Figure 7. SMBus Alert Timing Diagram

General Call Reset

The TMP112B

responds to the two-wire general call address 00h. The device acknowledges the

general call address and responds to commands in the second byte. If the second byte is 06h, the

TMP112B resets the internal registers to the power-up reset values, and aborts the current temperature

conversion. If the second byte is other value, the TMP112B will not respond.

High-Speed Mode

SCL

SDA

START by

Master

0

0

0

1

1

0

0

R/W

1

0

0

1

0

A1

A0

STATUS

NACK by

Master

1

9

1

9

STOP by

Master

ALERT

Time-Out Function

The TMP112B resets the serial interface if SCL is held low for 30ms (typical) between a START and STOP

condition, the TMP112B

releases the SDA bus and waits for a START condition. To avoid activating

the Time-Out function, a communication speed of at least 1kHz must be maintained.

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ACK by

Frame 1 SMBus ALERT Response Address Byte

Frame 2 Slave Address From TMP112B

UMW

R

TMP112B

For the two-wire bus to operate at frequencies above 400kHz, the host device must issue a High-Speed mode

host code (0000 1xxxb) as the first byte after a START condition to switch the bus to high-speed operation. The

TMP112B device does not acknowledge this byte, but it does switch the input filters on the SDA and SCL and the

output filters on the SDA to operate in High-Speed mode, allowing the bus to transmit data at frequencies up to

2.75MHz. After the High-Speed mode host code is issued, the host transmits a two-wire device address to initiate a

data transfer operation. The bus continues to operate in High-Speed mode until a STOP condition occurs on

the bus. Upon receiving the STOP condition, the TMP112B switches the input and output filters back to fast-mode

operation.