MAX1745 errornous output current

[lunar]

max1745

hi,
i am using ur "max 1745" component and i have designed the circuit exactly as mentioned in the application note "http://www.maxim-ic.com/appnotes.cfm/appnote_number/1845".

the ciruit doesnt provide output current more then 500mA, i was expecting it to be more then 2mA. kindly suggest me the changes that i should make in the circuit or advice me the alternative.

thanks.

 

[VVV]

Are you sure the sense resistor is the correct value? For 500mA it should be:

Rs=0.085V/(1.3*0.5A)=0.13Ω

Also, this resistor must be placed really close to the IC pins, or else noise pickup will cause the circuit to limit at lower currents or cause erratic operation.
Can you post the layout?

I assume you have checked eveything else, such as the correct type of MOSFET, the correct input voltage range, inductor, etc.