DA6512.003

2 December, 2016

25 (32)

VDD LEVEL MONITORING MODE

The MAS6512 has VDD level monitoring feature to

measure supply voltage level which is useful

especially in battery operated systems. In systems

in which VDD can vary the VDD level monitoring

could

be

also

used

to

compensate

VDD

dependency.

The VDD level monitoring measurement is started

by writing configuration data to the measurement

monitoring mode the regulator has to be disabled

(TEMPREGEN=0)

and

VDD

level monitoring

selected (SEL=01). The ratio and difference

converter bit (XRC) selection does not have any

influence on the result.

Typically the smallest over sampling ratio (OSR)

selection 256 offers sufficient resolution for the VDD

level monitoring.

VDD level monitoring model

The VDD level monitoring model for output code is following.











 





VDD

b

a

CODEFS

CODE

The output has inverse relationship to supply voltage VDD. The OSR selects full scale output code range value

CODEFS. See Electrical Characteristics for CODEFS at different OSR values.

The typical VDD level monitoring model parameter values a and b are as follows.

a=1.6375

b=2.6942

Note that these parameter values are subject to about two percent variations.

The supply voltage VDD can be solved from the output result as follows.

CODEFS

CODE

a

b

VDD





Figure 7 presents typical output code as function of supply voltage at OSR=256 (CODEFS=888).

Figure 8 present supply voltage as function of output code at OSR=256 (CODEFS=888).

100

200

300

400

500

600

700

800

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

VDD [V]

1.8

2

2.2

2.4

2.6

2.8

3

3.2

3.4

3.6

100

200

300

400

500

600

700

800

CODE [LSB]

Figure 7. CODE(VDD) at VDD level monitoring

Figure 8. VDD(CODE) at VDD level monitoring