The following operators can be used to better focus your queries.
( ) , AND, OR, NOT, W/#
? single char wildcard, not at start
* multi char wildcard, not at start
(Cat? OR feline) AND NOT dog?
Cat? W/5 behavior
(Cat? OR feline) AND traits
Cat AND charact*
This guide provides a more detailed description of the syntax that is supported along with examples.
This search box also supports the look-up of an IP.com Digital Signature (also referred to as Fingerprint); enter the 72-, 48-, or 32-character code to retrieve details of the associated file or submission.
Concept Search - What can I type?
For a concept search, you can enter phrases, sentences, or full paragraphs in English. For example, copy and paste the abstract of a patent application or paragraphs from an article.
Concept search eliminates the need for complex Boolean syntax to inform retrieval. Our Semantic Gist engine uses advanced cognitive semantic analysis to extract the meaning of data. This reduces the chances of missing valuable information, that may result from traditional keyword searching.
This article describes a circuit which enables accurate current sensing in a motor power driver that is configured in an H-bridge arrangement operating between positive and negative power supplies.
English (United States)
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
89% of the total text.
Page 1 of 2
Reduced Current Sense Offset Errors in a Motor Power Driver
This article describes a circuit which enables accurate current sensing in a
motor power driver that is configured in an H-bridge arrangement operating
between positive and negative power supplies.
The figure illustrates a typical H-bridge topology with the disclosed circuit
contained in the dashed box and labeled "Current Sense Circuit". The
configuration shown is for sensing current magnitude only. Magnitude and
polarity can be obtained by using two current sense resistors and two of the
current sense circuits feeding a differential amplifier.
When dual power supplies are used, current sensing is accomplished by
measuring the voltage across a small resistor, RS, that is inserted in series with
the load; one end of the resistor is connected to the negative power supply. The
current sense circuit operates at the negative supply and performs a level shift so
that the rest of the power driver can operate around ground. Amplifier AI must be
of the type that can operate at the negative rail, such as the LM324 (National
Semiconductor Corp.). The current that flows through RS is scaled via R1 and
mirrored into the collector of transistor Q5. The level shift is accomplished by the
collector of Q5 and resistor R2 reference, ground for the case shown in the
figure. The voltage VS at summer SI due to current sensing is: VS = -(R2/R1) x
IM x RS + VOS x (R2/R1)
VOS is the inherent input offset voltage of amplifier A...