US20060261790A1 - Direct current voltage boosting/bucking device - Google Patents
Direct current voltage boosting/bucking device Download PDFInfo
- Publication number
- US20060261790A1 US20060261790A1 US11/183,611 US18361105A US2006261790A1 US 20060261790 A1 US20060261790 A1 US 20060261790A1 US 18361105 A US18361105 A US 18361105A US 2006261790 A1 US2006261790 A1 US 2006261790A1
- Authority
- US
- United States
- Prior art keywords
- voltage
- boosting
- direct current
- load
- comparator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/575—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices characterised by the feedback circuit
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0045—Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
Definitions
- the invention relates to a direct current voltage boosting/bucking device, more particularly to a direct current voltage boosting/bucking device suitable for driving operation of a high-power light-emitting diode.
- FIG. 1 illustrates a conventional driver circuit 1 for a high-power light emitting diode (D).
- the driver circuit 1 utilizes a direct current voltage boosting chip 11 for boosting an input voltage (Vin) from an input voltage source (such as a battery of a mobile phone) so as to generate an output voltage (Vout) that is higher than the input voltage (Vin) and that is provided to the light-emitting diode (D).
- Vin input voltage
- Vout output voltage
- the input voltage (Vin) must be lower than the output voltage (Vout) in order to ensure normal operation of the direct current voltage boosting chip 11 .
- the voltage range of the input voltage source e.g., a lithium battery
- the input voltage (Vin) is 4.2 volts
- the output voltage (Vout) must be higher than 4.2 volts (e.g., 4.3 volts).
- FIG. 2 shows experimental results for the conventional driver circuit 1 to illustrate the power conversion rates for different input voltages (Vin) when the working current (ILED) is 600 mA. It is evident from the data that the power conversion rates decrease with a reduction in the magnitude of the input voltage (Vin). In addition, a change in the working voltage (V F ) of the light-emitting diode (D) necessitates corresponding adjustments in the resistances of the resistors (R 1 , R 2 , R 3 ) in the driver circuit 1 .
- FIG. 3 illustrates another conventional driver circuit 2 for a high-power light emitting diode (D).
- the driver circuit 2 utilizes a synchronous buck-boost driver chip 21 (such as LTC3453) that receives an input voltage (Vin) from an input voltage source (such as a lithium battery) and that performs voltage boosting or voltage bucking so as to generate a suitable output voltage (Vout) for driving the light-emitting diode (D).
- Vin input voltage
- Vout voltage boosting or voltage bucking
- FIG. 4 shows experimental results for the conventional driver circuit 2 to illustrate the power conversion rates for different input voltages (Vin) when the working current (I LED ) is 150 mA.
- the synchronous buck-boost driver chip 21 requires four MOS transistors (Q 1 , Q 2 , Q 3 , Q 4 ) so as to be able to perform the voltage boosting and voltage bucking operations, which results in higher costs incurred for the driver circuit 2 .
- the object of the present invention is to provide a direct current voltage boosting/bucking device that can overcome at least one of the aforesaid drawbacks associated with the prior art.
- a direct current voltage boosting/bucking device is adapted for driving a load, and comprises a direct current voltage boosting/bucking circuit and a low drop-out (LDO) linear voltage converting circuit.
- LDO low drop-out
- the direct current voltage boosting circuit boosts an input voltage so as to generate an output voltage higher than the input voltage.
- the LDO linear voltage converting circuit is adapted to be coupled electrically to the load, is coupled electrically to the direct current voltage boosting circuit for converting the output voltage into a load voltage that is to be provided to the load, and controls the direct current voltage boosting circuit in accordance with a feedback signal from the load such that the output voltage and the load voltage have a minimum drop-out voltage differential therebetween and such that current flow through the load is maintained at a determined level.
- FIG. 1 is a schematic circuit diagram of a conventional driver circuit for a high-power light-emitting diode
- FIG. 2 is a plot showing experimental results for the conventional driver circuit of FIG. 1 to illustrate power conversion rates for different input voltages
- FIG. 3 is a schematic circuit diagram of another conventional driver circuit for a high-power light-emitting diode
- FIG. 4 is a plot showing experimental results for the conventional driver circuit of FIG. 3 to illustrate power conversion rates for different input voltages
- FIG. 5 is a block diagram of the preferred embodiment of the direct current voltage boosting/bucking device according to the present invention.
- FIG. 6 is a schematic circuit diagram of the preferred embodiment
- FIG. 7 is a schematic circuit diagram to illustrate a direct current voltage boosting circuit of the preferred embodiment in greater detail
- FIG. 8 is a schematic circuit diagram to illustrate an alternative implementation of the device of the present invention.
- FIG. 9 is a plot showing experimental results for the device of the present invention to illustrate power conversion rates for different input voltages.
- the preferred embodiment of a direct current voltage boosting/bucking device 3 is adapted for application to a camera phone so as to drive operation of a high-power light-emitting diode (D) for supplying light when taking pictures.
- D high-power light-emitting diode
- the direct current voltage boosting/bucking device 3 comprises a direct current voltage boosting/bucking circuit 31 and a low drop-out (LDO) linear voltage converting circuit 32 .
- LDO low drop-out
- the direct current voltage boosting circuit 31 is a conventional booster that boosts an input voltage (Vin) so as to generate an output voltage (Vout) higher than the input voltage (Vin).
- the direct current voltage boosting circuit 31 includes a voltage boosting module 33 and a first comparator 34 .
- the voltage boosting module 33 includes a PWM (or PFM) controller 331 , and is used to receive and boost the input voltage (Vin).
