A1351
High Precision Linear Hall Effect Sensor IC
with a Push/Pull, Pulse Width Modulated Output
17
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
(Decimal Equivalent)
Code 5
Bit Field Selection
Address Code Format
Code in Binary
Fuse Blowing
Target Bits
Fuse Blowing
Address Code Format
(Binary)
1 0 1
Bit 2
Bit 0
Code 4 Code 1
(Decimal Equivalents)
Figure 3. Example of code 5 broken into its binary components,
equaling code 4 and code 1.
Locking the Device
After the desired code for each parameter is programmed, the
device can be locked to prevent further programming of any
parameters. See the Lock Mode section for lock pulse sequence.
Additional Guidelines
The additional guidelines in this section should be followed to
ensure the proper behavior of these devices:
" A 0.1 糉 blowing capacitor, C
BLOW
, must be mounted between
the PWMOUT pin and the GND pin during programming, to
ensure enough current is available to blow fuses.
" The final application capacitance, C
L
, should be used when
measuring the output duty cycle during programming. (The
maximum load capacitance is 14.7 nF for proper operation.)
" The blowing capacitor, C
BLOW
, should be removed during
measurements; it should only be applied when addressing bit
fields and when blowing fuses.
" The power supply used for programming must be capable of
delivering at least 26 V and 300 mA.
" Be careful to observe the t
LOW
delay time before powering
down the device after blowing each bit.
" The following programming order is recommended:
1. PWM carrier frequency
2. Coarse D
(Q)
3. Sens
4. D
(Q)
5. LOCK (only after all other parameters have been
programmed and validated, because this prevents any further
programming of the device)
Figure 4. Example of programming pulses applied to the PWMOUT pin that result in permanent parameter settings. In this example, the register
corresponding to key 1 is selected (twice) and code 5 is addressed and blown (in two stages).