Technical Consultation

Hi Sandy5 ,

This is to acknowledge that I’ve received your query regarding the ADG419. I’ll get back to you soon.

Thanks,

Gelo

Hi Sandy5 ,

Thank you for providing detailed information about the issues you’re experiencing with the ADG419BRZ-REEL7 components. To assist us in better understanding and analyzing the cause, could you please provide additional details on the following points:

1. Testing Environment: Could you describe the environmental conditions (e.g., temperature, humidity) during your testing and operation of the boards?
2. Power Supply Details: Are there any fluctuations or noise in the power supply voltages (+15V, 5V, -15V) that could affect the performance of the        ADG419BRZ-REEL7?
3. Circuit Design: Can you provide a schematic or detailed description of the circuit, particularly how pin 8 is handled and any other relevant connections?
4. Batch Information: Do you have the lot numbers or manufacturing dates for the ADG419BRZ-REEL7 components used in the affected boards?
5. Temperature Sensitivity: Have you observed any correlation between the temperature changes and the occurrence of the issue? If so, could you provide details on the temperature range during operation?
6. Cross-Validation Tests: Could you elaborate on the cross-validation tests performed and any specific findings that led to the conclusion that the ADG419BRZ-REEL7 is the cause?

Regards,

Gelo

Hi Gelo,

Thank you for reply. The response to your question is as follows.

I am still in the process of confirming questions 1 and 2.
Question 3, as shown in the picture.

Question 4, the date code of the part we used is 2128.
Question 5, I have uploaded the report in the attachment which has data about temperature and AD value.

PDF
Problem 6, after we removed the ADG419BRZ-REEL7, the wiring went back to normal, replaced it with a new ADG419BRZ-REEL7 on it and tested PASS.

Please help to analyze it, thanks.

Best regards,

Sandy

Hi Sandy5 ,

Sorry for the late reply; I was out of the office last Friday.

I'll review the responses you provided and get back to you as soon as possible!

Regards,

Gelo

Hi Sandy5 ,

Thank you for providing the circuit diagram. This helps in understanding the design and connections around the ADG419. Based on the schematic and the previous information, here are a few insights and additional suggestions for investigation:

1. Pin 8 Configuration:
   • I noticed that pin 8 (D) of the ADG419 (U5) appears to be left floating. While this can work in some applications, an unconnected drain pin may cause unexpected behavior, especially under varying conditions like temperature changes or power fluctuations.
   • If feasible, you might consider adding a high-value resistor from pin 8 to ground or another stable reference. This could help mitigate potential floating-node effects that might contribute to leakage.

2. Negative Voltage on Pin 1:
   • Since you’ve observed negative voltages on pin 1 when pin 6 (IN) is high, this indicates potential leakage paths that may be due to internal issues within the U5 or related circuitry, such as parasitic paths caused by thermal or mechanical stress.
   • This could also suggest that a transient condition in the power supply or the switching logic might be affecting the stability of the device.
   • To further isolate this, you could try grounding pin 8 temporarily and observe if the negative voltage issue at pin 1 persists. This may help determine if the floating state of pin 8 is contributing to the voltage discrepancies.

3. Circuit Layout and Design:
   • Since the component is sensitive to thermal changes, ensure that the layout minimizes any thermal stress points around U5 and that the solder joints are robust. Verify that the conformal coating does not affect the surrounding circuitry when heated or cooled.

4. Power Supply Stability:
   • If you have any updates on questions 1 and 2 (testing environment and power supply stability), it would be useful to assess if there are any transient spikes or noise that might be influencing the U5’s behavior, particularly given its temperature sensitivity.
   • Adding decoupling capacitors or ferrite beads to isolate noise on the power rails might stabilize U5’s performance.

5. Temperature Sensitivity:
   • U5 appears to be sensitive to temperature changes, with functionality sometimes restored after heating with a hot air gun. This behavior may suggest that certain internal connections or solder joints could be affected by temperature cycles, potentially indicating a weak or intermittent connection within the IC or at the board level.
6. Humidity and Moisture Impact:
   • Although moisture’s effect on the AD values was inconclusive, it’s advisable to consider how the board’s conformal coating (approximately 30 µm) might play a role. Even though it’s within the allowable range, its minimal thickness may allow for environmental factors to affect the board under prolonged use.

7. Replace U5 Components in Affected Boards:
   • If the thermal recovery using a heat gun temporarily restores functionality, it might be prudent to replace U5 on the affected boards, as the components could be prone to further degradation over time.
   • If possible, consider testing a batch of ADG419 components from a different lot to assess if the issue persists, ruling out any batch-related inconsistencies.

8. Additional Environmental Testing:
   • To verify the component’s robustness under typical operating conditions, conduct controlled thermal cycling (beyond 85°C if possible) to simulate real-world operating conditions. This may provide insights into the longevity and stability of U5 under field conditions.

By addressing the environmental, power, and layout factors, this analysis should help in further diagnosing and potentially mitigating the observed failures in the ADG419.

Please let me know if further clarification on any of these points is needed. We can continue to narrow down potential causes with these details.

Regards,

Gelo

Hi Gelo,

Thank you for your suggestions and we are referring to them for further validation.

I have one more question. We removed the ADG419 for electrical performance testing.
Including 2 pieces of good parts and 3 pieces of defective parts for testing the functional truth table and on-leakage current at room temperature.
We found that 2 pieces of good parts and 1 piece of defective part are qualified, and their output status, supply voltage and on-leakage current are normal during the test; 2 pieces of defective parts are not qualified, although the output status and supply voltage are normal during the test, but the on-leakage current of channel S2 is large.

I would like to know the possible reasons for this situation or the ones you mentioned before?

Best regards

Hi Gelo,

Did you get the last reply I sent?

I have one more question. We removed the ADG419 for electrical performance testing.
Including 2 pieces of good parts and 3 pieces of defective parts for testing the functional truth table and on-leakage current at room temperature.
We found that 2 pieces of good parts and 1 piece of defective part are qualified, and their output status, supply voltage and on-leakage current are normal during the test; 2 pieces of defective parts are not qualified, although the output status and supply voltage are normal during the test, but the on-leakage current of channel S2 is large.

Best regards

Hi Sandy5 ,

Thank you for your detailed observations regarding the ADG419 electrical performance testing. I apologize for the delay in my response.

I will thoroughly analyze the data and the issues you’ve mentioned regarding the on-leakage current of channel S2. Once I have completed the analysis, I will get back to you with my findings and possible reasons for the discrepancies.

For further discussions, please feel free to continue this conversation through my work email at (angelo.floralde@analog.com).

Thank you for your patience.

Best regards,
Gelo

Hi Gelo,

Is there a relationship between this abnormal result and electrostatic damage?

Best regards

Hi Sandy5 ,

Thank you for providing the detailed test results. I noticed a potential discrepancy in the reported test conditions and would like to clarify to ensure our analysis is accurate.

In your setup for the defective products, I observed that you wrote VD = 15V and VIN = 5V. However, from the images you provided, I observed that the supply voltage is ±16.5V and the source voltage is set at 15.5V. Could you please confirm if the drain voltage during the tests was indeed 15V, or if it should be 15.5V?

To ensure we have the correct data, could you please verify the following:

1. Supply Voltage: Confirm that the supply voltage is ±16.5V.
2. Source Voltage: Confirm that the source voltage is set at 15.5V.
3. Drain Voltage: Verify if the drain voltage during the tests was 15V or 15.5V.

Your confirmation will help me accurately analyze the on-leakage current issue and provide more precise recommendations.

Regards,

Gelo