PCT2075DP datasheet(13/37 Pages) NXP

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PCT2075

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Product data sheet

Rev. 9.1 — 21 April 2017

13 of 37

NXP Semiconductors

PCT2075

I2C-bus Fm+ digital temperature sensor and thermal watchdog

When a set-point register is read, all 16 bits are provided to the bus and must be collected

by the controller for a valid temperature. However, only the 9 most significant bits should

be used and the 7 LSB of the LSByte are equal to zero and should be ignored.

A single byte read of either Tos or Thyst is allowed.

Table 15 shows examples of the limit data and value.

7.4.5 Tidle register

For the device temperature sensor, the temperature is measured periodically to save

power. When the temperature is being measured, the device burns approximately 70

A

active current. Since the ambient temperature changes slowly, it is unnecessary to let the

temperature measurement continuously active. Instead, the device temperature sensor is

set to idle for a user-specified time to save power after temperature measurement is done.

The Tidle register allows users to specify the sampling period to measure the

temperature. The register is composed of 5-bit values TIDLE[4:0] at pointer address 04h.

The values of TIDLE[7:5] are ‘don’t care’ and have no effect on the temperature

measurement period. The temperature measurement period can be calculated by

TIDLE[4:0]

 100 ms. For example, if TIDLE[4:0] = 00001, the temperature sampling is

‘00001’

 100 ms = 100 ms. the temperature sensor allows a sampling period from

100 ms to 3.1 s by programming Tidle. If Tidle is set to ‘00000’, it will be treated the same

as Tidle = ‘00001’ and the temperature sensor will measure temperature at 100 ms

period.

Table 14.

Thyst register

MSByte

LSByte

Table 15.

Tos and Thyst limit data and value

11-bit binary

(two’s complement)

Hexadecimal value

Decimal value

Value

0 1111 1010

0FA

250

+125.0

C

0 0011 0010

032

+25.0

C

0 0000 0001

001

+0.5

C

0 0000 0000

000

0.0

C

1 1111 1111

1FF

1

0.5 C

1 1100 1110

1CE

50

25.0 C

1 1001 0010

192

110

55.0 C

Table 16.

Tidle - Temperature idle register (address 04h) bit allocation

Temperature idle register contains the value of time in between temperature measurements.

TIDLE[4:0] is the 5-bit Tidle value. Tidle

 100 ms is the temperature sampling period.

Bit

Symbol

TIDLE[4]

TIDLE[3]

TIDLE[2]

TIDLE[1]

TIDLE[0]

Reset

0001

Access

R/W

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