- the first comparator 34 has a first input that receives a first reference voltage (Vref 1 )(e.g., 0.8 volt), a second input that receives a feedback signal (FB), and an output that is coupled electrically to the PWM (or PFM) controller 331 .
- the first comparator 34 controls boosting operation of the voltage boosting module 33 by controlling the duty cycle of an output signal generated by the PWM (or PFM) controller 331 in a manner to be described hereinafter.
- the LDO linear voltage converting circuit 32 is a conventional voltage bucking circuit, is adapted to be coupled electrically to a load, is coupled electrically to the direct current voltage boosting circuit 31 for converting the output voltage (Vout) into a load voltage that is to be provided to the load, and controls the direct current voltage boosting circuit 31 in accordance with a feedback signal (LFB) from the load such that the output voltage (Vout) and the load voltage have a minimum drop-out voltage differential (such as 0.1 volt) therebetween, and such that current flow through the load is maintained at a determined level.
- a feedback signal (LFB) from the load such that the output voltage (Vout) and the load voltage have a minimum drop-out voltage differential (such as 0.1 volt) therebetween, and such that current flow through the load is maintained at a determined level.
- the load is a series connection of a high-power light-emitting diode (D) and a resistor (R 2 ).
- the LDO linear voltage converting circuit 32 includes a voltage regulating module 35 , a second comparator 36 , and a NMOS transistor (Q 1 ).
- the voltage regulating module 35 receives, bucks, and regulates the output voltage (Vout) so as to generate the load voltage.
- the voltage regulating module 35 includes a PMOS transistor (Q 1 ) and a resistor (R 1 ).
- the PMOS transistor (Q 1 ) has a source to receive the output voltage (Vout) of the direct current voltage boosting circuit 31 , a gate, and a drain adapted to be coupled electrically to a terminal of the light-emitting diode (D).
- the resistor (R 1 ) is connected between the source and the gate of the PMOS transistor (Q 1 ).
- the second comparator 36 has a first input that receives a second reference voltage (Vref 2 ) (e.g., 0.2 volt), a second input that receives the feedback signal (LFB) (i.e., the voltage drop across the resistor (R 2 )) from a junction of the resistor (R 2 ) and another terminal of the light-emitting diode (D), and an output.
- the NMOS transistor (Q 2 ) has a gate connected to the output of the second comparator 36 , a drain connected to the second input of the first comparator 34 and the gate of the PMOS transistor (Q 1 ), and a grounded source.
- the second comparator 36 controls operation of the NMOS transistor (Q 2 ) in accordance with the feedback signal (LFB) so as to control in turn operations of the first comparator 34 of the direct current voltage boosting circuit 31 and the PMOS transistor (Q 1 ) of the voltage regulating module 35 .
- the input voltage (Vin) supplied by the lithium battery usually ranges between 3.3 volts and 4.2 volts.
- the resistance of the resistor (R 2 ) can be determined accordingly such that, when the current flowing through the light-emitting diode (D) reaches 200 mA (i.e., the value of the working current (I LED )), the load voltage from the LDO linear voltage converting circuit 32 is maintained at a determined level of 3.5 volts (that is, the sum of the working voltage (V F ) of the light-emitting diode (D) (i.e., 3.3 volts) and the voltage drop across the resistor (R 2 ) (i.e., 0.2 volt)).
- the feedback signal (LFB) at the second input of the second comparator 36 is lower than the second reference voltage (Vref 2 ) (i.e., 0.2 volt).
- the output of the second comparator 36 is at a high logic level so as to trigger the NMOS transistor (Q 2 ) to conduct.
- the drain of the NMOS transistor (Q 2 ) is pulled to a low logic level such that the first comparator 34 outputs a high-logic signal for controlling the voltage boosting module 33 to boost the input voltage (Vin) quickly (that is, the output signal generated by the controller 331 (see FIG. 7 ) has a longer duty cycle).
- the output voltage (Vout) generated by the direct current voltage boosting circuit 31 is provided to the voltage regulating module 35 .
- the PMOS transistor (Q 1 ) is in a short-circuited state, and the output voltage (Vout) is provided directly to the light-emitting diode (D) until the output voltage (Vout) reaches 3.5 volts (that is, the sum of the working voltage (V F ) of the light-emitting diode (D) (i.e., 3.3 volts) and the voltage drop across the resistor (R 2 ) (i.e., 0.2 volt)).
- the light-emitting diode (D) then conducts, and the current flowing through the light-emitting diode (D) reaches 200 mA (i.e., the working current (ILED) of the light-emitting diode (D)).
- the feedback signal (LFB) at the second input of the second comparator 36 becomes higher than (or at least equal to) the second reference voltage (Vref 2 ) (i.e., 0.2 volt), and the output of the second comparator 36 changes to the low logic level.
- the NMOS transistor (Q 2 ) ceases to conduct, and the drain of the NMOS transistor (Q 2 ) is pulled to the high logic level.
- the first comparator 34 responds by providing a low-logic signal for controlling the voltage boosting module 33 to stop increasing the boosting extent of the input voltage (Vin) (that is, the duty cycle of the output signal of the controller 331 is no longer increased).
- the output voltage (Vout) is maintained at a level (such as 3.6 volts) slightly higher than the load voltage generated by the voltage regulating module 35 (This is because the response speed of the direct current voltage boosting circuit 31 is slower than that of the LDO linear voltage converting circuit 32 ).
- the LDO linear voltage converting circuit 32 then proceeds with voltage conversion (i.e., regulation) so as to convert the output voltage (Vout) from 3.6 volts to the required load voltage of 3.5 volts that is supplied to the load.
