dc dc converter step down

[arsen55591]

Dear all.
I have dc dc converter step down without inductor, in switch capacitors. Input voltage 2.7-5.5, output voltage must be 1.8-1.9. When output reach 1.8 voltage PFM mode pauses the oscillator.But after that output continue increase because current of output capacitor goes through output load (resistor). Whow can i regulate the output voltage ?

 

[chuckey]

without a circuit , I am guessing, how about putting a large capacitor across the load, so the voltage across the load changes more slowly and increasing the load or decreasing the input cap so as to equalise the input/output power ( V X I ).
Frank

 

[arsen55591]

Output cap is 4.7uF, R=1k , when output reaches 1.8 voltage it must not change, bu continue increase.
I connect output with negative input of comparator, is it right ?
When i connect output wiht positive input, i dont get pulse in comparator's output. Vref=1.8v

 

[vijay satija]

u try a zener voltage regulator .....