RX5C348A Datasheet, PDF (38/45 Pages) RICOH electronics devices division – 4-WIRE SERIAL INTERFACE

Rx5C348A/B
Connection of /INTR and 32KOUT Pin
The /INTR pin follows the N-channel open drain output logic and contains no protective diode on the power
supply side. As such, it can be connected to a pull-up resistor of up to 5.5v regardless of supply voltage.
The 32KOUT pin follows the N-channel open drain output logic, too. However, it contains protective diode on the
power supply side. As such, it cannot be connected to a pull-up resistor over VDD+0.3v. Such connection
involves considerations for the supply current requirements of a pull-up resistor, which can be roughly calculated
by the following equation:
I = 0.5 × (VDD or VCC) / Rp
/INTR or 32KOUT
OSCIN
OSCOUT
VSB
VSS
System power supply
(VDD)
A
*1)
B
32768Hz
Backup power supply
(VCC)
*1) Depending on whether the /INTR or 32KOUT
pins are to be used during battery backup, it
should be connected to a pull-up resistor at
the following different positions:
(1) Position A in the left diagram when it is not to
be used during battery backup.
(2) Position B in the left diagram when it is to be
used during battery backup.
Connection of CE Pin
Connection of the CE pin requires the following considerations:
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 0v.
2) The CE pin should also be driven low or open immediately upon the host going down (see "P.25
Considerations in Reading and Writing Time Data under special condition").
I/O
CONTROL
SCLK
SI
SO
CE
VDD
CE
Lower limit operating
voltage for the CPU
Backup power supply
0.2×VDD
Min.0µs Min.0µs Min.0µs
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Rev.2.01
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