- initial operation of the device 3 results in the feedback signal (LFB) at the second input of the second comparator 36 that causes the second comparator 36 to trigger the NMOS transistor (Q 2 ) to conduct, thereby enabling the first comparator 34 to output the high-logic signal for controlling the voltage boosting module 31 to boost the input voltage (Vin) and to enable the voltage regulating module 35 to provide the output voltage (Vout) to the light-emitting diode (D).
- LLB feedback signal
- the output voltage (Vout) (e.g., 4.3 volts) is already larger than the required load voltage of 3.5 volts (that is, the sum of the working voltage (V F ) of the light-emitting diode (D) (i.e., 3.3 volts) and the voltage drop across the resistor (R 2 ) (i.e., 0.2 volt)
- the feedback signal (LFB) at the second input of the second comparator 36 is higher than the second reference voltage (Vref 2 ) (i.e., 0.2 volt).
- the output of the second comparator 36 changes to the low logic level, the NMOS transistor (Q 2 ) ceases to conduct, and the first comparator 34 provides the low-logic signal for controlling the voltage boosting module 33 to stop boosting the input voltage (Vin).
- the voltage regulating module 35 operates to convert the output voltage (Vout) to a level, i.e., 3.5 volts, which is required by the load.
- the direct current voltage boosting circuit 31 is prevented from boosting the input voltage (Vin), and the voltage regulating module 35 operates to convert (i.e., bucking) and regulate the input voltage (Vin) such that the input voltage (Vin) is reduced to the required load voltage, such as below 3.5 volts.
- Boosting operation of the voltage boosting module 33 is enabled once again until the output voltage (Vout) is slightly larger than the required load voltage from the voltage regulating module 35 , which subsequently results in stopping of the boosting operation of the voltage boosting module 33 .
- the LDO linear voltage converting circuit 32 performs feedback control of the direct current voltage boosting circuit 31 and the voltage regulating module 35 according to a feedback voltage generated by the current flowing through the light-emitting diode (D) (that is, the feedback signal (LFB) at the second input of the second comparator 36 ), once the current flowing through the light-emitting diode (D) reaches the working current (I LED ), the LDO linear voltage converting circuit 32 controls the direct current voltage boosting circuit 31 and the voltage regulating module 35 such that a fixed load voltage (that is, the sum of the working voltage (V F ) of the light-emitting diode (D) and the voltage drop across the resistor (R 2 )) is outputted, thereby maintaining the current flow through the light-emitting diode (D) at a determined level (that is
- FIG. 8 illustrates an alternative implementation of the direct current voltage boosting/bucking device 3 of the present invention.
- the direct current voltage boosting circuit as well as the second comparator and the NMOS transistor of the LDO linear voltage converting circuit, can be integrated into a single integrated circuit (IC) chip 30 .
- IC integrated circuit
- FIG. 9 shows experimental results for the device 3 of the present invention to illustrate the power conversion rates for different input voltages (Vin) when the working current (I LED ) is 200 mA.
- the conversion rates exceed 90% for input voltages (Vin) in the range of 3 volts to 3.6 volts, and exceed 80% for input voltages (Vin) in the range of 3 volts to 4.2 volts.
- the present invention utilizes the direct current voltage boosting circuit 31 and the LDO linear voltage converting circuit 32 to form the direct current voltage boosting/bucking device 3 for driving operation of a load, such as a light-emitting diode (D).
- the LDO linear voltage converting circuit 32 controls operation of the direct current voltage boosting circuit 31 in accordance with a feedback signal from the load.
- a fixed load current can be generated regardless of the input voltage (Vin) and the working voltage (V F ) of a light-emitting diode load to achieve the object of a stable current output.
- the LDO linear voltage converting circuit 32 performs feedback control of the direct current voltage boosting circuit 31 such that the output voltage (Vout) of the direct current voltage boosting circuit 31 is maintained at a level slightly larger than the load voltage generated by the LDO linear voltage converting circuit 32 , optimum power conversion and utilization rates are possible in the device 3 of the present invention.
- the device 3 of the present invention is built from two major components, i.e., the direct current voltage boosting circuit 31 and the LDO linear voltage converting circuit 32 , the device 3 of this invention can be fabricated at a lower cost as compared to the conventional driver circuit 2 of FIG. 3 .
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Automation & Control Theory (AREA)
- Dc-Dc Converters (AREA)
Abstract
Description
- This application claims priority of Taiwanese application no. 094116547, filed on May 20, 2005.
- 1. Field of the Invention
- The invention relates to a direct current voltage boosting/bucking device, more particularly to a direct current voltage boosting/bucking device suitable for driving operation of a high-power light-emitting diode.
- 2. Description of the Related Art
- Current camera phones generally employ a high-power light-emitting diode for supplying light when taking pictures. Hence, a driver circuit is required for driving operation of the light-emitting diode.
