Patent ID: 7876077
Filing Date: 2011-01-25
Classification: H02M,Y02B

Abstract:
1. A current mode control type DC-DC converter control circuit comprising: a current detector for detecting a coil current value flowing in a choke coil; a first setting unit for determining an upper limit value of the coil current value; a second setting unit for determining a lower limit value of the coil current value; and a comparator for comparing the coil current value and the upper limit value outputted from the first setting unit and outputting a signal to set a main transistor in a non-conductive state when detecting the coil current value is higher than the upper limit value; and comparing the coil current value and the lower limit value outputted from the second setting unit and outputting a signal to set the main transistor in a conductive state in response to a comparing result of the coil current value and the lower limit value when detecting the coil current value is lower than the lower limit value, wherein the first setting unit is an error amplifier for receiving a first reference voltage and an output voltage of the current mode control the DC-DC converter, and wherein the second setting unit sets a value obtained by subtracting a specified voltage from the upper limit value as a lower limit value, a phase comparator for detecting the phase difference of a reference period and a switching period of the main transistor, wherein the phase comparator outputs a signal for increasing the specified voltage depending on the phase difference when the phase of the switching period is advanced from the phase of the reference period, or decreasing the specified voltage depending on the phase difference when the phase of the switching period is delayed from the phase of the reference period, and outputting a signal corresponding to a differential voltage of the first reference voltage and the output voltage of the current mode control type DC-DC converter.