LM75B_2

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 02 — 9 December 2008

15 of 29

NXP Semiconductors

LM75B

Digital temperature sensor and thermal watchdog

8.

Application design-in information

8.1 Typical application

8.2 LM75A and LM75B comparison

[1]

This option is updated to be compatible with the competitive parts. When the OS output has been activated in the interrupt mode due to

a temp limit violation, if the Configuration Shutdown bit B0 is set (to the LM75A), then the OS output activated status remains

unchanged, while (to the LM75B) the OS will be reset. The latter is compatible with the operation condition of the competitive parts.

[2]

The LM75 series is intentionally designed to provide two successive temperature data bytes (MSByte and LSByte) for the 11-bit data

resolution and both bytes should be read in a typical application. In some specific applications, when only the MSByte is read using a

single-byte read command, it often happens that if bit D7 of the LSByte is zero, then the device will hold the SDA bus in a LOW state

forever, resulting in a bus hang-up problem, and the bus cannot be released until the device power is reset. This condition exists for the

LM75A but not for the LM75B. For the LM75B the temperature can be read either one byte or two bytes without a hang-up problem.

[3]

The bus time-out is included for releasing the LM75B device operation whenever the SDA input is kept at a LOW state for too long

frequency operation to be limited to 20 Hz. This option is compatible with some of the latest versions of the competitive parts.

[4]

Fig 12. Typical application

002aad457

0.1

µF

10 k

Ω

DIGITAL LOGIC

LM75B

DETECTOR OR

INTERRUPT LINE

BUS

PULL-UP

RESISTORS

8

2

SCL

SDA

A2

A1

A0

5

6

1

7

4

3

OS

power supply

GND

10 k

Ω

10 k

Ω

Table 14.

LM75A and LM75B comparison

Description

LM75A

LM75B

availability of the XSON8U (3 mm

× 2 mm) package type

no

yes

OS output auto-reset when SHUTDOWN bit is set in interrupt mode[1]

no

yes

support single-byte reading of the Temp registers without bus lockup[2]

no

yes

bus fault time-out (75 ms, 200 ms)[3]

no

yes

10 ns

0 ns

ratio of conversion time / conversion period (typical)[5]

100 ms / 100 ms

10 ms / 100 ms

supply current in shutdown mode (typical value)

3.5

µA

0.2

µA

HBM ESD protection level (minimum)

>2000 V

>4500 V

MM ESD protection level (minimum)

>200 V

>450 V

CDM ESD protection level (minimum)

>1000 V

>2000 V