Recently I bought several LM2587-ADJ/NOPB, and now I meet some problems with application provided by datasheet.
Input 6V, 1A, DC source. The output side we connect 100ohms power resistor.
Actually, the circuit behaves well with no load, the output voltage is exactly like what we set 12V. However, as 100ohms resistor connect to the output side, the output voltage drop significantly, like 6-8V, and sometimes the chip gets hot and burns out.
Ask for help! How to set the output voltage when we get a load.
When you configure LM2587-ADJ in a boost topology, you have a traight path from input to output. So, when load the output with 100Ohm, basically you are shorting your supply and bypassing the switch.
In order to run this application you have to startup with a supply higher than 1A because this can easily reach 1A starting with load deoending on the inductor you are using. Or you slowly increase your load to 100Ohm. (0.12A). An external current limit circuit lower than 5A (current limit of the part) will be a protection not to burn your IC.
This part is mean for higher output current, you can use lower current parts on the same family or you enter your specs on our Webench tools to suggest optimized solutions for your application.
You mean the inductor and the load we used is to small? And the load is short the chip. However, our input is DC regulator which voltage is 6V and current is 1A, that means if the load short the circuit, our output should achieve the outpout voltage we want at startup moment. According to 5 times experiment, our output voltage never exceeded 7V. And that brings that if the load short the circuit, our diode has maximum reverse voltage which is 40V, and it could be impaired. However, what we burned is just IC.
And with the input current requirement you mentioned, our DC-DC converter burned out with input current exceeding 1.5A. So, I guess that it is the duty cycle problem or the DC-DC internal structure problem?
Can you post some more details. If possible it would help if I could see a waveform showing
Channel 1: Vin.
Channel 2: Vout
Channel 3: PIn four ot the 2857, the Switch node.
The time scale should be such that you can see several pulses on the switch node. One scope shot for no load, and one with the 100ohm load.
Can you give me a bill of materials for the design you are testing?
That should help me to diagnose the problem.
I also have a few questions for clarification.
1) I understood that with the 100ohm resistor tied to the output, the output voltage was 7V. Is this correct?
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