RV5C339A Datasheet, PDF (24/51 Pages) RICOH electronics devices division – 3-WIRE SERIAL INTERFACE REAL-TIME CLOCK ICs WITH VOLTAGE MONITORING FUNCTION

RV5C339A
USAGES
1. Data Transfer Formats
1.1 Timing Between CE Pin Transition and Data Input/Output
The RV5C339A adopts a 3-wire serial interface by which it uses the CE (Chip Enable), SCLK (Serial Clock), and SIO
(Serial Input/Output), pins to receive and send data to and from the CPU. The 3-wire serial interface provides two
types of input/output timings with which the output and input from the SIO pin output and input are synchronized
with the rising and falling edges of the SCLK pin input, respectively, and vice versa. The RV5C339A is configured to
select either one of two different input/output timings depending on the level of the SCLK pin in the low to high
transition of the CE pin. Namely, when the SCLK pin is held low in the low to high transition of the CE pin, the
models will select the timing with which the output and input from the SIO pin are synchronized with the rising and
falling edges of the SCLK pin input, respectively, as illustrated in the timing chart below.
tCES
CE
SCLK
tDS _tDH
tRD
SIO
(Input to the real-time clock)
SIO
(Output from the real-time clock)
Conversely, when the SCLK pin is held high in the low to high transition of the CE pin, the models will select the
timing with which the output and input from the SIO pin are synchronized with the falling and rising edges of the
SCLK pin input, respectively as illustrated in the timing chart below.
tCES
CE
SCLK
tDS tDH
SIO
tRD
(Input to the real-time clock)
SIO
(Output from the real-time clock)
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