LT8316 Output Instability Problem

Question

Hi, 
 
 Iam working 140VDC-70VDC range input 24V/1.5A range output DC-DC converter for railways application. 
 
 The circuit should give 24VDC/1.5A output in the 140VDC-70VDC input voltage range. 
 
 There is almost no output voltage variation at light load but at 1.5 A load, the output voltage is 24.20V at 140VDC and 23.68V at 70VDC. There were distortions in the gate signal at low load. I solved the light load ripple problem by putting a 33nf capacitor on the IREG/SS pin and putting a 3.9nF capacitor between the input and output of the transformer. 
 
 I am using a two layer pcb. How can ı design the PCB? 
 
 I have voltage fluctuation problem at high load. How can I solve this?

Birinci · Accepted Answer

With 22pF, the output voltage dropped to around 23.3V. I have rc filter on sense pin. (1nF 0R08//0R08) 
 In the application note, the switching frequency appears to be 70 khz in the 110V-24v design. My design is 39kHz - 40kHz. Does this pose a problem?

W.G · Answer

If a resistor is connected to the IREG/SS pin, make sure there is enough margin before current regulation control kicks in at full load.

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LT8316 Output Instability Problem

Hi,

Iam working 140VDC-70VDC range input 24V/1.5A range output DC-DC converter for railways application.

The circuit should give 24VDC/1.5A output in the 140VDC-70VDC input voltage range.

I am using a two layer pcb. How can ı design the PCB?

I have voltage fluctuation problem at high load. How can I solve this?

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