UJA1169ATK/F V1 undervoltage reset

[larry_he]

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?

[guoweisun]

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.

[JLDN0101]

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?

[guoweisun]

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[guoweisun]

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[larry_he]

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

[guoweisun]

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.

[JLDN0101]

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?

[larry_he]

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

[guoweisun]

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！