US5748461A
Expired / Lapsed
US
⏱️ 0.0 years remaining
SMPS with low load switching frequency stabilization
Assignee: Infineon Technologies AG
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Filing: 1996-06-19
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Granted: 1998-05-05
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Expires: 2016-06-19
Abstract
Abstract A switch-mode power supply has a control device with an input for a control voltage which is coupled to a secondary voltage and an output for controlling a transistor that is connected in series with a primary winding of a switch-mode power supply transformer. The control device additionally includes a device for inhibiting the switching transistor from switching on again when a control error that is formed in the control device is less than a reference value. The control signal input and the output of the control device are coupled through a coupling element having a low-pass filter characteristic. A switching-on pulse for the switching transistor is consequently superimposed on the control voltage, with a time delay. If the load to be supplied is small (standby mode), the switching of the switching transistor is inhibited until the switching-on pulse which is coupled to the control voltage has decayed. A stable switching frequency slightly above the audibility limit can be set for the standby mode. The power loss is accordingly low.
Inventors
- 👤 Peter Preller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:33
CPC Classifications
H; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/33507; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155; H02M1/00; H02M1/0003; H02M1/0032; Y; Y02; Y02B; Y02B70/00; Y02B70/10
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
168 words
A switch-mode power supply, comprising: a transformer having a primary winding and a secondary winding for connection of a load; a switching transistor being connected in series with said primary winding of said transformer for applying a rectified voltage in a pulsed manner to said primary winding of said transformer; a control device having: (a) an output connected to said switching transistor for controlling said switching transistor, (b) a signal input being connected to said transformer and being controlled by a voltage induced in said transformer, (c) a control signal input being controlled by a voltage coupled to a secondary voltage, and (d) a device connected between said control signal input and said output of said control device for inhibiting said switching transistor from switching on when a control error derived from the control signal has a magnitude being less than a threshold value; and a coupling element coupling said output and said control signal input of said control device, said coupling element having a low-pass filter characteristic.
Claim 2
Dependent Claim
168 words
A switch-mode power supply, comprising: a transformer having a primary winding and a secondary winding for connection of a load; a switching transistor being connected in series with said primary winding of said transformer for applying a rectified voltage in a pulsed manner to said primary winding of said transformer; a control device having: (a) an output connected to said switching transistor for controlling said switching transistor, (b) a signal input being connected to said transformer and being controlled by a voltage induced in said transformer, (c) a control signal input being controlled by a voltage coupled to a secondary voltage, and (d) a device connected between said control signal input and said output of said control device for inhibiting said switching transistor from switching on when a control error derived from the control signal has a magnitude being less than a threshold value; and a coupling element coupling said output and said control signal input of said control device, said coupling element having a low-pass filter characteristic.
Claim 3
Dependent Claim
56 words
The switch-mode power supply according to claim 1, wherein said coupling element has an input side, an output side, an input connected to said output of said control device, an output connected to said control signal input, a pulse storage device on said input side and an element with an RC characteristic on said output side.
Claim 4
Dependent Claim
37 words
Switch-mode power supply according to claim 2, wherein said pulse storage device includes a capacitor and a resistor connected in a parallel circuit, and a diode connecting said parallel circuit to said output of said control device.
Claim 5
Dependent Claim
34 words
The switch-mode power supply according to claim 3, wherein said coupling element includes a coupling capacitor for a DC voltage output connecting said pulse storage device to said RC element on said output side.
Claim 6
Dependent Claim
24 words
The switch-mode power supply according to claim 2, including an amplifier connected between said pulse storage device and said element having an RC characteristic.
Claim 7
Dependent Claim
29 words
The switch-mode power supply according to claim 1, including a capacitive coupling of said signal input connected to said transformer and said control signal input of said control device.
Claim 8
Dependent Claim
33 words
The switch-mode power supply according to claim 1, wherein said transformer has another secondary winding, and including an optocoupler connecting said control signal input of said control device to said other secondary winding.
References Cited (Backward Citations)
DE3312209A1
Cited
US4593347A
Cited
US4928220A
Cited
EP0380033A2
Cited
US4984145A
Cited
US4985818A
Cited
US5448469A
Cited
US5317499A
Cited
US5170333A
Cited
US5497311A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-05-04 | 2001-11-03 | 2002-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-05-04 | 2005-11-03 | 2006-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-05-04 | 2009-11-03 | 2010-05-05 | $7700.00 | Window Closed / Lapsed |