LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
1
DESCRIPTION
Demonstration circuit 907 includes six different Current
Sense circuits featuring the LTC6102/6101, LT6100,
LT1787, LTC2054, and LTC2439-1. The general
organization of the latest version, DC907A-B, is show n in
Figure 1. The original version, DC907A-A, provided the
A-grade LTC6101 instead of the ultra-precise LTC6102,
but w ith the same basic functionality. The DC907A-B
may be used w ith the IsenseB.exe softw are executable or
stand-alone (for DC907A-A, use Isense.exe instead). The
balance of this Quick Start Guide w ill refer to the new er
version, but unless indicated, w ill be valid for the older
combination as w ell.
Operation w ith PC softw are requires the use of USB
interface controller, DC590B. In stand-alone operation,
the LTC6102, LTC6101, LT6100, and LT1787 circuits w ill
pow er up from the positive pow er source voltage(s)
being monitored. The LTC2054 circuit (negative supply
monitor), requiring an additional positive supply, is most
conveniently used in the USB-pow ered environment (the
LTC2439-1 Analog-to-Digital connection requires the
DC590B and softw are).
Each of the six current sense circuits operate w ith their
ow n dedicated sense resistor and I/O connections, and
may all be operated concurrently. A V
IN
, V
OUT
, and GND
banana-jack connection is provided for each sense circuit
to make evaluation connections simple. Each circuit
represents a typical application solution and provides
operating characteristics as show n in the Performance
Summary table. For convenience, digitized voltage
readouts are provided for each circuit, along w ith the
current measurements.
Design files for this circuit board are available. Call
the LTC factory.
, LTC, LT, and QuickEval are registered trademarks of Linear Technology Corporation.
Other product names may be trademarks of the companies that manufacture the products.
LTC6101B
LTC6102
LT6100 LT1787HV
LTC2439-1
LTC2054
Figure 1. General Layout of DC907A-B
DEMO CIRCUIT
9 0 7
Q UICK S TA RT G UIDE
L TC6 10 2 / 6 10 1, L T6 10 0 , L T17 8 7 ,
L TC2 0 5 4 , a n d L TC2 4 3 9 -
1
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
2
PERF ORM A NCE SU M M A RY
Specifications are at T
A
= 25°C
SYM BOL PARAM ETER CONDITION S M IN TYP M AX UNITS
V
IN
Input Voltage Compliance Range LTC6101B
LTC6101A (DC907A-A only)
LTC6102 (DC907A-B only)
LT6100
LT1787HV
LTC2054
LTC2439-1
4
4
4
6.4
2.5
-72
0
60
60
60
48
60
0
5
V
V
V
V
V
V
V
OS
Input Offset Accuracy LTC6101B
LTC6101A (DC907A-A only)
LTC6102 (DC907A-B only)
LT6100
LT1787HV
LTC2054
LTC2439-1
±0.45
±0.3
±0.01
±0.3
±0.15
±0.003
±0.005
mV
mV
mV
mV
mV
mV
mV
I
OUT
Output Current Readout Accuracy
(using supplied resistors)
LT6100, LTC2439-1
Others
±1.5
±3
%
%
I
OUT
Output Current Readout Range
(using supplied resistors)
LTC6101B
LTC6101A (DC907A-A only)
LTC6102 (DC907A-B only)
LT6100
LT1787HV
LTC2054
LTC2439-1
0
0
0
0
-1
-10
-5
5
10
10
5
2
0
5
A
A
A
A
A
A
V
OUT
Output Voltage Readout Accuracy (using supplied resistors) ±2 %
F
SAM PLE
Update Rate of Readouts Acquiring from all circuits 1 Hz
OPERA TING PRINCIPL ES
The basic method of current sensing in this demo circuit
collection is the use of a precision low -value resistance
inserted into the current path to be monitored.
According to Ohm’s Law , the voltage drop across the
“sense” resistance w ill be proportional to the current
flow :
V
SENSE
= I
SENSE
⋅
R
SENSE
.
The circuits in DC907 show various solutions to scaling
and level-translating the small V
SENSE
signal to a level
appropriate for an analog-to-digital converter (ADC)
input.
In one circuit, the 5V compliance w indow of an
LTC2439-1 high-resolution differential-input ADC is used
to directly digitize V
SENSE
w ithout any additional
components. In low -voltage applications, this can often
be the best method to use. Since this is an inherently
bidirectional readout, it is useful in monitoring
charge/discharge of low -voltage pow er cells, for
example.
