SA56004GD datasheet(18/36 Pages) NXP

18 / 36 page

SA56004X_5

Product data sheet

Rev. 05 — 22 May 2008

18 of 36

NXP Semiconductors

SA56004X

Digital temperature sensor with overtemperature alarms

LOW. Furthermore, if the Remote HIGH Setpoint High Byte (RHSHB) register is set to a

value less than +127

°C and the Alert Mask is disabled, then the ALERT output will be

pulled LOW. Note that the OPEN bit itself will not trigger an ALERT.

When the D+ pin is shorted to ground or to D

−, the Remote Temperature High Byte

(RTHB) register is loaded with

−128 °C (1000 0000) and the OPEN (bit 2 in the Status

temperature reading represents this shorted fault condition. If the value in the Remote

Low Setpoint High Byte (RLSHB) register is more than

−128 °C and the Alert Mask is

disabled, the ALERT output will be pulled LOW.

7.10 SMBus interface

The device can communicate over a standard two-wire serial interface System

Management Bus (SMBus) or compatible I2C-bus using SCLK and SDATA. The device

employs four standard SMBus protocols: Write Byte, Read Byte, Receive Byte, and

Send Byte. Data formats of four protocols are shown in Figure 9. The following key points

of protocol are important:

• The SMBus master initiates data transfer by establishing a START condition (S) and

terminates data transfer by generating a STOP condition (P).

• Data is sent over the serial bus in sequences of 9 clock pulses according to each 8-bit

data byte followed by 1-bit status of device acknowledgement (A).

• The 7-bit slave address is equivalent to factory-programmed address of the device.

• The command byte is equivalent to the address of the selected device register.

• The Receive Byte format is used for quicker transfer data from a device reading

SA56004GD Datasheet(PDF) 18 Page - NXP Semiconductors