Contactless interface
First Claim
1. A circuit comprising:
- first and second input terminals;
a first supply rail energized from the first input terminal for providing a first supply voltage;
a shunt regulator operable to regulate the first supply voltage by establishing a shunt current between the first and second input terminals;
a second supply rail; and
a switching circuit coupled to the shunt regulator and operable by a switch control signal to direct the shunt current, in a first mode, to flow to the second supply rail for providing a second supply voltage and, in a second mode, to bypass the second supply rail to the second input terminal.
3 Assignments
0 Petitions
Accused Products
Abstract
Power extracted from an antenna inductively coupled to an alternating magnetic field is regulated to provide voltage supplies. In some implementations, a first voltage supply (e.g., 3.8 volts) provides regulated voltage to analog circuits and a second, lower, voltage supply (e.g., 1.4 volts) provides regulated voltage to digital circuits. The first voltage supply is regulated, using shunt regulation, by a first voltage regulator circuit. The second voltage supply is regulated, using a series regulation, by a second voltage regulator circuit. The second voltage regulator circuit is supplied by the shunted current from the first voltage regulator. Excess shunt current provided by the first regulator circuit can be bypassed (e.g., bypassed to ground). The second voltage regulator circuit can use a timer circuit to control the amount of charge transferred to a second voltage supply rail. The timer circuit can compensate for different currents from the first voltage regulator circuit.
17 Citations
15 Claims
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1. A circuit comprising:
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first and second input terminals; a first supply rail energized from the first input terminal for providing a first supply voltage; a shunt regulator operable to regulate the first supply voltage by establishing a shunt current between the first and second input terminals; a second supply rail; and a switching circuit coupled to the shunt regulator and operable by a switch control signal to direct the shunt current, in a first mode, to flow to the second supply rail for providing a second supply voltage and, in a second mode, to bypass the second supply rail to the second input terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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receiving an alternating voltage from an antenna; rectifying the alternating voltage, using a rectifier circuit, to provide a first supply voltage to a first supply rail;
supplying, using a current source, a shunt current; andconfiguring a switch coupled to the current source with a switch control signal to enable the shunt current to flow to a second supply rail to provide a second supply voltage on the second supply rail when the switch is in a first mode, and to bypass the second supply rail when the switch is in a second mode. - View Dependent Claims (14, 15)
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Specification