Power supply having selectable operation based on communications with load

• US 9,124,101 B2
• Filed: 03/31/2014
• Issued: 09/01/2015
• Est. Priority Date: 04/02/2013
• Status: Active Grant

• Current Assignee: Bel Fuse Limited (Bel Fuse)
• Original Assignee: Bel Fuse Limited (Bel Fuse)
• Inventors: Jutras, Mark, Moore, Scott
• Primary Examiner(s): Finch, III, Fred E
• Assistant Examiner(s): AHMED, YUSEF A
• Application Number:
  US14/230,364
• Publication Number:
  US 20140292297A1
• Time in Patent Office: 519 Days
• US Class Current: 1/1
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/335 using semiconductor devices only
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop

Abstract

A power supply includes signaling circuitry coupled to output terminals for engaging in bidirectional communications with a load. A controller is capable of conducting the bidirectional communications and selecting among different operating modes for the power supply based on the communications. The modes may include a constant-current mode suitable for applications such as battery charging and power LED lamps, and a constant-voltage mode suitable for a variety of conventional uses such as powering electronic circuitry. The signaling circuitry may include a power switching transistor in series with the load, which is pulsed in a binary fashion to transmit communications to the load. A signal-forming resistor in parallel with the power switching transistor develops a signaling voltage monitored by the controller to receive communications from the load.

Claims

1. A power supply, comprising:

power circuitry configured and operative to provide DC power to a separate load via a pair of conductive terminals, the power circuitry including a power switching transistor in series with the load via one of the terminals, the power switching transistor being closed when the power supply is delivering power to the load;

a signal-forming resistor in parallel with the power switching transistor providing a path for signaling current conducted by the load and generating a corresponding signaling voltage when the power switching transistor is open; and

a controller configured and operative to conduct bidirectional communications with the load via the pair of conductive terminals and to generate load-dependent values of configuration parameters of the power supply in response to the communications, the bidirectional communications including (i) in a transmit mode, supplying a pulsed binary control signal to the power switching transistor to convey an outgoing message to the load as a sequence of distinct signaling voltage values across the pair of conductive terminals, and (ii) in a receive mode, maintaining the power switching transistor open and monitoring the signaling voltage to receive incoming messages from the load as a sequence of distinct voltage values developed by the signal-forming resistor in response to corresponding signaling current values generated by signaling action of the load.

2. The power supply according to claim 1, wherein the load is one of a plurality of types of load for which corresponding distinct operating modes of the power supply are required, and wherein the load-dependent configuration parameters reflect selection among the distinct operating modes of the power supply based on the communications with the load indicating that the load has a given type.

3. The power supply according to claim 2, wherein the distinct operating modes include a constant-voltage mode and a constant-current mode, the constant-voltage mode maintaining a predetermined constant value of the output voltage over a range of values of the output current, the constant-current mode maintaining a predetermined constant value of the output current over a range of values of the output voltage.

4. The power supply according to claim 1, wherein the power circuitry includes primary-side power switching circuitry operable at a variable duty cycle according to a control signal received from the controller via a DC-isolating device, variation of the duty cycle causing corresponding variation of the output voltage and/or output current of the power supply, and wherein the controller is a secondary-side controller having the output voltage DC coupled thereto as a sensing voltage and performs constant-voltage operation in which the controller generates the control signal in a manner maintaining a constant value of the output voltage as represented by the sensing voltage, and wherein the load-dependent values of the configuration parameters generated in response to the communications with the load establish the constant value of the output voltage maintained by the controller.

5. The power supply according to claim 1, wherein the power circuitry includes primary-side power switching circuitry operable at a variable duty cycle according to a control signal received from the controller via a DC-isolating device, variation of the duty cycle causing corresponding variation of the output voltage and/or output current of the power supply, and wherein the controller is a secondary-side controller having a current-sense signal DC coupled thereto, the current-sense signal developed directly from output current of the power supply flowing through the power switching transistor, the controller performing constant-current operation in which the controller generates the control signal in a manner maintaining a constant value of the output current as represented by the current-sense signal, and wherein the load-dependent values of the configuration parameters generated in response to the communications with the load establish the constant value of the output current maintained by the controller.

