Enable pin using programmable hysteresis improvement
View Patent ↗An apparatus for providing programmable hysteresis control using an enable pin of a device is disclosed. An enable pin is configured to receive an input signal to enable and disable an associated device responsive to the input signal. A current sink is attached to the enable pin and is responsive to circuitry that disables the current sink responsive to application of the input signal at a first voltage level and enables the current sink responsive to application of the input signal at a second voltage level.
1. A DC-DC voltage converter package comprising:
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, the enable pin further receiving an input from a resistor divider network programming an amount of positive hysteresis and negative hysteresis;
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 a 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;
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.
2. The apparatus of claim 1 further including a resistor divider network connected between the input signal and the enable pin.
3. An integrated circuit device 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 input signal, the enable pin further receiving an input from a resistor divider network programming an amount of positive hysteresis and negative hysteresis;
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 a non-inverting input connected directly to the enable pin;
a constant current source for providing a constant current connected to the enable pin within the integrated circuit device 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, wherein the constant current source is enabled in the second mode of operation and disabled in a first mode of operation;
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 signal is greater than the reference 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 signal is less than the reference signal, wherein the enable pin is also multiplexed for alternative uses when the DC/DC voltage converter circuitry is enabled and the current sink is disabled.
4. The apparatus of claim 3 , wherein the enable pin may be multiplexed to perform the activation of test/trim modes within the DC/DC voltage converter circuitry while the DC/DC voltage converter circuitry is enabled.