Converter device
View Patent ↗A converter, for feeding a load via an inductor with a current having a controlled intensity between a maximum and a minimum level, includes a switch to permit or prevent, respectively, current towards said inductor, a first current sensor sensitive to the current flowing through switch when the switch is on, a second current sensor sensitive to the current flowing through said inductor when the switch is off, drive circuitry to turn the switch off and on upon receiving a first and a second logic signal, respectively, and comparison circuitry coupled to the first and the second current sensors to generate first and the second logic signals when, respectively: the current intensity detected by the first current sensor is offset a given amount with respect to the maximum level, and the current intensity detected by the second current sensor is offset a given amount with respect to the minimum level.
1. A converter for feeding a load via an inductor with a current having a controlled intensity between a maximum level and a minimum level, the converter comprising:
a switch switchable on and off to permit or prevent, respectively, feeding of current towards said inductor,
a first current sensor sensitive to the current flowing through said switch when said switch is on,
a second current sensor sensitive to the current flowing through said inductor when said switch is off,
drive circuitry of said switch to turn said switch off and on upon receiving a first and a second logic signal, respectively, and
comparison circuitry coupled to said first and second current sensors to generate first and a second logic signals when, respectively:
the current intensity detected by said first current sensor is offset of a given amount with respect to said maximum level,
the current intensity detected by said second current sensor is offset of a given amount with respect to said minimum level; and
wherein the comparison circuitry includes respective level comparators coupled to the first current sensor and the second current sensor and configured to identify a respective given amount of offset-being established between the intensity of the current detected by the current sensor coupled therewith with respect to said maximum level and said minimum level, respectively and/or wherein the comparison circuitry includes respective level comparators coupled to the first current sensor and the second current sensor via signal dividers to apply a compensation offset to the current intensity value detected by the first current sensor and the second current sensor.
2. The converter of claim 1 , wherein said comparison circuitry includes level comparators that receive:
on a first input, a signal representative of said maximum level, respectively, of said minimum level, and
on a second input, a signal representative of the current intensity value detected by said first current sensor, respectively, by said second current sensor having a compensation offset applied thereto by a respective signal divider.
3. The converter of claim 1 , wherein said comparison circuitry coupled to said first and second current sensors is configured to generate said first and said second logic signals when, respectively:
the current intensity detected by said first current sensor is offset of a given amount and is at a lower level with respect to said maximum level, and
the current intensity detected by said second current sensor is offset of a given amount and is at a higher level with respect to said minimum level.
4. The converter of claim 1 , wherein:
said second current sensor includes a resistor coupled to the converter output and sensitive to the current flowing through said inductor when said switch is off,
a further switch is interposed between said switch and said resistor; said further switch being conductive when said switch is turned off, whereby, with said switch turned off,
said resistor coupled to the converter output is traversed by current flowing through said inductor,
said drive circuitry is coupled to said second current sensor to turn said switch on as a function of the current detected by said second current sensor,
and wherein a bootstrap circuit is provided for feeding said drive circuitry, said bootstrap circuit including:
a bootstrap capacitor to accumulate a feeding charge for said drive circuitry, wherein said bootstrap capacitor is coupled to the converter output and to a bootstrap diode,
a coupling capacitor interposed between said further switch and said bootstrap diode;
a bootstrap resistor interposed between a power supply source and said bootstrap diode to charge said coupling capacitor from said power supply source, whereby, with said switch turned off, said bootstrap diode transfers charge from said coupling capacitor to said bootstrap capacitor and said resistor coupled to the converter output is traversed by the current flowing through said inductor.
5. The converter of claim 4 , wherein the following relationship applies for the resistance value of said bootstrap resistor and said resistor coupled to the converter output: R BOOT >>R SHL .
6. The converter of claim 4 , wherein the following relationship applies for the capacitance values of said coupling capacitor and said bootstrap capacitor: C COUP >>C BOOT .
7. The converter of claim 4 , wherein said further switch conductive when said switch is turned off is a diode.
8. The converter of claim 7 , wherein said coupling capacitor is interposed between the anodes of said bootstrap diode and said diode constituting said further switch conductive when said switch is turned off.
9. The converter of claim 1 , wherein said switch is an electronic switch, such as a mosfet.
10. Use of a converter to drive a load in the form of a light source the converter comprising:
a switch switchable on and off to permit or prevent, respectively, feeding of current towards said inductor,
a first current sensor sensitive to the current flowing through said switch when said switch is on,
a second current sensor sensitive to the current flowing through said inductor when said switch is off,
drive circuitry of said switch to turn said switch off and on upon receiving a first and a second logic signal, respectively, and
comparison circuitry coupled to said first and second current sensors to generate first and a second logic signals when, respectively:
the current intensity detected by said first current sensor is offset of a given amount with respect to said maximum level,
the current intensity detected by said second current sensor is offset of a given amount with respect to said minimum level; and
wherein the comparison circuitry includes respective level comparators coupled to the first current sensor and the second current sensor and configured to identify a respective given amount of offset-being established between the intensity of the current detected by the current sensor coupled therewith with respect to said maximum level and said minimum level, respectively and/or wherein the comparison circuitry includes respective level comparators coupled to the first current sensor and the second current sensor via signal dividers to apply a compensation offset to the current intensity value detected by the first current sensor and the second current sensor.