A1232 Datasheet, PDF (13/22 Pages) Allegro MicroSystems – Ultra-Sensitive, Hall-Effect Speed and Direction Sensor with TPOS

A1232
Ultra-Sensitive, Hall-Effect Speed
and Direction Sensor with TPOS
60 × 2
f_OUTPUTA (Hz) = _{60 seconds} × 2 = 4 Hz
1
T_OUTPUTA (s) = _{4 Hz} =250 ms
Key:
• V = Axle Shaft Speed (rpm)
• ω = Number of North and South Pole-Pairs per Axle
Mechanical Revolution
Ring magnet starts rotating
• f = Cycles per Second (Hz)
• T = Time Duration of One Mechanical Period (s)
Immediately after turn-on, the device will be in a special True
Power-On State (TPOS) mode. This mode allows the device to
detect and indicate that one or both of the switches is in the hys-
teresis region, i.e., that the applied field is between B_OP and B_RP.
Magnetic Field at
Hall Element E1
(pin 1 side)
Magnetic Field at
Hall Element E2
(pin 8 side)
Internal
Channel A
Internal
Channel B
D
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e
c
Pin 1 to 8
t
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n
C
h
a
n
g
e
DIRECTION
OUTPUT B
V = V_OUT(OFF)
XOR SPEED
OUTPUT A
V = V_OUT(MID)
t_ON
POS
Second Hall Transition
First Hall Transition
t_ON expires (typ. 50 µs)
Power ON
Figure 3: Typical System Timing
Pin 8 to 1
B_OP(E1)
B_RP(E1)
B_OP(E2)
B_RP(E2)
t_d
V = V_OUT(ON)
Internal
Stage
Output
Stage
time +
Allegro MicroSystems, LLC
13
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com