A1190 ALLEGRO [Allegro MicroSystems], A1190 Datasheet - Page 12

• Manufacturer Part Number: A1190
• Description: Programmable, Chopper-Stabilized, Two Wire Hall-Effect Switches
• Manufacturer: ALLEGRO [Allegro MicroSystems]

A1190, A1192,
and A1193
To correctly address the fuses to be blown, the code represent-
ing the required parameter value must be translated into a binary
number. For example, as shown in figure 7, decimal code 5 is
equivalent to the binary number 101. Therefore bit 2 must be
addressed and blown, the device power supply cycled, and then
bit 0 must be addressed and blown. The order of blowing bits,
however, is not important. Blowing bit 0 first, and then bit 2 is
acceptable.
Note: After blowing, the programming is not reversible, even
after cycling the supply power. Although a register bit field fuse
cannot be reset after it is blown, additional bits within the same
register can be blown at any time until the device is locked. For
example, if bit 1 (binary 10) has been blown, it is still possible to
blow bit 0. The end result would be binary 11 (decimal code 3).
Locking the Device
After the required code for each parameter is programmed, the
device can be locked to prevent further programming of any
parameters. To do so, perform the following steps:
1. Ensure that the C
2. Select the Programming Lock register (key 7).
3. Select Blow mode (key 9).
4. Address bit 3 (001000) by sending four V
5. Send one Blow pulse, at I
6. Delay for a t
7. Optionally check all fuses.
Fuse Checking
Incorporated in the A119x family is circuitry to simultaneously
check the integrity of the fuse bits. The fuse checking feature is
enabled by using the Fuse Check register (selection key 7), and
while in Try mode, applying the codes shown in table 2. The
register is only valid in Try mode and is available before or after
the Programming Lock bit is set.
t
BLOW
.
LOW
BLOW
interval, then power-down.
capacitor is mounted.
PP
and SR
BLOW
PM
, and sustain it for
pulses.
Programmable, Chopper-Stabilized,
Setting the fuse threshold high checks that all blown fuses are
properly blown. Setting fuse threshold low checks all un-blown
fuses are properly intact. The supply current increases by 250 μA
if a marginal fuse is detected. If all fuses are correctly blown or
fully intact, there will be no change in supply current.
Additional Guidelines
The additional guidelines in this section should be followed to
ensure the proper behavior of these devices:
• A 0.1 μF blowing capacitor, C
• The power supply used for programming must be capable of
• Be careful to observe the t
• Lock the device (only after all other parameters have been pro-
B
Selecting B
should be used to adjust B
the optimum B
Use the B
tion by one Magnetic Step Size, Step
bit field pulse (see figure 8). Use the B
register to decrease the B
bit field pulse (see figure 9). As an aid to programming, when
using down-counting method, the A119x automatically inverts
the bit field selection (code 0 in down-counting sets the bit field
value 111111, and the actual bit field value decreases until code
63 sets bit field value 000000).
Note that the release point, B
difference is specified by the Hysteresis, B
programmable.
the VCC pin and the GND pin during programming, to ensure
enough current is available to blow fuses.
delivering at least V
down the device after blowing each bit.
grammed and validated) to prevent any further programming of
the device.
OP
Selection
Two Wire Hall-Effect Switches
OP
OP
Trim Up Counting register to increase the B
should be done in two stages. First, Try mode
OP
is set permanently using Blow mode.
PH
and 175 mA.
OP
OP
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Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
LOW
selection by one Step
RP
and monitor the output state. Then
BLOW
, is a value below B
delay time before powering
, must be mounted between
BOP
OP
, increment with each
Trim Down Counting
HYS
, which is not
BOP
OP
with each
. The
OP
selec-
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