A1383ELHLT-T Allegro, A1383ELHLT-T Datasheet - Page 12

• Manufacturer Part Number: A1383ELHLT-T
• Manufacturer: Allegro

A1381, A1382,
A1383, and A1384
Parameter Selection
Each programmable parameter can be accessed through a specific
register. To select a register, a sequence of voltage pulses con-
sisting of a V
(with no V
the VOUT pin. The number of V
uniquely identifies each register. The pulse train used for selec-
tion of the first register, key 1, is shown in figure 1.
Figure 1. Parameter selection pulse train. This shows the sequence for
selecting the register corresponding to key 1, indicated by a single V
pulse.
Figure 2. Bit field addressing pulse train. Addressing the bit field by
incrementing the code causes the programmable parameter value to
change. The number of bits available for a given programming code, n,
varies among parameters; for example, the bit field for V
available, which allows 63 separate codes to be used.
CC
V
V
PH
V
P(HIGH)
P(LOW)
supply interruptions) must be applied serially to
P(MID)
V
V
V+
pulse, a series of V
P(HIGH)
V
P(LOW)
P(MID)
0
V+
0
PM
t
LOW
PM
pulses is called the key, and
pulses, and a V
Programmable Linear Hall Effect Sensors with Analog Output
Available in a Miniature Thin Profile Surface Mount Package
t
ACTIVE
Programming Procedures
OUT(Q)
PH
has 6 bits
pulse
PM
The A138x has three registers that select among the five pro-
grammable parameters:
•
•
•
Bit Field Addressing
After a programmable parameter has been selected, a V
transitions the programming logic into the bit field address-
ing state. Applying a series of V
the device, as shown in figure 2, increments the bit field of the
selected parameter.
When addressing the bit field, the number of V
resented by a decimal number called a code. Addressing activates
the corresponding fuse locations in the given bit field by incre-
menting the binary value of an internal DAC. The value of the bit
field (and code) increments by one with the falling edge of each
V
ming Logic table). As the value of the bit field code increases, the
value of the programmable parameter changes.
Measurements can be taken after each pulse to determine if the
desired result for the programmable parameter has been reached.
Cycling the supply voltage resets all the locations in the bit field
that have unblown fuses to their initial states.
Fuse Blowing
After the required code is found for a given parameter, its value
can be set permanently by blowing individual fuses in the appro-
priate register bit field. Blowing is accomplished by applying
a V
V
fuse internal to the device. Due to power requirements, the fuse
for each bit in the bit field must be blown individually. To accom-
plish this, the code representing the desired parameter value must
be translated to a binary number. For example, as shown
PM
P(HIGH)
Register 1:
Quiescent voltage output, V
Register 2:
Sensitivity, Sens
Register 3:
Sensitivity temperature coefficient, TC
Polarity, POL
Overall device locking, LOCK
PH
pulse, up to the maximum possible code (see the Program-
pulse, called a blow pulse, of sufficient duration at the
level to permanently set an addressed bit by blowing a
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Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
OUT(Q)
PM
pulses to the VOUT pin of
Sens
PM
pulses is rep-
PH
pulse
12