# US 2018/0323753 A1 · Audio amplifier power supply rail-balancing and anti-pumping system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323753 A1 - Document ID: US20180323753A1 - Status: Published application - Kind: A1 - Application number: 16/025,910 - Filed: 2018-07-02 - Published: 2018-11-08 - Earliest claimed: 2017-02-23 - Assignees: Crestron Electronics, Inc. - Applicants: Crestron Electronics, Inc. - Inventors: Robert Buono - Web page: https://patentgrep.com/patent/US20180323753A1 ## CPC - H03F 1/523: {for amplifiers using field-effect devices (H03F1/526 takes precedence)} - H03F 1/0211: {with control of the supply voltage or current} - H03F 3/185: with field-effect devices (H03F3/187 takes precedence) - H03F 3/217: Class D power amplifiers; Switching amplifiers - H03F 3/2171: {with field-effect devices (H03F3/2173 - H03F3/2178 take precedence)} - H03F 3/45179: {using MOSFET transistors as the active amplifying circuit (H03F3/45278 takes precedence)} - H03F 2200/03: the amplifier being designed for audio applications - H03F 2200/534: Transformer coupled at the input of an amplifier - H03F: AMPLIFIERS ## Abstract A rail balancing circuit is described herein for use with a power supply, the RBC comprising: a circuit adapted to respond to over-voltage and under-voltage conditions in the power supply that comprises a positive rail voltage source and a negative rail voltage source, such that any deviation from a balanced condition between the positive rail voltage source and the negative rail voltage source is substantially instantaneously corrected to bring both the positive and negative rail voltage sources back to the balanced condition. ## Claims ### Claim 1 A rail balancing circuit (RBC) for use with a power supply, the RBC comprising: a circuit adapted to respond to over-voltage and under-voltage conditions in the power supply that comprises a positive rail voltage source and a negative rail voltage source, such that any deviation from a balanced condition between the positive rail voltage source and the negative rail voltage source is substantially instantaneously corrected to bring both the positive and negative rail voltage sources back to the balanced condition. ### Claim 2 (depends on 1) The RBC according to claim 1, wherein the circuit is further adapted to respond, when in a first circuit state condition, to apply a positive rail voltage to a first input of a first transformer and a negative rail voltage to a second input of the first transformer. ### Claim 3 (depends on 2) The RBC according to claim 2, further comprising: a first transistor based circuit arrangement adapted to operate as a first power supply voltage balancer for both the positive and negative rail voltage sources when the positive rail voltage source is in either an over-voltage or under-voltage condition and the negative rail voltage source is in either an under-voltage or over-voltage condition. ### Claim 4 (depends on 3) The RBC according to claim 3, wherein the first circuit state condition comprises: the first transistor based circuit arrangement is in an on condition such that first transistor based circuit arrangement is substantially electrically equivalent to an electrical short, so that current can flow through the first transistor based circuit arrangement in a substantially unimpeded manner with substantially no voltage drop across the first transistor based circuit arrangement. ### Claim 5 (depends on 3) The RBC according to claim 3, wherein the circuit, when in the first circuit condition, and experiencing a positive rail voltage over-voltage situation, allows the positive rail voltage source to supply additional current to the negative rail voltage source through the first transistor based circuit arrangement and the first transformer such that a balanced condition is substantially instantaneously achieved. ### Claim 6 (depends on 3) The RBC according to claim 3, wherein first circuit state condition further comprises: a second transistor based circuit arrangement in an off condition such that each of the transistors is substantially electrically equivalent to an electrical open, so that current cannot flow through either of them. ### Claim 7 (depends on 3) The RBC according to claim 3, wherein the first transistor based circuit arrangement comprises: a first n-channel transistor (first transistor), a drain connection of which is connected to the positive rail voltage source, a source connection of which is connected to the first input of the first transformer, and a gate connection of which is connected to a switching on-off drive signal (switching drive signal), the switching drive signal turning the first transistor periodically on and off; and a second n-channel transistor (second transistor), a source connection of which is connected to the negative rail voltage source, a drain connection of which is connected to the second input of the first transformer, and a gate connection of which is connected to the switching drive signal to be periodically turned on and off substantially simultaneously with the first transistor. ### Claim 8 (depends on 1) The RBC according to claim 1, wherein the circuit is further adapted to respond, when in a second circuit state condition, to apply the positive rail voltage to the second input of the first transformer and the negative rail voltage to the first input of the first transformer. ### Claim 9 (depends on 8) The RBC according to claim 8, further comprising: a second transistor based circuit arrangement adapted to operate as a second power supply voltage balancer for both the positive and negative rail voltage sources when the positive rail voltage source is in either an under-voltage or over-voltage condition and the negative rail voltage source is in either an under-voltage or over-voltage condition. ### Claim 10 (depends on 9) The RBC according to claim 9, wherein the second circuit state condition comprises: the second transistor based circuit arrangement is in an on condition such that the second transistor based circuit arrangement is substantially electrically equivalent to an electrical short, so that current can flow through the second transistor based circuit arrangement in a substantially unimpeded manner with substantially no voltage drop across the second transistor based circuit arrangement. ### Claim 11 (depends on 9) The RBC according to claim 9, wherein the circuit, when in the second circuit condition, and experiencing a negative rail voltage over-voltage situation, allows the negative rail voltage source to supply additional current to the positive rail voltage source through the second transistor based circuit arrangement and the first transformer such that a balanced condition is substantially instantaneously