Timeline for Op Amp with positive feedback (hysteresis) driving N-MOSFET oscillates
Current License: CC BY-SA 4.0
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| Jun 11, 2020 at 15:10 | history | edited | CommunityBot |
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| Feb 29, 2020 at 6:28 | comment | added | Lt_Flash | Thanks a lot for your explanation and comments! I'll give it a go and if resistor won't help I will use a comparator. How do you think, MCP6541R is ok for this circuit? Thanks! | |
| Feb 29, 2020 at 2:25 | vote | accept | Lt_Flash | ||
| Feb 29, 2020 at 2:25 | |||||
| Feb 28, 2020 at 20:02 | history | edited | D.A.S. | CC BY-SA 4.0 |
added 1726 characters in body
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| Feb 28, 2020 at 15:02 | comment | added | D.A.S. | I hope there is no hidden load capacitance added across TLV431 Zener with only (2.5-1.24)/4.7k as per page 7 bottom | |
| Feb 28, 2020 at 14:30 | comment | added | D.A.S. | You did not post any measurements of Vgs or Vds. The NCS333 has typical BJT push-pull driver losses from each rail and is not Rail to Rail. | |
| Feb 28, 2020 at 8:24 | comment | added | Lt_Flash | According to DMN1019U datasheet at Vgs 1.5V and Idrain of 2A RdsOn = ~0.012Ohm. Am I wrong? And I'm using NCS333 to compare Supercap voltage to 1.24V set by TLV431B so Op Amp powered from ~2.5V could produce a full swing, there's a voltage divider on positive input of Op Amp for that. I really appreciate your help but need some additional information how to resolve this issue. I thought I've taken into account both MOSFET Vgs(th) and RdsOn and OpAmp swing. Thanks! | |
| Feb 28, 2020 at 8:04 | comment | added | Lt_Flash | docs.rs-online.com/29e2/0900766b814b9191.pdf | |
| Feb 28, 2020 at 7:58 | comment | added | Lt_Flash | 1. I'm comparing to 1.24V set by TLV431B 2. Vgth of DMN1019 is quite sufficient to work from as low as ~1V according to datasheet? Gate Threshold Voltage VGS(th) 0.35 0.53 0.8 V VDS = VGS, ID = 250µA. I can't attach a picture from datasheet in comments for some reason, but even V , DRAIN-SOURCE VOLTAGE (V) Figure 1 Typical Output Characteristics graph shows that at 1V of Vgs and 1V of Vds drain current is ~2.5A? | |
| Feb 28, 2020 at 7:54 | history | answered | D.A.S. | CC BY-SA 4.0 |