38D2 datasheet(49/136 Pages) RENESAS

49 / 136 page

Rev.3.02

Apr 10, 2008

Page 49 of 131

REJ03B0177-0302

38D2 Group

• LCD Power Circuit

The LCD power circuit has the dividing resistor for LCD power

which can be connected/disconnected with the LCD power

control register.

To use the LCD, apply a voltage externally to the VL3 pin and set

the VL3 connect bit to “1”. An external voltage should be applied

even if a voltage equivalent to VCC is used for the VL3 pin. When

the LCD is not used, perform either of the following.

• Set the VL3 connect bit to “0” and leave the VL3 pin open.

•Set the VL3 connect bit to “1” and apply a VCC level to VL3

pin.

Fig. 41 Structure of LCD power control register

Fig. 42 VL block diagram

Dividing resistor for LCD power control bit (LCDRON)

0 : Internal dividing resistor disconnected from LCD power circuit

1 : Internal dividing resistor connected to LCD power circuit

LCD power control register

(VLCON : address 001416)

VL pin input selection bit (VLSEL) (Note 2)

0 : Input invalid

1 : VL input function valid

Not used (Do not write to “1”.)

Dividing resistor for LCD power selection bits (RSEL) (Note 1)

b2b1

1 0 :

0 1 :

0 0 :

1 1 :

VL3 connection bit

0 : Connect LCD internal VL3 to VCC

1 : Connect LCD internal VL3 to VL3 pin

Notes 1: When voltage is applied to VL1 to VL3 by using the external resistor, write “102” to dividing resistor

for LCD power selection bits.

2: Setting to the VL pin input selection bit (VLSEL) = “1” has the most priority than setting to the port

P2 direction register (address 000516) and segment output disable register 2 (address 0FF616).

Larger resistor

Smaller resistor

Not used (Do not write to “1”.)

VL3

P27/SEG23/VL2

Bias control bit

(LCD mode register)

P26/SEG22/VL1

VL pin input

selection bit

Dividing resistor for LCD

power control bit

Vcc

Dividing resistor

for LCD power

Dividing resistor for LCD

power selection bits

VL3 connection bit

LCD internal VL3

LCD internal VL2

LCD internal VL1

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