Philips Semiconductors

Product data sheet

SE95

Ultra high accuracy digital temperature sensor and

thermal Watchdog

™

2004 Dec 21

10

The SE95 can be connected to a compatible 2-wire serial interface

device, using two device terminals, SCL and SDA. The controller

must provide the SCL clock signal and write/read data to/from the

then an external pull-up resistor, about 10 k

Ω, is needed for each of

these two terminals. The bus communication protocols are

described in the data communication section.

Slave address

logic applied to the device address pins A2, A1 and A0. Each pin is

These pins represent the three LSB bits of the device 7-bit address.

The other four MSB bits of the address data are preset to ‘1001’ by

hard wiring inside the SE95. Table 1 shows the device’s complete

address and indicates that up to 8 devices can be connected to the

same bus without address conflict. Because the input pins, SCL,

SDA, A2–A0, are not internally biased, it is important that they

should not be left floating in any application.

Table 1. Address table

1 = HIGH, 0 = LOW

MSB

LSB

1

0

0

1

A2

A1

A0

Register list

The SE95 contains 7 data registers. The registers can be 1 byte or

2 bytes wide, and are defined in Table 2. The registers are accessed

communication. The types of registers are: read only, read/write,

and reserved for manufacturer use. Note that when reading a

two-byte register, the host must provide enough clock pulses as

for the device to completely return both data bytes. Otherwise the

device may hold the SDA line as LOW state, resulting in a bus hang

condition.

Register pointer

The register pointer or pointer byte is an 8-bit data byte that is

used to identify the device register to be accessed for a write or read

operation. Its values are listed as pointer values in Table 2, “Register

byte may or may not need to be included within the command as

communication” on page 14.

The command statements of writing data to a register must always

include the pointer byte; while the command statements of reading

data from a register may or may not include it. To read a register that

is different from the one that has been recently read, the pointer byte

must be included. However, to re-read a register that has been

recently read, the pointer byte may not have to be included in the

reading.

At power-up, the pointer value is preset to ‘0’ for the Temp Register;

users can then read the temperature without specifying the pointer

byte.

Table 2. Register table

Register name

Pointer value

R/W

POR state

Description

Conf

01H

R/W

00H

Configuration Register.

Contains a single 8-bit data byte. To set an operating condition.

Temp

00H

Read only

N/A

Temperature Register.

Contains two 8-bit data bytes. To store the measured Temp data.

Tos

03H

R/W

50 00H

Over-temp Shutdown threshold Register.

Contains two 8-bit data bytes. To store the over-temp shut-down Tos limit.

Default = 80

°C.

Thyst

02H

R/W

4B 00H

Hysteresis Register.

Contains two 8-bit data bytes. To store the hysteresis Thyst limit.

B7–B0 are also used in OTP test mode to supply OTP write data.

Default = 75

°C.

ID

05H

Read only

A1H

ID Register.

Contains a single 8-bit data byte for the manufacturer ID code.

reserved

04H

N/A

N/A

Reserved.

reserved

06H

N/A

N/A

Reserved.