Datasheet

Measured
Temperature
THERMLimitandALERTHighLimit
ALERTLowLimitandTHERMLimitHysteresis
THERM
ALERT
SMBusALERT
Read Read
Time
Read
TMP431
TMP432
SBOS441F –SEPTEMBER 2009–REVISED AUGUST 2013 www.ti.com
Figure 23. SMBus Alert Timing Diagram
If multiple devices on the bus respond to the SMBus
Alert command, arbitration during the slave address
UNDERVOLTAGE LOCKOUT
portion of the SMBus Alert command determines
The TMP431/32 sense when the power-supply
which device clears its alert status. If the TMP431/32
voltage has reached a minimum voltage level for the
win the arbitration, the ALERT pin becomes inactive
ADC to function. The detection circuitry consists of a
at the completion of the SMBus Alert command. If the
voltage comparator that enables the ADC after the
TMP431/32 lose the arbitration, the ALERT pin
power supply (V+) exceeds 2.45V (typical). The
remains active.
comparator output is continuously checked during a
conversion. The TMP431/32 do not perform a
SHUTDOWN MODE (SD)
temperature conversion if the power supply is not
The TMP431/32 shutdown mode allows the user to valid. The last valid measured temperature is used for
save maximum power by shutting down all device the temperature measurement result.
circuitry other than the serial interface, reducing
current consumption to typically less than 3µA; see
GENERAL CALL RESET
typical characteristic curve Shutdown Quiescent
The TMP431/32 support reset via the Two-Wire
Current vs Supply Voltage (Figure 6). Shutdown
General Call address 00h (0000 0000b). The
mode is enabled when the SD bit of the Configuration
TMP431/32 acknowledge the General Call address
Register 1 is high; the device shuts down
and respond to the second byte. If the second byte is
immediately, aborting the current conversion. When
06h (0000 0110b), the TMP431/32 execute a
SD is low, the device maintains a continuous
software reset. This software reset restores the
conversion state.
power-on reset state to all TMP431/32 registers,
aborts any conversion in progress, and clears the
SENSOR FAULT
ALERT and THERM pins. The TMP431/32 take no
The TMP431/32 can sense a fault at the DXP input action in response to other values in the second byte.
that results from an incorrect diode connection or an
open circuit. The detection circuitry consists of a
FILTERING
voltage comparator that trips when the voltage at
Remote junction temperature sensors are usually
DXP exceeds (V+) – 0.6V (typical). The comparator
implemented in noisy environments. Noise is
output is continuously checked during a conversion. If
frequently generated by fast digital signals and if not
a fault is detected, the last valid measured
filtered properly can induce errors that corrupt
temperature is used for the temperature
temperature measurements. The TMP431/32 have a
measurement result, the OPEN bit (Status Register,
built-in 65kHz filter on the inputs of DXP and DXN to
bit 2) is set high, and, if the alert function is enabled,
minimize the effects of noise. However, a differential
ALERT asserts low.
low-pass filter can help attenuate unwanted coupled
When not using the remote sensor with the
signals. Exact component values are application-
TMP431/32, the DXP and DXN inputs must be
specific. It is also recommended that the capacitor
connected together to prevent meaningless fault
value remains between 0pF to 2200pF with a series
warnings.
resistance less than 1kΩ.
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