Rx5C348A/B
ꢁ
Voltage Monitoring Circuit
The supply monitoring circuit is configured to conduct a sampling operation during an interval of 7.8ms per
second to check for a drop in supply voltage below a threshold voltage of 2.1 or 1.6v for the VDSL bit setting of 0
(the default setting) or 1, respectively, in the Control Register 2, thus minimizing supply current requirements as
illustrated in the timing chart below. This circuit suspends a sampling operation once the VDET bit is set to 1 in
the Control Register 2. The supply voltage monitor is useful for back-up battery checking.
VDD
2.1v or 1.6v
7.8ms
XSTP
Internal
initialization
period
1s
(1 to 2sec.)
Sampling timing for
VDD supply voltage
VDET
(D6 in Address Fh)
VDET←0
XSTP←0
VDET←0
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Rev.2.01
- 33 -
RICOH [ RICOH ELECTRONICS DEVICES DIVISION ]
