LOGIC BUILT-IN SELF-TEST SYSTEM AND METHOD FOR APPLYING A LOGIC BUILT-IN SELF-TEST TO A DEVICE UNDER TEST

• US 20110221469A1
• Filed: 11/24/2008
• Published: 09/15/2011
• Est. Priority Date: 11/24/2008
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Schlagenhaft, Rolf
• Granted Patent: US 8,461,865 B2
• Time in Patent Office: Days
• US Class Current: 326/16
• CPC Class Codes: G01R 31/31724 Test controller, e.g. BIST state machine for scan test G01R31/318555
• CPC Class Codes: G01R 31/318541 Scan latches or cell details

Abstract

A logic built-in self test (LBIST) system comprises a device under test having a first plurality of first bistable multivibrator circuits an LBIST controller, and a second plurality of second bistable multivibrator circuits. Each second bistable multivibrator circuit is coupled to a corresponding first bistable multivibrator circuit to swap a second state value kept by the second bistable multivibrator circuit with a first state value kept by the corresponding first bistable multivibrator circuit depending on a first control signal from the LBIST controller and the second bistable multivibrator circuits are coupled to form one or more scan chains when receiving a second control signal from the LBIST controller.

Claims

1. A logic built-in self test system, comprising

a device under test having a first plurality of first bistable multivibrator circuits;

a logic built-in self test (LBIST) controller; and

a second plurality of second bistable multivibrator circuits,

each second bistable multivibrator circuit coupled to a corresponding first bistable multivibrator circuit and configured to swap a second state value kept by said second bistable multivibrator circuit with a first state value kept by said corresponding first bistable multivibrator circuit in response to a first control signal from said LBIST controller, and

said second bistable multivibrator circuits coupled to form one or more scan chains when receiving a second control signal from said LBIST controller.

2. The LBIST system as claimed in claim 1 further comprising:

each second bistable multivibrator circuit is further coupled to said corresponding first bistable multivibrator circuit to swap said first state value kept by said second bistable multivibrator circuit with said second state value kept by said corresponding first bistable multivibrator circuit in response to said first control signal from said LBIST controller.

3. The LBIST system as claimed in claim 1, wherein said second bistable multivibrator circuit comprises:

a first bistable multivibrator receiving and providing said first state value of said first bistable multivibrator circuit to said first bistable multivibrator circuit; and

a second bistable multivibrator providing and receiving said second state value from said first bistable multivibrator circuit.

4. The LBIST system as claimed in claim 1, wherein said second state values comprise test values.

5. The LBIST system as claimed in claim 1, wherein said second bistable multivibrator circuits are further configured to receive a second clock signal having a clock frequency different from a first clock signal received by said corresponding first bistable multivibrator circuits.

6. The LBIST system as claimed in claim 5, wherein a power consumption of said LBIST system is adjusted by varying said second clock signal.

7. The LBIST system as claimed in claim 1, wherein said second bistable multivibrator circuits are further configured to receive a second clock signal having a clock frequency identical to a first clock signal received by said corresponding first bistable multivibrator circuits.

8. The LBIST system as claimed in claim 1, wherein a length of time for swapping each of said second state values with said first state values is independent of the number of first bistable multivibrator circuits.

9. The LBIST system as claimed in claim 5, wherein a length of time for swapping each of said second state values with said first state values is the time required for one clock cycle of said first clock signal.

10. The LBIST system as claimed in claim 1, wherein one or more of said corresponding first bistable multivibrator circuits coupled to said second bistable multivibrator circuits forming said one or more scan chains are operable to change said first state values during a same period of time as said LBIST controller reads or writes said second state values of one or more of said second bistable multivibrator circuits forming said scan chains.

11. The LBIST system as claimed in claim 1 further comprising:

a pattern generator of said LBIST controller; and

a signature generator of said LBIST controller, wherein

at least one of said one or more scan chains comprises an input coupled to an output of the pattern generator of said LBIST controller and an output coupled to an input of the signature generator of said LBIST controller.

12. The LBIST system as claimed in claim 1, wherein said device under test is a partition of a microcontroller unit.

14. A safety critical system, comprising a logic built-in self-test (LBIST) system as claimed in claim 1.

15. A vehicle comprising the safety critical system as claimed in claim 14.

20. The LBIST system as claimed in claim 2, wherein said second bistable multivibrator circuit comprises:

a first bistable multivibrator receiving and providing said first state value of said first bistable multivibrator circuit to said first bistable multivibrator circuit; and

a second bistable multivibrator providing and receiving said second state value from said first bistable multivibrator circuit.

13. A method for applying a logic built-in self-test to a device under test having a first plurality of first bistable multivibrator circuits, the method comprising:

writing second state values into a second plurality of second bistable multivibrator circuits, each second bistable multivibrator circuit coupled to a corresponding first bistable multivibrator circuit;

swapping said second state values with first state values kept by said corresponding first bistable multivibrator circuits;

applying said second state values kept in said first bistable multivibrator circuits to said device under test;

capturing a test result in said second state values by applying a first clock signal to said first bistable multivibrator circuits;

swapping said second state values kept by said corresponding first bistable multivibrator circuits with said first state values kept by said second bistable multivibrator circuits; and

reading said second state values kept by said second bistable multivibrator circuits.

17. The method of claim 13 further comprising:

receiving a second clock signal, by the second bistable multivibrator circuits, wherein the second clock signal comprises a clock frequency different from the first clock signal.

18. The method of claim 17 further comprising:

adjusting a power consumption of said logic built-in self-test system by adjusting said second clock signal.

19. The method of claim 13 wherein said second state values comprise test values.

16. A non-transitory computer-readable storage medium storing instructions executable by a processor and configured to:

write second state values into a second plurality of second bistable multivibrator circuits, wherein each second bistable multivibrator circuit is coupled to a corresponding first bistable multivibrator circuit;

swap said second state values with first state values kept by said corresponding first bistable multivibrator circuits;

apply said second state values kept in said first bistable multivibrator circuits to a device under test;

capture a test result in said second state values by applying a first clock signal to said first bistable multivibrator circuits;

swap said second state values kept by said corresponding first bistable multivibrator circuits with said first state values kept by said second bistable multivibrator circuits; and

read said second state values kept by said second bistable multivibrator circuits.