Field-Programmable, Chopper-Stabilized,

Unipolar Hall-Effect Switches

A3251

11

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

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

www.allegromicro.com

V+

t

0

Address 1

Address 2

Address n (

≤ 63)

Figure 5. Pulse sequence to select addresses

V+

t

0

Encode Lock Bit

Enable

Address

Blow

7 pulses

65 pulses

Figure 6. Pulse sequence to encode lock bit

Lock Bit Programming.

is programmed, and all of the corresponding bitfield-level fuses

are blown, the device-level fuse should be blown. To do so, the

lock bit (bitfield address 65) should be encoded as 1 and have

its fuse blown. This is done in the same manner as permanently

setting the other bitfields, as shown in figure 6.

Address Selection

.

After addressing mode is enabled, the

target bitfield address, is indicated by a series of VPM pulses,

as shown in figure 3. When provisionally trying a value, this

delimit the address and set the corresponding bitfield. When

longer period of time, suffienct to not only set the bitfield to 1,

but also to blow the bitfield fuse.

Enabling Addressing Mode

.

The first segment of code is a

keying sequence used to enable the bitfield addressing mode. As

supply interruptions. This sequence is designed to prevent the

device from being programmed accidentally, such as by noise on

the supply line.

V+

t

0

Minimum 7 pulses

Figure 4. Addressing mode enable pulse sequence