TMP400 datasheet(7/25 Pages) TI

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DIFFERENTIAL INPUT CAPACITANCE

TEMPERATURE MEASUREMENT DATA

POINTER REGISTER

ResolutionRegister

ConfigurationRegister

StatusRegister

IdentificationRegisters

ConsecutiveAlertRegister

LocalTemperatureMin/Max

ConversionRateRegister

RemoteTemperatureMin/Max

LocalandRemoteLimitRegisters

LocalandRemoteTemperatureRegisters

SDA

SCL

PointerRegister

I/O

Control

Interface

TMP400

SBOS404 – DECEMBER 2007

byte

stores

the

decimal

fraction

value

the

temperature

and

allows

higher

measurement

The TMP400 tolerates differential input capacitance

resolution.

The

measurement

resolution

for

the

of up to 1000pF if RC = 1 (if RC = 0, input

remote channel is 0.0625

°C, and is not adjustable.

capacitance can be as high as 2200pF) with minimal

The measurement resolution for the local channel is

change

temperature

error.

The

effect

adjustable; it can be set for 0.5

°C, 0.25°C, 0.125°C,

capacitance on sensed remote temperature error is

or 0.0625

°C by setting the RES1 and RES0 bits of

illustrated in the typical characteristic curve, Remote

the Resolution Register; see the Resolution Register

Temperature

Error

Differential

Capacitance

section (Table 5).

(Figure 6).

The TMP400 contains multiple registers for holding

Temperature measurement data are taken over a

configuration information, temperature measurement

default range of –55

°C to +127.9375°C for both local

results, temperature comparator maximum/minimum,

and remote locations.

limits, and status information. These registers are

described in Figure 12 and Table 2.

Temperature data resulting from conversions within

the default measurement range are represented in

binary form, as shown in Table 1, Binary column.

Note that any temperature above

+127.9375

°C

Figure 12 shows the internal register structure of the

results

value

127.9375

(7Fh/F0h).

TMP400. The 8-bit Pointer Register is used to

Temperatures below –65

°C results in a value of –65

address a given data register. The Pointer Register

(BF/00h). The TMP400 is specified only for ambient

identifies which of the data registers should respond

temperatures

ranging

from

–40

°C to +125°C.

to a read or write command on the Two-Wire bus.

Parameters in the Absolute Maximum Ratings table

This register is set with every write command. A write

must be observed.

command must be issued to set the proper value in

the

Pointer

before

executing

read

Table 1. Temperature Data Format

command. Table 2 describes the pointer address of

REMOTE TEMPERATURE REGISTER

the registers available in the TMP400. The power-on

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

DIGITAL OUTPUT

(BINARY)

(0000 0000b).

TEMPERATURE

(

°C)

HIGH BYTE

LOW BYTE

HEX

128

0111 1111

1111 0000

7F/F0

127.9375

0111 1111

1111 0000

7F/F0

100

0110 0100

0000 0000

64/00

0101 0000

0000 0000

50/00

0100 1011

0000 0000

4B/00

0011 0010

0000 0000

32/00

0001 1001

0000 0000

19/00

0.25

0000 0000

0100 0000

00/40

0000 0000

00/00

–0.25

1111 1111

1100 0000

FF/C0

–25

1110 0111

0000 0000

E7/00

–55

1100 1001

0000 0000

C9/00

–65

1011 1111

0000 0000

BF/00

Both local and remote temperature data use two

Figure 12. Internal Register Structure

bytes for data storage. The high byte stores the

temperature with 1

°C resolution. The second (or low)

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