Production Forecast:
Project Name: MULTIPLE OUTPUTS SMPS USING VIPER37 CONVERTER
Case Description:
Hi dear STMicroelectronics teams,
We are working in a project that uses a lot of STMicroelectronics components like STM32MP1…etc. And to provide the power to the circuit we are designing we must make a multiple output SMPS power supply and after some searching, we found “eDesignSuite - Design, Circuit and Simulation Tools�? from STMicroelectronics.
The input of our circuit is
Input: 88 Vac - 276 Vac
The outputs we need are like that
Output 1: 24 V (2 %) - 17.04 W
Output 2: 10 V (2 %) - 3.2 W
Output 3: 10 V (2 %) - 3.2 W
Output 4: 5 V (2 %) - 500 mW
Output 5: 3.3 V (2 %) - 1.06 W
and according to our need we have used your eDesignSuite - Design, Circuit and Simulation Tools and the tool gave us this circuit in figure[1] (I also added the tools exported document with all parameters).
Figure [1]
And as you see in figure [1] the used converter is VIPER37HD, and we ordered it with the other components according to the schematic given in figure [1].
We also made 2 different transformers according to schematic that was given by eDesignSuite as shown below
For 60KHz switching frequency:
After we ordered all components, we made the circuit using VIPER37HD (SOIC -16) but our circuit did not work, after we did not get any desired outputs and after a lot of attempts and troubleshooting to solve this problem unfortunately the VIPER37HD(SOIC -16) we are using got damaged in the process so we tried to use another VIPER37HD(SOIC -16) but it turned out that the Vdd and Gnd pins it had were internally shorted (we tested it by using a multimeter while ensuring that nothing was connected to it), so we ordered another version of VIPER37 that is available in Turkey which is VIPER37L(DIP), but we noticed that this version of VIPER37 switches at a frequency of 60KHz, due to this reason we used a transformer that has a frequency rating of 60KHz. In the circuit we only changed VIPER37HD to VIPER37L and the transformer to a one with a suitable frequency rating and did no other modification.
According to the changes I mentioned previously We made the circuit as shown in figure [1] in the lab on PadBoard as shown in figure [2]
After applying power to our circuit, we still did not get our desired outputs while measuring using multimeters. we tested every component individually before testing VIPER37 and simulated it using proteus (simulated the circuit till the inputs of VIPER37).
We thought the source of our problem could be from VIPER37L, so we tried to test it according to the test circuit provided in the datasheet that we got from your official website. The test circuit is shown in figure [3].
We created the circuit according to figure [3], connecting all the DRAIN pins together alongside a 10KOhm resistor and using our DC power supply (1st channel) to provide it with 30V. The GND and BR pins were grounded. We provided 14V to the VDD pins using the other channel in our DC power supply and used an ARDUINO UNO alongside a voltage divider to give 2V to the FB pin and 5V to the COUNT pin. We made sure the grounds of the power supply and the ARDUINO UNO were connected together at one point.
After that we connected the positive side of the oscilloscope to the DRAIN pin and the ground of oscilloscope connected to GROUND.
And in the oscilloscope, we supposed to see a square wave as shown in figure [3] but we only saw an DC signal as shown in figure [4] and when changing the signal mode from DC to AC in oscilloscope we saw an noised AC signal as shown in figure [5].
So, we did not understand why we are not getting the square wave signal as shown in test circuit in the datasheet of VIPER37.
We are looking forward for your helping to troubleshoot this circuit and make it work as expected.
PLEASE GIUDE US TO TEST VIPER37 to continue our project
Our respect to STMicroelectronics team.