-
FIG. 1 illustrates aconventional driver circuit 1 for a high-power light emitting diode (D). Thedriver circuit 1 utilizes a direct currentvoltage boosting chip 11 for boosting an input voltage (Vin) from an input voltage source (such as a battery of a mobile phone) so as to generate an output voltage (Vout) that is higher than the input voltage (Vin) and that is provided to the light-emitting diode (D). It is noted that the input voltage (Vin) must be lower than the output voltage (Vout) in order to ensure normal operation of the direct currentvoltage boosting chip 11. However, since the voltage range of the input voltage source (e.g., a lithium battery) is usually between 4.2 volts and 3.3 volts, in the case where the input voltage (Vin) is 4.2 volts, the output voltage (Vout) must be higher than 4.2 volts (e.g., 4.3 volts). Therefore, when the light-emitting diode (D) has a working voltage (VF) of 3.2 volts and a working current (ILED) of 700 mA, in order to ensure that only an appropriate portion of the output voltage (Vout) will be present across the light-emitting diode (D) (which only requires 3.2 volts), a resistor (R3) must be coupled in series to the light-emitting diode (D) to bear the excess voltage portion (i.e., 4.3−3.2=1.1 volts). Moreover, in order to enable the direct currentvoltage boosting chip 11 to generate the fixed output voltage (Vout) (e.g., 4.3 volts), series-connected resistors (R1, R2) must be provided between an output terminal (OUT) and a feedback terminal (FB) of the direct currentvoltage boosting chip 11, and between the feedback terminal (FB) and the resistor (R3). Therefore, through a feedback voltage that is fed back to the direct currentvoltage boosting chip 11 and that is set by the resistances of the resistors (R1, R2), the direct currentvoltage boosting chip 11 is controlled to generate the fixed output voltage (Vout) (e.g., 4.3 volts). - In the
aforementioned driver circuit 1, it is noted that a considerable amount of power is consumed by the resistor (R3) such that the power conversion and utilization rates are significantly low.FIG. 2 shows experimental results for theconventional driver circuit 1 to illustrate the power conversion rates for different input voltages (Vin) when the working current (ILED) is 600 mA. It is evident from the data that the power conversion rates decrease with a reduction in the magnitude of the input voltage (Vin). In addition, a change in the working voltage (VF) of the light-emitting diode (D) necessitates corresponding adjustments in the resistances of the resistors (R1, R2, R3) in thedriver circuit 1. -
FIG. 3 illustrates anotherconventional driver circuit 2 for a high-power light emitting diode (D). Thedriver circuit 2 utilizes a synchronous buck-boost driver chip 21 (such as LTC3453) that receives an input voltage (Vin) from an input voltage source (such as a lithium battery) and that performs voltage boosting or voltage bucking so as to generate a suitable output voltage (Vout) for driving the light-emitting diode (D). During operation of thedriver circuit 2, the working current (ILED) flowing through the light emitting diode (ILED) is continuously detected. When the working current (ILED) is less than a preset value, a voltage boosting action is conducted to increase the output voltage (Vout) On the other hand, when the working current (ILED) becomes larger than (or at least equal to) the preset value, a voltage bucking action is conducted to decrease the output voltage (Vout). As a result, the working voltage (VF) and the working current (ILED) of the light emitting diode (D) can be maintained at the respective preset value for driving the light-emitting diode (D) to generate a fixed intensity output.FIG. 4 shows experimental results for theconventional driver circuit 2 to illustrate the power conversion rates for different input voltages (Vin) when the working current (ILED) is 150 mA. It is evident from the data that the power conversion rates for thedriver circuit 2 are higher than those for theconventional driver circuit 1 ofFIG. 1 . However, the synchronous buck-boost driver chip 21 requires four MOS transistors (Q1, Q2, Q3, Q4) so as to be able to perform the voltage boosting and voltage bucking operations, which results in higher costs incurred for thedriver circuit 2. - Therefore, the object of the present invention is to provide a direct current voltage boosting/bucking device that can overcome at least one of the aforesaid drawbacks associated with the prior art.
- According to the present invention, a direct current voltage boosting/bucking device is adapted for driving a load, and comprises a direct current voltage boosting/bucking circuit and a low drop-out (LDO) linear voltage converting circuit.
- The direct current voltage boosting circuit boosts an input voltage so as to generate an output voltage higher than the input voltage.
- The LDO linear voltage converting circuit is adapted to be coupled electrically to the load, is coupled electrically to the direct current voltage boosting circuit for converting the output voltage into a load voltage that is to be provided to the load, and controls the direct current voltage boosting circuit in accordance with a feedback signal from the load such that the output voltage and the load voltage have a minimum drop-out voltage differential therebetween and such that current flow through the load is maintained at a determined level.
- Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:
-
FIG. 1 is a schematic circuit diagram of a conventional driver circuit for a high-power light-emitting diode; -
FIG. 2 is a plot showing experimental results for the conventional driver circuit ofFIG. 1 to illustrate power conversion rates for different input voltages; -
FIG. 3 is a schematic circuit diagram of another conventional driver circuit for a high-power light-emitting diode; -
FIG. 4 is a plot showing experimental results for the conventional driver circuit ofFIG. 3 to illustrate power conversion rates for different input voltages; -
FIG. 5 is a block diagram of the preferred embodiment of the direct current voltage boosting/bucking device according to the present invention.; -
FIG. 6 is a schematic circuit diagram of the preferred embodiment; -
FIG. 7 is a schematic circuit diagram to illustrate a direct current voltage boosting circuit of the preferred embodiment in greater detail; -
FIG. 8 is a schematic circuit diagram to illustrate an alternative implementation of the device of the present invention; and -
FIG. 9 is a plot showing experimental results for the device of the present invention to illustrate power conversion rates for different input voltages. - Referring to
FIG. 5 , the preferred embodiment of a direct current voltage boosting/bucking device 3 according to the present invention is adapted for application to a camera phone so as to drive operation of a high-power light-emitting diode (D) for supplying light when taking pictures. However, it should be noted that the above application of the preferred embodiment is solely for the sake of illustration and should not be interpreted as being limited exclusively thereto. - The direct current voltage boosting/
bucking device 3 comprises a direct current voltage boosting/bucking circuit 31 and a low drop-out (LDO) linearvoltage converting circuit 32. - As shown in
FIG. 6 , the direct currentvoltage boosting circuit 31 is a conventional booster that boosts an input voltage (Vin) so as to generate an output voltage (Vout) higher than the input voltage (Vin). The direct currentvoltage boosting circuit 31 includes avoltage boosting module 33 and afirst comparator 34. With further reference toFIG. 7 , thevoltage boosting module 33 includes a PWM (or PFM)controller 331, and is used to receive and boost the input voltage (Vin). Thefirst comparator 34 has a first input that receives a first reference voltage (Vref1)(e.g., 0.8 volt), a second input that receives a feedback signal (FB), and an output that is coupled electrically to the PWM (or PFM)controller 331. Thefirst comparator 34 controls boosting operation of thevoltage boosting module 33 by controlling the duty cycle of an output signal generated by the PWM (or PFM)controller 331 in a manner to be described hereinafter. - Referring once again to
FIG. 6 , the LDO linearvoltage converting circuit 32 is a conventional voltage bucking circuit, is adapted to be coupled electrically to a load, is coupled electrically to the direct currentvoltage boosting circuit 31 for converting the output voltage (Vout) into a load voltage that is to be provided to the load, and controls the direct currentvoltage boosting circuit 31 in accordance with a feedback signal (LFB) from the load such that the output voltage (Vout) and the load voltage have a minimum drop-out voltage differential (such as 0.1 volt) therebetween, and such that current flow through the load is maintained at a determined level. - In this embodiment, the load is a series connection of a high-power light-emitting diode (D) and a resistor (R2).
