with ESP-NOW, it brown out with 500ma max current ldo ht7833

trustmiao
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with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby trustmiao » Wed Sep 19, 2018 2:32 am

We try to design an application powered by one 14500, 3.7 lipo. At early tests, we prefer ht7833 to ams1117, as the drop-out voltage of ams1117 is up to 1.3v. We tried as many ldo regulator as possible and finally choose ht7833. However, three of the test boards all failed after we upload the code. The code is basically ESP-NOW as STA and AP to transfer between each other. Once the code if flashed, the boards browned out and can never start to work. Could just guess the peak current and voltage drop out browns out the ESP32.

We are running out of option, any voltage regulator recommend ? All inputs are welcomed

ESP_Angus
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Re: with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby ESP_Angus » Wed Sep 19, 2018 5:26 am

Do your boards have enough capacitance on the input & output of the LDO? Are you able to show us an image of the layout?

Are you using modules or a chip? If a chap, are all power pins correctly connected?

trustmiao
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Re: with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby trustmiao » Wed Sep 26, 2018 6:33 am

Sorry for late reply, just back from national holiday.

We have got the 1uf between vin-gnd, 2.2uf between vout-gnd. We left a jumper to bypass the HT7833 for testing, as the skech below.
微信图片_20180926140634.png
微信图片_20180926140634.png (11.73 KiB) Viewed 588 times
We are using ESP-WROOM-32.
Vout then connects to 3v3 and all the sensor's vcc, while at the expemerient no sensor is currently connected. gnd connects to gnd.

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loboris
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Re: with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby loboris » Wed Sep 26, 2018 8:51 am

Try to put 0.1uF + 22uF (or greater) in parallel close to ESP32 Vcc pin.

trustmiao
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Re: with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby trustmiao » Wed Sep 26, 2018 10:09 am

loboris wrote:Try to put 0.1uF + 22uF (or greater) in parallel close to ESP32 Vcc pin.
Haven't got a 22uf in arm's reach, therefore tried 0.1uf+1000uf. and it works like charm.

and then we tested add 1000uf only, and it works as well without observable difference in performance. Is 0.1uF a must have?

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loboris
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Re: with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby loboris » Wed Sep 26, 2018 7:11 pm

The smaller capacitor (0.1 uF - 1 uF) is there to deal with high frequency noise (it should be ceramic). If the the larger one is ceramic or low-ESR tantalum, you can probably omit the smaller one.

trustmiao
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Re: with ESP-NOW, it brown out with 500ma max current ldo ht7833

Postby trustmiao » Thu Sep 27, 2018 4:08 am

loboris wrote:The smaller capacitor (0.1 uF - 1 uF) is there to deal with high frequency noise (it should be ceramic). If the the larger one is ceramic or low-ESR tantalum, you can probably omit the smaller one.
Cool, learnt alot, very appreciated!

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