Ultrasensitive Two-Wire Field-Programmable

Chopper-Stabilized Unipolar Hall Effect Switches

A1186

11

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

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

www.allegromicro.com

V+

t

0

Enable

Address

Address

Blow

Blow

Enable

Figure 6. Pulse sequence to permanently encode calibration value 5 (101 binary, or

bitfield address 3 and bitfield address 1).

V+

t

0

Enable

Address

Clear

Optional

Monitoring

The pulse sequences consist of the following groups of pulses:

1. An enable sequence.

2. A bitfield address sequence.

ing pulse. (Note: Blown bit fuses cannot be reset.)

be allowed to drop to zero between each pulse sequence, in

order to clear all registers. However, when provisionally set-

sequences, in order to maintain the prior bitfield settings while

preparing to set additional bitfields.

Bitfields that are not set are evaluated as zeros. The bitfield-level

fuses for 0 value bitfields are never blown. This prevents inad-

vertently setting the bitfield to 1. Instead, blowing the device-

level fuse protects the 0 bitfields from being accidentally set in

the future.

When provisionally trying the calibration value, one pulse

sequence is used, using decimal values. The sequence for setting

When permanently setting values, the bitfields must be set indi-

sequences for permanently setting the calibration value 5 are

period, enough to blow the corresponding bitfield-level fuse.

Figure 5. Pulse sequence to provisionally try calibration value 5.