- The LDO linear
voltage converting circuit 32 includes a voltage regulatingmodule 35, asecond comparator 36, and a NMOS transistor (Q1). The voltage regulatingmodule 35 receives, bucks, and regulates the output voltage (Vout) so as to generate the load voltage. In this embodiment, the voltage regulatingmodule 35 includes a PMOS transistor (Q1) and a resistor (R1). The PMOS transistor (Q1) has a source to receive the output voltage (Vout) of the direct currentvoltage boosting circuit 31, a gate, and a drain adapted to be coupled electrically to a terminal of the light-emitting diode (D). The resistor (R1) is connected between the source and the gate of the PMOS transistor (Q1). Thesecond comparator 36 has a first input that receives a second reference voltage (Vref2) (e.g., 0.2 volt), a second input that receives the feedback signal (LFB) (i.e., the voltage drop across the resistor (R2)) from a junction of the resistor (R2) and another terminal of the light-emitting diode (D), and an output. The NMOS transistor (Q2) has a gate connected to the output of thesecond comparator 36, a drain connected to the second input of thefirst comparator 34 and the gate of the PMOS transistor (Q1), and a grounded source. Thesecond comparator 36 controls operation of the NMOS transistor (Q2) in accordance with the feedback signal (LFB) so as to control in turn operations of thefirst comparator 34 of the direct currentvoltage boosting circuit 31 and the PMOS transistor (Q1) of the voltage regulatingmodule 35. Taking the lithium battery of a camera phone as an example, the input voltage (Vin) supplied by the lithium battery usually ranges between 3.3 volts and 4.2 volts. In the case of a light-emitting diode (D) having a working voltage (VF) of 3.3 volts and a working current (ILED) of 200 mA, since the second reference voltage (Vref2) of thesecond comparator 36 is set to 0.2 volt, the resistance of the resistor (R2) can be determined accordingly such that, when the current flowing through the light-emitting diode (D) reaches 200 mA (i.e., the value of the working current (ILED)), the load voltage from the LDO linearvoltage converting circuit 32 is maintained at a determined level of 3.5 volts (that is, the sum of the working voltage (VF) of the light-emitting diode (D) (i.e., 3.3 volts) and the voltage drop across the resistor (R2) (i.e., 0.2 volt)). - Therefore, as shown in
FIG. 6 , in the case where the input voltage (Vin) is 3.3 volts, when thedevice 3 is powered on, since the current initially flowing through the light-emitting diode (D) is almost equal to zero, the feedback signal (LFB) at the second input of thesecond comparator 36 is lower than the second reference voltage (Vref2) (i.e., 0.2 volt). The output of thesecond comparator 36 is at a high logic level so as to trigger the NMOS transistor (Q2) to conduct. The drain of the NMOS transistor (Q2) is pulled to a low logic level such that thefirst comparator 34 outputs a high-logic signal for controlling thevoltage boosting module 33 to boost the input voltage (Vin) quickly (that is, the output signal generated by the controller 331 (seeFIG. 7 ) has a longer duty cycle). The output voltage (Vout) generated by the direct currentvoltage boosting circuit 31 is provided to thevoltage regulating module 35. At this time, since the drain of the NMOS transistor (Q2) is at the low logic level, the PMOS transistor (Q1) is in a short-circuited state, and the output voltage (Vout) is provided directly to the light-emitting diode (D) until the output voltage (Vout) reaches 3.5 volts (that is, the sum of the working voltage (VF) of the light-emitting diode (D) (i.e., 3.3 volts) and the voltage drop across the resistor (R2) (i.e., 0.2 volt)). The light-emitting diode (D) then conducts, and the current flowing through the light-emitting diode (D) reaches 200 mA (i.e., the working current (ILED) of the light-emitting diode (D)). At this moment, the feedback signal (LFB) at the second input of thesecond comparator 36 becomes higher than (or at least equal to) the second reference voltage (Vref2) (i.e., 0.2 volt), and the output of thesecond comparator 36 changes to the low logic level. The NMOS transistor (Q2) ceases to conduct, and the drain of the NMOS transistor (Q2) is pulled to the high logic level. Thefirst comparator 34 responds by providing a low-logic signal for controlling thevoltage boosting module 33 to stop increasing the boosting extent of the input voltage (Vin) (that is, the duty cycle of the output signal of thecontroller 331 is no longer increased). Hence, the output voltage (Vout) is maintained at a level (such as 3.6 volts) slightly higher than the load voltage generated by the voltage regulating module 35 (This is because the response speed of the direct currentvoltage boosting circuit 31 is slower than that of the LDO linear voltage converting circuit 32). The LDO linearvoltage converting circuit 32 then proceeds with voltage conversion (i.e., regulation) so as to convert the output voltage (Vout) from 3.6 volts to the required load voltage of 3.5 volts that is supplied to the load. Therefore, apart from the function of maintaining the load current flowing through the light-emitting diode (D) at a determined level so that the light-emitting diode (D) is able to generate a fixed intensity output, only a slight voltage differential is present between the input voltage of the voltage regulating module 35 (i.e., the output voltage (Vout) of