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The RI8589A FET Pulser TIM can fail if the sense resistor is exposed to large current when in low current sense mode. The sense resistor is used to prevent shorted paths from damaging the components in the FET Pulser. For hardware model revisions A1 thru A4 with model Y000C0C3 boards, test plans that are run on a DUT with shorted pins that contain a voltage sweep in low current measurement modes can damage this resistor, causing the TIM to fail.

Status: Proactive TIMs exchanges are being issued. Notifications issued and RMAs still outstanding.

Action Required
Review and modify test plans with the "Suggested Testplan Mitigation Changes" below and contact [email protected] to schedule an RMA Upgrade for any affected TIMs. Upgrades must be handled at the factory to update the Y000C0C3 board with the "3rd generation" sense resistor circuit. There are two planned updates, current one with upgraded resistor network that provides 4.5 Watts (three (3) 1 ohm 1812 size 1.5 Watt resistors) and future upgraded PCB design that is still pending (as of April 2018).

Minimum Patch Required
The following patch is required to package the necessary RiBaseInstDef and board firmware needed to support the improvement.
Patch 180-158

Suggested Testplan Mitigation Changes
Please read the CH 2: Graphical Programming of the Cassini Reference Guide for information about using TIMs. (excerpt below)
Set Global Defaults for Pulse Range and Pulse OCP to the highest expected values in the testplan. For example, Set Pulse Range to '26A' and Pulse OCP to '26' for the Fet Pulser instrument so the TIM remains in a state with the most robust voltage protection unless specified in Section Defaults or a Test.
Modify the test plan to include a Test that sets a flag based on a continuity measurement that detects a DUT with shorted pins and skipIfTrue or abortIfTrue conditional statement logic in subsequent test sections that would contain a low voltage sweep.
Additionally, a Test Exec configuration with Abort On Fail option should be selected.
See "Reference" section below for more details.

Affected TIMs
All 16 TIMs that have been assembled and shipped prior to 01/26/2018 that would require factory upgrades have been upgraded. (Strikethrough have been upgraded)
TIM Model Numbers: RI8589A2, RI8589A3, RI8589A4, RI8589A5
Serial Numbers:
B1 - New PCB layout (pending) + new faster voltage measure

Upgraded TIMs By Date
The following TIM Serial Numbers have been upgraded with the 3rd Gen (three (3) 1 ohm 1812 size 1.5 Watt resistors). TIMs listed below should NOT be returned to factory for an upgrade since it has already been completed.
16 of 16 upgraded as of 08/26/2018
Serial Number : Date
RRGCCC0A : 02/06/2018
RRWCWK0A : 02/28/2018
RRWCYE0A : 04/06/2018
RTF0B60A : 04/27/2018
RU79F30A : 05/14/2018
RU64UZ0A: 05/30/2018
RRGCCC0A: 05/31/2018
RS37UK0A: 06/07/2018
RU9SNG0A:: 6/11/2018
RTGZGM0A: 6/11/2018
RTZTMM0A: 6/11/2018
RRRC220A: 6/25/2018
RRE2RK0A: 6/26/2018
RU4S380A: 7/5/2018
RTGZGY0A: 7/6/2018
RPMV0T0A: 8/26/2018

Permanent Solution with improved TIM Circuit Protection
For longer term protection, we found a pulse proof resistor network which can handle the 55W pulse for up to 1000uS. While it is best to not test shorted devices that could damage the socket, this should protect the TIM. These will be released as A6 or B1, depending on the other generation boards in the assembly.

The low current sense resistor can fail when specific test plan conditions are run with a shorted DUT. The low range sense resistor can be exposed to large amounts of current if the TIM is not configured properly when high current is applied. After the resistor is damaged, the TIM protection prevents future measurements from this circuit and the TIM diagnostics FAIL. The damaged TIM must be returned to RI for repair and calibration. All TIMs returned to factory get all necessary modifications during the refurbish process.

Specific test plans conditions that can cause a TIM Failure:
  1. FetPulser Hv# range buttons that sets a series of low current voltages, also described as 'voltage sweep' tests, may create a condition when the voltage duty cycle on the protection circuit can exceed the maximum performance specifications and cause component damage. Avoid these measurements by aborting the test section containing these tests.
  2. FetPulser - Pulse Range buttons set with values of '500mA' and '50 mA' changes the TIM to use a circuit protection network to detect low current range and is less resistant to relatively long duration exposure to high current.
  3. FetPulser - Pulse Ocp values larger than of '1' and '0.5' respectively should be used. Pulse Ocp sets peak current limit on the pulse output in Amps.

See Cassini Reference Guide, CH 2 Graphical Programming, Introduction (pg. 144)

Conditional Statements
The Conditional Statements section allows the user to insert control statements that can modify or alter the test program flow during run time, (i.e. skip all tests in a test section or abort the test program). The logic statements are defined by the System buttons found in the ‘Flow Control’ panel of the Editor: abortIfTrue, abortIfFalse, skipIfTrue, skipIfFalse, PromptIfFalse, and Prompt. The first four button types when placed in the Conditional Statements section check the true/false status of conditional flag defined by the user via the Set Flag input block. If the conditional flag status matches the button/s in the conditional section, the test program flow is altered accordingly. See the Flow Control edit panel button descriptions in Section 11 - RI8574: System Controller (EPC) for more information. Conditional Statement panels are located at the beginning of every test section, allowing the user to apply the test program flow changes to all test panels/measurements contained therein.

Excerpt From: Roos Instruments. “Cassini ATE System Reference Guide.” Roos Instruments, 2016. iBooks. https://itunes.apple.com/us/book/cassini-ate-system-reference-guide/id816739794?mt=11


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