RV5C339A_03 Datasheet, PDF (40/46 Pages) RICOH electronics devices division – 3-WIRE SERIAL INTERFACE REAL-TIME CLOCK IC WITH VOLTAGE MONITORING FUNCTION

RV5C339A
6.4 Connection of CE Pin
Observe the following precautions when you connect the CE pin.
1) The CE pin is configured to enable the oscillation halt sensing circuit only when driven low. As such, it should be
driven low or open at power-on from 0 volts.
2) The CE pin should also be driven low or open immediately upon the host going down (see “1.5 Considerations in
Reading and Writing Time Count Data”).
3) The reading function should be disrupted when the CE signal goes to “low” during read cycle. While, the upper 4
bits of the data might be written to the inner shift register when the CE signal goes to “low” during write cycle.
(Because the writing function is executed 4 bits by 4 bits.) In either case, after the CE signal returns to “High”,
no trouble will occur in the next read or write cycle.
I/O
CONTROL
2 SCLK
3 SIO
7 CE
Lower limit operating voltage
for the CPU
VDD
Backup voltage
CE
0.2×VDD
MIN. 0µs MIN. 0µs MIN. 0µs
40