Datasheet

TMP411-Q1
SBOS527F –DECEMBER 2010–REVISED NOVEMBER 2013 www.ti.com
HIGH-SPEED MODE
masked. The ALERT/THERM2 pin can also be
configured for use as THERM2, a second THERM pin
For the two-wire bus to operate at frequencies above
(Configuration Register: AL/TH bit = 1). The default
400 kHz, the master device must issue a high-speed
setting configures pin 6 to function as ALERT (AL/TH
mode (Hs-mode) master code (00001XXX) as the
= 0).
first byte after a START condition to switch the bus to
high-speed operation. The TMP411-Q1 does not
The THERM pin asserts low when either the
acknowledge this byte, but switches the input filters
measured local or remote temperature is outside of
on SDA and SCL and the output filter on SDA to
the temperature range programmed in the
operate in Hs-mode, allowing transfers at up to 3.4
corresponding Local or Remote THERM Limit
MHz. After the Hs-mode master code has been
Register. The THERM temperature limit range can be
issued, the master transmits a two-wire slave address
programmed with a wider range than that of the limit
to initiate a data transfer operation. The bus
registers, which allows ALERT to provide an earlier
continues to operate in Hs-mode until a STOP
warning than THERM. The THERM alarm resets
condition occurs on the bus. Upon receiving the
automatically when the measured temperature
STOP condition, the TMP411-Q1 switches the input
returns to within the THERM temperature limit range
and output filters back to fast-mode operation.
minus the hysteresis value stored in the THERM
Hysteresis Register. The allowable values of
TIME-OUT FUNCTION
hysteresis are shown in Table 11. The default
hysteresis is 10°C. When the ALERT/THERM2 pin is
When bit 7 of the Consecutive Alert Register is set
configured as a second thermal alarm (Configuration
high, the TMP411-Q1 time-out function is enabled.
Register: bit 7 = 0, bit 5 = 1), it functions the same as
The TMP411-Q1 resets the serial interface if either
THERM, but uses the temperatures stored in the
SCL or SDA is held low for 30 ms (typical) between a
Local/Remote Temperature High/Low Limit Registers
START and STOP condition. If the TMP411-Q1 is
to set its comparison range.
holding the bus low, it releases the bus and waits for
a START condition. To avoid activating the time-out
When ALERT/THERM2 (pin 6) is configured as
function, it is necessary to maintain a communication
ALERT (Configuration Register: bit 7 = 0, bit 5 = 0),
speed of at least 1 kHz for the SCL operating
the pin asserts low when either the measured local or
frequency. The default state of the time-out function
remote temperature violates the range limit set by the
is enabled (bit 7 = high).
corresponding Local/Remote Temperature High/Low
Limit Registers. This alert function can be configured
THERM (PIN 4) AND ALERT/THERM2 (PIN 6)
to assert only if the range is violated a specified
number of consecutive times (1, 2, 3, or 4). The
The TMP411-Q1 has two pins dedicated to alarm
consecutive violation limit is set in the Consecutive
functions, the THERM and ALERT/THERM2 pins.
Alert Register. False alerts that occur as a result of
Both pins are open-drain outputs that each require a
environmental noise can be prevented by requiring
pullup resistor to V+. These pins can be wire-ORed
consecutive faults. ALERT also asserts low if the
together with other alarm pins for system monitoring
remote temperature sensor is open-circuit. When the
of multiple sensors. The THERM pin provides a
MASK function is enabled (Configuration Register: bit
thermal interrupt that cannot be software-disabled.
7 = 1), ALERT is disabled (that is, masked). ALERT
The ALERT pin is intended for use as an earlier
resets when the master reads the device address, as
warning interrupt, and can be software disabled, or
long as the condition that caused the alert no longer
persists, and the Status Register has been reset.
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