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• TI Thinks Resolved

# LM5022: tolerance slope compensation

Part Number: LM5022

Dear team,

for the design of the compensation I would need to know the correct value and the tolerance of the "45uA typical" current ramp.

Unfortunately only the combination out of the current ramp and the internal 2k resistor is speced as Vslope 83mV...110mV...137mV.

Further it can be found that the text describes a typical Vslope of 100mV. (45uA*2kOhm= 90mV).

It also can be found that the 83mV...110mV...137mV tolerance range was revised and is higher now - compared originally spec.

This means either the 2kOhm resistor is larger or the 45uA current ramp is actually higher.

I need to know the exact spec of the internal current ramp. What is the typical and what is min/max?

many thanks

Lutz

• The actual slope compensation is tested with the resulted ramp voltage, which is the product of the slope injection current source and the internal 2k resistor. The 45uA and 2k are the design target, but they were not separately characterized. The datasheet's EC table info is the actual characterization data of the injection voltage. So, the typical is 110mV, and the min and max are 83mV and 137mV.
• In reply to Youhao Xi:

Thanks for this clarification. However, if there is an extra external resistor for slope compensation it would be good to know the tolerance of the injection current source. The external resistor will have a tolerance of about 1%. The internal 2k-resistor has probably much higher tolerance. So, with the external 1% resistor the overall tolerance (percentage) of the slope compensation will become smaller than only with the internal resistor, right?

Mario
• In reply to Mario Willenberg:

When you have the external resistor for additional slope compensation, you can actually measure the additional slope. Also knowing the internal, then you just need to make sure the total is adequate.