A constant off-time controlled boost converter with adaptive current sensing technique

Using adaptive current sensing (ACS) technique, a constant off-time controlled boost converter with an improved off-time generator (OTG) is presented. With the ACS technique, this boost converter achieves wide conversion range operation without external compensation circuits. An improved OTG is proposed to compensate the switching frequency variation. The converter has been implemented in 0.5um 40V BCD process. Measurement results show that a conversion range of 5V input to 5.5~36V output and switching frequency variation of 1% can be obtained. The overshoot or undershoot in different conversion ratios is only about 0.5% of the output voltage with a load current step of 200mA.