Boosting The Lcd Drive Power Supply - Hitachi H8S/2646 Hardware Manual

Table 18-4 Power-Down Modes and Display Operation
Mode Reset Active
Clock ø Runs
ø Runs
SUB
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 ø
clock.
*4 The clock supplied to the LCD stops.
18.3.4

Boosting the LCD Drive Power Supply

When a panel is driven, the on-chip power supply capacity may be insufficient. The recommended
solution in this case is to connect bypass capacitors of around 0.1 to 0.3 µF to pins V1 to V3, or to
connect a new split-resistance externally, as shown in figure 18-13.
LPV
H8S/2646 Series
V
SS
Figure 18-13 Connection of External Split-Resistance
652
Sleep
Runs Runs
Runs Runs
Stops Stops
Functions Functions Functions
VR
CC
V1
V2
V3
Watch Subactive Subsleep
Stops Stops
Runs Runs
Stops Stops
* 3
Functions
, ø /2, or ø
SUB SUB
R = several kΩ to
R
several MΩ
R
R
Standby
Stops Stops
Runs Stops
Stops Stops
*3 * 3
Functions Stops
/4 is selected as the operating
SUB
C = 0.1 to 0.3 µF
Module
Standby
*4
Stops
*1 *4
Stops
*2
Stops
*2
Stops