
S1C6S3N7 TECHNICAL HARDWARE
EPSON
I-59
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (SVD Circuit and Heavy Load Protection Function)
In the heavy load protection mode, the internally regu-
lated voltage is generated by the liquid crystal driver
source output VL2 so as to operate the internal circuit.
Consequently, more current is consumed in the heavy
load protection mode than in the normal mode. Unless it
is necessary, be careful not to set the heavy load protec-
tion mode with the software. Also, to reduce current
consumption, do not set the SVDON to ON in the heavy
load protection mode.
Note that in S1C6S3L7/S1C6S3B7, the range of operat-
ing voltage differs during CR oscillation and during
crystal oscillation.
(2) In case of S1C6S3N7
The S1C6S3N7 has the heavy load protection function for
when the battery load becomes heavy and the source
voltage changes, such as when an external buzzer sounds
or an external lamp lights. The state where the heavy load
protection function is in effect is called the heavy load
protection mode. Compared with the normal operation
mode, this mode can reduce the output voltage variation of
the constant voltage or voltage booster/reducer of the LCD
system.
The normal mode changes to the heavy load protection
mode in the following case:
When the software changes the mode to the heavy load
protection mode (HLMOD = 1)
The heavy load protection mode switches the constant
voltage circuit of the LCD system to the high-stability
mode from the low current consumption mode. Conse-
quently, more current is consumed in the heavy load
protection mode than in the normal mode. Unless it is
necessary, be careful not to set the heavy load protection
mode with the software.
Fig. 4.9.1
Configuration of SVD and
heavy load protection circuits
VS1
VL1
VSS
HLMOD
SVDDT
VSS
SVDON
SVD
circuit
Regurated
voltage circuit
Data
bus
Address 0FAH
SVD sampling
control
D3
D1
D0
VDD