 Longitudinal magnetic recording media with fine grain crystal magnetic layer |
| OF THE EMBODIMENTS The surface of a disk substrate of an aluminum alloy containing 4% by weight of ... |
|
| Oxidation resistant low expansion superalloys |
| The embodiments of the invention in which an exclusive property or privilege is claimed are defined ... |
|
| Electric contact material and a manufacturing method therefor |
| OF THE INVENTION As shown in the sectional view of the FIGURE, an electric contact material ... |
|
| Nickel alloy |
| OF PREFERRED EMBODIMENT The alloy of the present invention comprises 8 to 34 atom% of Al, 2 to 70 ... |
|
| Magneto-optic memory allowing direct overwrite of data |
| In accordance with the present invention, a magneto-optic media is described comprising a first ... |
|
| Thin-film recording medium with soft magnetic layer |
| In one aspect, the invention includes an improvement in a longitudinal magnetic recording medium ... |
|
| Metal thin film magnetic recording medium and manufacturing method thereof |
| As has been described above, the isotropic texture has been formed for decreasing the flying height ... |
|
| Fuel cells employing integrated fluid management platelet technology |
| OF THE BEST MODE The following detailed description illustrates the invention by way of example, ... |
|
| Liftable driver's seat for automobiles |
| It is a primary object of the present invention to provide a driver's seat for automobiles which ... |
|
|
Apparatus and method for digital control of a power converter current
| Details |
Inventors: Oglesbee, John W.;
Assignee: Motorola, Inc. (Schaumburg, IL)
Primary Examiner: Wong; Peter S.
Assistant Examiner: Vu; Bao Q.
Attorney, Agent or Firm: Farley; Felipe J.
A digital control circuit is used for controlling the load current of a power converter circuit (102), and comprises a reference circuit (302), analog comparator circuit (304), control logic circuit (306), and a counter circuit (308). The control logic circuit controls the operation of a power switch (110), and uses counters (314, 316) in conjunction with the analog comparator circuit and reference circuit, to determine when to open and close the power switch. The load current is allowed to vary between a first and second preselected load current levels. |
|
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT While the specification concludes with claims defining the features of the invention that are regarded as novel, it is believed that the invention will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
An appreciation of the invention can be gained by a brief examination of the prior art.
Referring now to FIG.
1, there is shown a schematic diagram 100 of a power converter circuit 102 and control circuit 104 in accordance with the prior art.
Briefly, a source voltage Vs 106 is applied to the power converter circuit, and filtered by an input capacitor 108.
A power switch 110 permits or interrupts electric current, or simply current, from the source.
When the switch is closed (conducting), current flows through the switch, when the switch is open, no current flows through the switch.
The power converter shown has a buck topology, and thus it is required that the source voltage be higher than the output voltage of the power converter.
When the switch is closed, the source voltage level is apparent across a free wheel diode 112, which will be reverse biased.
Load current will flow in the direction of arrow 113 through an inductor 114, a load 116, and a means for providing a current sense signal on line 117, such as a current sense resistor 118.
Typically an output capacitor 120 is used to reduce the output voltage ripple.
After the power switch has been closed one cycle, and current allowed to flow through the inductor, energy is stored in the magnetic field of the inductor.
Upon opening the switch, the voltage across the inductor will reverse polarity, causing the free wheel diode to become forward biased, and conduct the load current.
The current sense signal is fed to control circuit 104 which compares it with a reference voltage level.
The control circuit generates a pulse width modulation (PWM) signal on line 122, which operates the power switch directly, or operates a power switch driver 124, which operates the power switch
|
|
Metal Working 
