LM75BDP View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

Manufacturer

LM75BDP

Digital temperature sensor and thermal watchdog

NXP Semiconductors. 

NXP Semiconductors

LM75B

Digital temperature sensor and thermal watchdog

7.2 I2C-bus serial interface

The LM75B can be connected to a compatible 2-wire serial interface I2C-bus as a slave

device under the control of a controller or master device, using two device terminals, SCL

and SDA. The controller must provide the SCL clock signal and write/read data to/from the

device through the SDA terminal. Notice that if the I2C-bus common pull-up resistors have

not been installed as required for I2C-bus, then an external pull-up resistor, about 10 k,

is needed for each of these two terminals. The bus communication protocols are

described in Section 7.10.

7.2.1 Bus fault time-out

If the SDA line is held LOW for longer than tto (75 ms minimum / 13.3 Hz; guaranteed at

50 ms minimum / 20 Hz), the LM75B will reset to the idle state (SDA released) and wait

for a new START condition. This ensures that the LM75B will never hang up the bus

should there be conflict in the transmission sequence.

7.3 Slave address

The LM75B slave address on the I2C-bus is partially defined by the logic applied to the

device address pins A2, A1 and A0. Each of them is typically connected either to GND for

logic 0, or to VCC for logic 1. 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 LM75B. Table 4 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 and A2 to A0, are not internally biased, it is important that they should not

be left floating in any application.

Table 4. Address table

1 = HIGH; 0 = LOW.

MSB

LSB

1

0

0

1

A2

A1

A0

7.4 Register list

The LM75B contains four data registers beside the pointer register as listed in Table 5.

The pointer value, read/write capability and default content at power-up of the registers

are also shown in Table 5.

Table 5. Register table

Register Pointer R/W

name value

Conf

01h

R/W

Temp 00h

read only

Tos

03h

R/W

Thyst 02h

R/W

POR

state

00h

n/a

5000h

4B00h

Description

Configuration register: contains a single 8-bit data

byte; to set the device operating condition; default = 0.

Temperature register: contains two 8-bit data bytes;

to store the measured Temp data.

Overtemperature shutdown threshold register:

contains two 8-bit data bytes; to store the

overtemperature shutdown Tth(ots) limit;

default = 80 C.

Hysteresis register: contains two 8-bit data bytes;

to store the hysteresis Thys limit; default = 75 C.

LM75B

Product data sheet

All information provided in this document is subject to legal disclaimers.

Rev. 6.1 — 6 February 2015

© NXP B.V. 2015. All rights reserved.

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