ACS709 Allegro MicroSystems, Inc., ACS709 Datasheet - Page 13

• Manufacturer Part Number: ACS709
• Description: High Bandwidth, Fast Fault Response Current Sensor Ic In Thermally Enhanced Package
• Manufacturer: Allegro MicroSystems, Inc.

ACS709
6.
7. When the FAULT_EN pin is brought low, if the fault condi-
8. At this point there is a fault condition, and the part is enabled
Chopper Stabilization Technique
Chopper Stabilization is an innovative circuit technique that is
used to minimize the offset voltage of a Hall element and an asso-
ciated on-chip amplifier. Allegro patented a Chopper Stabiliza-
tion technique that nearly eliminates Hall IC output drift induced
by temperature or package stress effects. This offset reduction
This curve shows V
through the internal PMOS pull-up. The slope is determined
by C
tion still exists, the latched ¯ F ¯ ¯ A ¯ ¯ U ¯ ¯ L ¯ ¯ T ¯ pin will stay low until
the fault condition is removed, then it will start resetting.
before the ¯ F ¯ ¯ A ¯ ¯ U ¯ ¯ L ¯ ¯ T ¯ pin can charge to V
user-set delay, so the fault is latched earlier. The new delay
time can be calculated by equation 1, after substituting the
voltage seen on the ¯ F ¯ ¯ A ¯ ¯ U ¯ ¯ L ¯ ¯ T ¯ pin for V
OC
.
CC
charging external capacitor C
Hall Element
High Bandwidth, Fast Fault Response Current Sensor IC
CC
CC
.
Regulator
. This shortens the
Concept of Chopper Stabilization Technique
OC
technique is based on a signal modulation-demodulation process.
Modulation is used to separate the undesired dc offset signal from
the magnetically induced signal in the frequency domain. Then,
using a low-pass filter, the modulated DC offset is suppressed
while the magnetically induced signal passes through the filter.
As a result of this chopper stabilization approach, the output
voltage from the Hall IC is desensitized to the effects of tempera-
ture and mechanical stress. This technique produces devices that
have an extremely stable Electrical Offset Voltage, are immune to
thermal stress, and have precise recoverability after temperature
cycling.
This technique is made possible through the use of a BiCMOS
process that allows the use of low-offset and low-noise amplifiers
in combination with high-density logic integration and sample
and hold circuits.
Clock/Logic
Amp
In Thermally Enhanced Package
Low-Pass
Filter
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
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