DA6512.003
2 December, 2016
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.
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.
The VDD level monitoring measurement is started
by writing configuration data to the measurement
control register (E2/62HEX). In the VDD level
VDD level monitoring model
The VDD level monitoring model for output code is following.
b
CODE CODEFS a
VDD
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.
b
VDD
CODE
a
CODEFS
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).
800
700
600
500
400
300
200
100
3.6
3.4
3.2
3
2.8
2.6
2.4
2.2
2
1.8
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
VDD [V]
CODE [LSB]
Figure 7. CODE(VDD) at VDD level monitoring
Figure 8. VDD(CODE) at VDD level monitoring
25 (32)
MAS [ MICRO ANALOG SYSTEMS ]
