CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (SVD Circuit)

4.13 SVD (Supply Voltage Detection) Circuit

4.13.1 Configuration of SVD circuit

The S1C63558 has a built-in SVD (supply voltage detection) circuit, so that the software can find when the source voltage lowers. It is possible to check an external voltage drop, other than the supply voltage, by mask option.

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.

VDD

SVD

 

 

 

Detection output

 

 

 

SVD circuit

 

SVDDT

 

terminal

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SVDON

 

 

 

VSS

 

 

 

 

 

 

 

 

 

 

 

 

Criteria voltage

 

SVDS3

 

 

 

 

 

 

 

 

 

 

 

setting circuit

 

 

 

 

 

 

 

SVDS0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Data bus

Fig. 4.13.1.1 Configuration of SVD circuit

4.13.2 Mask option

Besides the supply voltage (VDD terminal–VSSterminal) drop detection, the SVD circuit can detect the external voltage (SVD terminal–VSSterminal) input from the SVD terminal by comparing it with the detected voltage (1.05 V). This function can select whether or not to use with the mask option.

4.13.3 SVD operation

The SVD circuit compares the criteria voltage set by software and the supply voltage (VDD terminal–VSSterminal) or the external voltage (SVD terminal–VSSterminal) 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 set for the 12 types shown in Table 4.13.3.1 by the SVDS3–SVDS0 registers. When "0" is written to the SVDS3–SVDS0 register, the supply voltage detection voltage is set to 2.20 V. However, when "External voltage detection" is selected by mask option, the SVD circuit does not compare the supply voltage (VDD terminal–VSSterminal) but compares between the external voltage (SVD termi- nal–VSSterminal) input from the SVD terminal and 1.05 V.

Table 4.13.3.1 Criteria voltage setting

SVDS3

SVDS2

SVDS1

SVDS0

Criteria

voltage (V)

 

 

 

 

 

0

1

1

1

2.50

0

1

1

0

2.40

0

1

0

1

2.30

0

1

0

0

2.20

0

0

1

1

2.20

0

0

1

0

2.20

0

0

0

1

2.20

0

0

0

0

2.20/1.05

 

 

 

 

 

Criteria

SVDS3 SVDS2 SVDS1 SVDS0 voltage (V)

1

1

1

1

3.30

1

1

1

0

3.20

1

1

0

1

3.10

1

1

0

0

3.00

1

0

1

1

2.90

1

0

1

0

2.80

1

0

0

1

2.70

1

0

0

0

2.60

S1C63558 TECHNICAL MANUAL

EPSON

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