the direct current voltage boosting circuit 31) and the load voltage, thereby resulting in a marked increase (3.3/3.6=91%) in the utilization (i.e., conversion) rate of the power source. On the other hand, in the case where the input voltage (Vin) is 4.2 volts, initial operation of thedevice 3 results in the feedback signal (LFB) at the second input of thesecond comparator 36 that causes thesecond comparator 36 to trigger the NMOS transistor (Q2) to conduct, thereby enabling thefirst comparator 34 to output the high-logic signal for controlling thevoltage boosting module 31 to boost the input voltage (Vin) and to enable thevoltage regulating module 35 to provide the output voltage (Vout) to the light-emitting diode (D). However, since the output voltage (Vout) (e.g., 4.3 volts) is already larger than the required load voltage of 3.5 volts (that is, the sum of the working voltage (VF) of the light-emitting diode (D) (i.e., 3.3 volts) and the voltage drop across the resistor (R2) (i.e., 0.2 volt)), the feedback signal (LFB) at the second input of thesecond comparator 36 is higher than the second reference voltage (Vref2) (i.e., 0.2 volt). The output of thesecond comparator 36 changes to the low logic level, the NMOS transistor (Q2) ceases to conduct, and thefirst comparator 34 provides the low-logic signal for controlling thevoltage boosting module 33 to stop boosting the input voltage (Vin). At the same time, thevoltage regulating module 35 operates to convert the output voltage (Vout) to a level, i.e., 3.5 volts, which is required by the load. Therefore, in the case where the input voltage (Vin) is already larger than the required load voltage, the direct currentvoltage boosting circuit 31 is prevented from boosting the input voltage (Vin), and thevoltage regulating module 35 operates to convert (i.e., bucking) and regulate the input voltage (Vin) such that the input voltage (Vin) is reduced to the required load voltage, such as below 3.5 volts. Boosting operation of thevoltage boosting module 33 is enabled once again until the output voltage (Vout) is slightly larger than the required load voltage from thevoltage regulating module 35, which subsequently results in stopping of the boosting operation of thevoltage boosting module 33. As a result, there is a minimum voltage differential between the input voltage and the output voltage of thevoltage regulating module 35 to ensure an optimum conversion efficiency. - Moreover, even in the case of a drift in the working voltage (VF) of the light-emitting diode (D) due to a difference in specifications or manufacturing bias voltages, since the LDO linear
voltage converting circuit 32 performs feedback control of the direct currentvoltage boosting circuit 31 and thevoltage regulating module 35 according to a feedback voltage generated by the current flowing through the light-emitting diode (D) (that is, the feedback signal (LFB) at the second input of the second comparator 36), once the current flowing through the light-emitting diode (D) reaches the working current (ILED), the LDO linearvoltage converting circuit 32 controls the direct currentvoltage boosting circuit 31 and thevoltage regulating module 35 such that a fixed load voltage (that is, the sum of the working voltage (VF) of the light-emitting diode (D) and the voltage drop across the resistor (R2)) is outputted, thereby maintaining the current flow through the light-emitting diode (D) at a determined level (that is, the working current (ILED)). Therefore, regardless of changes in the working voltage (VF) of the light-emitting diode (D), a determined load current can be achieved without the need to modify any portion of the direct current voltage boosting/bucking device 3. -
FIG. 8 illustrates an alternative implementation of the direct current voltage boosting/bucking device 3 of the present invention. As compared to the circuit shown inFIG. 6 , the direct current voltage boosting circuit, as well as the second comparator and the NMOS transistor of the LDO linear voltage converting circuit, can be integrated into a single integrated circuit (IC)chip 30. -
FIG. 9 shows experimental results for thedevice 3 of the present invention to illustrate the power conversion rates for different input voltages (Vin) when the working current (ILED) is 200 mA. The conversion rates exceed 90% for input voltages (Vin) in the range of 3 volts to 3.6 volts, and exceed 80% for input voltages (Vin) in the range of 3 volts to 4.2 volts. - It has thus been shown that the present invention utilizes the direct current
voltage boosting circuit 31 and the LDO linearvoltage converting circuit 32 to form the direct current voltage boosting/bucking device 3 for driving operation of a load, such as a light-emitting diode (D). The LDO linearvoltage converting circuit 32 controls operation of the direct currentvoltage boosting circuit 31 in accordance with a feedback signal from the load. As a result, a fixed load current can be generated regardless of the input voltage (Vin) and the working voltage (VF) of a light-emitting diode load to achieve the object of a stable current output. - Moreover, since the LDO linear
voltage converting circuit 32 performs feedback control of the direct currentvoltage boosting circuit 31 such that the output voltage (Vout) of the direct currentvoltage boosting circuit 31 is maintained at a level slightly larger than the load voltage generated by the LDO linearvoltage converting circuit 32, optimum power conversion and utilization rates are possible in thedevice 3 of the present invention. - Furthermore, since the
