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4 POWER SUPPLY
4-2
Seiko Epson Corporation
S1C17554/564 TECHNICAL MANUAL
Embedded Regulator (S1C17564)
4.5
The S1C17564 includes a voltage regulator that allows use of a 2 V or higher single power supply for IC opera-
tions.
Regulator input (VIN):
2.0 V to 5.5 V
Regulator output (VOUT): 1.8 V
When a single power supply is used, supply the voltage within the range shown above to the VIN, HVDD, and AVDD
pins. Also the same voltage should be supplied to the REGEN pin to enable the regulator to operate. The regulator
generates a 1.8 V (typ.) voltage and outputs it to the VOUT pin. By supplying the output voltage to the LVDD pin, the
core and internal circuits can be operated.
For power supply connection examples, see the “Basic External Connection Diagram” chapter.
The embedded regulator supports economy mode (power saving mode) to reduce current consumption in the regu-
lator during low-speed (32 kHz) operation or standby mode (HALT or SLEEP).
Control Register Details (S1C17564)
4.6
6.1 Power Control Register
Table 4.
Address
Register name
Function
0x5121
VD1_CTL
VD1 Control Register
Controls the regulator operation mode.
The power control register (S1C17564) is described in detail below.
Note: When data is written to the registers, the “Reserved” bits must always be written as 0 and not 1.
VD1 Control Register (VD1_CTL)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
VD1 Control
Register
(VD1_CTL)
S1C17564
0x5121
(8 bits)
D7–2 –
reserved
–
0 when being read.
D1–0 VD1ECO
[1:0]
Regulator operation mode select
VD1ECO[1:0]
Mode
0x0 R/W
0x3
0x2
0x1
0x0
reserved
Auto-control
Economy
Normal
D[7:2]
Reserved
D[1:0]
VD1ECO[1:0]: Regulator Operation Mode Select Bits
Sets the operation mode of the embedded regulator.
6.2 Regulator Operation Mode
Table 4.
VD1ECO[1:0]
Operation mode
0x3
Reserved
0x2
Auto-control mode
0x1
Economy (power saving) mode
0x0
Normal mode
(Default: 0x0)
For normal operation (while the IC is operating with a clock other than OSC1), set VD1ECO[1:0] to
0x0 (default).
Setting VD1ECO[1:0] to 0x1 places the regulator into economy mode. The economy mode can reduce
current consumption, note, however, that the regulator may become unstable due to changes of load that
cannot be responded. The regulator should be set to economy mode before the slp instruction is execut-
ed.
Setting VD1ECO[1:0] to 0x2 places the regulator into auto-control mode. In this mode, the hardware
automatically performs switching between normal mode and economy mode according to changes of
load. The regulator enters economy mode when both IOSC and OSC3 are stopped or when the IC en-
ters SLEEP mode, or enters normal mode otherwise.
While the IC is operating with a high-speed clock (other than OSC1), the regulator should not be set to
economy mode, as the regulator output voltage may become unstable. Even if the IC is operating with
OSC1, set the regulator to normal mode when driving a heavy load such as a lamp or buzzer.