Browse Prior Art Database

Device AC test by self execution

IP.com Disclosure Number: IPCOM000015183D
Original Publication Date: 2002-Apr-11
Included in the Prior Art Database: 2003-Jun-20
Document File: 3 page(s) / 80K

Publishing Venue

IBM

Abstract

Device AC test by self execution A new AC test method The key concept of the new AC test method is isolated execution . By using isolated execution, this AC test can be performed on wafers or modules even if the test environment is using an inexpensive VLSI tester and a poor contact method. However, the method can be applied to only a limited range of products.

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Device AC test by self execution A new AC test method

 The key concept of the new AC test method is isolated execution. By using isolated execution, this AC test can be performed on wafers or modules even if the test environment is using an inexpensive VLSI tester and a poor contact method. However, the method can be applied to only a limited range of products.

Function requirements

 Fig. 1 shows the new AC test concept and a device function diagram. This method requires the following functional capabilities on the DUT:

SRAM : To store Test

Program MPU : To execute Self Test PLL : To generate system clock

MPU SRAM

PLL

Figure 1 Device function diagram

Test sequence

 All of the test sequences of this AC test are not executed under LSSD test mode, but in application mode. This means the DUT always uses the system clock that is provided by the PLL. Here is the basic test sequence:

1. Download executable MPU code from I/O to SRAM (as shown Fig. 2)
2. Execute code and store result (as shown Fig. 3)
3. Read stored result and judge pass or fail (as shown Fig. 4)

 I/O operations between the VLSI tester and the DUT occur at Steps 1 and 3. Only Step 2 performs at-speed operations, but it does not require any I/O operations. This is the reason why this AC test does not require a high performance test environment.

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MPU SRAM

LDAD LDAD E,#03EFFE E,#03EFFE

TESX TESX

LDTX #0300H LDTX #0300H

LDDX LDDX

3,#03E8C0H 3,#03E8C0H

ORAM RAMCTRL ORAM RAMCTRL

LDX #0000H LDX #0000H

Y-r...