In telecom applications w ith –48V pow er sources to
monitor, special translation methods are needed to
accommodate the w ide range, below ground voltage
compliance that is required. One such application is
demonstrated on DC907 using the ultra-precise LTC2054
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
3
operational-amplifier to detect the V
SENSE
signal. The
configuration uses the amplifier to control a transistor
conductance, forming a precision voltage-to-current
conversion. The controlled current is then draw n from a
load resistor returned to a potential above ground, thus
the controlled current is reconverted to a voltage-drop
that is in the w orking range of the ADC. The overall
circuit function provides unidirectional voltage
amplification that is essentially as accurate as the
resistors chosen in the circuit. Pow er is provided to the
LTC2054 by a locally connected w ide input-range 5V
regulator (LT3010-5), so that the amplifier “rides” on the
negative pow er feed.
For w ide-range bidirectional current monitoring, the
LT1787HV circuit is useful to consider. This part
performs a voltage-to-current-to-voltage operation
similar to the previous method described, but is
completely integrated and suited to positive voltage
applications. This part has a fixed gain of 8 and an
excellent offset-error specification.
Another fully integrated positive monitor is the LT6100.
This unidirectional sense amplifier provides several pin-
strappable gains. This part is unusual in that it is
pow ered from a low voltage and the sense inputs operate
at higher potentials than the supply. Additionally, the
current in the sense pins remains at a vanishingly small
level even w hen the pow er to the part is off, making it
attractive in battery applications.
For positive unidirectional monitoring, the most flexible
parts are the LTC6101 and LTC6102. These use another
voltage-to-current-to-voltage type function, but the gain
resistors are provided by the user, so the gain and
accuracy of the circuit can be tailored to the application.
DC907A-B provides circuits for both the LTC6101B and
LTC6102 parts. For the more precise LTC6102 device,
the sense resistance is low er (and gain higher) to
demonstrate additional useful measurement range that
the part offers.
The LTC2439-1 ADC previously mentioned is also used
to digitize the current and voltages for all the other
current-sense sub-circuits on DC907.
The Bill-of-M aterial and electrical Schematic diagram of
DC907 are show n in Figures 17 and 18, respectively.
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
4
Q U ICK STA RT PROCEDU RE F OR COM PU TER-B A SED EV A L U A TION
Demonstration circuit 907 is easy to set up to evaluate
the performance of the LTC6102/6101, LT6100,
LT1787, LTC2054, and LTC2439-1 using the
QuickEval™ USB adapter and a dedicated softw are
executable.
For stand-alone evaluation, relevant test signals can be
measured at various test-turrets as described in later
sections. The data acquisition rate of the ADC used in
DC907 does not necessarily reflect the available
bandw idth of the monitor signal being evaluated. An
oscilloscope and load step producing equipment are
required for detailed time-domain response
evaluations.
Follow the procedure below for all part evaluations
using the USB adapter:
1.
Obtain DC590B and dow nload the IsenseB.exe
softw are. Use Isense.exe for the DC907A-A version.
2.
Connect J3 on the DC590B QuickEval™ USB
Controller to a host PC using the supplied USB
interface cable.
3.
Connect DC907 J1 to the DC590B USB Controller J4
using the supplied 14-w ire ribbon cable. Start the
IsenseB.exe application and the user screen for the
DC907 w ill appear as show n in Figure 2. The
application w ill automatically abort if either of the
DC590B cables are not connected or the DC907
version does not correspond correctly w ith the
application.
4.
This completes the setup of the data-acquisition
functionality of the DC907. The follow ing sections
detail the hookup and operation specific to each
evaluation sub-circuit. Refer to the DC907
schematic diagram in Figure 18 to understand each
specific sub-circuit implementation on the demo
board.
Figure 2. IsenseB.exe Startup Window w hen the DC907A-B
Current Sense Dem o Board is Properly Connected.
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
5
EVALU ATIO N OF THE LTC6101B
The LTC6101B is the SO T-23 device (U1) in the upper
left corner of DC907. Perform the follow ing steps to
properly connect and operate this demo sub-circuit:
1.
Refer to Figure 3 for the follow ing connections.
2.
Connect a pow er source (betw een 4V and 60V) to
J3 (+VIN1), w ith a pow er return to J2 (GND). If
desired, a current measuring instrument may be
placed in series w ith the pow er connection as
show n.
3.
