rs5c62 RICOH Co.,Ltd., rs5c62 Datasheet - Page 22

• Manufacturer Part Number: rs5c62
• Description: Real-time Clock
• Manufacturer: RICOH Co.,Ltd.

18
RP/RF/RS5C62
1.2 Writing Operation
forming the process of addressing through the A3 to A0 pin inputs, then [3] driving low the CS pin, [4] causing the
WR pin to transition from its high to low to high levels, and thereby [5] causing the D3 to D0 pins to input data to be
written. The writing timing is shown in the chart below.
2. Handling of CE Pin
ing the system power supply (see the typical power supply circuit), the CE pin must be driven low before the voltage
across the system power supply drops below the lower limit to the operating voltage of the CPU (at the point ( [1] )
in the timing chart below) and then driven high after the supply voltage rises above the lower limit to the operating
voltage of the CPU (at the point ( [2] ) in the timing chart below).
*
*
*
*
The requirements for writing data to the internal registers and counters are: [1] holding the CE pin high, [2] per-
Normally, the CE pin is connected to the supply voltage detection circuit of the system power supply. In switch-
1) The CS and WR pin inputs are interchangeable. The diagonally shaded sections marked in the above timing chart may be set to both high and low
2) “
3) “
) The CE pin must be driven as low as the V
held low).
levels. (Consequently, the CS and WR pin inputs may be caused to transition from their high to low levels before the process of addressing.)
are driven low.
input is driven high.
t
t
AS
AH
(WR)” indicates the time required to perform the process of addressing before the start of write operation at which both the WR and CS pin inputs
(WR)” indicates the time required to maintain the result of addressing after the completion of write operation at which either the WR or CS pin
WR
VDD
CS
(Write Data)
CE
D0 to D3
A0 to A3
or
Voltage across system
power supply
WR
CS
CE
0.2VDD
[1]
SS
t
pin whenever possible in order to minimize battery consumption in battery backup (while the CE pin is
CES
MIN.0µs
t
[3]
AS(WR)
[2]
Lower limit to operating voltage of CPU
[1]
[4]
Battery voltage
t
[5]
t
DS
W
Valid
MIN.0µs
t
t
AH(WR)
DH
t
CEH
[2]
0.2VDD