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TMP36FS-REEL View Datasheet(PDF) - Analog Devices

Part Name
Description
Manufacturer
TMP36FS-REEL
ADI
Analog Devices ADI
TMP36FS-REEL Datasheet PDF : 20 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
TMP35/TMP36/TMP37
FUNCTIONAL DESCRIPTION
An equivalent circuit for the TMP3x family of micropower,
centigrade temperature sensors is shown in Figure 22. The core
of the temperature sensor is a band gap core that comprises
transistors Q1 and Q2, biased by Q3 to approximately 8 μA. The
band gap core operates both Q1 and Q2 at the same collector
current level; however, because the emitter area of Q1 is 10
times that of Q2, the VBE of Q1 and the VBE of Q2 are not equal
by the following relationship:
ΔVBE
= VT
× ln⎜⎜⎝⎛
AE,Q1
AE,Q2
⎟⎞
⎟⎠
Resistors R1 and R2 are used to scale this result to produce
the output voltage transfer characteristic of each temperature
sensor and, simultaneously, R2 and R3 are used to scale the VBE of
Q1 as an offset term in VOUT. Table 4 summarizes the differences
in the output characteristics of the three temperature sensors.
The output voltage of the temperature sensor is available at the
emitter of Q4, which buffers the band gap core and provides
load current drive. The current gain of Q4, working with the
available base current drive from the previous stage, sets the
short-circuit current limit of these devices to 250 μA.
+VS
SHUTDOWN
25µA
3X 2X
Q2
Q4
1X
R1
Q1
10X
R3
VOUT
R2
7.5µA
Q3
2X
6X
GND
Figure 22. Temperature Sensor Simplified Equivalent Circuit
Table 4. TMP3x Output Characteristics
Offset
Output Voltage
Sensor Voltage (V) Scaling (mV/°C)
TMP35 0
10
TMP36 0.5
10
TMP37 0
20
Output Voltage
@ 25°C (mV)
250
750
500
Rev. F | Page 8 of 20
 

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