Keysight Technologies D9020DDRC, Manual

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7 Single-Ended Signals AC parameter tests for Strobe Signals
124 DDR2(+LP) Compliance Testing Methods of Implementation
V
SEL(AC)
(strobe) - Test Method of Implementation
V
SEL(AC)
- Single- ended Low Level Voltage.
The purpose of this test is to verify that the minimum low pulse voltage must be within the
conformance limit of the V
SEL(AC)
value as specified in the JEDEC specification.
The value of V
DDQ
(which directly affects the conformance limit) is set to 1.2V for the compliance
limit set used. You may choose to use the User Defined Limit feature in the application to perform
this test against a customized test limit set based on different values of V
DDQ
.
Signals of Interest
Mode Supported: LPDDR2 only
Signal cycle of interest: WRITE
Signal(s) of Interest:
• Data Strobe Signals (supported by Data Signals)
Signals required to perform the test on the oscilloscope:
• Pin Under Test, PUT - Data Strobe Signals
• Supporting Pin - Data Signals
Test Definition Notes from the Specification
Test References
See Table 79 - Single-ended Levels for CK_t, DQS_t, CK_c, and DQS_c in the JESD209-2B .
PASS Condition
The worst measured V
SEL(AC)
shall be within the specification limit.
Measurement Algorithm
1 Acquire and split read and write bursts of the acquired signal.
2 Take the first valid WRITE burst found.
3 Find all valid strobe negative pulses in this burst. A valid strobe negative pulse starts at the V
REF
crossing on a valid strobe falling edge and ends at the V
REF
crossing on the following valid strobe
rising edge.
4 For the first valid strobe negative pulse, zoom in on the pulse so that it appears on the
oscilloscope’s display and perform T
MIN
. Then perform V
TIME
at the found T
MIN
to get the
minimum voltage of the pulse. Take the V
TIME
measurement result as the V
SEL(AC)
value.
5 Continue the previous step for the rest of the valid strobe negative pulses that were found in the
burst.
6 Determine the worst result from the set of V
SEL(AC)
measured.
Table 76 LPDDR2 Single-ended Levels for CK_t, DQS_t, CK_c, and DQS_c
Symbol Parameter LPDDR2-1066 to LPDDR2-466 LPDDR2-400 to LPDDR2-200 Units Notes
Min Max Min Max
V
SEL(AC)
Single-ended low level for strobes Note 3 (V
DDQ
/2) - 0.220 Note 3 (V
DDQ
/2) - 0.300 V 1, 2