A1128 Datasheet, PDF (15/20 Pages) Allegro MicroSystems – Highly Programmable Hall-Effect Switch

A1128
Highly Programmable Hall-Effect Switch
to the MSB. Read mode is available only before the LOCK bit
has been set.
After the final V_PH key pulse, and after each V_PM address pulse,
if V_OUT is low, the corresponding fuse can be considered blown
(the status of the Output Polarity bit, POL, does not affect Read
mode output values, allowing POL to be tested also). If the output
state is high, the fuse can be considered un-blown. During Read
mode VOUT must be pulled high using a pull-up resistor (see
R_LOAD in the Typical Application Circuit diagram).
V_PH
V_PM
V_PL
GND
Register (and Mode)
Selection Key
Bit Field
Address Codes
1234
1 2 3 4 5 6 7 8 9 10 11
Figure 10. Example of Try mode programming pulses applied to the VCC pin. In this example, B_OP Positive Trim, Down-
Counting register is addressed to code 12 by the eleven V_PM pulses (code 1 is selected automatically at the falling edge
of the register-mode selection key).
V_PH
V_PM
V_PL
GND
Register (and Mode) Selection Key
Bit Field (Fuse)
Address Codes
1 2 3 4 5 6 7 8 9 10 11
1
2
3
Blow
Pulse
Figure 11. Example of Blow mode programming pulses applied to the VCC pin. In this example, the B_OP Magnitude
Selection register (BOPSEL) is addressed to code 8 (bit 3, or 3 V_PM pulses) and its value is permanently blown.
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