| Electronics > Projects, Designs, and Technical Stuff |
| PSA: do not use the TPS61099 boost reg in your designs |
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| fireworks:
--- Quote from: BrianHG on January 23, 2019, 04:29:17 am ---Their own engineers couldn't decipher their own documentation... It took 5 days and a few friends who specialized in math and physics to reverse engineer the notation in their .pdf data sheet and to get the IC to dynamically be programmed to do exactly what I want. --- End quote --- Hi Brian, Which TI datasheet was that ? I want to take a look at the weird formulas ☺ |
| TheDane:
--- Quote from: jeremy on January 22, 2019, 02:36:36 am --- If anyone has any ideas about how I could work around something like this, I'm all ears :-// Thanks, Jeremy --- End quote --- Not much of a TI device work around; more a protection in general: ESD Suppressors / TVS Diodes UNIDIRECTIONAL 3.3V + a polyfuse on the input. Getting the correct part for your device can be tricky, as operating voltage vs. clamping voltage is quite close so not to blow up everything. What is your device supply absolute max rating, and the device current draw? https://www.mouser.com/datasheet/2/80/CPDH3V3UP-HF_RevB034941-1481125.pdf Clamping voltage - 5V5, I_PP = 1 A Punch-through voltage - 3V5, I_PT = 2uA Snap-back voltage - 2V8, I_SB = 50mA Fig.3 - Clamping voltage vs. peak pulse current - 8V@5A down and stops at 1A@5V5, extrapolating it down could result in a working protection solution for you? |
| JPortici:
--- Quote from: Siwastaja on January 22, 2019, 06:19:58 am ---These things are IC design equivalents of spaghetti code from a total beginner. If this was a software, a fix would be another overcomplicated "UVLO filter unit" which would reduce the number of issues, but increase complexity again. But ICs can't be updated. --- End quote --- And yet newer TI chips ARE updated. I've used some of their newer LDOs in a design and between batches (like 6 to 12 months later) the exact partnumber didn't even exist anymore, but a partnumber followed with "A1" was available. then "A2" and so on... |
| forrestc:
--- Quote from: Siwastaja on January 22, 2019, 06:19:58 am ---Sounds like typical TI engineering. I use their power conversion/management ICs less and less - they are overcomplicated and have excess state space, and therefore tend to hit unwanted states - and a typical "wrong state" tends to mean: blow up everything. --- End quote --- I miss National Semiconductor. Back before TI gobbled them, I found the national power conversion IC's to be top notch and just work. I never had the same luck with TI. Right now I'm sort of looking for a replacement for a buck converter which was an original National design. It's old enough that it's got a way high I(q) but it sure makes me nervous to try something else especially when you hear stories like this on a fairly regular basis. |
| jeremy:
--- Quote from: TheDane on January 23, 2019, 09:49:22 am --- --- Quote from: jeremy on January 22, 2019, 02:36:36 am --- If anyone has any ideas about how I could work around something like this, I'm all ears :-// Thanks, Jeremy --- End quote --- Not much of a TI device work around; more a protection in general: ESD Suppressors / TVS Diodes UNIDIRECTIONAL 3.3V + a polyfuse on the input. Getting the correct part for your device can be tricky, as operating voltage vs. clamping voltage is quite close so not to blow up everything. What is your device supply absolute max rating, and the device current draw? https://www.mouser.com/datasheet/2/80/CPDH3V3UP-HF_RevB034941-1481125.pdf Clamping voltage - 5V5, I_PP = 1 A Punch-through voltage - 3V5, I_PT = 2uA Snap-back voltage - 2V8, I_SB = 50mA Fig.3 - Clamping voltage vs. peak pulse current - 8V@5A down and stops at 1A@5V5, extrapolating it down could result in a working protection solution for you? --- End quote --- Thanks for the pointers. I’ve been measuring some zener diodes I have around but as I suspected even a good 5.1V zener had around 100uA of leakage at 3.6V. Unfortunately my entire power budget during sleep is 100uA @ ~3V at Vin (incl regulator efficiency loss and Iq), but of course I’m trying to beat that. I’ll have to do some reading on these esd devices, I didn’t realise the reverse leakage was so good. System can withstand up to 4.2V, and needs about 250mA peak at 3.6V when radio activity is heavy, but it normally stays around 20-30mA otherwise. My other concern with clamping is that it doesn’t actually reset the converter and in my experience with this problem it needs a reset to be fixed. I’ve managed to get my double voltage supervisor down to 10uA, which I think I can live with. But testing it with this intermittent problem is tricky... Edit: sorry, I see you mentioned polyfuse as well. That could cause a UVLO reset perhaps |
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