device 3 of the present invention is built from two major components, i.e., the direct currentvoltage boosting circuit 31 and the LDO linearvoltage converting circuit 32, thedevice 3 of this invention can be fabricated at a lower cost as compared to theconventional driver circuit 2 ofFIG. 3 . - While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
Claims (8)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
TW094116547 | 2005-05-20 | ||
TW094116547A TW200642246A (en) | 2005-05-20 | 2005-05-20 | DC buck/boost converter |
Publications (2)
Publication Number | Publication Date |
---|---|
US20060261790A1 true US20060261790A1 (en) | 2006-11-23 |
US7148666B1 US7148666B1 (en) | 2006-12-12 |
Family
ID=37447745
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US11/183,611 Active 2025-07-19 US7148666B1 (en) | 2005-05-20 | 2005-07-18 | Direct current voltage boosting/bucking device |
Country Status (2)
Country | Link |
---|---|
US (1) | US7148666B1 (en) |
TW (1) | TW200642246A (en) |
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070218324A1 (en) * | 2006-03-14 | 2007-09-20 | Chun-Chin Tung | Fuel cell voltage stabilization apparatus |
US20080111800A1 (en) * | 2006-11-09 | 2008-05-15 | Beyond Innovation Technology Co., Ltd. | Driving apparatus and method thereof |
US20080180073A1 (en) * | 2007-01-29 | 2008-07-31 | Richtek Technology Corporation | Power supply with high efficiency and low noise |
US20100289471A1 (en) * | 2009-05-18 | 2010-11-18 | Fujitsu Semicondctor Limited | Power control device, power supply device, and power control method |
US20110012747A1 (en) * | 2009-07-15 | 2011-01-20 | Fih (Hong Kong) Limited | Electrostatic protector of portable electronic devices |
US20140192096A1 (en) * | 2013-01-07 | 2014-07-10 | Panasonic Liquid Crystal Display Co., Ltd. | Liquid crystal display device |
CN110021973A (en) * | 2019-02-03 | 2019-07-16 | 华为技术有限公司 | The method of terminal device and control conversion circuit |
CN111373644A (en) * | 2017-12-25 | 2020-07-03 | 德州仪器公司 | Voltage monitoring circuit for handling voltage drift caused by negative bias temperature instability |
CN111464027A (en) * | 2020-06-04 | 2020-07-28 | 重庆邮电大学 | Programmable digital power supply system and method integrating switch power supply and linear power supply |
US11003201B1 (en) * | 2019-11-26 | 2021-05-11 | Qualcomm Incorporated | Low quiescent current low-dropout regulator (LDO) |
CN114683955A (en) * | 2022-04-08 | 2022-07-01 | 重庆金康赛力斯新能源汽车设计院有限公司 | Boost control device and method and related equipment |
CN117411320A (en) * | 2023-12-15 | 2024-01-16 | 北京七星华创微电子有限责任公司 | Voltage stabilizing circuit |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100045190A1 (en) * | 2008-08-20 | 2010-02-25 | White Electronic Designs Corporation | Led backlight |
US8729877B2 (en) | 2011-09-13 | 2014-05-20 | Texas Instruments Incorporated | Fast startup algorithm for low noise power management |
US10305384B2 (en) | 2011-09-13 | 2019-05-28 | Texas Instruments Incorporated | Power management system and method with adaptive noise control |
US9344077B2 (en) * | 2012-04-04 | 2016-05-17 | Cree, Inc. | High voltage driver |
US8963576B2 (en) | 2012-10-19 | 2015-02-24 | Cree, Inc. | Increased transition speed switching device driver |
US8994219B2 (en) * | 2012-12-25 | 2015-03-31 | Shenzhen China Star Optoelectronics Technology Co., Ltd | DC/DC module of LCD driving circuit |
CN104052260A (en) * | 2013-03-15 | 2014-09-17 | 海洋王(东莞)照明科技有限公司 | Boost control circuit |
US10185342B2 (en) * | 2016-11-04 | 2019-01-22 | Qualcomm Incorporated | Configurable charge controller |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5589761A (en) * | 1994-04-15 | 1996-12-31 | Linear Technology Corporation | Dual polarity voltage regulator circuits and methods for providing voltage regulation |
US6617832B1 (en) * | 2002-06-03 | 2003-09-09 | Texas Instruments Incorporated | Low ripple scalable DC-to-DC converter circuit |
US6661683B2 (en) * | 2002-03-18 | 2003-12-09 | Texas Instruments Incorporated | Charge pump having very low voltage ripple |
US6703815B2 (en) * | 2002-05-20 | 2004-03-09 | Texas Instruments Incorporated | Low drop-out regulator having current feedback amplifier and composite feedback loop |
US6956429B1 (en) * | 2004-02-09 | 2005-10-18 | Fairchild Semiconductor Corporation | Low dropout regulator using gate modulated diode |
-
2005
- 2005-05-20 TW TW094116547A patent/TW200642246A/en not_active IP Right Cessation
- 2005-07-18 US US11/183,611 patent/US7148666B1/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5589761A (en) * | 1994-04-15 | 1996-12-31 | Linear Technology Corporation | Dual polarity voltage regulator circuits and methods for providing voltage regulation |
US6661683B2 (en) * | 2002-03-18 | 2003-12-09 | Texas Instruments Incorporated | Charge pump having very low voltage ripple |
US6703815B2 (en) * | 2002-05-20 | 2004-03-09 | Texas Instruments Incorporated | Low drop-out regulator having current feedback amplifier and composite feedback loop |
US6617832B1 (en) * | 2002-06-03 | 2003-09-09 | Texas Instruments Incorporated | Low ripple scalable DC-to-DC converter circuit |
US6956429B1 (en) * | 2004-02-09 | 2005-10-18 | Fairchild Semiconductor Corporation | Low dropout regulator using gate modulated diode |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070218324A1 (en) * | 2006-03-14 | 2007-09-20 | Chun-Chin Tung | Fuel cell voltage stabilization apparatus |
