Functional Description
ARM DDI 0402F
Copyright © 2007-2010 ARM. All rights reserved.
2-11
ID011711
Non-Confidential
2.2
Functional operation
The functional operation is described in:
•
Timing
•
Bitmap mode
on page 2-13
.
2.2.1
Timing
A 60-bit instruction, loaded serially at the start of each test, controls the operation of the MBIST
controller.
Chapter 3
MBIST Instruction Register
describes how to write the instruction.
The timing diagrams in this section show the clock running at two different speeds:
•
the slower clock relates to the clock driven by your ATE
•
the faster clock relates to the clock driven by an on-chip
Phase Locked Loop
(PLL).
If you do not have an on-chip PLL, both clocks relate to the clock driven by your ATE.
Timing diagrams in the following sections show the procedures for operating the MBIST
controller:
•
Instruction load
•
Starting MBIST
•
Failure detection
on page 2-12
•
Data log retrieval
on page 2-12
.
Instruction load
To load an MBIST instruction, drive
MBISTSHIFT
HIGH. At the next rising clock edge, the
61-bit shift sequence begins as shown in
Figure 2-6
. To enable data input from the ATE, the PLL
is in bypass mode, and the clock is not running at test frequency.
Figure 2-6 Loading the MBIST controller instruction
Starting MBIST
Reset the MBIST engine. After loading the MBIST instruction, drive
MBISTSHIFT
LOW and
disable
CLK
. With
CLK
disabled, drive
MBISTRUN
HIGH and, after an
MBISTRUN
setup
time, start the PLL at the test frequency as shown in
Figure 2-7
.
Figure 2-7 Starting the MBIST test
i[60]
i[59]
i[1]
i[0]
CLK
MBISTRUN
MBISTSHIFT
MBISTDATAIN
CLK
MBISTRUN
MBISTSHIFT