pvi-100

PVI-100Pulsed V/I – 100 Amp

The PVI-100 is a fully floating instrument for the generation and measurement of high current pulses. The floating

capability allows both positive and negative pulses to be generated and keeps ground return currents from upset-

ting the rest of the systems accuracy. The PVI-100 does not require any bulky system power supplies to generate

very high current pulses. At the extremes, the PVI-100 is capable of generating 100A 20V pulses and 50V 1A pulses.

To generate a pulse, a capacitor bank on the PVI-100 is charged up from a +65V system power supply. When the

charge exceeds a set minimum value, the supply is disconnected and the load is connected. The forcing voltage and

current parameters are then set and a drive signal is issued. The control loop then will drive the load going into

either voltage or current compliance as dictated by the forcing parameters and the load. After a specified period

has elapsed the voltage across or the current through the load is measured and the drive is turned off. At this point

the PVI-100 could be set up to make another measurement or returned to the charging state. (cont.)

CURRENTSENSE

RESISTORS

+DIFF

-

+DIFF

-

+-CONTROLANDDRIVE

+-

DRIVERTEMP

SENSOR

15 BITS

IN

IN

IN

IN

OUT

OUT

OUT

OUT

IN OUT

SYSTEMGROUND-REFERENCED

CIRCUITRY

FLOATINGGROUND-REFERENCED

CIRCUITRY

SYSTEMWITH BUS

LATCHESOPTICALLY COUPLEDSWITCH, RANGE, ANDCOMPENSATIONCONTROLS

DRIVE ON/OFF

DAC16 BITS

DAC16 BITS

ADC

TEMP MEAS

I MEAS

V MEAS

CHARGE MEAS

+65 V

I SET

V SET

V SENSE

I SENSE

0.5 ACURRENTLIMITER

V MEASRANGE

V DRIVERANGE

LOAD

FORCE SWITCHES SENSE SWITCHES

+

+

+

+

+

-

-

-+-

-

-

+

+

+

+

-

-

-

-

7000mF CAPACITOR

BANK

PVI 100 Diagram

System overview

Theory of operation

PVI-100 features • Fully floating Instrument for high current pulses

• 1V, 3V, 10V, 30V, 100V(50V max) ranges

• 100mA, 300mA, 1A, 3A, 10A, 30A, 100A ranges

Division

• 16 bit current and voltage forcing resolution

• 15 bit current and voltage measurement resolution

Division

Theory of operation (cont.) Connections from the PVI-100 to the load are made withforce and sense lines. Five sets of these lines are avail-able. Optically isolated switches control which of the linesare active and whether their polarity is positive or nega-tive. This arrangement allows for up to four loads to beconnected to the PVI-100 or for force lines to be paral-leled when driving very high currents. Discrete powerMOSFETs were used for the pass elements in the forceswitches so there are no contacts to fuse under high cur-rents.

Control of the forcing voltage and current is done fromsystem ground referenced DACs whose outputs arepassed across the isolation barrier to the floating controlloop via isolation amplifiers. The current and voltagemeasurements are also via isolation amplifiers driving asystem ground referenced ADC. In addition, the ADC isused to monitor the charge on the capacitor bank and thetemperature of the output driver. Power for the floatingside of the isolation amplifiers, the control loop, and thefloating measurement circuitry is supplied by isolated DCto DC converters.

The charging rate for the capacitor bank is set at a con-stant 0.5Amps. With the maximum output current of100Amps, the worst case average duty cycle is 0.5%. Withthis duty cycle, test times need not be negatively impactedsince the capacitor bank has 7000uF of capacitance,which provides sufficient charge to make multiple high

current tests before charging is necessary. Also, charg-ing can occur during all other times the PVI-100 is notbeing used.

The PVI-100 has selectable compensation that sets thenominal bandwidth of the control loop to 10kHz,20kHz, 40kHz, and 80kHz. The 10kHz setting is fordriving loads that might be hard to stabilize at thefaster setting. The upper two settings are for caseswhere the amount of feedback to the control loop hasbeen attenuated which lowers the effective loop band-width. This occurs when the PVI-100 is in currentcompliance and driving very low impedance loads. Inthis situation, there can be a larger voltage drop acrossthe cumulative resistance of the traces, connectors,current sense resistor, and force switches than acrossthe load. This same condition can occur when the PVI-100 is in voltage compliance except here the feedbackcomes from the current sense resistor instead of theload. For both modes, the higher settings will allow thespecified settling times to be met if the load is withinthe limits shown below.

Sustainable pulse duration verses output voltage andcurrent for the PVI-100 is shown in the following chart.The drop in the voltage as the duration increases is dueto the discharge of the capacitor bank. The drop in thevoltage as the current increases is due to the cumula-tive resistance in the force path. The 100 Amp curve iswith force lines paralleled.

PV-100Specifications

Voltage Force and MeasureForcing Resolution 16 BitsForcing Accuracy +/- 0.5% of Range*Measuring Resolution 15 BitsMeasuring Accuracy +/- 0.5% of RangeRanges 1V, 3V, 10V, 30V, 100V

Current Force and MeasureForcing Resolution 16 BitsForcing Accuracy +/- 1.0% of RangeMeasuring Resolution 15 BitsMeasuring Accuracy +/- 1.0% of RangeRanges 0.1A, 0.3A, 1A, 3A, 10A,

30A,100A

Settling Time to 1.0%Drive with Measure (Resistive Loads)Voltage Ranges < 200us Typical

< 300us Worst CaseCurrent Ranges < 200us Typical

< 2300us Worst Case* +/- 1.0% on 1 Volt Range

LS 0009 PNT (D-TMT/PVI-100 1.0)

Selected Current Voltage Compliance Mode Current Compliance Mode Range Maximum Load Minimum Load

100mA 600 ohms 6.0 ohms

300mA 600 ohms 2.0 ohms

1 Amp 60 ohms .6 ohms

3 Amp 20 ohms .2 ohms

10 Amp 5.8 ohms 0.06 ohms



©2000 Credence Systems Corporation. All rights reserved.Specifications are subject to change without notice. Credence,Credence Systems, and TMT are trademarks of Credence SystemsCorporation. All other company and product names are trademarksof their respective owners.

Pulse Duration vs Voltage Current

1.00E-04 1.00E-04 seconds 1.00E-02

100A

volts50

40

30

20

10

0

50A

10A

1A

5A

Credence Systems CorporationTMT Division435 Lakeside DriveSunnyvale, CA 94086Tel: (408) 730-5000Fax: (408 730-5650

pvi-100

Documents