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User’s Manual U13655EJ2V1UD
291
CHAPTER 22 SUB-HALT TEST PROGRAM
22.1 Sub-HALT Test Program Overview
The
μ
PD780957(A) and 780958(A) feature a considerably lower current consumption compared with existing
products. In the HALT mode during subsystem clock 1 operation, the current consumption is 4.0
μ
A (MAX.) (T
A
= -40
to +60°C), which is approximately one fourth the level of existing products, so that there is the risk that defective
samples may get mixed in when conventional shipment screening methods are used. Shipment screening in the
same environment as the actual operation environment is made possible through the incorporation of the sub-HALT
current test program (program that reflects the check items listed in the Verification Form in section 22.3) in the user
program, thereby enabling a stable supply of acceptable samples.
During user program tape out, be sure to verify the check items (check off each item in the Judgment column) on
the Verification Form shown in section 22.3, and after inputting any other required items, submit the Verification Form
to an NEC Electronics sales representative or authorized NEC Electronics distributor (copies of the Verification Form
can be made).
22.2 Sub-HALT Test Program Flowchart
Program start
(initial setting)
P50 input level judgment
Does operation time (t)
from program start satisfy:
0 ms < t
≤
10 ms
Sub-HALT mode
Correct the program.
Yes
No
·
Power application
·
Low level input to P50 pin
·
Release reset (low level
Note
→
high level)
Note
Low-level input during the time required
for the subsystem clock 1 oscillation to
stabilize
·
Securing of automatic wait of 250 ms
·
Perform same setting as normally set for SFR
register in sub-HALT mode.
·
Main system clock/subsystem clock 2 must
be stopped.
·
HALT mode cannot be released other than
through reset input.
·
Do not make pins to which a pull-up resistor
has been connected via mask option low level.
·
Execute the settings listed in the Verification
Form shown in section 22.3.
(Software)
(Hardware)
Main program
Low level
High level