AD22151

–3–

REV. 0

PIN CONFIGURATION

TOP VIEW

(Not to Scale)

8

7

6

5

1

2

3

4

AREA OF SENSITIVITY*

TC1

TC2

TC3

GND

REF

GAIN

OUTPUT

AD22151

(Not to Scale)

8

7

6

5

1

2

3

4

* SHADED AREA REPRESENTS

MAGNETIC FIELD AREA OF

SENSITIVITY (20MILS

20MILS)

• POSITIVE B FIELD INTO TOP OF

PACKAGE RESULTS IN A POSITIVE

VOLTAGE RESPONSE

PIN FUNCTION DESCRIPTIONS

Pin No.

Description

Connection

1

Temperature Compensation 1

Output

2

Temperature Compensation 2

Output

3

Temperature Compensation 3

Input/Output

4

Ground

5

Output

Output

6

Gain

Input

7

Reference

Output

8

Positive Power Supply

CIRCUIT OPERATION

The AD22151 consists of epi Hall plate structures located at

the center of the die. The Hall plates are orthogonally sampled

by commutation switches via a differential amplifier. The two

amplified Hall signals are synchronously demodulated to pro-

vide a resultant offset cancellation (see Figure 3). The demodu-

lated signal passes through a noninverting amplifier to provide

final gain and drive capability. The frequency at which the

output signal is refreshed is 50 kHz.

TEMPERATURE – C

0.005

–0.004

140

–40

120

100

80

60

40

20

0

–20

0.004

0

–0.001

–0.002

–0.003

0.003

0.001

0.002

Figure 3. Relative Quiescent Offset vs. Temperature

TEMPERATURE DEPENDENCIES

AD22151 is the result of fundamental physical properties asso-

ciated with silicon bulk Hall plate structures. Low doped Hall

plates operated in current bias mode exhibit a temperature

relationship determined by the action of scattering mechanisms

and doping concentration.

The relative value of sensitivity to magnetic field can be altered

by the application of mechanical force upon silicon. The mecha-

nism is principally the redistribution of electrons throughout the

“valleys” of the silicon crystal. Mechanical force on the sensor

is attributable to package-induced stress. The package material

acts to distort the encapsulated silicon altering the Hall cell gain

by

±2% and G

This is the observable alteration of gain with respect to tempera-

ture with Pin 3 (TC3) held at a constant 2.5 V (uncompensated).

If a permanent magnet source used in conjunction with the

ing into the total temperature compensation of the sensor

assembly.

Figures 5 and 6 represent typical overall temperature/gain per-

Figure 5 is the total drift in volts over a –40

°C to +150°C tem-

perature range with respect to applied field. Figure 6 represents

typical percentage gain variation from +25

°C. Figures 7 and 8

TEMPERATURE – C

14

–4

–40

10

60

110

160

12

4

2

0

–2

10

6

8

–6

Figure 4. Uncompensated Gain Variation (from +25

°C) vs.

Temperature