LTC6103 Linear Integrated Systems, LTC6103 Datasheet - Page 12

• Manufacturer Part Number: LTC6103
• Description: High Side Current Sense Amplifier
• Manufacturer: Linear Integrated Systems

APPLICATIONS INFORMATION
will give a lowpass response. This will reduce unwanted
noise from the output, and may also be useful as a charge
reservoir to keep the output steady while driving a switch-
ing circuit such as a mux or ADC. This output capacitor
in parallel with an output resistor will create a pole in the
output response at:
Useful Equations
Reverse Supply Protection
Some applications may be tested with reverse-polarity
supplies due to an expectation of this type of fault during
operation. The LTC6103 is not protected internally from
LTC6103
12
Figure 5. Schottky Prevents Damage During Supply Reversal
Input Voltage: V
Current Gain:
Transconductance:
Transimpedance:
f
Voltage
–
3
dB
=
2
G G ain:
• •
π
I I
R
V
SENSE
I
LOAD
SENSE
V
OUT
OUT
SENSE
1
OUT
I
1/2
LTC6103
LOAD
I
SENSE
V
V
•
V
OUT
S
=
+ –
C
I
SEN
= I
OUT
R
=
OUT
+IN
R
SENSE
R
OUT
OUT
SENSE
R
S S E
SENSE
R
=
R
OUT
V
IN
IN
R
+
=
–IN
R
SENSE
IN
R
www.DataSheet4U.com
•
1
IN
R
V
6103 F05
–
D1
SENSE
•
R
R
O O UT
IN
external reversal of supply polarity. To prevent damage
that may occur during this condition, a Schottky diode
should be added in series with V
limit the reverse current through the LTC6103. Note that
this diode will limit the low voltage performance of the
LTC6103 by effectively reducing the supply voltage to the
part by V
In addition, if the output of the LTC6103 is wired to a
device that will effectively short it to high voltage (such as
through an ESD protection clamp) during a reverse sup-
ply condition, the LTC6103’s output should be connected
through a resistor or Schottky diode (Figure 6).
Response Time
The LTC6103 is designed to exhibit fast response to inputs
for the purpose of circuit protection or signal transmis-
sion. This response time will be affected by the external
circuit in two ways, delay and speed. If the output current
is very low and an input transient occurs, there may be an
increased delay before the output voltage begins changing.
This can be improved by increasing the minimum output
current, either by increasing R
effect of increased output current is illustrated in the step
response curves in the Typical Performance Characteristics
of this data sheet. Note that the curves are labeled with
respect to the initial output currents.
D
Figure 6. Additional Resistor, R3, Protects
Output During Supply Reversal
.
TO P
ADC
LOAD
1/2
LTC6103
I
LOAD
SENSE
V
S
+ –
8
R3
R
+IN
R
SENSE
OUT
OUT
–
or decreasing R
(Figure 5). This will
V
7
1
+
–IN
R
IN
4
V
6103 F06
–
D1
IN
. The
6103f