# US 10,481,193 B2 · Programmable load transient circuit

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- Number: US 10,481,193 B2
- Document ID: US10481193B2
- Status: Granted
- Kind: B2
- Application number: 15/887,531
- Filed: 2018-02-02
- Published: 2019-08-08
- Granted: 2019-11-19
- Earliest claimed: 2018-02-02
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Daniel Alexander Katz; Michael James Munroe
- Web page: https://patentgrep.com/patent/US10481193B2

## CPC

- G01R 31/59: while the cable continuously passes the testing apparatus, e.g. during manufacture
- G01R 19/16519: {using FET's}
- G01R 31/2834: {Automated test systems [ATE]; using microprocessors or computers (G01R31/317 takes precedence; ATE for detection of defective computer hardware G06F11/2736)}
- G01R 31/3004: {Current or voltage test}
- G01R 31/318516: {Test of programmable logic devices [PLDs]}
- G01R 31/31905: {Interface with the device under test [DUT], e.g. arrangements between the test head and the DUT, mechanical aspects, fixture}
- G01R 31/31924: {Voltage or current aspects, e.g. driver, receiver}
- H03K 19/00384: {in field effect transistor circuits}
- G01R 31/40: Testing power supplies (testing photovoltaic devices H02S50/10)
- H02M 1/0029: {Circuits or arrangements for limiting the slope of switching signals, e.g. slew rate}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

A programmable load transient circuit includes a switchable power device for coupling a DUT output to its non-control node in series with a current sense device. A feedback loop is between the current sense device and the power device's control node that includes an integrator including an amplifier coupled to receive a signal that is a function of an average load current (IDavg) supplied by the DUT from the current sense device and to receive a reference voltage (Vref). The integrator provides an output drive voltage that is coupled to an input of a level shifter which receives a pulse signal or DC level at another of its inputs. The level shifter provides an output waveform or DC voltage to the power device's control node that is a function of IDavg.

## Claims

### Claim 1

A programmable load transient circuit (PLTC), comprising:
a switchable power device providing a voltage controlled current source adapted to couple to an output of a device under test (DUT) to a non-control node of said switchable power device, said switchable power device in series with a current sense device that is connected to ground;
a feedback loop between said current sense device and a control node of said switchable power device, said feedback loop including:
an integrator comprising an amplifier coupled to receive a signal that is a function of an average load current (IDavg) supplied by said DUT from said current sense device, said amplifier adapted to receive a reference voltage (Vref) and to provide an output drive voltage,
wherein an output of said amplifier is coupled to a first input of a level shifter to provide said output drive voltage, wherein said level shifter is adapted to also receive a pulse signal or DC level from a pulse signal or DC source at its second input,
said level shifter providing an output waveform or a DC voltage to said control node of said switchable power device that is a function of said IDavg.

### Claim 2 (depends on 1)

The PLTC of claim 1, wherein said current sense device comprises a differential amplifier connected across a sense resistor, and wherein said amplifier comprises an operational amplifier having an RC network comprising an input resistor R and a feedback capacitor C.

### Claim 3 (depends on 2)

The PLTC of claim 2, wherein said PLTC during transient testing is configured to have said integrator adjust said output drive voltage until a voltage across said current sense device equals said Vref.

### Claim 4 (depends on 3)

The PLTC of claim 3, wherein an adjustment time during said transient testing is based on a time constant of said RC network.

### Claim 5 (depends on 2)

The PLTC of claim 2, wherein said sense resistor comprises an integrated on-chip resistor.

### Claim 6 (depends on 1)

The PLTC of claim 1, wherein said switchable power device comprises a metal oxide semiconductor (MOS) transistor.

### Claim 7 (depends on 1)

The PLTC of claim 1, wherein said PLTC has no dependence of said load current on an output voltage at said output of said DUT.

### Claim 8 (depends on 1)

The PLTC of claim 1, wherein said PLTC is adapted to be receive its programmability for said load current by changing said Vref or by said pulse signal or DC source changing its pulse signal frequency to change its duty cycle.

### Claim 9 (depends on 1)

The PLTC of claim 1, wherein said amplifier is configured as a unity gain amplifier.

### Claim 10

A method of automated load transient response testing of a device under test (DUT), comprising:
testing said DUT utilizing a programmable load transient circuit (PLTC) across multiple output voltages without changing any hardware, comprising:
configuring a switchable power device in a feedback loop that utilizes said switchable power device as a voltage controlled current source that is in series with a current sense device, where a voltage amplitude of a pulse signal applied to a control node of said switchable power device is adjustable and changes said switchable power device's operating current which is supplied as load current (ID) by said DUT;
setting a voltage reference (Vref) input in said feedback loop to a first Vref value and then testing said DUT at a first output voltage, and
setting said Vref input to a second Vref value and then retesting said DUT at a second output voltage.

### Claim 11 (depends on 10)

The method of claim 10, wherein said PLTC has no dependence of said ID on said output voltage of said DUT.

### Claim 12 (depends on 10)

The method of claim 10, wherein said feedback loop comprises an integrator including an amplifier coupled to receive a signal that is a function of an average of said ID from said current sense device, and
wherein an output of said amplifier is coupled to a first input of a level shifter that is adapted to also receive a pulse signal or DC level from a pulse signal or DC source at its second input.

### Claim 13 (depends on 12)

The method of claim 12, wherein said pulse signal or DC source comprises a pulse generator.

### Claim 14 (depends on 10)

The method of claim 10, wherein a frequency of said pulse signal determines a frequency of a current load step provided to said DUT.

### Claim 15 (depends on 10)

The method of claim 10, wherein said current sense device comprises a differential amplifier connected across a sense resistor, and wherein said amplifier comprises an operational amplifier configured as an integrator having an RC network comprising an input resistor R and a feedback capacitor C.

### Claim 16 (depends on 15)

The method of claim 15, wherein said PLTC during transient testing comprises said integrator adjusting said output drive voltage until a voltage across said current sense device equals a present level of said Vref input.

### Claim 17 (depends on 16)

The method of claim 16, wherein an adjustment time during said transient testing is based on a time constant of said RC network.

### Claim 18 (depends on 10)

The method of claim 10, wherein said switchable power device comprises a metal oxide semiconductor (MOS) transistor.

### Claim 19 (depends on 10)

The method of claim 10, wherein said PLTC has no dependence of said load current on an output voltage of said DUT.

### Claim 20 (depends on 10)

The method of claim 10, further comprising programming said PLTC for said ID by changing a level of said Vref input or by said pulse signal or DC source changing its pulse signal frequency to change its duty cycle.