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LT6107
1
V
V
µA
A
µA
DEMO CIRCUIT
1 3 6 3
Q UICK S TA RT G UIDE
L T6 1 0 7
H ig h Te m p e ra tu re H ig h S id e
2 3
DESCRIPTION
Cu rre n t S e n se in a S OT-
Demonstration circuit 1363 is a General Purpose H ighSide Current-Sense Amplifier featuring the LT6107.
This demo board amplifies an on-board current-sense
resistor voltage-drop, providing a precision uni-polar
output voltage proportional to load current. The demo
circuit includes scaling resistors that program the gain of
the circuit to 50V/V. The LT6107 is pow ered from the
same supply that the sense resistor is connected to and
provides a ground referenced output. The LT6107 can
processing such as A/D conversion). Remote loading can
be evaluated by simply removing the on board load
resistor (R3).
DC1363 is fabricated from FR-406 high-temp epoxyglass so that the full 150° operation of the LT6107 can
be demonstrated. O ther key performance characteristics
of the LT6107 and DC1363 are show n in the
Performance Summary below .
perform current measurements on supplies ranging from
2.7V to 36V. Since the output voltage is developed as a
controlled current through a load resistance, groundloop errors can be eliminated by simply locating the load
resistor at the destination point (subsequent signal
Design files for this circuit board are available. Call
the LTC factory.
L
, LT are registered trademarks of Linear Technology Corporation. O ther product names
may be trademarks of the companies that manufacture the products.
PERF ORM ANCE SU M M ARY
SYM BO L PAR AM ETER CO N DITIO N S M IN TYP M AX UNITS
V
IN
V
M O N
I
M ON
I
OUT
I
INQ
tR V
M onitored Supply Input Range
M easurement Output Signal I
M easurement Output Signal (current mode) I
Output Load Current Range Thermal limit of R
VIN Quiescent Current V
step-response time I
M O N
Specifications are at TA = 25°C
= 5A
OUT
= 5A, R3 removed
OUT
=12V, I
IN
OUT
OUT
step from 0A to 5A 5 µs
5
SEN SE
= 0A
2.7 3… 28 36
2.5
500
65
OPERATING PRINCIPL ES
The LT6107 operates by amplifying the voltage drop on a
sense resistor placed in series w ith the pow er source of a
load to be monitored. The sense inputs of the amplifier
differentially measure the sense-resistor drop to control
an internal variable current source that allow s translation
of the input information to a level referenced to V–
(ground in this demo circuit). The circuit gain is
established by the ratio of the output resistor to the input
resistor and is essentially as accurate as the resistors
used. In DC1363 as shipped, the sense resistor installed
is 10mΩ and the resistor ratio sets the gain to 50V/V, so
the nominal output scaling is 500mV per Ampere of load
current. Other scalings can be produced by resistor
replacement on the demo circuit.
The DC1363 Schematic diagram is shown in Figure 2.
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LT6107
2
Q U ICK START PROCEDU RE
Demonstration circuit 1363 is easy to set up to evaluate
the performance of the LT6107. Refer to Figure 1 for
proper measurement equipment setup and follow the
procedure below :
1.
W ith pow er off, connect the pow er supply positive to
IN and the common to G N D. This supply should be in
the range of 2.7V to 36V. If this supply is not equipped
w ith an accurate current readout, a DM M (set to
measure Amperes) may be connected in series w ith
the supply as shown in Figure 1.
NOTE.
Be sure that the current capacity of the DM M is adequate to
handle the intended load current.
POWER
SUPPLY
+ COM
2.
Connect a voltmeter or oscilloscope probe to the M O N
terminal, w ith the common connection or ground clip
tied to GND.
3.
Connect a load to the OU T terminal (positive) and
return (negative) to the common of the pow er supply.
The load may be a pow er resistor, active load
instrument, or other circuit of interest.
4.
Turn on the pow er supply.
5.
M easure an output voltage that corresponds to the
load current. V
resistors.
DMM
A COM V
= 0.5×I
M ON
DMM
A COM V
for the factory installed
OUT
LOAD
(10Ω)
Figure 1. Proper M easurem ent Equipm ent Setup
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LT6107
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Figure 2. DC1363 Schem atic Diagram
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