Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
  • G05F3/00—Non-retroactive systems for regulating electric variables by using an uncontrolled element, or an uncontrolled combination of elements, such element or such combination having self-regulating properties
  • G05F3/02—Regulating voltage or current
  • G05F3/08—Regulating voltage or current wherein the variable is DC
• • 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
  • G05F1/613—Regulating voltage or current  wherein the variable actually regulated by the final control device is DC using semiconductor devices in parallel with the load as final control devices
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J3/00—Circuit arrangements for AC mains or AC distribution networks
  • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
  • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
  • H02J7/0068—Battery or charger load switching, e.g. concurrent charging and load supply

Definitions

• Embodiments disclosed herein relate to power supplies, and more specifically to managing transient load currents in a power supply.
• Modern mobile devices such as laptops, smartphones and tablets typically include a re-chargeable battery to power the electronics inside.
• the batteries are often kept as small as possible in order to make the mobile device smaller and lighter. As a consequence, these batteries have finite capacity and a finite ability to deliver current to the load.
• a battery's ability to deliver current is quantified by the internal resistance of the battery. When the battery is not connected to any loading circuit, it will show a particular voltage across its terminals called the "open circuit voltage.” When a loading circuit is connected to the battery, current flows from the battery through the loading circuit. This increase in current causes the voltage across the terminals of the battery to droop below its open circuit voltage. Batteries with a larger internal resistance will produce a larger voltage droop for a given load current.
• load currents may be particularly large in modern electronic devices that include multiple circuits operating from a single battery, such as for example, application processors, digital baseband processors, image processors, etc.
• application processors digital baseband processors
• image processors etc.
• the battery's voltage may fall until the voltage is no longer sufficient to sustain the operation of the loading circuits, causing the entire device to reset.
• FIG. 1 is a circuit diagram illustrating a first embodiment of a load transient suppression circuit.
• FIG. 2 is a waveform diagram illustrating example waveforms associated with operation of a load transient suppression circuit.
• FIG. 3 is a circuit diagram illustrating a second embodiment of a load transient suppression circuit.
• FIG. 1 illustrates a first embodiment of a load transient suppression circuit 120 coupled in parallel with a battery 110 and an electronic device 130. Battery 110 is represented in FIG.
• Load transient suppression circuit 120 ensures that voltage Vdd does not drop below a threshold voltage (e.g., a minimum operating voltage of electronic device 130) during transient load conditions.
• the load transient suppression circuit 120 comprises an operational amplifier XI, capacitors C3-C4, resistor R3, and an operational amplifier input circuit 140 including capacitors C1-C2, resistors R1-R2 and voltage subtraction circuit 104.
• Operational amplifier input circuit 140 produces differential voltage V+, V- provided to the operational amplifier XI to supply a positive differential voltage under transient conditions and a negative differential voltage under nominal conditions.
• Voltage subtraction circuit 104 can be implemented using any conventional technique, such as, for example, a differential amplifier in a voltage subtraction configuration. During nominal load conditions, voltage V+ at the positive input node of operational amplifier XI is below voltage V- of the negative input node due to the voltage drop VI .
• Vout 0V
• operational amplifier XI does not deliver or consume any current other than its bias current.
• the supply terminal of operational amplifier XI receives a supply voltage Vcc.
• the supply voltage Vcc approaches Vdd under nominal conditions and both C4 and C3 are charged to approximately Vdd. Assuming R4 is small, Vdd is approximately Vo.
• the current from operational amplifier XI come from the power supply voltage Vcc of operational amplifier XI .
• C4 starts discharging.
• Resistor R3 ensures that the current flowing from C3 boosts Vdd and does not charge C4.
• C3 and C4 will continue to sustain the output voltage at Vdd until both capacitors are roughly Vo/2
• C3 and C4 are selected such that the voltages across them do not reach Vo/2 until the end of the transient period. Once the transient period ends, capacitors C3 and C4 slowly charge back to approximately Vo.
• R3 is generally larger than R4. If R3 is too small, charge pumped out by capacitor C3 may be dissipated in large portion by resistor R3. However, if R3 is large compared to R4, then most of the charge from capacitor C3 will flow to device 130. However, a larger value of R3 will increase the time it takes to recharge capacitor C4 after the transient event. Thus, the exact value of R3 may be determined based on the desired tradeoffs.
• FIG. 2 illustrates example waveforms representing operation of load transient suppression circuit 120 of FIG. 1.
• load current lout spikes up to 5A which causes Vdd to begin to drop.
• the drop in Vdd causes voltage V+ to rise above voltage V-, which in turn causes Vout to begin to rise.
• the rise in Vout stabilizes Vdd and prevents Vdd from dropping further.
• the rising Vout increases current through capacitor C3 during the transient condition (between time ti and time t 2 in FIG. 2).
• C3 furthermore discharges to provide current to device 130 and prevent Vdd from collapsing.
• Vcc also drops between t] and t 2 as C4 discharges.
• the transient period ends and output current lout drops back down to 100mA.
• C3 and C4 begin to charge back up, thus causing Vout to drop and Vcc to increase back up to approximately 3V.
• Vdd rises back up to approximately 3V once Vout reaches approximately 0V and capacitor C3 is fully charged at time t$.
• FIG. 3 illustrates an alternative embodiment of a load transient suppression circuit 320.
• resistor R3 is replaced with a switch SI (e.g., a transistor) that is controlled based on the detection of a transient event, but otherwise the embodiment of FIG. 3 is similar to that of FIG. 2.
• SI e.g., a transistor
• a sense circuit 322 senses a transient event by monitoring voltage Vdd or current lout. For example, sense circuit 322 detects a transient condition when Vdd drops below a threshold voltage or when a magnitude of a rate of change of Vdd exceeds below a threshold rate. Alternatively, sense circuit 322 may detect the transient condition when lout rises about a threshold current or when a magnitude of a rate of change of lout rises above a threshold rate. In response to detecting the transient condition, sense circuit 322 turns switch SI off, thus causing the Vcc node of operational amplifier XI to draw current from capacitor C4. When sense circuit senses 322 that the transient condition ends, switch SI is turned back on. Switch SI remains on during nominal conditions, thus allowing capacitor C4 to charge back up to approximately Vdd.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Automation & Control Theory (AREA)
• Charge And Discharge Circuits For Batteries Or The Like (AREA)
• Continuous-Control Power Sources That Use Transistors (AREA)
• Control Of Voltage And Current In General (AREA)
• Amplifiers (AREA)

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• 2014
  • 2014-03-12 JP JP2016501710A patent/JP6227110B2/ja active Active
  • 2014-03-12 US US14/207,292 patent/US9535441B2/en active Active
  • 2014-03-12 EP EP14773369.5A patent/EP2973916B1/en active Active
  • 2014-03-12 WO PCT/US2014/024994 patent/WO2014159752A1/en not_active Ceased
  • 2014-03-12 KR KR1020157024694A patent/KR102259224B1/ko active Active
  • 2014-03-12 CN CN201480013247.5A patent/CN105075044B/zh active Active
• 2016
  • 2016-11-29 US US15/363,108 patent/US10466730B2/en active Active
• 2017
  • 2017-08-22 JP JP2017159271A patent/JP6495983B2/ja active Active

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