Datasheet

CONFIGURATION REGISTER CONVERSION RATE
EXTENDED MODE (EM)
Startup Startof
Conversion
Delay
(1)
26ms
26ms
ALERT (AL Bit)
SHUTDOWN MODE (SD)
THERMOSTAT MODE (TM)
TMP112
www.ti.com ......................................................................................................................................................... SBOS473B – MARCH 2009 – REVISED JUNE 2009
The Configuration Register is a 16-bit read/write The conversion rate bits, CR1 and CR0, configure the
register used to store bits that control the operational TMP112 for conversion rates of 8Hz, 4Hz, 1Hz, or
modes of the temperature sensor. Read/write 0.25Hz. The default rate is 4Hz. The TMP112 has a
operations are performed MSB first. The format and typical conversion time of 26ms. To achieve different
power-up/reset values of the Configuration Register conversion rates, the TMP112 makes a conversion
are shown in Table 7 . For compatibility, the first byte and then powers down and waits for the appropriate
corresponds to the Configuration Register in the delay set by CR1 and CR0. Table 8 shows the
TMP75 and TMP275 . All registers are updated byte settings for CR1 and CR0.
by byte.
Table 8. Conversion Rate Settings
Table 7. Configuration and Power-Up/Reset
CR1 CR0 CONVERSION RATE
Formats
0 0 0.25Hz
BYTE D7 D6 D5 D4 D3 D2 D1 D0
0 1 1Hz
OS R1 R0 F1 F0 POL TM SD
1 0 4Hz (default)
1
0 1 1 0 0 0 0 0
1 1 8Hz
CR1 CR0 AL EM 0 0 0 0
2
After a power-up or general-call reset, the TMP112
1 0 1 0 0 0 0 0
immediately starts a conversion, as shown in
Figure 12 . The first result is available after 26ms
(typical). The active quiescent current during
The Extended mode bit configures the device for conversion is 40 µ A (typical at +27 ° C). The quiescent
Normal mode operation (EM = 0) or Extended mode current during delay is 2.2 µ A (typical at +27 ° C).
operation (EM = 1). In Normal mode, the
Temperature Register and high- and low-limit
registers use a 12-bit data format. Normal mode is
used to make the TMP112 compatible with the
TMP75 .
Extended mode (EM = 1) allows measurement of
temperatures above +128 ° C by configuring the
Temperature Register, and high- and low-limit
registers, for 13-bit data format.
(1) Delay is set by CR1 and CR0.
Figure 12. Conversion Start
The AL bit is a read-only function. Reading the AL bit
provides information about the comparator mode
status. The state of the POL bit inverts the polarity of
data returned from the AL bit. For POL = 0, the AL bit
reads as '1' until the temperature equals or exceeds
The Shutdown mode bit saves maximum power by
T
HIGH
for the programmed number of consecutive
shutting down all device circuitry other than the serial
faults, causing the AL bit to read as '0'. The AL bit
interface, reducing current consumption to typically
continues to read as '0' until the temperature falls
less than 0.5 µ A. Shutdown mode is enabled when
below T
LOW
for the programmed number of
the SD bit = '1'; the device shuts down when current
consecutive faults, when it again reads as '1'. The
conversion is completed. When SD = '0', the device
status of the TM bit does not affect the status of the
maintains a continuous conversion state.
AL bit.
The Thermostat mode bit indicates to the device
whether to operate in Comparator mode (TM = 0) or
Interrupt mode (TM = 1). For more information on
Comparator and Interrupt modes, see the High- and
Low-Limit Registers section.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 9
Product Folder Link(s): TMP112