High Precision, Output Pin Programmable
Linear Hall Effect Sensor ICs
A1373 and
A1374
21
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
This example demonstrates the programming of the devices by
setting the register for Sensitivity Temperature Coefficient to
00110.
1. Power-on the system. This will reset the unprogrammed bits
in all registers to 0. The device enters the Initial state.
2. Send one V
PH
pulse to enter the Mode Selection state.
3. Send one V
PL
pulse to select Try Value mode.
4. Send one V
PH
pulse to enter the Register Selection state.
5. Send four V
PL
pulses to select the TC register.
6. Send one V
PH
pulse to enter Bitfield Selection state (Write
mode). The TC register is reset to 00000 (assuming all of
those bitfields have intact fuses).
7. Send five V
PL
pulses to set bitfields 0 and 2 (00101).
Now we can measure the device output to see if this is the
desired value. We may find that the value we programmed is not
correct. So we will proceed to change it, as follows:
8. Send one V
PL
pulse to increase the code to 6 (setting bitfields
1 and 2: 00110).
We measure the device and find that this is the correct TC we
require. We are finished with trying values, and now want to set
the value permanently. In the following steps, remember that
blowing fuses is done one bit at a time.
9. Send one V
PH
pulse to exit Bitfield Selection mode. (The
device returns to the Mode Selection state.)
10. RESET the device by powering it off and on.
11. Send one V
PH
pulse to enter the Mode Selection state.
12. Send two V
PL
pulses to select Blow Fuse mode.
Programming Example
13. Send one V
PH
pulse to enter the Register Selection state.
14. Send four V
PL
pulses to select the TC register.
15. Send one V
PH
pulse to enter Bitfield Selection state (Write
Mode). The TC register is reset to 00000.
16. Send four V
PL
pulses to set bit 2 (00100, decimal 4).
17. Send one V
PH
pulse to exit Bitfield Selection state. The
bitfield fuse is blown, and the device returns to the Mode
Selection state.
One of the two bitfields is programmed. Now we program the
other bitfield.
18. Repeat steps 10 to 15 to select the TC register again. This
time, however, the register resets to 00100, because bit 2 has
been permanently set.
19. Send two V
PL
pulses to set bit 1 (00010, decimal 2).
20. Send one V
PH
pulse to exit Bitfield Selection state. The
bitfield fuse is blown, and the device returns to the Mode
Selection state.
After repeating the above steps to program all parameters, we
can lock the device:
21. RESET the device by powering it off and on.
22. Send one V
PH
pulse to enter the Mode Selection state.
23. Send three V
PL
pulses to select Lock Device mode.
24. Send one V
PH
pulse to enter the Bitfield Selection state. (We
do not need to select a register for locking the device).
25. Send one V
PL
pulse to set the Lock bit to 1.
26. Send one V
PH
pulse to exit Bitfield Selection state. The
bitfield fuse is blown, and the device returns to the Mode
Selection state.
27. Programming the device is complete. Optionally, test the
results, or power-off the device.
