Datasheet

"#$$
SBOS383C − DECEMBER 2006 − REVISED MAY 2008
www.ti.com
6
APPLICATIONS INFORMATION
The TMP411 is a dual-channel digital temperature sensor
that combines a local die temperature measurement
channel and a remote junction temperature measurement
channel in a single MSOP-8 or SO-8 package. The
TMP411 is Two-Wire- and SMBus interface-compatible
and is specified over a temperature range of −40°C to
+125°C. The TMP411 contains multiple registers for
holding configuration information, temperature
measurement results, temperature comparator
maximum/minimum limits, and status information.
User-programmed high and low temperature limits stored
in the TMP411 can be used to trigger an over/under
temperature alarm (ALERT
) on local and remote
temperatures. Additional thermal limits can be
programmed into the TMP411 and used to trigger another
flag (THERM
) that can be used to initiate a system
response to rising temperatures.
The TMP411 requires only a transistor connected between
D+ and D− for proper remote temperature sensing
operation. The SCL and SDA interface pins require pull-up
resistors as part of the communication bus, while ALERT
and THERM are open-drain outputs that also need pull−up
resistors. ALERT
and THERM may be shared with other
devices if desired for a wired-OR implementation. A 0.1µF
power-supply bypass capacitor is recommended for good
local bypassing. Figure 11 shows a typical configuration
for the TMP411.
0.1
µ
F
10k
Ω
(typ)
10k
Ω
(typ)
10k
Ω
(typ)
10k
Ω
(typ)
TMP411
D+
D
−
V+
1
8
7
6
4
5
3
2
R
S
(2)
R
S
(2)
C
DIFF
(3)
C
DIFF
(3)
R
S
(2)
R
S
(2)
GND
SCL
SDA
ALERT/THERM2
THERM
+5V
SMBus
Controller
Fan Controller
Diode−connected configuration
(1)
:
Series Resistance
Transistor−connected configuration
(1)
:
(1) Diode−connected configuration provides better settling time.
Transistor−connected configuration provides better series resistance cancellation.
(2) R
S
(optional) should be < 1.5k
Ω
in most applications. Selection of R
S
depends on
specific application; see Filtering section.
(3) C
DIFF
(optional) should be < 1000pF in most applications. Selection of C
DIFF
depends on specific application; see Filtering section and Figure 6, Remote
Temperature Error vs Differential Capacitance.
NOTES:
Figure 11. Basic Connections