SA56004AD NXP Semiconductors, SA56004AD Datasheet - Page 17

• Manufacturer Part Number: SA56004AD
• Description: Board Mount Temperature Sensors I2C LOC +/- 2OC AND REM +/- 1OC TS
• Manufacturer: NXP Semiconductors

Specifications of SA56004AD

• Full Temp Accuracy: +/- 1 C, +/- 3 C
• Package / Case: SOT-96
• Digital Output - Bus Interface: I2C
• Digital Output - Number Of Bits: 11 bit
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Output Type: Digital
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: SA56004AD,112

NXP Semiconductors
SA56004X_5
Product data sheet
7.9.4 Remote diode selection
7.9.5 Diode fault detection
To measure the remote temperature or the temperature of an externally attached diode,
the device automatically forces two successive currents of about 160 A and 10 A at D+
pin. It measures the voltage (V
two V
the basic PTAT voltage formula as shown in
38 ms to perform a measurement during each conversion period or cycle, which is
selectable by programming the conversion rate register.
Where:
Because the device does not directly convert the sensed V
temperature measurement systems, the V
device remote temperature error is adjusted at the manufacturer to meet the specifications
with the use of the reference diode-connected transistors such as the 2N3904/2N3906.
The diode type to be used in customer applications must have the characteristics as close
to the 2N3904/2N3906 as possible in order to obtain optimal results. Finally, to prevent the
effects of system noise on the measured V
2200 pF connected between the D+ and D pins as well as the grounded-shield cable for
the diode connection wires are recommended.
The SA56004X is designed with circuitry to detect the fault conditions of the remote diode.
When the D+ pin is shorted to V
register is loaded with +127 C, the Remote Temperature Low Byte (RTLB) register is
loaded with 0 C, and the OPEN bit (bit 2 of the Status register) is set. Under the above
conditions of D+ shorted to V
+127 C, and T_CRIT Mask are disabled, then, the T_CRIT output pins will be pulled
V
Event F: Three consecutive measurements have been made with the remote
temperature below the RCS
HIGH).
Event G: The remote temp falls below the Remote LOW setpoint.
Event H: Three consecutive measurements are made with the temp below the Remote
LOW setpoint; ALERT output is activated (goes LOW).
Event I: The ALERT output is de-activated (goes HIGH) after a above_low_limit
temperature measurement is completed.
n = diode ideality factor
k = Boltzmann’s constant
T = absolute temperature ( K) = 273 C + T ( C)
q = electron charge
ln = natural logarithm
l2, l1 = two source currents
BE
BE
=
voltages or the V
n
kT
------
q
ln
l2
---- -
l1
Rev. 05 — 22 May 2008
BE
DD
Digital temperature sensor with overtemperature alarms
and then converts the V
BE
DD
or floating, if the Remote T_CRIT setpoint is set less than
TH threshold; the T_CRIT output is de-activated (goes
) between D+ and D , detects the difference between the
or floating, the Remote Temperature High Byte (RTHB)
BE
BE
Equation
calibration is not required. Furthermore, the
signals, an external capacitor of about
1. The device typically takes about
BE
into a temperature data using
BE
as in the old method of
SA56004X
© NXP B.V. 2008. All rights reserved.
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