Fast transient current mode control circuit and method

A fast transient current mode control method, which is applicable for a power converter, the power converter including an upper bridge switch, a lower bridge switch, a storage inductor and a first capacitor, the upper bridge switch being connected to the lower bridge switch, one terminal of the storage inductor being connected to a node between the upper bridge switch and the lower bridge switch, the other terminal of the storage inductor being grounded through the first capacitor, the fast transient current mode control method comprising the following steps:

• detecting an output voltage signal from the output terminal of the power converter between the storage inductor and the first capacitor by a slope detector circuit;
• determining whether or not an output voltage of the output voltage signal drops sharply and a slope of the output voltage signal is larger than a slope threshold by the slope detector circuit, in response to determining that the output voltage of the output voltage signal does not drop sharply or the slope of the output voltage signal is not larger than the slope threshold, returning to the previous step;
• in response to determining that the output voltage of the output voltage signal drops sharply and the slope of the output voltage signal is larger than the slope threshold, outputting a transient enhanced signal to enable an oscillator circuit to output a clock signal by the slope detector circuit, a rising edge of a pulse wave of the transient enhanced signal being aligned with a starting point from which the output voltage signal drops sharply, a falling edge of the pulse wave being aligned with a transition point from which the output voltage signal stops falling and begins to rise, and a rising edge of a pulse wave of the clock signal being aligned with the rising edge of the pulse wave of the transient enhanced signal;
• and
• triggering a switch controller circuit to output a switch control signal to the upper bridge switch to turn on the upper bridge switch during a duty cycle of the pulse wave according to the transient enhanced signal by the clock signal, such that an inductor current flowing through the storage inductor increases to be equal to a load current flowing through a load of a system connected to the output terminal of the power converter.