17 SVD (SuPPlY VOlTaGe DeTeCTiOn) CiRCuiT
S1C63003/004/008/016 TeChniCal Manual
Seiko epson Corporation
17-1
(Rev. 1.1)
SVD (Supply Voltage Detection) Circuit
17
[S1C63004/008/016]
Note: The S1C63003 has no SVD circuit included.
Configuration of SVD Circuit
17.1
The S1C63004/008/016 has a built-in SVD (supply voltage detection) circuit, so that the software can find when the
source voltage lowers. Turning the SVD circuit on/off and the SVD criteria voltage setting can be done with software.
Figure 17.1.1 shows the configuration of the SVD circuit.
V
Detection output
Data bus
DD
V
SS
SVDON
SVDS4
|
SVDS0
Criteria voltage
setting circuit
SVD circuit
SVDDT
1.1 Configuration of SVD circuit
Figure 17.
SVD Operation
17.2
The SVD circuit compares the criteria voltage set by software and the supply voltage (V
DD
terminal–V
SS
terminal)
and sets its results into the SVDDT latch. By reading the data of this SVDDT latch, it can be determined by means
of software whether the supply voltage is normal or has dropped.
The criteria voltage can be selected from 29 types shown in Table 17.2.1 using the SVDS[4:0] register.
2.1 Criteria voltage
Table 17.
SVDS[4:0]
Criteria voltage (V)
SVDS[4:0]
Criteria voltage (V)
1FH
3.20
0FH
1.65
1EH
3.10
0EH
1.60
1DH
3.00
0DH
1.55
1CH
2.90
0CH
1.50
1BH
2.80
0BH
1.45
1AH
2.70
0AH
1.40
19H
2.60
09H
1.35
18H
2.50
08H
1.30
17H
2.40
07H
1.25
16H
2.30
06H
1.20
15H
2.20
05H
1.15
14H
2.10
04H
1.10
13H
2.00
03H
1.05
12H
1.90
02H
11H
1.80
01H
10H
1.70
00H
When the SVDON register is set to "1," supply voltage detection by the SVD circuit is executed. As soon as the SV-
DON register is reset to "0," the result is loaded to the SVDDT latch and the SVD circuit goes off.
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
When the SVD circuit is on, the IC draws a large current, so keep the SVD circuit off unless it is necessary.