ATS645 Allegro MicroSystems, Inc., ATS645 Datasheet - Page 11

• Manufacturer Part Number: ATS645
• Description: Ats645lsh True Zero Speed Miniature Gear-tooth Sensors
• Manufacturer: Allegro MicroSystems, Inc.

ATS645LSH
SENSOR OPERATION
Each operating mode is described in detail below.
Power-On
When power (V
period of time is required to power the various portions of the
IC. During this period, the ATS645 is guaranteed to power-on in
the high current state, I
Initial Offset Adjust
The sensor intially cancels the effects of chip, magnet, and
installation offsets. Once offsets have been cancelled, the digital
tracking DAC is ready to track the signal and provide output
switching. The period of time required for both Power-On and
Initial Offset Adjust is defi ned as the Power-On Time.
Calibration Mode
The calibration mode allows the sensor to automatically select
the proper signal gain and continue to adjust for offsets. The
AGC is active, and selects the optimal signal gain based on the
amplitude of the V
the AGC DAC, the Offset DAC is also adjusted to ensure the
CC
PROC
> V
CCMIN
CC(High)
signal. Following each adjustment to
) is applied to the device, a short
.
True Zero Speed Miniature Differential Peak-
internal analog signal is properly centered.
During this mode, the tracking DAC is active and output switch-
ing occurs, but the duty cycle is not guaranteed to be within
specifi cation.
Diagnostics
The regulated current output is confi gured for two wire appli-
cations, requiring one less wire for operation than do switches
with the more traditional open-collector output. Additionally,
the system designer inherently gains diagnostics because there
is always output current flowing, which should be in either of
two narrow ranges. Any current level not within these ranges
indicates a fault condition.
Running Mode
After the initial calibration period, C
gain is established, the device moves to Running mode. During
Running mode, the sensor tracks the input signal and gives an
output edge for every peak of the signal. AOA remains active to
compensate for any offset drift over time.
Detecting Gear Tooth Sensor
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
I
, during which a signal
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