RS5C348A RICOH Co.,Ltd., RS5C348A Datasheet - Page 38

• Manufacturer Part Number: RS5C348A
• Description: 4-wire Serial Interface Real-time Clock
• Manufacturer: RICOH Co.,Ltd.

Rx5C348A/B
Rev.2.01
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:
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").
Connection of /INTR and 32KOUT Pin
/INTR or 32KOUT
Connection of CE Pin
12345
CONTROL
I/O
OSCOUT
OSCIN
VSB
VSS
I = 0.5 × (VDD or VCC) / Rp
32768Hz
A
B
SI
SO
SCLK
CE
System power supply
(VDD)
Backup power supply
(VCC)
*1)
VDD
CE
- 38 -
*1) Depending on whether the /INTR or 32KOUT
(1) Position A in the left diagram when it is not to
(2) Position B in the left diagram when it is to be
Min.0µs
pins are to be used during battery backup, it
should be connected to a pull-up resistor at
the following different positions:
be used during battery backup.
used during battery backup.
Min.0µs
Min.0µs
Lower limit operating
voltage for the CPU
0.2×VDD
Backup power supply