A3250 ALLEGRO [Allegro MicroSystems], A3250 Datasheet - Page 10

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

The pulse sequences consist of the following groups of pulses:
1. An enable sequence.
2. A bitfield address sequence.
3. When permanently setting the bitfield, a long V
4. When permanently setting the bitfield, the level of V
Bitfields that are not set are evaluated as zeros. The bitfield-level
A3250-DS
ing pulse. (Note: Blown bit fuses cannot be reset.) When
provisionally trying a value, a short V
be allowed to drop to zero between each pulse sequence, in
order to clear all registers. However, when provisionally set-
ting bitfields, V
sequences, in order to maintain the prior bitfield settings while
preparing to set additional bitfields.
Field-Programmable, Chopper-Stabilized, Unipolar Hall-Effect Switches
CC
must be maintained at V
V
V
V
V
V
V
PM
PH
PL
PM
PH
PL
0
0
V+
V+
Figure 2. Pulse sequence to provisionally try calibration value 5 (101 binary, or bitfield
address 3 and bitfield address 1).
Figure 3. Pulse sequence to permanently encode calibration value 5 (101 binary, or
bitfield address 3 and bitfield address 1).
7 pulses
7 pulses
Enable
Enable
PH
Try 00100
pulse.
PL
Encode 00100
between pulse
A3250 and A3251
2
PH
(4
10
fuse-blow-
)
Address
Address
CC
2
(4
must
10
)
Blow
Monitoring
Optional
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.
Two pulse sequences for provisionally trying the calibration
value 5 are shown in figure 2. Because the bitfields must be set
individually, 5
set to 1 (000100
which is 1
Two pulse sequences for permanently setting the calibration
value 5 are shown in figure 3. The final V
used as a short delimiter when trying values, is maintained for a
longer period, enough to blow the corresponding bitfield-level
fuse.
10
Try 00001
7 pulses
7 pulses
). Bit 2 is ignored, and so remains 0.
Enable
Enable
10
Encode 00001
2
must be programmed as binary 101. Bit 3 is
, which is 4
2
(1
10
)
2
(1
10
Address
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Monitoring
10
)
Address
Blow
Optional
), then bit 1 is set to 1 (000001
t
Clear
t
PH
pulse, which was
2
10
,