tny276 problem
Posted by: zzbsfere
on
a power design with tny276.at the beginning,tny276 can work ,the voltage of en pin is 0.98v,bp pin is 5.8v; after 2 minutes,tny276 can't work,the voltage of en pin is 1.4v,bp pin is 4.9v;what's wrong? thanks
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tny276 problem.pdf
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Comments
THE non linear resistor is ptc,drain voltage and drain current waveforms are ok.when tny276 is good ,the impedance between drain and source is Mohm,but the impedance of this tny276 only Kohm,what's reason ? ESD? SURGE?
I donot think the problem is caused by TNY276, since Tny switch used a lot by customer. Could you open/ short the two nonlinear resistors at input side and double check the polarity of aluminum cap?
Have you checked the DC input voltage, Ids and Vds? These waveforms will give you some idea.
RV1 and another non linear resistor close to RV1 are NTC or PTC? And PLS check the polarity of all output capacitors.