AB-RTC-XLA-32.768kHz-2

Ultra-Low Power RTC Module

Revision: Initial Release

9/9/2025

Page 5

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I2C BUS Timing Characteristics

Caution:

When communicating with the AB-RTC-XLA-32.768kHz-2 module, the series of operations from transmitting the

START (or repeated START) condition to transmitting the STOP (or repeated START) condition should occur within 1

second. If this series of operations requires 1 second or more, the I2C-bus interface will be automatically cleared and

set to standby mode by the bus timeout function of the AB-RTC-XLA-32.768kHz-2 module.

SYMBOL

PARAMETER

MIN

MAX

UNIT

fSCL

SCL input clock frequency

0

400

kHz

tLOW

Low period of SCL clock

1.3

µs

tHIGH

High period of SCL clock

0.6

µs

tRISE

Rise time of SDA and SCL

20

300

ns

tFALL

Fall time of SDA and SCL

20 x (VDD / 5.5V)

300

ns

tHD:STA

START condition hold time

0.6

µs

tSU:STA

START condition setup time

0.6

µs

tSU:DAT

SDA setup time

100

ns

tHD:DAT

SDA hold time

0

µs

tSU:STO

STOP condition setup time

0.6

µs

tBUF

Bus free time before a new transmission

1.3

µs

tVD:DAT

Data valid time

0

0.9

µs

tVD:ACK

Data valid acknowledge time

0

0.9

µs

tSP

Spike pulse width

0

50

ns

Cb

Capacitive load for each bus line

400

pF

S = Start condition, Sr = Repeated Start condition, P = Stop condition

I2C AC Characteristics (VDD = 1.8, to 5.5V TA = -40 to +85°C)