolonged period of time, the LCD dis-
play may be adversely affected, such as blurring. The multiplexed pins (input/output port, external bleeder resistance
connection or segment output) are configured as external bleeder resistance connection pins.
RA000
Page 391
2012/5/18