SA56004X_5

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 05 — 22 May 2008

5 of 36

NXP Semiconductors

SA56004X

Digital temperature sensor with overtemperature alarms

7.

Functional description

Refer to Figure 1 “Block diagram”.

7.1 Serial bus interface

The SA56004X should be connected to a compatible two-wire serial interface System

Management Bus (SMBus) as a slave device using the two device terminals SCLK and

SDATA. The ALERT pin can optionally be used with the SMBus protocol to implement the

ARA response. The controller will provide a clock signal to the device SCLK pin and

write/read data to/from the device through the device SDATA pin. External pull-up

resistors, about 10 k

Ω each, are needed for these device pins due to open-drain circuitry.

Data of 8-bit digital byte or word are used for communication between the controller and

the device using SMBus 2.0 protocols which are described more in Section 7.10 “SMBus

interface”. The operation of the device to the bus is described with details in the following

sections.

7.2 Slave address

The SA56004X has a 7-bit slave address register which is factory programmed in OTP

memory. Eight unique devices are available with different slave addresses as defined in

Table 2 “Ordering options”. Up to eight devices can reside on the same SMBus without

conflict, provided that their addresses are unique.

7.3 Register overview

The SA56004X contains three types of SMBus addressable registers. These are

read-only (R), write-only (W), and read-write (R/W). Attempting to write to any R-only

register or read data from any W-only register will produce an invalid result. Some of the

R/W registers have separate addresses for reading and writing operations.

The registers of the SA56004X serve four purposes:

Table 4 describes the names, addresses, Power-On Reset (POR), and functions of each

register. The data of the temperature-related registers is in 2’s complement format in

which the MSB is the sign bit. The 8-bit data of other registers is in 8-bit straight format.