A1369 Datasheet, PDF (16/22 Pages) Allegro MicroSystems – Customer Programmable Linear Hall-Effect Sensor

A1369
Customer Programmable Linear Hall-Effect Sensor
Optimized for Use in Current Sensing Applications
PROGRAMMING MODES
Try Mode
Try mode allows multiple programmable parameters to be tested
simultaneously without permanently setting any values. In this
mode, each high pulse will indefinitely loop the programming
logic through the mode, register, and bit field states. There must
be no interruptions in the V_CC supply.
After powering the V_CC supply, select mode key 1, the desired
parameter register, and address its bit field. When addressing the
bit field, each V_PM pulse increments the value of the parameter
register up to the maximum possible code (see Programming
Logic section). The addressed parameter value will be stored in
the device even after the programming drive voltage is removed
from the VOUT pin, allowing its value to be measured. To test
an additional programmable parameter in conjunction with the
original, enter an additional V_PH pulse on the VOUT pin to re-
enter the parameter selection field. Select a different parameter
register, and address its bit field without any supply interruptions.
Both parameter values will be stored and can be measured after
removing the programming drive voltage. Multiple programming
combinations can be tested to achieve optimal application accu-
racy. See Figure 11 for an example of the Try Mode pulse train.
Registers can be addressed and re-addressed an indefinite number
of times in any order. Once the desired code is found for each
register, cycle the supply and blow the bit field using blow mode.
Note that for accurate time measurements the blow capacitor,
C_BLOW, should be removed during output voltage measurement.
Blow Mode
After the required value of the programmable parameter is found
using Hold/Try mode, the corresponding code should be blown to
make its value permanent. To do this, select the required param-
eter register, and address and blow each required bit separately
(as described in the Fuse Blowing section). The supply must be
cycled between blowing each bit of a given code. After a bit is
blown, cycling the supply will not reset its value.
Read Mode
The state of the internal fuses can be read at any time in Read
Mode. Read Mode is available before, and after locking the
device. Read mode allows the programmer to verify that the
intended bits were blown.
After power the V_CC supply, select mode key 3, the desired
parameter register, and address its bit field. Upon completing the
selection of mode key 3, I_CC will increase by 250 µA to indicate
the device is in read fuse mode. On the falling edge of the V_PH
pulse that terminates the register selection, I_CC will increase by
another 250 µA (total of 500 µA above normal I_CC) to indicate
a fuse is blown, or decrease by 250 µA (total of 0 µA above
nominal I_CC) to indicate an un-blown fuse. On each consecutive
falling edge of V_P\M pulses the A1369 will modify I_CC to indicate
the state of each fuse (500 µA above I_CC for a blown fuse, and 0
µA above I_CC for an un-blown fuse).
The read mode indicates the fuse values of the selected register
in a serial fashion where one bit is read at a time. The LSB (B0)
is selected on the falling edge of the V_PH pulse that terminates
the key parameter selection, and begins the addressing code. The
successive V_PM pulses select the succeeding bits in this order:
B1, B2, B3, B4, B5, B6, B7, B8. See Figure 12 for an example
pulse train.
V_P(HIGH)
V_P(MID)
V_P(LOW)
0
1
2
Mode Selection
(Key 2)
1
2
Parameter Selection
(Key 2)
1
2
Addressing Code 2
(Bit 1)
Next
Parameter
Figure 11: Example of Try Mode Programming Pulses Applied to the VOUT Pin.
In this example, Sensitivity (Parameter Key 1) is addressed to code 3 and QVO (Parameter Key 2) is addressed to code 2.
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