US20080111800A1 (en) * | 2006-11-09 | 2008-05-15 | Beyond Innovation Technology Co., Ltd. | Driving apparatus and method thereof |
US20100225622A1 (en) * | 2006-11-09 | 2010-09-09 | Beyond Innovation Technology Co., Ltd. | Driving apparatus |
US20080180073A1 (en) * | 2007-01-29 | 2008-07-31 | Richtek Technology Corporation | Power supply with high efficiency and low noise |
US8125204B2 (en) * | 2007-01-29 | 2012-02-28 | Richtek Technology Corporation | Two-stage power supply with feedback adjusted power supply rejection ratio |
US20120112717A1 (en) * | 2007-01-29 | 2012-05-10 | Richtek Technology Corporation | Two-Stage Power Supply with Feedback Adjusted Power Supply Rejection Ratio |
US20100289471A1 (en) * | 2009-05-18 | 2010-11-18 | Fujitsu Semicondctor Limited | Power control device, power supply device, and power control method |
US8541996B2 (en) * | 2009-05-18 | 2013-09-24 | Fujitsu Semiconductor Limited | Power control device, power supply device, and power control method |
US8421645B2 (en) * | 2009-07-15 | 2013-04-16 | Fih (Hong Kong) Limited | Electrostatic protector of portable electronic devices |
US20110012747A1 (en) * | 2009-07-15 | 2011-01-20 | Fih (Hong Kong) Limited | Electrostatic protector of portable electronic devices |
US20140192096A1 (en) * | 2013-01-07 | 2014-07-10 | Panasonic Liquid Crystal Display Co., Ltd. | Liquid crystal display device |
CN111373644A (en) * | 2017-12-25 | 2020-07-03 | 德州仪器公司 | Voltage monitoring circuit for handling voltage drift caused by negative bias temperature instability |
CN110021973A (en) * | 2019-02-03 | 2019-07-16 | 华为技术有限公司 | The method of terminal device and control conversion circuit |
US11003201B1 (en) * | 2019-11-26 | 2021-05-11 | Qualcomm Incorporated | Low quiescent current low-dropout regulator (LDO) |
CN111464027A (en) * | 2020-06-04 | 2020-07-28 | 重庆邮电大学 | Programmable digital power supply system and method integrating switch power supply and linear power supply |
CN114683955A (en) * | 2022-04-08 | 2022-07-01 | 重庆金康赛力斯新能源汽车设计院有限公司 | Boost control device and method and related equipment |
CN117411320A (en) * | 2023-12-15 | 2024-01-16 | 北京七星华创微电子有限责任公司 | Voltage stabilizing circuit |
Also Published As
Publication number | Publication date |
---|---|
TW200642246A (en) | 2006-12-01 |
TWI295876B (en) | 2008-04-11 |
US7148666B1 (en) | 2006-12-12 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US7148666B1 (en) | Direct current voltage boosting/bucking device | |
US7564196B2 (en) | Power supply device, and LED device and electronic device using same | |
US8044649B2 (en) | Dual mode regulation loop for switch mode power converter | |
US7851940B2 (en) | Methods and apparatus for DC-DC converter having independent outputs | |
TWI509959B (en) | Electronic circuit and method of providing a regulated voltage to a load | |
US8853960B2 (en) | Dimming control circuit and method for generating analog and digital signals according to one analog control signal | |
US7218086B1 (en) | Switching regulator with programmable output levels using a single input pin | |
WO2006018923A1 (en) | Power supply apparatus | |
JP3759133B2 (en) | Power supply | |
EP1385074A2 (en) | Power supplying method and apparatus capable of quickly responding to variations in input and output voltages to output a stable voltage | |
US20090146633A1 (en) | Step-up switching regulator and its control circuit and electronic apparatus employing it | |
WO2018133136A1 (en) | Backlight control circuit and electronic device | |
US9069366B2 (en) | Switching regulator | |
US20210194369A1 (en) | Buck-boost converting circuit | |
CN111417239B (en) | LED system with PVT adjusted headroom | |
US20140210439A1 (en) | Switching Regulator and Control Circuit Thereof | |
JP2008295237A (en) | Switching pulse formation circuit and regulator using same | |
KR20100066267A (en) | Apparatus for detecting current, and driver for light emitting diode comprising the same | |
US11172556B2 (en) | Light emitting element drive device | |
US9942956B1 (en) | Boost converter design with 100%-pass mode for WLED backlight and camera flash applications | |
JP4467395B2 (en) | Power supply | |
TW201316831A (en) | Light emitting diode driving integrated circuit with a multi-step current setting function and method of setting a multi-step current of a light emitting diode driving integrated circuit | |
KR100696563B1 (en) | Apparatus for supplying power source | |
TWI559812B (en) | Feedback device and method for constant current driver | |
US20130038243A1 (en) | Current-controlled stages, constant current control systems, and current control methods for driving leds |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: RICHTEK TECHNOLOGY CORP., TAIWAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:TAI, LIANG-PIN;CHEN, CHUN-TSUNG;YEH, CHIN-CHIANG;AND OTHERS;REEL/FRAME:016828/0252 Effective date: 20050708 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
FPAY | Fee payment |
Year of fee payment: 4 |
|
FEPP | Fee payment procedure |
Free format text: PAT HOLDER NO LONGER CLAIMS SMALL ENTITY STATUS, ENTITY STATUS SET TO UNDISCOUNTED (ORIGINAL EVENT CODE: STOL); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
FPAY | Fee payment |
Year of fee payment: 8 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 12TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1553) Year of fee payment: 12 |