LM75B_2

© NXP B.V. 2008. All rights reserved.

Product data sheet

Rev. 02 — 9 December 2008

5 of 29

NXP Semiconductors

LM75B

Digital temperature sensor and thermal watchdog

In OS comparator mode, the OS output behaves like a thermostat. It becomes active

Reading the device registers or putting the device into shutdown does not change the

state of the OS output. The OS output in this case can be used to control cooling fans or

thermal switches.

In OS interrupt mode, the OS output is used for thermal interruption. When the device is

it remains active indefinitely until being reset by a read of any register. Once the OS output

by a read of any register. The OS interrupt operation would be continued in this sequence:

device into the shutdown mode by setting the bit 0 of the configuration register also resets

the OS output.

In both cases, comparator mode and interrupt mode, the OS output is activated only if a

number of consecutive faults, defined by the device fault queue, has been met. The fault

queue is programmable and stored in the two bits, B3 and B4, of the Configuration

register. Also, the OS output active state is selectable as HIGH or LOW by setting

accordingly the configuration register bit B2.

The temp reading data is not available until the first conversion is completed in about

100 ms.

The OS response to the temperature is illustrated in Figure 5.

(1) OS is reset by either reading register or putting the device in shutdown mode. It is assumed that

Fig 5.

OS response to temperature

002aae334

(1)

(1)

(1)

OS reset

OS active

OS reset

OS active

OS output in comparator mode

OS output in interrupt mode

reading temperature limits