Connect a load to J4 (+VOUT1) w ith a current return
to J5 (GND). Be sure the load current w ill not
exceed the indicated capability of 5A, or component
overheating and/or damage to the circuit could
occur (this limitation is due to component selections
used and not the LTC6101B specifically).
4.
M ouse-click a check in the VOUT1 LTC6101BCS5
enable box and then mouse-click the START box.
The w indow w ill then show , as in Figure 4, a
continuously updated current and voltage as
furnished to the load connections. To suspend
updating, mouse-click the PAUSE box. The RESET
box returns the program to the initial setup state so
that other demo sub-circuits can be activated, etc. A
red readout represents an out-of-range result or
condition that may be beyond safe limits. A yellow
readout is acceptable, but indicates being near a
limit. Green readouts are w ell w ithin nominal
conditions.
5.
For time-domain measurements and/or stand-alone
evaluation, the current-monitor output signal is
available on the CH0 turret as indicated in Figure 3.
+
LOAD
_
+ COM
POWER
SUPPLY
DMM
A COM V
To DC590A
LTC6101B
Output (CH0)
GND
Figure 3. LTC6101B Pow er and Load Connections
Figure 4. LTC6101B IsenseB.exe display (Current and Voltage
at +VOUT1)
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
6
EVALU ATIO N OF THE LTC6102 (OR LTC6101A IN
DC907A-A)
The LTC6102 is the M SOP-8 device (U2) in the low er
left-hand side of DC907A-B. In DC907A-A this device is
the LTC6101A, performing the same function (but w ith
less precision). Perform the follow ing steps to properly
connect and operate this demo sub-circuit:
1.
Refer to Figure 5 for the follow ing connections.
2.
Connect a pow er source (betw een 4V and 60V) to
J6 (+VIN2), w ith a pow er return to J8 (GND). If
desired, a current measuring instrument may be
placed in series w ith the pow er connection as
show n.
3.
Connect a load to J7 (+VOUT2) w ith a current return
to J5 (GND). Be sure the load current w ill not
exceed the indicated capability of 10A, or
component overheating and/or damage to the circuit
could occur (this limitation is due to component
selections used and not the LTC6101 or LTC6102
specifically).
4.
M ouse-click a check in the VOUT2 LTC6102CM S8
enable box and then mouse-click the START box to
begin data-acquisition (w ith DC907A-A and
Isense.exe, this field is labeled for the
LTC6101ACM S8). The display w ill then show , as in
Figure 6, a continuously updated current and
voltage as furnished to the load connections. To
suspend updating, mouse-click the PAUSE box. The
RESET box returns the program to the initial setup
state. A red readout represents an out-of-range
result or condition that may be beyond safe limits. A
yellow readout is acceptable, but indicates being
near a limit. Green readouts are w ell w ithin nominal
conditions.
5.
For time-domain measurements and/or stand-alone
evaluation, the current-monitor output signal is
available on the CH2 turret as indicated in Figure 5.
+
LOAD
_
+ COM
POWER
SUPPLY
DMM
A COM V
To DC590A
LTC6101A
Output (CH2)
GND
Figure 5. LTC6102 Pow er and Load Connection
Figure 6. LTC6102 IsenseB.exe display (Current and Voltage at
+VO U T2)
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
7
EVALU ATIO N OF THE LT6100
The LT6100 is the M SOP-8 device (U3) in the left
bottom side of DC907. Perform the follow ing steps to
properly connect and operate this demo sub-circuit:
1.
Refer to Figure 7 for the follow ing connections.
2.
Connect a pow er source (betw een 6.4V and 48V) to
J9 (+VIN3), w ith a pow er return to J8 (GND). If
desired, a current measuring instrument may be
placed in series w ith the pow er connection as
show n.
3.
Connect a load to J10 (+VOUT3) w ith a current
return to J11 (GND). Be sure the load current w ill
not exceed the indicated capability of 5A, or
component overheating and/or damage to the circuit
could occur (this limitation is due to component
selections used and not the LT6100 specifically).
4.
M ouse-click a check in the VOUT3 LT6100CM S8
enable box and then select a gain of 10 from the
pop-up menu list. Set or verify that the JP1 and JP2
configuration matches the pop-up draw ing and
mouse-click the OK box. M ouse-click the START
box to begin data-acquisition. The IsenseB.exe
presentation w ill then show , as in Figure 8, a
continuously updated current and voltage as
furnished to the load connections. To suspend
updating, mouse-click the PAUSE box. The RESET
box returns the program to the initial setup state. A
red readout represents an out-of-range result or
condition that may be beyond safe limits. A yellow
readout is acceptable, but indicates being near a
limit. Green readouts are w ell w ithin nominal
conditions.
