Deviation Parameters
The deviation parameters V
ref(dev)
and I
ref(dev)
are defined as the differences between the maximum and minimum
values obtained over the recommended temperature range. The average full-range temperature coefficient of the
reference voltage, α
Vref
, is defined as:
where:
∆T
A
is the recommended operating free-air temperature range of the device.
can be positive or negative, depending on whether minimum V
ref
or maximum V
ref
, respectively, occurs at
the lower temperature.
Example: V
ref
= 2495 mV at 25°C, V
I(dev)
= 14 mV, ∆T
A
= 165°C for TL432B
Because minimum V
ref
occurs at the lower temperature, the coefficient is positive.
Dynamic Impedance
The dynamic impedance is defined as:
When the device is operating with two external resistors (see Figure 3), the total dynamic impedance of the circuit
is given by:
Maximum V
ref
Minimum V
ref
∆T
A
V
I(dev)
Ť
a
V
ref
Ť
ǒ
ppm
°C
Ǔ
+
ǒ
V
I
(
dev
)
V
ref
at 25°C
Ǔ
10
6
DT
A
Ť
a
V
ref
Ť
+
ǒ
14 mV
2495 mV
Ǔ
10
6
165°C
[ 34
ppm
°C
|
z
KA
|
+
DV
KA
DI
KA
|
zȀ
|
+
DV
DI
[
|
z
KA
|
ǒ
1 )
R1
R2
Ǔ
a
V
ref
TL432A-Q1
TL432B-Q1
www.ti.com
SLVS900A –NOVEMBER 2008–REVISED JULY 2012
Figure 1. Calculating Deviation Parameters and Dynamic Impedance
Copyright © 2008–2012, Texas Instruments Incorporated Submit Documentation Feedback 5
Product Folder Link(s): TL432A-Q1 TL432B-Q1
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