US4806842A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Soft start for five pin switching regulators
Assignee: National Semiconductor Corp
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Filing: 1988-05-09
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Granted: 1989-02-21
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Expires: 2008-05-09
Abstract
Abstract A soft start circuit for a switching regulator is disclosed. The circuit does not require any off-chip parts and, therefore, a five-pin package can be employed. The operation of a soft start circuit in conjunction with a switching regulator operating in the voltage boost mode is set forth in detail.
Inventors
- 👤 Harry J. Bittner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:33
CPC Classifications
H; H02; H02M; H02M1/00; H02M1/36; H02M3/00; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155; H02M3/156; Y; Y10; Y10S; Y10S323/00; Y10S323/901
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
195 words
A switching regulator including a switch, means for driving said switch in a controlled duty cycle fashion in response to the output of a duty cycle comparator, an error amplifier driving said duty cycle comparator, a compensation capacitor and means for developing a reference potential against which said error amplifier operates, a soft start circuit comprising: R-S flip flop means having set, reset and output terminals; means for resetting said R-S flip flop when said compensation capacitor is discharged; a soft start comparator having an output coupled to said set terminal of said flip flop, an inverting input coupled to said reference potential, a noninverting input coupled to said error amplifier input whereby said R-S flip flop is set when said error amplifier input exceeds said reference potential; switch means coupled in series with the output of said error amplifier and responsive to said output to said R-S flip flop for disconnecting said error amplifier when said R-S flip flop is reset; and a current source coupled to charge said compensation capacitor at a controlled rate controlled by said output of said R-S flip flop to be one when said R-S flip flop is reset.
Claim 2
Dependent Claim
195 words
A switching regulator including a switch, means for driving said switch in a controlled duty cycle fashion in response to the output of a duty cycle comparator, an error amplifier driving said duty cycle comparator, a compensation capacitor and means for developing a reference potential against which said error amplifier operates, a soft start circuit comprising: R-S flip flop means having set, reset and output terminals; means for resetting said R-S flip flop when said compensation capacitor is discharged; a soft start comparator having an output coupled to said set terminal of said flip flop, an inverting input coupled to said reference potential, a noninverting input coupled to said error amplifier input whereby said R-S flip flop is set when said error amplifier input exceeds said reference potential; switch means coupled in series with the output of said error amplifier and responsive to said output to said R-S flip flop for disconnecting said error amplifier when said R-S flip flop is reset; and a current source coupled to charge said compensation capacitor at a controlled rate controlled by said output of said R-S flip flop to be one when said R-S flip flop is reset.
Claim 3
Dependent Claim
47 words
The switching regulator soft start circuit of claim 1 further including a shutdown circuit responsive to either excessive integrated circuit chip temperature or low power supply output voltage to reset said R-S flip flop, said shutdown circuit operating to close a switch connected across said compensation capacitor.
Claim 4
Dependent Claim
44 words
The switching regulator soft start circuit of claim 2 further including a power up comparator responsive to the charge on said compensation capacitor and operatively coupled to reset said R-S flip flop when said charge falls below a predetermined fraction of said reference voltage.
Claim 5
Dependent Claim
36 words
The switching regulator soft start circuit of claim 3 wherein said power up comparator output and said shutdown circuit are coupled to said reset terminal of said R-S flip flop by means of an OR gate.
Claim 6
Dependent Claim
48 words
The switching regulator soft start circuit of claim 1 wherein said switching regulator is in the form of an integrated circuit having a power input pad, a ground pad, a compensation capacitor pad, a switch terminal pad, and a feedback pad mounted in a five pin power package.
References Cited (Backward Citations)
US3959714A
Cited
US4598351A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-21 | 2000-08-22 | 2001-02-21 | $7700.00 | Window Closed / Lapsed |