5.
For time-domain measurements and/or stand-alone
evaluation, the current-monitor output signal is
available on the CH4 turret as indicated in Figure 7.
+
LOAD
_
+ COM
POWER
SUPPLY
DMM
A COM V
To DC590A
LT6100
Output (CH4)
GND
Figure 7. LT6100 Pow er and Load Connection
Figure 8. LT6100 IsenseB.exe display (Current and Voltage at
+VO U T3)
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
8
EVALU ATIO N OF THE LT1787H V
The LT1787HV is the M SO P-8 device (U4) in the right
bottom side of DC907. Perform the follow ing steps to
properly connect and operate this demo sub-circuit:
1.
Refer to Figure 9 for the follow ing connections.
2.
Connect a pow er source (betw een 2.5V and 60V, at
least 3V to properly pow er-up ancillary circuitry on
the DC907 in stand-alone evaluation) to J12
(+VIN4), w ith a pow er return to J11 (GND). If
desired, a current measuring instrument may be
placed in series w ith the pow er connection as
show n.
3.
Connect a load to J13 (+VOUT4) w ith a current
return to J14 (GND). Be sure the bi-directional load
current w ill not exceed the indicated capability of
+2A/-1A, or component overheating and/or damage
to the circuit could occur (this limitation is due to
component selections used and not the LT1787HV
specifically).
4.
M ouse-click a check in the VOU T4 LT1787HVCM S8
enable box and then mouse-click the START box to
begin data-acquisition. The display w ill then show ,
as in Figure 10, a continuously updated current and
voltage as furnished to the load connections. To
suspend updating, mouse-click the PAUSE box. The
RESET box returns the program to the initial setup
state. A red readout represents an out-of-range
result or condition that may be beyond safe limits. A
yellow readout is acceptable, but indicates being
near a limit. Green readouts are w ell w ithin nominal
conditions.
5.
For time-domain measurements and/or stand-alone
evaluation, the differential current-monitor output
signal is available on the CH6/CH11 turrets as
indicated in Figure 9.
+
LOAD
_
+ COM
POWER
SUPPLY
DMM
A COM V
To DC590A
LT1787 Output
(CH6/CH11
differential, CH6
more positive for
power flowing to the
load)
Figure 9. LT1787 Pow er and Load Connection
Figure 10. LT1787 IsenseB.exe display (Current and Voltage at
+VO U T4)
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
9
EVALU ATIO N OF THE LTC2054
The LTC2054 is the SOT-23 device (U4) in the low er
right side of DC907. Perform the follow ing steps to
properly connect and operate this demo sub-circuit:
1.
Refer to Figure 11 for the follow ing connections.
2.
Connect a NEG ATIVE pow er source (betw een 0.0V
and -72V) to J16 (-VIN5), w ith a pow er return to
J15 (GN D). If desired, a current measuring
instrument may be placed in series w ith the pow er
connection as show n. For stand-alone tests, a
positive supply of at least 6V must also be
connected to J3 (or J6, J9, or J12) to properly
pow er-up ancillary circuitry on the DC907.
3.
Connect a load to J17 (-VOUT5) w ith a current
return to J14 (GND). Be sure the load current w ill
not exceed the indicated capability of -10A, or
component overheating and/or damage to the circuit
could occur (this limitation is due to component
selections used and not the LTC2054 specifically).
4.
M ouse-click a check in the VOUT4 LTC2054CS5
enable box and then mouse-click the START box to
begin data-acquisition. The IsenseB.exe
presentation w ill then show , as in Figure 12, a
continuously updated current and voltage as
furnished to the load connections. To suspend
updating, mouse-click the PAUSE box. The RESET
box returns the program to the initial setup state. A
red readout represents an out-of-range result or
condition that may be beyond safe limits. A yellow
readout is acceptable, but indicates being near a
limit. Green readouts are w ell w ithin nominal
conditions.
5.
For time-domain measurements and/or stand-alone
evaluation, the current-monitor output signal is
available differentially on the CH10/CH11 turrets as
indicated in Figure 11.
+
LOAD
_
+ COM
POWER
SUPPLY
DMM
A COM V
To DC590A
LTC2054 Output
(CH10 / CH11
differential, CH11
more positive)
Figure 11. LTC2054 Pow er and Load Connection
Figure 12. LTC2054 IsenseB.exe display (Current and Voltage
at –VOUT5)
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
10
EVALU ATIO N OF THE LTC2439-1
The LTC2439-1 multi-channel ADC is the SSO P-28
device (U8) near the J1 ribbon connector of DC907.
