Position Sensor IC with Speed and Direction Output

A1696PKH

7

Allegro MicroSystems

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

Figure 4: Definition of TTARGET

Figure 5: Establishment of Thresholds,

Using Internal Hysteresis (Speed Channel)

Figure 6: Differential Signature Amplification

and Sequential Signal Variation

Detected

Channel

Switching

On

On

ff

O

ff

O

0

100

0

100

B

Switch Points

ST

BST

VPROCST

+VPROC(hys)

–VPROC(hys)

Ring Magnet

Target

Sequential Region

Signature

Region

BSEQ(min)

BSEQ(max)

BSEQ(sig)

N

NN

N

N

S

SS

S

SS

BSEQ(n)

BSEQ(n+1)

Sequential Region

VPROC

TVPROC

TTARGET

Ferromagnetic

Target

S

N

S

N

Ring Magnet

Target

VPROC = the processed analog signal of the sinusoidal magnetic input (per channel)

TTARGET = period between successive sensed target magnetic edges of the same

polarity (for a ring magnet target, both north-to-south or both

south-to-north edges; for a ferromagnetic target, both rising or both falling

mechanical edges )

Tooth

Valley

Figure 3: Definition of Output Fall Time and Delay Time

td

tr

Time

Time

Magnetic Signal

Switch Point

VOUT (high)

90% VOUT

10% VOUT

VOUT (low)