Datasheet

www.ti.com
TRANSIENT PROTECTION OUTPUT VOLTAGE RANGE
INPUT FILTERING
Gain Error% + 100 *
ǒ
100
5kW
5kW ) R
FILT
Ǔ
(3)
Load
1
2
3
4
5
6
7
14
13
12
11
10
9
8
1.2V REF OUT
CMP1 OUT
CMP2 OUT
CMP2 DELAY
CMP1
RESET
V
IN+
V
IN–
OUT
CMP1 IN+
CMP2 IN–
CMP2 IN+/0.6V REF
GND
INA206–INA208
SO--14, TSSOP--14
1.2V REF
CMP1IN–/0.6VREF
V
S
R
SHUNT
<<R
3m
FILTER
W
R
FILTER
<100W R
FILTER
<100W
V
SUPPLY
C
FILTER
f
–3dB
f
–3dB
=
1
2 (2R Cp
FILTER FILTER
)
INA206
INA207
INA208
SBOS360E – JUNE 2006 – REVISED OCTOBER 2007
The – 16V to +80V common-mode range of the The output of the INA206, INA207, and INA208 is
INA206, INA207, and INA208 is ideal for withstanding accurate within the output voltage swing range set by
automotive fault conditions ranging from 12V battery the power supply pin, V+. This performance is best
reversal up to +80V transients, since no additional illustrated when using the INA208 (a gain of 100
protective components are needed up to those levels. version), where a 100mV full-scale input from the
In the event that the INA206, INA207, and INA208 shunt resistor requires an output voltage swing of
are exposed to transients on the inputs in excess of +10V, and a power-supply voltage sufficient to
their ratings, then external transient absorption with achieve +10V on the output.
semiconductor transient absorbers (zeners or
Transzorbs) will be necessary. Use of MOVs or VDRs
is not recommended except when they are used in
An obvious and straightforward location for filtering is
addition to a semiconductor transient absorber.
at the output of the INA206, INA207, and INA208
Select the transient absorber such that it will never
series; however, this location negates the advantage
allow the INA206, INA207, and INA208 to be
of the low output impedance of the internal buffer.
exposed to transients greater than +80V (that is,
The only other option for filtering is at the input pins
allow for transient absorber tolerance, as well as
of the INA206, INA207, and INA208, which is
additional voltage due to transient absorber dynamic
complicated by the internal 5k Ω + 30% input
impedance). Despite the use of internal zener-type
impedance; this is shown in Figure 33 . Using the
ESD protection, the INA206, INA207, and INA208 do
lowest possible resistor values minimizes both the
not lend themselves to using external resistors in
initial shift in gain and effects of tolerance. The effect
series with the inputs since the internal gain resistors
on initial gain is given by Equation 3 :
can vary up to ± 30% but are closely matched. (If gain
accuracy is not important, then resistors can be
added in series with the INA206, INA207, and
INA208 inputs with two equal resistors on each
input.)
Total effect on gain error can be calculated by
replacing the 5k Ω term with 5k Ω – 30%, (or 3.5k Ω ) or
5k Ω + 30% (or 6.5k Ω ). The tolerance extremes of
R
FILT
can also be inserted into the equation. If a pair
of 100 Ω 1% resistors are used on the inputs, the
initial gain error will be 1.96%. Worst-case tolerance
conditions will always occur at the lower excursion of
the internal 5k Ω resistor (3.5k Ω ), and the higher
excursion of R
FILT
– 3% in this case.
Figure 33. Input Filter (Gain Error – 1.5% to – 2.2%)
14 Submit Documentation Feedback Copyright © 2006 – 2007, Texas Instruments Incorporated
Product Folder Link(s): INA206 INA207 INA208