TMP411CD datasheet(15/32 Pages) TI

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TMP411

SBOS383C − DECEMBER 2006 − REVISED MAY 2008

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SOFTWARE RESET

The TMP411 may be reset by writing any value to Pointer

of the TMP411 registers as well as abort any conversion

in process and clear the ALERT and THERM pins.

The TMP411 also supports reset via the two-wire general

call address (00000000). The TMP411 acknowledges the

general call address and responds to the second byte. If

the second byte is 00000110, the TMP411 executes a

software reset. The TMP411 takes no action in response

to other values in the second byte.

CONSECUTIVE ALERT REGISTER

The value in the Consecutive Alert Register (address 22h)

determines

how

many

consecutive

out-of-limit

measurements must occur on a measurement channel

before the ALERT signal is activated. The value in this

of one, two, three, or four consecutive conversions can be

selected; one conversion is the default. This function

allows additional filtering for the ALERT pin. The

consecutive alert bits are shown in Table 9.

Table 9. Consecutive Alert Register

CONSECUTIVE ALERT REGISTER

(READ = 22h, WRITE = 22h, POR = 01h)

NUMBER OF CONSECUTIVE

OUT-OF-LIMIT MEASUREMENTS

NOTE: Bit 7 of the Consecutive Alert Register controls the

enable/disable of the timeout function. See the Timeout

Function section for a description of this feature.

THERM HYSTERESIS REGISTER

The THERM Hysteresis Register, shown in Table 11,

stores the hysteresis value used for the THERM pin alarm

function. This register must be programmed with a value

that is less than the Local Temperature High Limit Register

value, Remote Temperature High Limit Register value,

Local THERM Limit Register value, or Remote THERM

Limit

value;

otherwise,

the

respective

temperature comparator will not trip on the measured

temperature falling edges. Allowable hysteresis values

are shown in Table 10. The default hysteresis value is

°C, whether the device is operating in the standard or

extended mode setting.

Table 10. Allowable THERM Hysteresis Values

THERM HYSTERESIS VALUE

TEMPERATURE

(

°C)

TH[11:4]

(STANDARD BINARY)

(HEX)

0000 0000

0000 0001

0000 0101

0000 1010

0001 1001

0011 0010

0100 1011

100

0110 0100

125

0111 1101

127

0111 1111

150

1001 0110

175

1010 1111

200

1100 1000

225

1110 0001

255

1111 1111

BUS OVERVIEW

The TMP411 is SMBus interface-compatible. In SMBus

protocol, the device that initiates the transfer is called a

master, and the devices controlled by the master are

slaves. The bus must be controlled by a master device that

generates the serial clock (SCL), controls the bus access,

and generates the START and STOP conditions.

To address a specific device, a START condition is

initiated. START is indicated by pulling the data line (SDA)

from a high to low logic level while SCL is high. All slaves

on the bus shift in the slave address byte, with the last bit

indicating whether a read or write operation is intended.

During the ninth clock pulse, the slave being addressed

responds to the master by generating an Acknowledge

and pulling SDA low.

Data transfer is then initiated and sent over eight clock

pulses followed by an Acknowledge bit. During data

transfer SDA must remain stable while SCL is high,

because any change in SDA while SCL is high is

interpreted as a control signal.

Once all data has been transferred, the master generates

a STOP condition. STOP is indicated by pulling SDA from

low to high, while SCL is high.

TMP411CD Datasheet(PDF) 15 Page - Texas Instruments

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