Perform the follow ing steps to properly connect and
operate this direct ADC connection demonstration:
1.
Refer to Figure 13 for the follow ing connections.
Note that the IsenseB.exe environment is required to
exercise the ADC functionality of this sub-circuit,
therefore stand-alone operation is not defined.
2.
Connect a low -voltage pow er source (betw een 0.0V
and 5.0V) to J18 (+VIN6), w ith a pow er return to
J15 (GN D). If desired, a current measuring
instrument may be placed in series w ith the pow er
connection as show n.
3.
Connect a load to J19 (+VOUT6) w ith a current
return to J20 (GND). Be sure the bi-directional load
current w ill not exceed the indicated capability of
+5A/-5A, or component overheating and/or damage
to the circuit could occur (this limitation is due to
component selections used and not the LTC2439-1
specifically).
4.
M ouse-click a check in the VOUT6 LTC2439-1CGN
enable box and then mouse-click the START box to
begin data-acquisition. The IsenseB.exe
presentation w ill then show , as in Figure 14, a
continuously updated current and voltage as
furnished to the load connections. To suspend
updating, mouse-click the PAUSE box. The RESET
box returns the program to the initial setup state. A
red readout represents an out-of-range result or
condition that may be beyond safe limits. A yellow
readout is acceptable, but indicates being near a
limit. Green readouts are w ell w ithin nominal
conditions.
5.
For accuracy verification measurements, the sense-
resistor signal is available differentially on the
CH14/CH 15 turrets as indicated in Figure 13.
+
LOAD
_
+ COM
POWER
SUPPLY
DMM
A COM V
To DC590A
LTC2439-1 sense-
resistor signal
(CH14 / CH15
differential, CH14
more positive for
power flowing to the
load)
Figure 13. LTC2439-1 Pow er and Load Connection
Figure 14. LTC2439-1 IsenseB.exe display (Current and
Voltage at +VO U T6)
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
11
M O RE FEATU RES OF DC907 SOFTWARE
1.
In the setup screen of the DC907 softw are, any
combination of enable boxes may be selected prior
to mouse-clicking the START box. All the selected
sub-circuits w ill display concurrently in the same
fashion they did individually. Figure 15 show s a case
w here all six sub-circuits are active.
2.
The softw are also provides the ability to modify
scaling factors and offsets in both the current and
voltage calculations of each demonstration sub-
circuit. This is useful for fine-tuning the constants to
perform accurate calibrations, or to allow flexible
reprogramming to reflect intentional component
changes. This feature is accessed during data
acquisition by w ay of the Calibrate… selection
under the Tools menu. For each active demo sub-
circuit, a small calibration screen can be opened that
allow s modification of the four constants. Figure 16
show s a typical calibrate screen. Each constant may
be modified by mouse-clicking to place an editing
cursor into the appropriate field and then making a
change. After all desired changes have been made,
mouse-click the Set box to begin using the new
values. If undesirable changes are made, the Default
box may be mouse-clicked to restore factory entries
(the Set box w ill still need to be used afterw ard).
The Cancel box is used to simply close out a screen
w ithout taking changes. Any value changes made
are lost w hen the setup screen RESET box is used
or the DC907 program is terminated.
3.
Under the View menu, there is a View Product Page
selection that further expands to provide convenient
w eb resource links for each demo sub-circuit device
of the DC907.
4.
Note that pow er for the DC907 data acquisition is
derived from the USB connection, but provided by
an isolated DC/DC conversion on the DC590 card.
This means the potential of the GND jacks on the
board is floating w ith respect to Earth, though each
demo sub-circuit is interconnected to that same
GND reference potential. This prevents ground-loop
noise from perturbing the readings and virtually
eliminates any possibility of damaging the USB port
of the PC due to any mis-configuration of the
current monitor circuits (damage to DC907 and/or
DC590 might occur, how ever!).
Figure 15. All Dem o Sub-Circuits Displaying Concurrently
Figure 16. Individual Calibration Screens allow Tuning of the
Display Functions
________________________________________________________________________________________
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
12
Figure 17. DC907A-B Bill of M aterial
LTC6102/6101, LT6100
, LT1787, LTC2054, A
ND LTC2439
-
1
13
Figure 18. DC907 Schem atic Diagram
