Browse Prior Art Database

Self-Limiting Analog Comparators

IP.com Disclosure Number: IPCOM000043472D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Frankeny, RF: AUTHOR [+2]

Abstract

In discrete circuit implementation, the voltage across a motor current sense resistor (for a given phase winding) is compared against a fixed reference voltage (chop mode) or against the amplified feedback transducer signal for that phase (current track mode). Mode selection is achieved with logic control signals. Additionally, voltage offsets and current limiting functions are required to control properly the chopper and phase drivers for each phase. The present self-limiting analog comparator, for printers, allows a complex function to be implemented in integrated circuit form with an inherent improvement in function accuracy and component failure rate by integrating all sensing and stepper driver controls into a single chip.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 63% of the total text.

Page 1 of 2

Self-Limiting Analog Comparators

In discrete circuit implementation, the voltage across a motor current sense resistor (for a given phase winding) is compared against a fixed reference voltage (chop mode) or against the amplified feedback transducer signal for that phase (current track mode). Mode selection is achieved with logic control signals. Additionally, voltage offsets and current limiting functions are required to control properly the chopper and phase drivers for each phase. The present self-limiting analog comparator, for printers, allows a complex function to be implemented in integrated circuit form with an inherent improvement in function accuracy and component failure rate by integrating all sensing and stepper driver controls into a single chip. This circuit compares three input signals, two at a time, removes the requirement for transducer voltage amplification prior to the comparator stage, and has a self-limiting function during the current track mode. VSENSE = Sense resistor voltage proportional to the motor phase current.

VREF = Voltage reference used for normal mode chop

current control. It also represents the maximum

allowable motor phase current level.

VTRAN = Feedback transducer signal proportional to

the position and velocity of the motor. It is

typically a fraction of the corresponding

motor phase current.

SDTN = Detent control logic signal. SDTN = 1

represents normal chop mode; SDTN = 0

represents current track mode.

VRS, VRST = Compara...