TMP37FSZ Analog Devices Inc, TMP37FSZ Datasheet - Page 8

• Manufacturer Part Number: TMP37FSZ
• Description: IC SENSOR TEMP 2.7/5.5V 8SOIC
• Manufacturer: Analog Devices Inc

Specifications of TMP37FSZ

• Sensing Temperature: 5°C ~ 100°C
• Output Type: Voltage
• Voltage - Supply: 2.7 V ~ 5.5 V
• Accuracy: ±1°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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 V
by the following relationship:
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 V
Q1 as an offset term in V
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.
Δ
V
BE
=
V
T
×
ln
⎛
⎜
⎜
⎝
A
A
BE
E,Q1
E,Q2
OUT
of Q1 and the V
. Table 4 summarizes the differences
⎞
⎟
⎟
⎠
BE
of Q2 are not equal
BE
Rev. F | Page 8 of 20
of
Table 4. TMP3x Output Characteristics
Sensor
TMP35
TMP36
TMP37
SHUTDOWN
V
GND
+V
OUT
Figure 22. Temperature Sensor Simplified Equivalent Circuit
S
Q4
Offset
Voltage (V)
0
0.5
0
Output Voltage
Scaling (mV/°C)
10
10
20
6X
10X
Q1
Q3
7.5µA
Q2
1X
R3
25µA
3X
Output Voltage
@ 25°C (mV)
250
750
500
R1
R2
2X
2X