Programmable load transient circuit

Patent metadata

Field	Value
Publication number	US-10481193-B2
Application number	US-201815887531-A
Country	US
Kind code	B2
Filing date	Feb 2, 2018
Priority date	Feb 2, 2018
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

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.

First claim

The invention claimed is:

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 (I Davg ) 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 I Davg .

2. 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.

3. 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.

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

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

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

7. 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.

8. 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.

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

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 (I D ) 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.

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

12. 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 I D 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.

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

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

15. 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.

16. 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.

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

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

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

20. The method of claim 10 , further comprising programming said PLTC for said I D 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.

Assignees

• Texas Instruments Inc

Inventors

• Katz Daniel Alexander
• Munroe Michael James

Classifications

• G01R31/59 Primary

  while the cable continuously passes the testing apparatus, e.g. during manufacture · CPC title

• G01R31/40

  Testing power supplies (testing photovoltaic devices H02S50/10) · CPC title

• G01R31/2834

  Automated test systems [ATE]; using microprocessors or computers (G01R31/317 takes precedence; ATE for detection of defective computer hardware G06F11/2736) · CPC title

• H03K19/00384 Primary

  in field effect transistor circuits · CPC title

• G01R19/16519

  using FET's · CPC title