TMP435 datasheet(13/35 Pages) TI1

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TMP435

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SBOS495A – MARCH 2010 – REVISED APRIL 2010

Pointer Register

Limit Registers

Figure 14 shows the internal register structure of the

The TMP435 has registers for setting comparator

TMP435. The 8-bit Pointer Register is used to

limits for both the local and remote measurement

address a given data register. The Pointer Register

channels. These registers have read and write

identifies which of the data registers should respond

capability. The High and Low Limit Registers for both

to a read or write command on the two-wire bus. This

channels span two registers, as do the temperature

registers. The local temperature high limit is set by

command must be issued to set the proper value in

writing the high byte to pointer address 0Bh and

the

Pointer

before

executing

read

writing the low byte to pointer address 16h, or by

command. Table 3 describes the pointer address of

using a single two-byte write command (high byte

the registers available in the TMP435. The power-on

first) to pointer address 0Bh.

reset (POR) value of the Pointer Register is 00h

The local temperature high limit is obtained by

(0000 0000b).

reading the high byte from pointer address 05h and

the low byte from pointer address 16h, or by using a

Temperature Registers

two-byte read command from pointer address 05h.

The power-on reset value of the local temperature

The TMP435 has four 8-bit registers that hold

high limit is 55h/00h (+85°C in standard temperature

temperature measurement results. Both the local

mode; +21°C in extended temperature mode).

channel and the remote channel have a high byte

Similarly, the local temperature low limit is set by

of the temperature analog-to-digital converter (ADC)

writing the high byte to pointer address 0Ch and

result and a low byte register that contains the least

writing the low byte to pointer address 17h, or by

significant bits (LSBs) of the temperature ADC result.

using a single two-byte write command to pointer

The local channel high byte address for the TMP435

address 0Ch. The local temperature low limit is read

is 00h; the local channel low byte address is 15h. The

by reading the high byte from pointer address 06h

remote channel high byte is at address 01h; the

and the low byte from pointer address 17h, or by

remote channel low byte address is 10h. These

using a two-byte read from pointer address 06h. The

registers are read-only and are updated by the ADC

power-on reset value of the local temperature low

each time a temperature measurement is completed.

limit register is 00h/00h (0°C in standard temperature

mode; –64°C in extended mode).

The TMP435 contains circuitry to assure that a low

byte register read command returns data from the

The remote temperature high limit for the TMP435 is

same

analog-to-digital

(A/D)

conversion

the

set by writing the high byte to pointer address 0Dh

immediately preceding high byte read command. This

and writing the low byte to pointer address 13h, or by

assurance remains valid only until another register is

using a two-byte write command to pointer address

read. For proper operation, the high byte of a

0Dh. The remote temperature high limit is obtained

temperature register should be read first. The low

by reading the high byte from pointer address 07h

byte register should be read in the next read

and the low byte from pointer address 13h, or by

command. The low byte register may be left unread if

using a two-byte read command from pointer address

the

LSBs

are

not

needed.

Alternatively,

the

07h. The power-on reset value of the Remote

temperature registers may be read as a 16-bit

Temperature High Limit Register is 55h/00h (+85°C in

standard temperature mode; +21°C in extended

from address 00h for the local channel result, or from

temperature mode).

address 01h for the remote channel result (23h for

the second remote channel result). The high byte is

The remote temperature low limit for the TMP435 is

output first, followed by the low byte. Both bytes of

set by writing the high byte to pointer address 0Eh

this

read

operation

are

from

the

same

A/D

and writing the low byte to pointer address 14h, or by

conversion.

The

power-on

reset

value

both

using a two-byte write to pointer address 0Eh. The

temperature registers is 00h.

remote temperature low limit is read by reading the

high byte from pointer address 08h and the low byte

from pointer address 14h, or by using a two-byte read

from pointer address 08h. The power-on reset value

of the Remote Temperature Low Limit Register is

00h/00h (0°C in standard temperature mode; –64°C

in extended mode).

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