Programmable, Chopper-Stabilized,

Two Wire Hall-Effect Switches

A1190, A1192,

and A1193

10

Allegro MicroSystems, Inc.

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

Table 2. Programming Logic Table

Register

Bit Field Address (Code)

Description

Key

Name

Binary Format

[MSB → LSB]

Decimal

Equivalent

Try Mode

000000

0

starts with code 1); Code corresponds to bit field value (code

1 selects bit field value 000001)

111111

63

111111

0

starts with code 1); Code is automatically inverted (code 1

selects bit field value 111110)

000000

63

7

Fuse Check

000111

7

Check integrity of all fuse bits versus low threshold

001111

15

Check integrity of all fuse bits versus high threshold

Blow Mode

000000

0

of 1 bit per sequence)

111111

63

allows selection of 1 bit per sequence)

7

Programming Lock

001000

8

Locks out access to all registers except Fuse Check

Code. The number used to identify the combination of fuses

activated in a bit field, expressed as the decimal equivalent of the

binary value. The LSB of a bit field is denoted as code 1, or bit 0.

Addressing. Setting the bit field code in a selected register by

serially applying a pulse train through the VCC pin of the device.

Each parameter can be measured during the addressing process,

but the internal fuses must be blown before the programming

code (and parameter value) becomes permanent.

permanently set an addressed bit by blowing a fuse internal to the

device. Once a bit (fuse) has been blown, it cannot be reset.

addressed fuse.

Cycling the Supply. Powering-down, and then powering-up the

supply voltage. Cycling the supply is used to clear the program-

ming settings in Try mode.

Programming Procedure

Programming involves selection of a register, a mode, and then

setting values for parameters in the register for evaluation or for

fuse blowing. Figure 10 provides an overview state diagram.

Register Selection Each programmable parameter can be

accessed through a specific register. To select a register, a

pulses is called the key, and uniquely identifies each register. The

pulses for selection of register key 1, is shown in figure 5. No

table 2.

Mode Selection After register selection, the mode is selected,

either Try or Blow mode. Try mode is selected by default. To

select Blow mode, that mode selection key must be sent.