achieved. ### Claim 12 (depends on 9) The RBC according to claim 9, wherein second circuit state condition further comprises: a second transistor based circuit arrangement in an off condition such that the second transistor based circuit arrangement is substantially electrically equivalent to an electrical open, so that current cannot flow through the second transistor based circuit arrangement. ### Claim 13 (depends on 9) The RBC according to claim 9, wherein the second transistor based circuit arrangement comprises: a third n-channel transistor (third transistor), a source connection of which is connected to the negative rail voltage source, a drain connection of which is connected to the first input of the first transformer, and a gate connection of which is connected to a switching on-off drive signal (switching drive signal), the switching drive signal turning the third transistor periodically on and off; and a fourth n-channel transistor (fourth transistor), a drain connection of which is connected to the positive rail voltage source, a source connection of which is connected to the second input of the first transformer, and a gate connection of which is connected to the switching drive signal to be periodically turned on and off substantially simultaneously with the third transistor. ### Claim 14 (depends on 1) The RBC according to claim 1, further comprising: a first pair of transistors adapted to balance the positive and negative rail voltage sources when an over-voltage condition exists on the positive rail voltage source and an under-voltage condition occurs on the negative rail voltage source; a second pair of transistors adapted to balance the positive and negative rail voltage sources when an over-voltage condition exists on the negative rail voltage source and an under-voltage condition occurs on the positive rail voltage source; a timing circuit adapted to alternatively turn on and off the first and second pair of transistors, such that when the first pair of transistors is on, the second pair of transistors is off, and when the second pair of transistors is on, the first pair of transistors is off; and an over-current circuit adapted to turn off both the first pair and second pair of transistors when an over-current condition exists through the first transformer. ### Claim 15 A method for operating a rail balancing circuit (RBC) for use in maintaining a balanced condition in a power supply with equal but opposite polarity outputs, the method comprising: substantially continuously switching a positive rail voltage source and a negative rail voltage source; and when the positive rail voltage source has experienced an over-voltage condition and the negative rail voltage source has experienced an under-voltage condition, turning on a first pair of transistors adapted to balance the positive and negative rail voltage sources when the over-voltage condition exists on the positive rail voltage source and the under-voltage condition occurs on the negative rail voltage source, and when the negative rail voltage source has experienced an over-voltage condition and the positive rail voltage source has experienced an under-voltage condition, turning on a second pair of transistors adapted to balance the positive and negative rail voltage sources when the over-voltage condition exists on the negative rail voltage source and the under-voltage condition occurs on the positive rail voltage source. ### Claim 16 (depends on 15) The method according to claim 15, wherein the step of turning on a first pair of transistors comprises: applying a positive rail voltage to a first input of a first transformer and a negative rail voltage to a second input of the first transformer. ### Claim 17 (depends on 15) The method according to claim 15, wherein the step of turning on a first pair of transistors comprises: operating the first pair of transistors as a first power supply voltage balancer for both the positive and negative rail voltage sources when the positive rail voltage source is in the over-voltage condition and the negative rail voltage source is in the under-voltage condition. ### Claim 18 (depends on 17) The method according to claim 17, wherein the first pair of transistors are in an on condition such that each of the transistors is substantially electrically equivalent to an electrical short, so that current can flow through each of them in a substantially unimpeded manner with substantially no voltage drop across the transistor. ### Claim 19 (depends on 18) The method according to claim 18, further comprising: the positive rail voltage source supplying additional current to the negative rail voltage source through the first and second transistors and the first transformer such that a balanced condition is substantially instantaneously achieved. ### Claim 20 (depends on 17) The method according to claim 17, further comprising: a second pair of transistors being in an off condition such that each of the transistors is substantially electrically equivalent to an electrical open, so that current cannot flow through either of them. ### Claim 21 (depends on 15) The method according to claim 15, wherein the step of turning on the second pair of transistors comprises: applying the positive rail voltage to the second input of the first transformer and the negative rail voltage to the first input of the first transformer. ### Claim 22 (depends on 15) The method according to claim 15, wherein the step of turning on the second pair of transistors comprises: operating the second pair of transistors as a second power supply voltage balancer for both the positive and negative rail voltage sources when the positive rail voltage source is in the under-voltage condition and the negative rail voltage source is in the over-voltage condition. ### Claim 23 (depends on 22) The method according to claim 22, wherein the second pair of transistors are in an on condition such that each of the transistors is substantially electrically equivalent to an electrical short, so that current can flow through each of them in a substantially unimpeded manner with substantially no voltage drop across the transistor. ### Claim 24 (depends on 23) The method according to claim 23, further comprising: the negative rail voltage source supplying additional current to the positive rail voltage source through the third and fourth transistors and the first transformer such that a balanced condition is substantially instantaneously achieved. ### Claim 25 (depends on 22) The method according to claim 22, further comprising: a first pair of transistors being in an off condition such that each of the transistors is substantially electrically equivalent to an electrical open, so that current cannot flow through either of them.