DEMO CIRCUIT 9 0 7 LTC6102/6101, LT6100, LT1787, LTC2054, AND Q UICK S TALTC2439-1 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 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 additionalpositive 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 VIN , VOUT, and GN D 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 QuickEvalare registered trademarks of Linear Technology Corporation. Other product names may be trademarks of the companies that manufacture the products. LTC6101B LTC2439-1 LTC6102 LTC2054 LT6100 LT1787HV Figure 1. General Layout of DC907A-B 1 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 PERF ORM A NCE SU M M A RY Specifications are at TA = 25C SYM BOL VIN PARAM ETER Input Voltage Compliance Range VOS Input Offset Accuracy IOUT Output Current Readout Accuracy (using supplied resistors) Output Current Readout Range (using supplied resistors) IOUT VOUT FSAM PLE Output Voltage Readout Accuracy Update Rate of Readouts CONDITIONS LTC6101B LTC6101A (DC907A-A only) LTC6102 (DC907A-B only) LT6100 LT1787HV LTC2054 LTC2439-1 LTC6101B LTC6101A (DC907A-A only) LTC6102 (DC907A-B only) LT6100 LT1787HV LTC2054 LTC2439-1 LT6100,LTC2439-1 Others LTC6101B LTC6101A (DC907A-A only) LTC6102 (DC907A-B only) LT6100 LT1787HV LTC2054 LTC2439-1 (using supplied resistors) Acquiring from allcircuits M IN 4 4 4 6.4 2.5 -72 0 TYP 0 0 0 0 -1 -10 -5 1 M AX 60 60 60 48 60 0 5 0.45 0.3 0.01 0.3 0.15 0.003 0.005 1.5 3 5 10 10 5 2 0 5 2 UNITS V V V V V V mV mV mV mV mV mV mV % % A A A A A A % 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 : VSENSE = ISENSERSENSE. The circuits in DC907 show various solutions to scaling and level-translating the small VSENSE signal to a level appropriate for an analog-to-digital converter (ADC) input. 2 In one circuit, the 5V compliance w indow of an LTC2439-1 high-resolution differential-input ADC is used to directly digitize VSEN SE 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, AND LTC2439-1 operational-amplifier to detect the VSENSE 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. 3 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 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 QuickEvalTM 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 QuickEvalTM 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. 4 Figure 2. IsenseB.exe Startup Window w hen the DC907A-B Current Sense Dem o Board is Properly Connected. LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 EVALU ATIO N OF THE LTC6101B The LTC6101B is the SOT-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 initialsetup 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. DMM POWER SUPPLY + COM To DC590A A COM V LTC6101B Output (CH0) GND + LOAD _ Figure 3. LTC6101B Pow er and Load Connections 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. Figure 4. LTC6101B IsenseB.exe display (Current and Voltage at +VO UT1) 5 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 EVALU ATIO N OF THE LTC6102 (O R 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: POWER SUPPLY DMM A COM V + COM To DC590A LTC6101A Output (CH2) GND 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). + LOAD _ Figure 5. LTC6102 Pow er and Load Connection 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 ellw 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. 6 Figure 6. LTC6102 IsenseB.exe display (Current and Voltage at +VO U T2) LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 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 initialsetup 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. DMM A COM V POWER SUPPLY + COM To DC590A LT6100 Output (CH4) GND + LOAD _ Figure 7. LT6100 Pow er and Load Connection 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. Figure 8. LT6100 IsenseB.exe display (Current and Voltage at +VO U T3) 7 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 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-directionalload 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 VOUT4 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 ellw ithin nominal conditions. DMM A COM V POWER SUPPLY + COM To DC590A LT1787 Output (CH6/CH11 differential, CH6 more positive for power flowing to the load) + LOAD _ Figure 9. LT1787 Pow er and Load Connection 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. Figure 10. LT1787 IsenseB.exe display (Current and Voltage at +VO U T4) 8 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 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 NEGATIVE pow er source (betw een 0.0V and -72V) to J16 (-VIN5), w ith a pow er return to J15 (GND). 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 initialsetup 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. POWER SUPPLY DMM A COM V + COM To DC590A LTC2054 Output (CH10 / CH11 differential, CH11 more positive) + LOAD _ Figure 11. LTC2054 Pow er and Load Connection 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. Figure 12. LTC2054 IsenseB.exe display (Current and Voltage at -VO UT5) 9 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 EVALU ATIO N OF THE LTC2439-1 The LTC2439-1 multi-channel ADC is the SSOP-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: DMM A COM V 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 (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 J19 (+VOUT6) w ith a current return to J20 (GND). Be sure the bi-directionalload 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). POWER SUPPLY To DC590A + COM LTC2439-1 senseresistor signal (CH14 / CH15 differential, CH14 more positive for power flowing to the load) + LOAD _ Figure 13. LTC2439-1 Pow er and Load Connection 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 initialsetup 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 senseresistor signal is available differentially on the CH14/CH15 turrets as indicated in Figure 13. 10 Figure 14. LTC2439-1 IsenseB.exe display (Current and Voltage at +VO UT6) LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 M O RE FEATU RES OF DC907 SO FTWAR E 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 allsix 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 subcircuit. This is usefulfor 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 subcircuit,a smallcalibration screen can be opened that allow s modification of the four constants. Figure 16 show s a typicalcalibrate 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 Cancelbox 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. 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 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 Figure 16. Individual Calibration Screens allow Tuning of the Display Functions ________________________________________________________________________________________ 11 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 Figure 17. DC907A-B Bill of M aterial 12 LTC6102/6101, LT6100, LT1787, LTC2054, AND LTC2439-1 Figure 18. DC907 Schem atic Diagram 13