A1185_06 Datasheet, PDF (11/14 Pages) Allegro MicroSystems – Ultrasensitive Two-Wire Field-Programmable Chopper-Stabilized Unipolar Hall-Effect Switches

A1185 and
A1186
Ultrasensitive Two-Wire Field-Programmable
Chopper-Stabilized Unipolar Hall Effect Switches
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_PH fuse-blow-
ing pulse. (Note: Blown bit fuses cannot be reset.)
4. When permanently setting the bitfield, the level of V_CC must
be allowed to drop to zero between each pulse sequence, in
order to clear all registers. However, when provisionally set-
ting bitfields, V_CC must be maintained at V_PL between pulse
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
the value 5₁₀ is shown in figure 5.
When permanently setting values, the bitfields must be set indi-
vidually, and 5₁₀ must be programmed as binary 101. Bit 3 is
set to 1 (000100₂, which is 4₁₀), then bit 1 is set to 1 (000001₂,
which is 1₁₀). Bit 2 is ignored, and so remains 0.Two pulse
sequences for permanently setting the calibration value 5 are
shown in figure 6. The final V_PH pulse is maintained for a longer
period, enough to blow the corresponding bitfield-level fuse.
V+
VPH
V_PM
VPL
0
Enable
Address
Try 510
Optional
Monitoring
Clear
t
Figure 5. Pulse sequence to provisionally try calibration value 5.
V+
VPH
V_PM
VPL
Address
0
Enable
Address
Blow
Enable
Blow
Encode 001002 (410)
Encode 00001₂ (1₁₀)
t
Figure 6. Pulse sequence to permanently encode calibration value 5 (101 binary, or
bitfield address 3 and bitfield address 1).
Allegro MicroSystems, Inc.
11
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com