ASM1117 does not have an output voltage of 3.3v, I don't know why

xbxdbd

ASM1117 does not have an output voltage of 3.3v, I don't know why [Copy link]

 

When I was soldering ASM1117 last night, I tested the voltage. There was input voltage and output voltage, and I could download the program. Today, when I downloaded the program on CH340G, I couldn't download it, but there was a serial port. Then I measured the ASM1117-3.3 and there was no output voltage. I originally soldered capacitors C20, C16, C17, and C15, but now there is no output voltage. Could this be the problem? Because I later found out that the designer set the input and output capacitors of ASM1117 like this. The input and output capacitors were originally designed to be 10UF and 100nF. I thought I would only solder 10uf and 100nF for input and output, and there was no problem when I tested it. When I downloaded the program again this morning, the program could not be downloaded and ASM1117 had no output voltage of 3.3v, but there was an input voltage of 5v.

bigbat

1. First check whether the asm1117 package matches the schematic diagram

2. Check whether there are any circuit errors in the schematic diagram

xbxdbd

bigbat posted on 2023-10-18 10:31 1. First check whether the asm1117 package matches the schematic diagram. 2. Check whether there are any circuit errors in the schematic diagram.

No problem and the package matches the schematic

bigbat

Is the 5V input normal? Also, check carefully what package your chip is in and whether there are any successful cases of using this package.

呜呼哀哉

Use an oscilloscope to check the 3.3V output to see if there is any overcurrent protection or something. The simplest way is to check whether the 3.3V is short-circuited. At worst, just replace the chip. SOT223 is not difficult to disassemble.

xbxdbd

Alas, published on 2023-10-18 11:12 Use an oscilloscope to check the 3.3V output to see if it is always off or if there is overcurrent protection or something. If it is simple, just check if the 3.3V is short-circuited. If not, just replace it directly...

Changed the chip but still no output

xbxdbd

bigbat posted on 2023-10-18 10:55 Is the 5V input normal? Also, what package is your chip in? Check carefully. Do you have any successful cases of using this package?

The 5V output is normal, SOT package. The name in the question is wrong, AMS1117-3.3, changing the chip does not work, after plugging in the power supply, the chip is very hot for a while, and there is no output voltage 3.3V

damiaa

Is the output terminal of AMS1117-3.3 short-circuited? You can use a multimeter to measure the resistance from 3.3V to ground after turning off the power.

ph19900507

xbxdbd posted on 2023-10-18 11:17 The 5V output is normal, sot package. The name above is wrong, AMS1117-3.3, and it doesn't work to change the chip. After plugging in the power supply, it will...

Obviously, there is a short circuit in the 3.3V output stage. The reason for the heat is that the impedance of the stage is too small and the output current is too large.

qwqwqw2088

Use a multimeter to measure whether the output capacitor 3.3V is short-circuited to the ground.

秦天qintian0303

Is it necessary to use tantalum capacitors for 1117?

led2015

If there is no problem with the circuit connection and component selection, the capacitor may cause the voltage regulation performance of ASM1117 to decrease, resulting in unstable output voltage or no output voltage.

dabiaoke

Elimination method: disconnect the output, power on the chip alone and observe whether the output waveform is normal. Generally, if the input is normal but there is no output, it means that the output stage is short-circuited or overloaded.

fjdeepblue

AS117 is overheated, it may be due to the following reasons: wrong package pins, short circuit, chip damage