6. The power supply according to claim 5, wherein the controller is configured and operative when the power switching transistor is closed to sense presence of the load by a sufficiently high value of the current-sense signal, and the power circuitry further includes a secondary switching circuit capable of providing current to a sufficiently light load and generating a higher value of the output voltage than is generated when the first switching transistor is closed, and the controller is configured and operative to turn off the power switching transistor and to turn on the secondary switching circuit to monitor for presence of the load as a sufficiently high value of the output voltage under light loading conditions.

7. The power supply according to claim 1, wherein at a time of connection of the load the power supply has a maximum output voltage, and wherein the signal-forming resistor has a resistance value that limits the outrush current to substantially less than a maximum current that the power supply can provide.

8. The power supply according to claim 1, wherein the controller is further configured and operative to provide protection against a short circuit of the output terminals by (a) when supplying power to the load, monitoring for a value of the output voltage greater than a threshold value corresponding to a maximum permissible output current, and (b) upon detecting that the value of the output voltage exceeds the threshold value, turning off the power switching transistor to prevent flow of output current.

9. A power supply, comprising:

power circuitry configured and operative to provide DC power to a separate load via a pair of conductive terminals, the load being of either a first type requiring a first mode of power delivery or a second type requiring a distinct second mode of power delivery;

communications signaling circuitry coupled to the load via the pair of conductive terminals for bidirectional communications between the power supply and the load, the bidirectional communications including (i) transmitting messages as sequences of binary pulses of signaling voltages detected by the load, and (ii) receiving messages by detecting sequences of binary pulses of signaling current conducted by the load; and

a controller configured and operative to conduct bidirectional communications with the load via the communications signaling circuitry and the pair of conductive terminals and, in response to the bidirectional communications, to (1) select from among a set of two or more power delivery modes for the power supply including at least the first power delivery mode and second power delivery mode, the first power delivery mode being selected when the load has communicated that it is of the first type, and the second power delivery mode being selected when the load has communicated that it is of the second type, and (2) configure the power supply to operate in the selected power delivery mode,

wherein the power circuitry includes a power switching transistor in series with the load via one of the terminals, the power switching transistor being closed when the power supply is delivering power to the load,

and wherein the communications signaling circuitry includes a signal-forming resistor in parallel with the power switching transistor providing a path for signaling current conducted by the load and generating a corresponding signaling voltage when the power switching transistor is open.

10. The power supply according to claim 9, wherein the first and second power delivery modes are a constant-current mode and a constant-voltage mode respectively, the constant-current mode providing a constant value of the output current over a range of values of the output voltage, the constant-voltage mode providing a constant value of the output voltage over a range of values of the output current, and wherein the first type includes a rechargeable battery type requiring the constant-current mode of operation of the power supply.

11. The power supply according to claim 9, wherein the load regularly disconnects from and re-connects to the power supply over a normal operating period, and wherein the controller is further configured and operative according to a sequence of operating states including an idle state, a power-delivery state, a load-determining state, and a communication state, the controller transitioning among operating states based on detecting connection and disconnection of the load as well as on communication with the load in the communication state.

12. The power supply according to claim 9, wherein the controller conducts the bidirectional communications with the load by (i) in a transmit mode, supplying a pulsed binary control signal to the power switching transistor to convey an outgoing message to the load as a sequence of distinct signaling voltage values across the pair of conductive terminals, and (ii) in a receive mode, maintaining the power switching transistor open and monitoring the signaling voltage to receive incoming messages from the load as a sequence of distinct voltage values developed by the signal-forming resistor in response to corresponding signaling current values generated by signaling action of the load.

13. The power supply according to claim 12, wherein the controller is further configured and operative to provide protection against a short circuit of the output terminals by (a) when supplying power to the load, monitoring for a value of the output voltage greater than a threshold value corresponding to a maximum permissible output current, and (b) upon detecting that the value of the output voltage exceeds the threshold value, turning off the power switching transistor to prevent flow of output current.

14. The power supply according to claim 9, wherein the first type for the load is a battery type requiring charging by the power supply according to a multi-step charging cycle, and wherein the first power delivery mode is a first one of a sequence of power delivery modes used in respective steps of the charging cycle, and wherein the communications from load specifies charge parameters for one or more of the sequence of power delivery modes, and wherein the controller is further configured and operative to operate the power supply according to the sequence of power delivery modes to effect the multi-step charging cycle for the load.

15. The power supply according to claim 14, wherein the sequence of power delivery modes includes at least one constant-current power delivery mode followed by at least one constant-voltage power delivery mode.

16. The power supply according to claim 15, wherein during a final constant-voltage power delivery mode the power switch is open.