TMP275

SBOS363A − JUNE 2006 − REVISED JUNE 2006

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7

CONVERTER RESOLUTION (R1/R0)

The Converter Resolution Bits control the resolution of the

internal Analog-to-Digital (A/D) converter. This control

allows the user to maximize efficiency by programming for

higher resolution or faster conversion time. Table 8

identifies the Resolution Bits and the relationship between

resolution and conversion time.

R1

R0

RESOLUTION

CONVERSION TIME

(typical)

0

0

9 Bits (0.5

°C)

27.5ms

0

1

10 Bits (0.25

°C)

55ms

1

0

11 Bits (0.125

°C)

110ms

1

1

12 Bits (0.0625

°C)

220ms

Table 8. Resolution of the TMP275

ONE-SHOT (OS)

The

TMP275

features

a

One-Shot

Temperature

Measurement Mode. When the device is in Shutdown

Mode, writing a ‘1’ to the OS bit starts a single temperature

conversion. The device returns to the shutdown state at

the completion of the single conversion. This mode is

useful for reducing power consumption in the TMP275

when continuous temperature monitoring is not required.

When the configuration register is read, the OS always

reads zero.

HIGH AND LOW LIMIT REGISTERS

In Comparator Mode (TM = 0), the ALERT pin of the

TMP275 becomes active when the temperature equals or

number of faults according to fault bits F1 and F0. The

ALERT pin remains active until the temperature falls below

In Interrupt Mode (TM = 1), the ALERT pin becomes active

consecutive number of fault conditions. The ALERT pin

remains active until a read operation of any register

occurs, or the device successfully responds to the SMBus

Alert Response Address. The ALERT pin is also cleared

if the device is placed in Shutdown Mode. Once the ALERT

pin is cleared, it only becomes active again by the

remain active until cleared by a read operation of any

register or a successful response to the SMBus Alert

Response Address. Once the ALERT pin is cleared, the

above cycle repeats, with the ALERT pin becoming active

ALERT pin can also be cleared by resetting the device with

the General Call Reset command. This command also

clears the state of the internal registers in the device,

returning the device to Comparator Mode (TM = 0).

Both operational modes are represented in Figure 3.

first, followed by the least significant byte. Power-up reset

for the Temperature Register.

BYTE

D7

D6

D5

D4

D3

D2

D1

D0

1

H11

H10

H9

H8

H7

H6

H5

H4

BYTE

D7

D6

D5

D4

D3

D2

D1

D0

2

H3

H2

H1

H0

0

0

0

0

BYTE

D7

D6

D5

D4

D3

D2

D1

D0

1

L11

L10

L9

L8

L7

L6

L5

L4

BYTE

D7

D6

D5

D4

D3

D2

D1

D0

2

L3

L2

L1

L0

0

0

0

0

are used in the comparisons for the ALERT function for all

can affect the ALERT output even if the converter is

configured for 9-bit resolution.

SERIAL INTERFACE

The TMP275 operates only as a slave device on the

Two-Wire bus and SMBus. Connections to the bus are

made via the open-drain I/O lines SDA and SCL. The SDA

and SCL pins feature integrated spike suppression filters

and Schmitt triggers to minimize the effects of input spikes

and bus noise. The TMP275 supports the transmission

protocol for fast (1kHz to 400kHz) and high-speed (1kHz

to 3.4MHz) modes. All data bytes are transmitted MSB

first.

SERIAL BUS ADDRESS

To communicate with the TMP275, the master must first

address slave devices via a slave address byte. The slave

address byte consists of seven address bits, and a

direction bit indicating the intent of executing a read or

write operation.

The TMP275 features three address pins allowing up to

eight devices to be connected per bus. Pin logic levels are

described in Table 11. The address pins of the TMP275 are

read after reset, at start of communication, or in response

to a Two-Wire address acquire request. Following reading

the state of the pins the address is latched to minimize

power dissipation associated with detection.