FS23 V1 output abnormal

[seerlu]

V1 output is abnormal as below waveform:

C1 was VSUP,C2 was VBOS,C3 was V2;C4 was V1(power to MCU)V1 without npn

How can I thoroughly solve the problems I am currently facing?

if you want to get more information,please let me know.

[seerlu]

VBOS>3.06V TO V1 UPing used 13.2ms

[guoweisun]

You can try to disconnect  MCU with V1 and test it again for example add some loading 50mA. 

[seerlu]

This is testing.

by the way, we check the manual and found 19.4.6 V1UVLP monitoring chapter shows "V1 is also monitored for V1UVLP when the device powers up after a wake up from LPON, and during a cold start after TSOFT_START_V1. If, at the end of the softstart, V1 is still under V1UVLP threshold, then the device goes into Fail-Safe state."

does it mean V1 should beyond V1UVLP threshold after TSOFT_START_V1(type,300us)?

in addition ,this V1 abnormal issue happened in low temperature (-30℃ ） and low Vsup power(8v)。in this condition, we increased VSUP to 12V，V1 output OK。

[guoweisun]

A lots of confuse for your test result ,you can see when Vbat< Vsup_uv,the V1 should be stay 0,why your V1 follow up VBAT from 0? I suppose your test waveform yellow is VBAT,Green is V1,am I right?

[seerlu]

Channel 1 was VSUP,C2 was VBOS,C3 was V2;C4 was V1(power to MCU)

[seerlu]

which one indicate V1 follow up VBAT from 0?
current test results show VBOS>3.06V TO V1 UPing used 13.2ms, please check

[guoweisun]

在8V Vin的情况下能否把这个上面圈出来的波形的时间轴放小些，我想看V1启动了多久？

另外12V VIN的情况下也测试下相同的波形可以嘛？

我这里没有高低温试验箱无法做太多的测试只能看你们的结果了。

[seerlu]

我们新测了个波形，在输入12V时也发现V1有时第一次启动是失败的。

这是第一次启动失败的波形V1第一次启动未成功图

这是第二次启动成功的波形V1第二次启动成功图

这个是不是和那个V1 在软启动之后的欠压检测有关联，但是软启动的时间是典型值300，最大值500us。现在为啥感觉是超过500us就启动不起来，低于500us好像就行。

能否帮忙描述下软启动的内容，看手册没有太多描述

[guoweisun]

这个问题大概率是V1 发生了OC在软启动的过程中导致启动失败然后又恢复的这个过程。

解决方案可以外加管子阔流在V1端口然后FS23 OTP的时候把这个功能打开，也可以选择我们的HVBUCK的版本。

要么就是适当的去掉一些输出电容让softstart更顺畅，我建议选择上面两个方案更稳妥

[seerlu]

能否帮忙在解释下softstart过程？

包括这一段“19.4.6 V1UVLP monitoring chapter shows "V1 is also monitored for V1UVLP when the device powers up after a wake up from LPON, and during a cold start after TSOFT_START_V1. If, at the end of the softstart, V1 is still under V1UVLP threshold, then the device goes into Fail-Safe state."”到底是要求什么样的V1启动波形？

谢谢

[guoweisun]

这个图可以解释框出来的上面的是softstart的条件，假如都满足了V1开始上电了进入M5的时序，他的时间是150-500us，假如超过了这个时间还没有启动成功就会进入FS状态然后100ms以后重启这样一个大概的过程

[guoweisun]

1：原理图PIN37不用的话接地。

2：V1的负载电流不大的最大才100mA确认下您那里的负载

3：V1_IN的decouple 电容是1uF.

4: 就像上面这个情况第一次启动不成功第二次起来了能否读取寄存器 M_GEN_FLAG register 看看发生了什么？

先改上面这些看看结果。

[guoweisun]

You can see below circled part.