4 POWER SUPPLY
S1C17704 TECHNICAL MANUAL
EPSON
4-3
4.3 Controlling the Power Supply Circuit
In order to generate the internal operating voltage properly according to the power supply voltage and operating
mode, or to reduce current consumption, the power supply circuit is designed to be controlled with software.
Switching the operating mode
The S1C17704 has two kinds of operating modes.
1. Normal operation mode
This mode is provided for running the application program.
V
DD
= 1.8 to 3.6 V, internal operating voltage V
D1
= 1.8 V
2. Flash erase/program mode
This mode is provided for erasing and programming the Flash memory.
V
DD
= 2.7 to 3.6 V, internal operating voltage V
D1
= 2.5 V
The
V
D1
voltage value must be switched according to the operating mode as shown above using the VD1MD bit
(D0/VD1_CTL register). Normally set VD1MD to 0 (V
D1
= 1.8 V, default setting). It should be set to 1 before
erasing/programming the Flash memory.
∗
VD1MD
: Flash Erase/Program Mode Bit in the V
D1
Control (VD1_CTL) Register (D0/0x5120)
Note
: When the operating mode is switched, the internal operating voltage requires 5 ms (max.) to
stabilize. Flash memory programming should be started after the stabilization time has elapsed.
Controlling the LCD power source
The LCD system voltage regulator must be driven with a 2.5 V or more power voltage to generate appropriate
LCD drive voltages V
C1
to V
C5
. When the power supply voltage (V
DD
) is within the range from 1.8 V to 2.5 V,
use the power voltage booster to generate double the V
DD
voltage and drive the LCD system voltage regulator
with the V
D2
output voltage. Set the PBON bit (D0/LCD_PWR register) to 1 to turn the power voltage booster
on. In addition, set the VDSEL bit (D1/LCD_PWR register) to 1 to drive the LCD system voltage regulator
with the V
D2
voltage output from the power voltage booster. PBON must be set to 1 before the drive voltage can
be switched to V
D2
.
∗
PBON
: Power Voltage Booster Control Bit in the LCD Power Voltage Booster Control (LCD_PWR) Register
(D0/0x50a4)
∗
VDSEL
: Regulator Power Source Select Bit in the LCD Power Voltage Booster Control (LCD_PWR) Register
(D1/0x50a4)
When the power supply voltage (V
DD
) is 2.5 V or more, drive the LCD system voltage regulator with V
DD
. The
power voltage booster should be turned off to reduce current consumption. In this case, PBON and VDSEL are
both set to 0 (default).
Note
: When the power voltage booster is turned on, the V
D2
output voltage requires about 1 ms to
stabilize. Do not switch the power source for the LCD system voltage regulator to V
D2
until the
stabilization time has elapsed.
The LCD drive voltages V
C1
to V
C5
will be supplied to the LCD driver by setting the DSPC[1:0] bits (D[1:0]/
LCD_DCTL register) to a value other than 0x0 (display off).
∗
DSPC[1:0]
: LCD Display Control Bits in the LCD Display Control (LCD_DCTL) Register (D[1:0]/0x50a0)
When the internal LCD driver is not used, the power voltage booster and LCD system voltage regulator should
be turned off to reduce current consumption. Set PBON, VDSEL, and DSPC[1:0] to 0 (default).
Summary of Contents for S1C17704
Page 1: ...TECHNICAL MANUAL S1C17704 CMOS 16 BIT SINGLE CHIP MICROCOMPUTER ...
Page 22: ...1 OVERVIEW 1 10 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 42: ...3 MEMORY MAP BUS CONTROL 3 12 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 82: ...6 INTERRUPT CONTROLLER ITC 6 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 108: ...8 CLOCK GENERATOR CLG 8 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 112: ...9 PRESCALER PSC 9 4 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 138: ...10 I O PORTS P 10 26 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 156: ...11 16 BIT TIMERS T16 11 18 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 208: ...14 8 BIT OSC1 TIMER T8OSC1 14 16 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 234: ...16 STOPWATCH TIMER SWT 16 14 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 242: ...17 WATCHDOG TIMER WDT 17 8 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 264: ...18 UART 18 22 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 300: ...20 I2C 20 20 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 320: ...21 REMOTE CONTROLLER REMC 21 20 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 360: ...24 ON CHIP DEBUGGER DBG 24 6 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...
Page 362: ...25 BASIC EXTERNAL WIRING DIAGRAM 25 2 EPSON S1C17704 TECHNICAL MANUAL THIS PAGE IS BLANK ...