The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 19, 2004
Filed:
Oct. 04, 2001
Applicant:
Inventors:
Assignee:
Abbott Laboratories, Abbott Park, IL (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H02P 8/18 ; H02P 8/12 ; H02P 8/22 ;
U.S. Cl.
CPC ...
H02P 8/18 ; H02P 8/12 ; H02P 8/22 ;
Abstract
A stepper motor control circuit reduces ripple current by applying both fast and slow current decays to a motor phase when current is being reduced in the motor phase while following a falling current waveform. The control circuit uses an initial fast decay to reduce a winding current and then switches to a slow decay until a winding current is sampled again. The control circuitry samples a winding current and compares the sampled current to a reference current to determine if current is to be applied or reduced using fast and/or slow decay methods. Different phase current sample circuits allow either constant current sensing or selective current sensing.