Datasheet

POLARITY (POL) CONVERTER RESOLUTION (R1/R0)
ONE-SHOT/CONVERSION READY (OS)
HIGH- AND LOW-LIMIT REGISTERS
Measured
Temperature
T
HIGH
T
LOW
TMP112 ALERTPIN
(ComparatorMode)
POL=0
TMP112 ALERTPIN
(InterruptMode)
POL=0
TMP112 ALERTPIN
(ComparatorMode)
POL=1
TMP112 ALERTPIN
(InterruptMode)
POL=1
Read Read
Time
Read
FAULT QUEUE (F1/F0)
TMP112
SBOS473B – MARCH 2009 – REVISED JUNE 2009 ......................................................................................................................................................... www.ti.com
The Polarity bit allows the user to adjust the polarity R1/R0 are read-only bits. The TMP112 converter
of the ALERT pin output. If POL = 0, the ALERT pin resolution is set on start up to '11'. This sets the
becomes active low, as shown in Figure 13 . For POL temperature register to a 12 bit-resolution.
= 1, the ALERT pin becomes active high, and the
state of the ALERT pin is inverted.
The TMP112 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. During the conversion, the
OS bit reads '0'. The device returns to the shutdown
state at the completion of the single conversion. After
the conversion, the OS bit reads '1'. This feature is
useful for reducing power consumption in the
TMP112 when continuous temperature monitoring is
not required.
As a result of the short conversion time, the TMP112
can achieve a higher conversion rate. A single
conversion typically takes 26ms and a read can take
place in less than 20 µ s. When using One-Shot mode,
30 or more conversions per second are possible.
In Comparator mode (TM = 0), the ALERT pin
becomes active when the temperature equals or
exceeds the value in T
HIGH
and generates a
consecutive number of faults according to fault bits
F1 and F0. The ALERT pin remains active until the
temperature falls below the indicated T
LOW
value for
Figure 13. Output Transfer Function Diagrams
the same number of faults.
In Interrupt mode (TM = 1), the ALERT pin becomes
active when the temperature equals or exceeds the
value in T
HIGH
for a consecutive number of fault
A fault condition exists when the measured
conditions (as shown in Table 9 ). The ALERT pin
temperature exceeds the user-defined limits set in the
remains active until a read operation of any register
T
HIGH
and T
LOW
registers. Additionally, the number of
occurs, or the device successfully responds to the
fault conditions required to generate an alert may be
SMBus Alert Response address. The ALERT pin is
programmed using the fault queue. The fault queue is
also cleared if the device is placed in Shutdown
provided to prevent a false alert as a result of
mode. Once the ALERT pin is cleared, it becomes
environmental noise. The fault queue requires
active again only when temperature falls below T
LOW
,
consecutive fault measurements in order to trigger
and remains active until cleared by a read operation
the alert function. Table 9 defines the number of
of any register or a successful response to the
measured faults that may be programmed to trigger
SMBus Alert Response address. Once the ALERT
an alert condition in the device. For T
HIGH
and T
LOW
pin is cleared, the above cycle repeats, with the
register format and byte order, see the High- and
ALERT pin becoming active when the temperature
Low-Limit Registers section.
equals or exceeds T
HIGH
. The ALERT pin can also be
cleared by resetting the device with the General Call
Table 9. TMP112 Fault Settings
Reset command. This action also clears the state of
F1 F0 CONSECUTIVE FAULTS
the internal registers in the device, returning the
device to Comparator mode (TM = 0).
0 0 1
0 1 2
1 0 4
1 1 6
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