The controllers are fast-reacting, high-frequency, scalable output power controllers capable of driving two external N-MOSFETs. They use a D-CAP2 control scheme that optimizes transient responses at high load currents for such applications as CORE and DDR supplies. The output voltage is compared with internal reference voltage after divider resistors. The PWM comparator determines the timing to turn on the high-side MOSFET. The PWM comparator response maintains a very small PWM output ripple voltage. Because the device does not have a dedicated oscillator for control loop on board, switching cycle is controlled by the adaptive ON time circuit. The ON time is controlled to meet the target switching frequency by feed-forwarding the input and output voltage into the ON time one-shot timer.

The D-CAP2 control scheme has an injected ripple from the SW node that is added to the reference voltage to simulate output ripple, which eliminates the need for ESR-induced output ripple from D-CAP™ mode control. Thus, low-ESR output capacitors (such as low-cost ceramic MLCC capacitors) can be used with the controllers.

Figure 7-3 Controller Block Diagram