Ultrasensitive Two-Wire Field-Programmable

Chopper-Stabilized Unipolar Hall Effect Switches

A1186

8

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Application Information

For additional general application information, visit the Allegro

Web site at www. allegromicro.com.

GND

A118x

VCC

V+

0.01 uF

A

B

B

GND

ECU

Package UA Only

A

B Maximum separation 5 mm

R

SENSE

C

BYP

Figure 3. Typical application circuit

Typical Application and Programming Circuit

The A118x family of devices MUST be protected by an exter-

both external noise and the noise generated by the chopper-sta-

bilization function. As shown in figure 3, a 0.01 μF capacitor

is typical. (For programming the device, a 0.1 μF capacitor is

recommended for proper fuse blowing.)

it to the A118x pins are no greater than 5 mm in length. (For

programming the device, the capacitor may be further away from

the device, including mounting on the board used for program-

ming the device.)

high-frequency interferences conducted along the supply lines

load ECU (electronic control unit) must have sufficient protec-

code and lock-bit programming, should be done with direct

connections to VCC and GND, with the use of a 0.1uF bypass

capacitor. Programming across the series resistor or sense resis-

tor may not allow enough energy to properly blow the fuses

in the device, as required for proper programming. The result

would be incorrect switchpoints.