608 OPERATION The MT3608 uses a fixed frequency, peak current The output voltage of the error amplifier the power mode boost regulator architecture to regulate MOSFET is turned off. The voltage at the output of voltage at the feedback pin. The operation of the the error amplifier is an amplified version of the MT3608 can be understood by referring to the block dif erence between the 0.6V bandgap reference diagram of Figure 3. At the start of each oscil ator voltage and the feedback voltage. In this way the cycle the MOSFET is turned on through the control peak current level keeps the output in regulation. If circuitry. To prevent sub-harmonic oscil ations at the feedback voltage starts to drop, the output of the duty cycles greater than 50 percent, a stabilizing error amplifier increases. These results in more ramp is added to the output of the current sense current to flow through the power MOSFET, thus amplifier and the result is fed into the negative input increasing the power delivered to the output. The of the PWM comparator. When this voltage equals MT3608 has internal soft start to limit the amount of input current at startup and to also limit the amount of overshoot on the output.
Figure 3. Functional Block Diagram Aerosemi Technology Co., Ltd 4 Document Outline MT3608-P1 MT3608_P2 FUNCTION NAME
