17 SVD (SuPPlY VOlTaGe DeTeCTiOn) CiRCuiT
17-2
Seiko epson Corporation
S1C63003/004/008/016 TeChniCal Manual
(Rev. 1.1)
i/O Memory of SVD Circuit
17.3
Table 17.3.1 shows the I/O addresses and the control bits for the SVD circuit.
3.1 Control bits of SVD circuit
Table 17.
Address
Register name R/W Default
Setting/data
Function
FF04H
(
*
6)
D3
SVDS3
R/W
0
1F
1E
1D
1C
1B
3.20
3.10
3.00
2.90
2.80
1A
19
18
17
16
2.70
2.60
2.50
2.40
2.30
15
14
13
12
11
2.20
2.10
2.00
1.90
1.80
10
F
E
D
C
1.70
1.65
1.60
1.55
1.50
B
A
9
8
7
1.45
1.40
1.35
1.30
1.25
6
5
4
3
2
1.20
1.15
1.10
1.05
1.05
1
0
1.05
1.05
SVD criteria voltage (V) setting
←
SVDS[4:0]
D2
SVDS2
R/W
0
D1
SVDS1
R/W
0
D0
SVDS0
R/W
0
FF05H
(
*
6)
D3 0 (
*
3)
R
– (
*
2)
–
Unused
D2 SVDS4
R/W
0
(See FF04H)
SVD criteria voltage (V) setting
D1
SVDDT
R
0
1 Low
0 Normal
SVD evaluation data
D0
SVDOn
R/W
0
1 On
0 Off
SVD circuit On/Off
*
1 Initial value at initial reset
*
2 Not set in the circuit
*
3 Constantly "0" when being read
*
4 Unused in the S1C63003/004/008
*
5 Unused in the S1C63003/004
*
6 Unused in the S1C63003
SVDS[4:0]: SVD criteria voltage setting register (FF05h•D2, FF04h)
Criteria voltage for SVD is set as shown in Table 17.2.1. At initial reset, this register is set to "0."
SVDOn: SVD circuit On/Off register (FF05h•D0)
Turns the SVD circuit on and off.
When "1" is written: SVD circuit On
When "0" is written: SVD circuit Off
Reading: Valid
When SVDON is set to "1," a source voltage detection is executed by the SVD circuit. As soon as SVDON is
reset to "0," the result is loaded to the SVDDT latch. To obtain a stable detection result, the SVD circuit must be
on for at least 500 µsec. At initial reset, this register is set to "0."
SVDDT: SVD evaluation data (FF05h•D1)
This is the result of supply voltage detection.
When "1" is read: Supply voltage (V
DD
–V
SS
) < Criteria voltage
When "0" is read: Supply voltage (V
DD
–V
SS
)
≥
Criteria voltage
Writing: Invalid
The result of supply voltage detection at time of SVDON is set to "0" can be read from this latch. At initial reset,
SVDDT is set to "0."
Precautions
17.4
• To obtain a stable detection result, the SVD circuit must be on for at least 500 µsec. So, to obtain the SVD detection
result, follow the programming sequence below.
1. Set SVDON to "1"
2. Maintain for 500 µsec minimum
3. Set SVDON to "0"
4. Read SVDDT
• The SVD circuit should normally be turned off because SVD operation increase current consumption.