Boosting The Lcd Drive Power Supply - Renesas H8 Series Hardware Manual

Section 13 LCD Controller/Driver
Table 13.4 Power-Down Modes and Display Operation
Mode Reset Active
φ
Clock Runs
φw
Runs
Display ACT = 0 Stops
operation
ACT = 1 Stops
Notes: 1. The subclock oscillator does not stop, but clock supply is halted.
2. The LCD drive power supply is turned off regardless of the setting of the PSW bit.
3. Display operation is performed only if φw, φw/2, or φw/4 is selected as the operating
clock.
4. The clock supplied to the LCD stops.
13.3.4

Boosting the LCD Drive Power Supply

When a large panel is driven, the on-chip power supply capacity may be insufficient. If the power
supply capacity is insufficient when V
must be reduced. This can be done by connecting bypass capacitors of around 0.1 to 0.3 µF to
pins V to V , as shown in figure 13.9, or by adding a split-resistance externally.
1 3
V
This LSI
V
Figure 13.9 Connection of External Split-Resistance
Rev. 7.00 Mar 10, 2005 page 434 of 652
REJ09B0042-0700
Sleep
Runs Runs
Runs Runs
Stops Stops
Functions Functions Functions *
is used as the power supply, the power supply impedance
CC
CC
V
1
V
2
V
3
SS
Sub-
Watch active
Stops Stops
Runs Runs
Stops Stops
3 Functions *
R
R = several kΩ to
R
several MΩ
R
R
Sub-
sleep Standby
Stops Stops
Stops * 1
Runs
Stops * 2
Stops
3 Functions * 3 Stops * 2
C = 0.1 to 0.3 µF
Module
Standby
Stops * 4
Stops * 4
Stops
Stops