The term D-CAP means the current information is Direct connection to the output CAPacitor. TI’s first D-CAP™ controller, the TPS51116, was realized by combining a controller with a constant on-time modulator. Today, TI has a family of products featuring various modulators and next-generation forms of the original D-CAP™ control.

The first generation D-CAP™ requires large ESR at the output bulk cap to stabilize the loop. D-CAP2™ doesn't have this requirement, supports the output ceramic capacitors with internal phase compensation. An internal inductor ripple current “emulator” circuit is used to generate a sufficient ramp for D-CAP2™ control to compare the output voltage vs. the reference voltage to determine whether to turn the PWM on or not.

D-CAP3™ also supports the output ceramic capacitors with internal phase compensation. D-CAP3™ mode improves the output voltage set-point accuracy by implementing specialized circuits to remove the half time ramp magnitude.