ADT7317ARQ-REEL Analog Devices Inc, ADT7317ARQ-REEL Datasheet - Page 41

• Manufacturer Part Number: ADT7317ARQ-REEL
• Description: IC SENSOR TEMP 10BIT DAC 16QSOP
• Manufacturer: Analog Devices Inc

Specifications of ADT7317ARQ-REEL

• Rohs Status: RoHS non-compliant
• Function: Temp Monitoring System (Sensor)
• Topology: ADC, Comparator, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 120°C, External Sensor
• Output Type: I²C™, MICROWIRE™, QSPI™, SMBus™, SPI™
• Output Alarm: No
• Output Fan: No
• Voltage - Supply: 2.7 V ~ 5.5 V
• Operating Temperature: -40°C ~ 120°C
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP

LAYOUT CONSIDERATIONS
Digital boards can be electrically noisy environments, and
care must be taken to protect the analog inputs from noise,
particularly when measuring the very small voltages from a
remote diode sensor. Take the following precautions:
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Place the ADT7316/ADT7317/ADT7318 as close as
possible to the remote sensing diode. Provided that the
worst noise sources, such as clock generators, data/address
buses, and CRTs are avoided, this distance can be 4 inches
to 8 inches.
Route the D+ and D− tracks close together, in parallel, with
grounded guard tracks on each side. Provide a ground
plane under the tracks if possible.
Use wide tracks to minimize inductance and reduce noise
pickup. A 10 mil track minimum width and spacing is
recommended.
GND
GND
D+
D–
Figure 61. Arrangement of Signal Tracks
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
Rev. B | Page 41 of 44
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Try to minimize the number of copper/solder joints, which
can cause thermocouple effects. Where copper/ solder joints
are used, make sure that they are in both the D+ and D−
paths and at the same temperature. Thermocouple effects
should not be a major problem as 1°C corresponds to about
240 μV, and thermocouple voltages are about 3 μV/°C of
the temperature difference. Unless there are two thermo-
couples with a big temperature differential between them,
thermocouple voltages should be much less than 200 mV.
Place 0.1 μF bypass and 2200 pF input filter capacitors
close to the ADT7316/ADT7317/ADT7318.
If the distance to the remote sensor is more than 8 inches,
the use of the twisted pair cable is recommended. This
works for distances from 6 feet to 12 feet.
For really long distances (up to 100 feet), use shielded twisted
pair, such as Belden #8451 microphone cable. Connect the
twisted pair to D+ and D− and the shield to GND close to
the ADT7316/ADT7317/ADT7318. Leave the remote end
of the shield unconnected to avoid ground loops.
Because the measurement technique uses switched current
sources, excessive cable and/or filter capacitance can affect
the measurement. When using long cables, the filter capacitor
may be reduced or removed.
Cable resistance can also introduce errors. Series resistance
of 1 Ω introduces about 0.5°C error.
ADT7316/ADT7317/ADT7318