A1365 Datasheet, PDF (25/32 Pages) Allegro MicroSystems – Low-Noise, High-Precision, Programmable Linear Hall-Effect Sensor IC

A1365
Low-Noise, High-Precision, Programmable Linear Hall-Effect Sensor IC
With High-Bandwidth (120 kHz) Analog Output and Integrated Fault Comparator
Writing to EEPROM
In order for the external controller to write to non-volatile
EEPROM, a Write command must be transmitted on the VCC
pin. The controller must also send two Programming pulses,
long high-voltage strobes, via the VOUT pin. These strobes are
detected internally, allowing the A1365 to boost the voltage on
the EEPROM gates. The required sequence is shown in figures
22 and 23.
To ensure EEPROM integrity over lifetime, EEPROM should not
be exposed to more than 100 Write cycles.
Reading from EEPROM or Volatile Memory
In order for the external controller to read from EEPROM or
volatile memory, a Read command must be transmitted on
the VCC line. Within time t_{start_read} , the VOUT line will stop
responding to the magnetic field and the Read Acknowledge
frame will be transmitted on the VOUT line. The Read Acknowl-
edge frame contains Read data.
After the Read Acknowledge frame has been received from the
A1365, the VOUT line resumes normal operation after time
t_READ . The required sequence is shown in Figure 24.
Error Checking
The serial interface uses a cyclic redundancy check (CRC) for
data-bit error checking (synchronization bits are ignored during
the check). The CRC algorithm is based on the polynomial g(x)
= x3 + x + 1, and the calculation is represented graphically in
Figure 25. The trailing 3 bits of a message frame comprise the
CRC token. The CRC is initialized at 111. If the serial interface
receives a command with a CRC error, the command is ignored.
VCC
VOUT
Write
to Register R#
Normal Operation
EEPROM
Programming
Pulses
High
Impedance
Normal Operation
t
t_sPULSE(E)
t_WRITE(E)
Figure 22: Writing to EEPROM
VOUT
t
Figure 23: EEPROM Programming Pulses
VCC
Read from
Register R#
VOUT
Normal Operation
Read Acknowledge
R#
Normal Operation
t
t_{start_read}
t_READ
Figure 24: Reading from EEPROM or Volatile Memory
C0
C1
C2
Input Data
1x ⁰
1x ¹
0x ²
1x ³ = x³ + x + 1
Figure 25: CRC Calculation
Allegro MicroSystems, LLC
25
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com