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THS4032: pin-to-pin replacement for cost down and failure analysis

BX27
Genius 3890 points
Part Number: THS4032
Other Parts Discussed in Thread: OPA564, , OPA2210

Hi there,

We have this step motor drive board which need to be cost down. the signal chain is as below.  

DAC7811----> THS4032 (signal conditoning stages) x2----->  OPA564 (howland current source, power drvie stage) ------> motor coils

THS4032 will see max 2.2V amplitude sine wave signal amplitude (Vpp 4.4V) and max freq. = 500HZ. Vs = +/- 10V.  I think it is unnecessary to use high-bandwidth amp like THS4032.  SCH would be update tomorrow after my boss approved.

Two question to consult TI expert:

(1) would you pls recommend a pin-to-pin (SOIC8) Replacement device, so we can test it on our existing board? 

(2) we are in pre-mass-production phase now, and already found 3pcs among 40pcs THS4032 damaged, this happens just occasionally therefore hard to identify how and when it is damaged. The only phenomenon is we measured correct input sine wave signals while the ouput of THS4032 is at power rail , +10V or -10V, and after we replace it with new device, the circuit recover working.

One possible reason may be ESD issue when debugging or mounting the board, but it is hard to ensure this, and I can not found a good way to reproduce the potential error environment to evoke the damage. Maybe an IC Failure Analysis at factory could provide useful info, but not sure how long and how much cost it would take.

Any comments are welcom, thanks!

  • 0
    TI__Genius 15565 points

    Hello Yi,

    (1) I will forward this thread to a colleague to help recommend a lower frequency part. Are there any other requirements such as noise, power consumption, etc?

    (2) Can you further clarify on the damage of these parts? Are the damaged parts still showing typical power consumption? Do both amplifiers in the dual package exhibit the same behavior?

    Let me know if you cannot provide the schematic on the forum and we can discuss privately. 

    Best,

    Hasan Babiker

  • 0
    Guru 140200 points

    Hi Yi,

    keep in mind that an inductive load can generate a highly destructive kick back voltage when turned-off. Because of this, it's wise to mount freewheeling diodes from the output of OPAmp to the supply rails.

    Kai

  • 0
    TI__Intellectual 1515 points

    Hello Xiao

    We have another precision device with lower bandwidth and appealing noise specs. Its voltage noise is 2.2nV and its current noise density is 400fA. The device is called OPA2210 (IDR for SOIC) and uses Super Beta input transistors. 

    Let me know what you think. 

    Soufiane 

  • 0 in reply to Hasan Babiker31
    Genius 3890 points

    Hi Hasan, SCH is attached.

    (1) Your colleague  recommends OPA2210, I will look into that, thanks.

    And we do not have low power requirement， power consumption is not a concern. Noise should be low, but I can not identify the specific number that how low it should be. That's why I search for a pin-to-pin to do on-board verification. 

    (2) I checked with the guy who firstly found this problem. It is U18 that occasionally damaged. The IC seems not overheating ( I assume it is under typical power consumption). But not sure whether both channel of THS4032 are damaged, he tested U18 net DAC_COS is correct, but net  DRV_COS is at power rail instead of expected sine wave, then he replaced it with a new device.

    Some of my thought: As your colleague  mentioned inductive could generate a highly destructive kick back voltage when turned-off, and we indeed add freewheeling diodes (D14, D15). I test the Normal sine voltage and current wave of net DRVP1 (R113), and motor spec also listed as below. 

    PLEASE Note at now we still used power supply +/-5V for THS4032 while +/-10V for OPA564. I am doubting is it possible that the downstream large signal(as you can see from the waveform that Vpp is 17.4V) MIGHT damged the upstream amplifier under some special situation.That's why I plan to change TH4032 power supply to also +/-10V in next version HW.

    (3) Can TI implement IC failure analysis? What is the procedure and time, cost it takes? 

    Thank you for helping!

  • 0 in reply to BX27
    TI__Genius 15565 points

    Hello Yi,

    (2) Nothing in your schematic design stands out to me as cause for damage on U18. In terms of kickback voltage the 100k resistor R115 should provide sufficient isolation to the THS4032 for this not to be a concern. I believe your initial assumption of ESD damage is likely the cause of these damaged parts.

    (3) Please refer to the following link for FA details:

    Procedure is begun by beginning a return process of the parts:

    Best,

    Hasan Babiker