这个我碰到类似问题了，等于没工作，换了TPS61040上去就好了，MT3608很多假货，测管脚电阻是对的，一上电就击穿，估计是厂家的良品筛选下来的

你把R30/R32各放大10倍试试？电感用的对不对？电容对不对？二极管对不对？布局对不对？

以下是关于器件选型的描述：

Setting the Output Voltage
The internal reference VREF is 0.6V (Typical).The
output voltage is divided by a resistor divider,R1 and
R2 to the FB pin. The output voltage is given by
(1 +R1/R2)*Vref=Vout

Inductor Selection
The recommended values of inductor are 4.7 to
22μH. Small size and better efficiency are the major
concerns for portable device, such as MT3608 used
for mobile phone. The inductor should have low core
loss at 1.2MHz and low DCR for better efficiency. To
avoid inductor saturation current rating should be
considered.
Capacitor Selection
Input and output ceramic capacitors of 22μF are
recommended for MT3608 applications. For better
voltage filtering, ceramic capacitors with low ESR
are recommended. X5R and X7R types are suitable
because of their wider voltage and temperature
ranges.
Diode Selection
Schottky diode is a good choice for MT3608
because of its low forward voltage drop and fast
reverses recovery. Using Schottky diode can get
better efficiency. The high speed rectification is also
a good characteristic of Schottky diode for high
switching frequency. Current rating of the diode must
meet the root mean square of the peak current and
output average current multiplication as following :
I D (RMS) ≈ I OUT × I PEAK
The diode’ s reverse breakdown voltage should be
larger than the output voltage.

以下是布局的要求：
  
Layout Consideration
For best performance of the MT3608, the following
guidelines must be strictly followed.
 Input and Output capacitors should be placed
close to the IC and connected to ground plane
to reduce noise coupling.
 The GND should be connected to a strong
ground plane for heat sinking and noise
protection.
 Keep the main current traces as possible as
short and wide.
 SW node of DC-DC converter is with high
frequency voltage swing. It should be kept at a
small area.
 Place the feedback components as close as
possible to the IC and keep away from the
noisy devices.

个人感觉,这个问题是很容易解决的,帖子的审核时间就有找到问题所在了
1,先看EN脚的电压有没有达到数据手册的要求电压
2,换一个电感试一下,吹一个电感下来,再换上去,整个过程不会超过5分钟
3,测量二极管是不是好的
4,如果前面几步都换不到问题,如果手头上还有另外一个芯片,换一个试一下
以上整个过程,不会超过20分钟

感觉是没升压，二极管压降0.3V，加电感的压降差不多4v

ZHAOBAO511 发表于 2022-6-28 16:53
谢谢，是的，啥都没接。电感不会坏的吧。不过我两个电容都是电解的，不影响吧

大多情况下，电解电容还是贴片电容都不影响，容值够就行了
电感也是会坏的，特别是选的电感过电流不是很充足的时候，特别容易坏

sttt300 发表于 2022-6-28 16:46
8V输出什么都不接的时候也是这样吗？
如果是的话，芯片和电感都换新的试试吧

谢谢，是的，啥都没接。电感不会坏的吧。不过我两个电容都是电解的，不影响吧

8V输出什么都不接的时候也是这样吗？
如果是的话，芯片和电感都换新的试试吧