topic Re: UJA1169ATK/F V1 undervoltage reset in Power Management

UJA1169ATK/F V1 undervoltage reset

larry_he — Mon, 18 Sep 2023 02:40:40 GMT

Hello, we use battery to supply VBAT(6.66V~7V), V1RTSUC is 80% and V1RTC is 90%, then SBC will reset, and RSS in Main status register(03h) will return 10011(V1 undervoltage).

V1 undervoltage,VBAT is OK

Increase the voltage on VBAT to 8V, the temperature will influence V1: UJA1169 will be OK below 65℃；while it will reset due to V1 undervoltage above 65℃.

When VBAT is 13V, the SBC is OK.

So, why VBAT and temperature will result in V1 undervoltage?

Re: UJA1169ATK/F V1 undervoltage reset

guoweisun — Mon, 18 Sep 2023 06:04:51 GMT

V1 is the internal LDO of UJA1169, so the MOSFET Rdson will increase when temperature rise.

So you can get the temperature affect the V1 of UJA1169.

Re: UJA1169ATK/F V1 undervoltage reset

larry_he — Mon, 18 Sep 2023 06:43:41 GMT

But will 65℃ make undervoltage happen? And when VBAT is 13V, 65℃ will not result in V1 undervoltage.

Re: UJA1169ATK/F V1 undervoltage reset

guoweisun — Mon, 18 Sep 2023 07:56:49 GMT

For the LDO,VOUT= Vin - Vdrop, Vdrop will be affected by the Rdson of internal MOSFET, when the VIN and VOUT are similar value, the UV condition will easily happen.

Re: UJA1169ATK/F V1 undervoltage reset

larry_he — Mon, 18 Sep 2023 08:59:44 GMT

Is Rdson RON(BAT-V1) (Can VBAT be 2.8V?)? Or do you have the value of Rdson?

Re: UJA1169ATK/F V1 undervoltage reset

guoweisun — Fri, 22 Sep 2023 00:15:05 GMT

是这个参数，我从你抓的波形上看V1输出往下掉的很厉害，可能是瞬态电流太大导致的。

你可以问问客户他这个测试条件瞬态电流能到多少？是不是超出了规格？正常值带载能力也就是200mA左右！

Re: UJA1169ATK/F V1 undervoltage reset

JLDN0101 — Fri, 13 Oct 2023 09:20:50 GMT

HI.guoweisun

I would like to ask a technical question about the UJA1169A, and since I didn't find a way how to post a new thread, this is the only way I can ask you.

As shown in the figure below, Vth(sw)r is the threshold for the rising edge from a low level to a high level, and Vth(sw)f is the threshold for the falling edge from a high level to a low level, why is there an intersection between these two thresholds?2.8V is contained within 3.75VHow is this understood?

For the UJA1169A, can the WAKE pin be internally configured with a pull-up or pull-down circuit? If the input signal is active low, must the WAKE pin have a resistor pull-up circuit?

Re: UJA1169ATK/F V1 undervoltage reset

guoweisun — Fri, 13 Oct 2023 09:27:29 GMT

如果是其他的topic，我建议您直接提交ticket下面的链接需要您的邮箱注册，我们会一对一的提供支持，回复的内容只有您自己看得到：

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Re: UJA1169ATK/F V1 undervoltage reset

JLDN0101 — Mon, 16 Oct 2023 01:21:37 GMT

HI.guoweisun

I would like to ask a technical question about the UJA1169A, and since I didn't find a way how to post a new thread, this is the only way I can ask you.

For the UJA1169A, can the WAKE pin be internally configured with a pull-up or pull-down circuit? If the input signal is active low, must the WAKE pin have a resistor pull-up circuit?

Re: UJA1169ATK/F V1 undervoltage reset

guoweisun — Mon, 16 Oct 2023 09:32:43 GMT

这个客户提交了一个ticket今天已经帮他回复了