TPS25751AS datasheet(46/85 Pages) TI2

46 / 85 page

Any number of data bytes can be transferred from the transmitter to receiver between the Start and the Stop

conditions. Each byte of eight bits is followed by one ACK bit. The transmitter must release the SDA line before

the receiver can send an ACK bit. The device that acknowledges must pull down the SDA line during the ACK

clock pulse, so that the SDA line is stable low during the high pulse of the ACK-related clock period. When a

target receiver is addressed, it must generate an ACK after each byte is received. Similarly, the controller must

generate an ACK after each byte that it receives from the target transmitter. Setup and hold times must be met

for proper operation.

A controller receiver signals an end of data to the target transmitter by not generating an acknowledge (NACK)

after the last byte has been clocked out of the target by holding the SDA line high. In this event, the transmitter

must release the data line to enable the controller to generate a Stop condition.

Figure 8-26 shows the start and stop conditions of the transfer. Figure 8-27 shows the SDA and SCL signals for

transferring a bit. Figure 8-28 shows a data transfer sequence with the ACK or NACK at the last clock pulse.

Start Condition

Stop Condition

SDA

SCL

Figure 8-26. I2C Definition of Start and Stop Conditions

Data Line

Change

SDA

SCL

Figure 8-27. I2C Bit Transfer

SCL from

Controller

Figure 8-28. I2C Acknowledgment

8.3.10.2.1.1 I2C Clock Stretching

The TPS25751A features clock stretching for the I2C protocol. The TPS25751A target I2C port can hold the clock

line (SCL) low after receiving (or sending) a byte, indicating that the bus is not yet ready to process more data.

The controller communicating with the target must not finish the transmission of the current bit and must wait

until the clock line actually goes high. When the target is clock stretching, the clock line remains low.

TPS25751A

SLVSJG7 – MAY 2026

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TPS25751AS Datasheet(PDF) 46 Page - Texas Instruments