sx8744emstrt Semtech Corporation, sx8744emstrt Datasheet - Page 7

• Manufacturer Part Number: sx8744emstrt
• Description: Precision Diode Digital Temperature For Up To 3 External Sensors
• Manufacturer: Semtech Corporation

3. Configuration
3.1. General Presentation
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
External sensor
Differential
Single-ended
Algorithmic track resistance cancellation
3-point track resistance cancellation
Kelvin (4-wire) track resistance cancellation
Alarm #
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.
ADVANCED COMMUNICATIONS & SENSING
4
3
2
6
SX8743
2
3
6
SX8744
1
6
P3
P4
P1
P2
SX8733
D2-
D1+
D1-
D2+
D3+
D3-
AL2
AL1
+
+
-
+
-
-
Table 4 Features Available With SX8743
0
1
x
0
1
1
x
x
0
SMBUS
2
1
0
x
x
+
-
3
0
2
Page 7
ALARM
ADC
4
2
x
0
5
2
x
x
0
SMBCLK
SMBDAT
SX8733/SX8743/SX8744
VDD
VSS
Precision Diode Digital Temperature
6
1
1
x
4
3
5
2
7
1
1
x
x
8
7
1
5
8
1
2
x
For Up To 3 External Sensors
SX8733 / SX8743 / SX8744 include an on-
chip PN junction to measure local tempera-
ture T
The device has a 2-level current source
and an ADC to measure each diode’s
forward
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
reached the programmable threshold.
The chip is configured with a 2-wire
SMBUS serial line.
The functional diagram is shown in
Figure 2.
9
1
2
x
x
10 11 12 13 14 15 16 17 18 20
1
2
x
x
J
.
2
0
x
voltage
2
x
x
0
2
x
2
2
x
x
2
to
www.semtech.com
DATASHEET
2
x
x
1
compute
3
x
1
3
x
x
1
3
x
x
0
the
1
x
x
0