PCT2075DP datasheet(10/37 Pages) NXP

10 / 37 page

PCT2075

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Product data sheet

Rev. 3 — 21 May 2013

10 of 37

NXP Semiconductors

PCT2075

I2C-bus Fm+ digital temperature sensor and thermal watchdog

7.4.1 Pointer register

The Pointer register contains an 8-bit data byte, of which the three LSB bits represent the

pointer value of the other five registers, and the other five MSB bits are equal to 0, as

shown in Table 8 and Table 9. The Pointer register is not accessible to the user, but is

used to select the data register for write/read operation by including the pointer data byte

in the bus command.

Because the Pointer value is latched into the Pointer register when the bus command

(which includes the pointer byte) is executed, a read from the device may or may not

include the pointer byte in the statement. To read again a register that has been recently

read and the pointer has been preset, the pointer byte does not have to be included. To

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

must be included. However, a write to the device must always include the pointer byte in

the statement. The bus communication protocols are described in Section 7.10.

At power-up, the Pointer value is equal to 000b and the Temp register is selected; users

can then read the Temp data without specifying the pointer byte.

Anything not shown in Table 9 is reserved and should not be used.

Table 8.

Pointer register

B[2:0]

00000pointer value

Table 9.

Pointer value

Selected register

Temperature register (Temp)

Configuration register (Conf)

Hysteresis register (Thyst)

Overtemperature shutdown register (Tos)

Idle register (Tidle)

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