9 SUPPLY VOLTAGE DETECTOR (SVD3)
9-2
Seiko Epson Corporation
S1C17M12/M13 TECHNICAL MANUAL
(Rev. 1.2)
9.2 Input Pins and External Connection
9.2.1 Input Pins
Table 9.2.1.1 shows the SVD3 input pins.
Table 9.2.1.1 SVD3 Input Pins
Pin name
I/O
*
Initial status
*
Function
EXSVD0
A
A (Hi-Z)
External power supply voltage detection pin 0
EXSVD1
A
A (Hi-Z)
External power supply voltage detection pin 1
*
Indicates the status when the pin is configured for SVD3.
If the port is shared with the EXSVD0/1 pin and other functions, the EXSVD0/1 function must be assigned to the
port before SVD3 can be activated. For more information, refer to the “I/O Ports” chapter.
9.2.2 External Connection
SVD3
External power
supply/regulator
etc.
SVD
analog block
EXSVD0/1
R
EXT
R
EXSVD
V
SS
Figure 9.2.2.1 Connection between EXSVD0/1 Pin and External Power Supply
R
EXT
resistance value must be determined so that it will be sufficiently smaller than the EXSVD input impedance
R
EXSVD
. For the EXSVD0/1 pin input voltage range and the EXSVD input impedance, refer to “Supply Voltage De-
tector Characteristics” in the “Electrical Characteristics” chapter.
9.3 Clock Settings
9.3.1 SVD3 Operating Clock
When using SVD3, the SVD3 operating clock CLK_SVD3 must be supplied to SVD3 from the clock generator.
The CLK_SVD3 supply should be controlled as in the procedure shown below.
1. Write 0x0096 to the MSCPROT.PROT[15:0] bits. (Remove system protection)
2. Enable the clock source in the clock generator if it is stopped (refer to “Clock Generator” in the “Power Supply,
Reset, and Clocks” chapter).
3. Set the following SVDCLK register bits:
- SVDCLK.CLKSRC[1:0] bits
(Clock source selection)
- SVDCLK.CLKDIV[2:0] bits
(Clock division ratio selection = Clock frequency setting)
4. Write a value other than 0x0096 to the MSCPROT.PROT[15:0] bits. (Set system protection)
The CLK_SVD3 frequency should be set to around 32 kHz.
9.3.2 Clock Supply in SLEEP Mode
When using SVD3 during SLEEP mode, the SVD3 operating clock CLK_SVD3 must be configured so that it will
keep supplying by writing 0 to the CLGOSC.
xxxx
SLPC bit for the CLK_SVD3 clock source.
If the CLGOSC.
xxxx
SLPC bit for the CLK_SVD3 clock source is 1, the CLK_SVD3 clock source is deactivated
during SLEEP mode and SVD3 stops with the register settings maintained at those before entering SLEEP mode.
After the CPU returns to normal mode, CLK_SVD3 is supplied and the SVD3 operation resumes.