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CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (SVD Circuit)
4.13 SVD (Supply Voltage Detection) Circuit
4.13.1 Configuration of SVD circuit
The S1C6P366 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 4.13.1.1 shows the configuration of the SVD circuit.
4.13.2 SVD operation
The SVD circuit compares the criteria voltage set by software and the supply voltage (V
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 set for the 2 types shown in Table 4.13.2.1 by the SVDS3–SVDS0 registers.
SVDS3
SVDS2
0
1
0
1
0
1
0
1
0
0
0
0
0
0
0
0
Be aware that the SVD circuit in the S1C6P366 does not operate properly if the SVDS register is set to 13
or less, the SVD operation cannot be guaranteed since the lower limit of the operating voltage is 2.7 V.
When the SVDON register is set to "1", source voltage detection by the SVD circuit is executed. As soon as
the SVDON 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 l00 µsec. So, to obtain the SVD
detection result, follow the programming sequence below.
1. Set SVDON to "1"
2. Maintain for 100 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.
92
V
DD
Detection output
SVD circuit
V
SS
Criteria voltage
setting circuit
Fig. 4.13.1.1 Configuration of SVD circuit
Table 4.13.2.1 Criteria voltage setting
Criteria
SVDS1
SVDS0
voltage ( V )
1
1
Not allowed
1
0
Not allowed
0
1
Not allowed
0
0
Not allowed
1
1
Not allowed
1
0
Not allowed
0
1
Not allowed
0
0
Not allowed
SVDDT
SVDON
SVDS3
|
SVDS0
SVDS3
SVDS2
SVDS1
1
1
1
1
1
1
1
1
1
0
1
0
1
0
1
0
EPSON
–V
) and sets
DD
SS
Criteria
SVDS0
voltage ( V )
1
1
2.80
1
0
2.70
0
1
Not allowed
0
0
Not allowed
1
1
Not allowed
1
0
Not allowed
0
1
Not allowed
0
0
Not allowed
S1C6P366 TECHNICAL MANUAL
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