PULSE CONTROLLED SOFT START SCHEME FOR BUCK CONVERTER
First Claim
1. A system for generating a ramped reference voltage to soft start a buck converter, comprising:
- a current source coupled to a positive power supply;
a capacitor coupled to a ground; and
a switch coupled to the current source and the capacitor in series,wherein the ramped reference voltage is a voltage formed across the capacitor; and
wherein the switch is regulated by a control pulse to direct a flow of a current from the current source for generating a pulsed current forwarded to the capacitor.
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Abstract
A pulse controlled soft start scheme for a buck converter using a low value of on-chip capacitor is disclosed. In one embodiment, a system for generating a ramped reference voltage to soft start a buck converter, includes a current source coupled to a positive power supply, a capacitor coupled to a ground, a pass transistor device coupled to the current source and the capacitor in series, and a control pulse generator for generating a control pulse forwarded to the pass transistor device. The ramped reference voltage forwarded to the buck converter includes a voltage across the capacitor. The control pulse regulates a flow of a current from the current source to the capacitor via the pass transistor device for generating the ramped reference voltage.
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Citations
20 Claims
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1. A system for generating a ramped reference voltage to soft start a buck converter, comprising:
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a current source coupled to a positive power supply; a capacitor coupled to a ground; and a switch coupled to the current source and the capacitor in series, wherein the ramped reference voltage is a voltage formed across the capacitor; and wherein the switch is regulated by a control pulse to direct a flow of a current from the current source for generating a pulsed current forwarded to the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for generating a ramped reference voltage to soft start a buck converter, comprising:
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a current source coupled to a positive power supply; a capacitor coupled to a ground; a pass transistor device coupled to the current source and the capacitor in series; and a control pulse generator for generating a control pulse forwarded to the pass transistor device, wherein the ramped reference voltage forwarded to the buck converter comprises a voltage formed across the capacitor; and wherein the control pulse regulates a flow of a current from the current source to the capacitor via the pass transistor device for generating the ramped reference voltage. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A buck converter on a system on chip, comprising:
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a first switch coupled to a voltage source; an inductor coupled to the first switch; a capacitor coupled to the inductor and to a ground in series; a second switch coupled to the inductor and to the capacitor; a pulse width modulation (PWM) controller for regulating the first switch and the second switch by comparing an output voltage measured across the capacitor and a ramped reference voltage; and a soft start circuit for forwarding the ramped reference voltage, comprising; a current source coupled to a positive power supply; a first capacitor coupled to the ground; and a third switch coupled to the current source and the first capacitor in series, wherein the ramped reference voltage is a voltage formed across the first capacitor; and wherein the third switch is regulated by a control pulse to direct a flow of a current from the current source for generating a pulsed current forwarded to the first capacitor. - View Dependent Claims (19, 20)
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Specification