Patent ID: 7928787
Filing Date: 2011-04-19
Classification: H02M,Y02B

Abstract:
1. A DC-DC voltage converter package comprising: a DC-DC voltage converter circuitry; an enable pin for receiving an external voltage signal to enable and disable the DC-DC voltage converter circuitry responsive to the external voltage signal; a comparator within the DC-DC voltage converter package for comparing the external voltage signal to a reference voltage signal, the comparator having an inverting input connected to receive the reference voltage signal and the non-inverting input connected directly to the enable pin; a constant current source for providing a constant current sink over a variety of operating conditions connected directly to the enable pin within the DC-DC voltage converter package and the non-inverting input of the comparator and actively pulling down a voltage on the enable pin of the DC-DC voltage converter circuitry in a second mode of operation, wherein the constant current source is enabled in the second mode of operation and disabled in a first mode of operation; a resistor divider network connected to the enable pin, the resistor divider including a first resistor connected between the external voltage signal and the enable pin and a second resistor connected between the enable pin and ground, the resistor divider network enabling programming of an amount of positive hysteresis and negative hysteresis; wherein the comparator generates a control signal at a logical “high” voltage level for disabling the current sink and enabling the DC-DC voltage converter circuitry in the first mode of operation if the input voltage signal is greater than the reference voltage signal and generates the control signal at a logical “low” voltage level for enabling the current sink and disabling the DC-DC voltage converter circuitry in the second mode of operation if the input voltage signal is less than the reference signal; wherein the current sink actively pulls down the voltage on the enable pin to provide an additional voltage offset at the enable pin in the second mode of operation adding negative feedback hysteresis; and wherein deactivation of the current source in the first mode of operation increases the voltage on the enable pin adding positive hysteresis.