TEMPERATURE REGISTERS

STATUS REGISTER

CONFIGURATION REGISTER 1

TMP441

TMP442

The TMP441/42 have four 8-bit registers that hold

The

Status

Register

reports

the

state

of

the

temperature measurement results. Both the local

temperature

ADCs.

Table

4 shows

the

Status

channel and the remote channel have a high byte

Register bits. The Status Register is read-only, and is

register that contains the most significant bits (MSBs)

read by accessing pointer address 08h. The BUSY bit

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

= '1' if the ADC is making a conversion; it is set to '0'

result and a low byte register that contains the least

if the ADC is not converting.

significant bits (LSBs) of the temperature ADC result.

The local channel high byte address is 00h; the local

channel low byte address is 10h. The remote channel

Configuration Register 1 (pointer address 09h) sets

high byte is at address 01h; the remote channel low

the temperature range and controls shutdown mode.

byte address is 11h. For the TMP442, the second

The Configuration Register is set by writing to pointer

remote channel high byte address is 02h; the second

address 09h and read by reading from pointer

remote channel low byte is 12h. These registers are

address 09h. The shutdown (SD) bit (bit 6) enables or

read-only and are updated by the ADC each time a

disables the temperature measurement circuitry. If

temperature measurement is completed.

SD = '0', the TMP441/42 convert continuously at the

The TMP441/42 contain circuitry to assure that a low

rate set in the conversion rate register. When SD is

byte register read command returns data from the

set to '1', the TMP441/42 stop converting when the

same ADC conversion as the immediately preceding

current conversion sequence is complete and enters

high byte read command. This condition remains

a shutdown mode. When SD is set to '0' again, the

valid only until another register is read. For proper

TMP441/42 resume continuous conversions. When

operation, the high byte of a temperature register

SD = '1', a single conversion can be started by writing

should be read first. The low byte register should be

to the One-Shot Register.

read in the next read command. The low byte register

The temperature range is set by configuring bit 2 of

may be left unread if the LSBs are not needed.

the Configuration Register. Setting this bit low

Alternatively, the temperature registers may be read

configures

the

TMP441/42

for

the

standard

as a 16-bit register by using a single two-byte read

measurement range (–55°C to +127°C); temperature

command from address 00h for the local channel

conversions are stored in the standard binary format.

result, or from address 01h for the remote channel

Setting bit 2 high configures the TMP441/42 for the

result (02h for the second remote channel result).

extended measurement range (–55°C to +150°C);

The high byte is output first, followed by the low byte.

temperature conversions are stored in the extended

Both bytes of this read operation are from the same

binary format (see Table 1). The remaining bits of the

ADC conversion. The power-on reset value of all

Configuration Register are reserved and must always

temperature registers is 00h.

be set to '0'. The power-on reset value for this

register is 00h. Table 5 summarizes the bits of

Configuration Register 1.

Table 4. Status Register Format

STATUS REGISTER (Read = 08h, Write = NA)

BIT #

D7

D6

D5

D4

D3

D2

D1

D0

BIT NAME

BUSY

0

0

0

0

0

0

0

POR VALUE

0

0

0

0

0

0

0

(1)

The BUSY changes to '1' almost immediately (< 100

µs) following power-up, as the TMP441/42 begins the first temperature conversion.

It is high whenever the TMP441/42 converts a temperature reading.

Table 5. Configuration Register 1 Bit Descriptions

CONFIGURATION REGISTER 1 (Read/Write = 09h, POR = 00h)

BIT

NAME

FUNCTION

POWER-ON RESET VALUE

7

Reserved

—

0

0 = Run

6

SD

0

1 = Shut down

5, 4, 3

Reserved

—

0

0 = –55°C to +127°C

2

Temperature Range

0

1 = –55°C to +150°C

1, 0

Reserved

—

0

12

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