a1181 Allegro MicroSystems, Inc., a1181 Datasheet - Page 6

• Manufacturer Part Number: a1181
• Description: Two-wire, Programmable, Chopper-stabilized, Unipolar Hall-effect Switch Microsystems
• Manufacturer: Allegro MicroSystems, Inc.

The operate points are programmed by serially addressing the devices through the supply terminal V
correct operate point is determined, the device programming bits are permanently blown, and a locking bit is blown to
prevent any further programming.
Switch Point Program Enable. To program the device, a keying sequence is used to activate / enable the addressing
mode as shown in Figure 1. This sequence consisting of a VPP pulse, one VPH pulse, and a VPP pulse with no supply
interruptions, is designed to prevent the device from being programmed accidentally (e.g., as a result of noise on the
supply line).
PROGRAMMING PROTOCOL (T
6
provide the current necessary to blow the fuse.
A118X Family
Part Number
Programming Voltages are measured at Pin #1 (Vcc) of SIP. A minimum capacitance of 0.1uF must be connected from Vcc to GND of the SIP to
TWO-WIRE, PROGRAMMABLE, UNIPOLAR HALL-EFFECT SWITCH FAMILY
Rev. 1.8 25 April 2003
Page 6
Programming Voltage
Programming Current
Pulse width
Pulse Rise Time
Pulse Fall Time
(PRELIMINARY INFORMATION – SUBJECT TO CHANGE)
Valid over operating temperature range unless otherwise noted.
Characteristics
A
= +25 °C)
Figure 1. Program Enable Pulse Sequence.
PROGRAMMING PROTOCOL
6
Symbol
V
V
V
t
t
I
t
d(0)
d(1)
PP
dP
t
t
PH
PP
PL
f
r
Minimum voltage range
during programming
t
C
OFF time between bits
Pulse duration for enable
and addressing
sequences
Pulse duration for fuse
blowing
V
V
r
bypass
PL
PH
= 11us, 5V
to V
Test Conditions
or V
= 0.1uF
PH
PP
or V
to V
26V,
PP
PL
115 Northeast Cutoff, Box 15036
Worcester, Massachus etts 01615-0036 [phone]
Copyright © 1993, 1995 Allegro MicroSystems, Inc.
Min.
11.5
100
4.5
25
20
20
5
5
-
Typ.
12.5
190
300
26
5
-
-
-
-
Limits
CC
(pin 1). After the
Max.
13.5
100
100
5.5
27
-
-
-
-
Units
mA
V
V
V
s
s
s
s
s