A3250 ALLEGRO [Allegro MicroSystems], A3250 Datasheet - Page 11

• Manufacturer Part Number: A3250
• Description: Field-Programmable, Chopper-Stabilized Unipolar Hall-Effect Switches
• Manufacturer: ALLEGRO [Allegro MicroSystems]

Enabling Addressing Mode.
keying sequence used to enable the bitfield addressing mode. As
shown in figure 4, this segment consists of one short V
seven or more V
interruptions. This sequence is designed to prevent the device
from being programmed accidentally, such as by noise on the
supply line.
Address Selection.
target bitfield address, is indicated by a series of VPM pulses,
as shown in figure 3. When provisionally trying a value, this
sequence is followed by a short V
delimit the address and set the corresponding bitfield. When
permanently setting a bitfield, the V
longer period of time, suffienct to not only set the bitfield to 1,
but also to blow the bitfield fuse.
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.
A3250-DS
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
PM
pulses, and one V
After addressing mode is enabled, the
After the desired B
The first segment of code is a
PH
PH
pulse, which serves to
PH
pulse is continued for a
pulse, with no supply
OP
calibration value
A3250 and A3251
PH
pulse,
V
V
V
V
V
V
V
V
V
PH
PM
PH
PM
PH
PM
PL
PL
PL
0
0
0
V+
V+
V+
Figure 6. Pulse sequence to encode lock bit
Figure 4. Addressing mode enable pulse sequence
Figure 5. Pulse sequence to select addresses
Falling edge of final B
7 pulses
Enable
Address 1
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Encode Lock Bit
Minimum 7 pulses
Address 2
OP
address digit
65 pulses
Address
Address n ( ≤ 63)
t
Blow
t
t
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