SX8744 데이터 시트보기 (PDF) - Semtech Corporation
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SX8744 Datasheet PDF : 24 Pages
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SX8733/SX8743/SX8744
Digital temperature sensor
ADVANCED COMMUNICATIONS & SENSING
DATASHEET
3. Configuration
3.1. General Presentation
4
2
1 P1
P2
3
36
P3
2
P4
6
6
AL1
AL2
D1+
+
D1-
-
D2+
+
D2-
-
D3+
+
D3-
-
SX8733
SX8744
SX8743
ALARM
+
ADC
-
SMBUS
SMBCLK 4
SMBDAT 3
VDD 5
VSS 2
SX8733 / SX8743 / SX8744 include an on-
chip PN junction to measure local tempera-
ture TJ.
The device has a 2-level current source
and an ADC to measure each diode’s
forward voltage to compute the
temperature. The input multiplexer allows 3
external and 1 internal sensors to be
connected to the ADC.
Two alarms can provide to the system the
information that a sensor temperature has
8 reached the programmable threshold.
7 The chip is configured with a 2-wire
1 SMBUS serial line.
5 The functional diagram is shown in
Figure 2.
Figure 2. Functional Diagram
3.2. Modes
The mode set in RegConfig allows numerous circuit configurations described in Figure 3 and Figure 4.
Up to 3 external sensors can be connected. Theses are configured with differential or single-ended connections.
Some modes provide a track resistance cancellation feature to decrease temperature inaccuracy linked to long PCB traces
connecting the external sensor to the chip. This is set in RegControl (bits Point3 or Algo). Table 4 presents the mode for the
SX8743.
Mode
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 20
External sensor
11102211111222223331
Differential
xx
xx
xx
x
Single-ended
x
xxxx
x
xxxxxx
Algorithmic track resistance cancellation
x
x
x
x
x
x
x
3-point track resistance cancellation
x
x
x
x
Kelvin (4-wire) track resistance cancellation
x
Alarm #
00020011222002211100
Table 4 Features Available With SX8743
Due to their limited number of ports, SX8733 and SX8744 do not offer all theses features. SX8733 does not provide ports
P3 and P4 so modes 8 to 20 should not be used. Also port P3 is not available on SX8744 and this typically reduces the
number of alarm or the number of external sensors.
ACS Revision 2.91/February 2010
©2010 Semtech Corp.
Page 7
www.semtech.com
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