A1242
Two-Wire Chopper-Stabilized Hall Effect Latch
The A1242 Hall effect latch is a two-wire latch especially suited for operation
over extended temperature ranges, from –40 to +150°C. Superior high-tempera-
ture performance is made possible through the Allegro
®
patented dynamic offset
cancellation technique, which reduces the residual offset voltage normally caused
by device overmolding, temperature dependencies, and thermal stress.
The current-switching output technique allows for the reduction in cost in the
wiring harness because only two connections to the sensor are required. The cur-
rent-switching output structure also inherently provides more immunity against
EMC/ESD transients. These sensors have low magnetic thresholds, thereby
enabling more flexibility in the magnetic circuit design.
The Hall effect latch will be in the high output current state in the presence of a
magnetic South Pole field of sufficient magnitude and will remain in this state
until a sufficient North Pole field is present.
The A1242 includes the following on a single silicon chip: a voltage regulator,
Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trig-
ger, and a current source output. Advanced BiCMOS wafer fabrication process-
ing takes advantage of low-voltage requirements, component matching, very low
input-offset errors and small component geometries.
Suffix ‘L-’ devices are rated for operation over a temperature range of –40°C
to +150°C; suffix ‘E-’ devices are rated for operation over a temperature range
of –40°C to +85°C. Two A1242 package styles provide magnetically optimized
solutions for most applications. Package LH is a SOT23W, a miniature low-pro-
file surface-mount package, while package UA is a three-lead ultra-mini SIP for
through-hole mounting. Each package is available lead (Pb) free, with 100% matte
tin plated leadframes.
1
2
3
Package LH, 3-pin Surface Mount
3
1
2
NC
1
2
3
Package UA, 3-pin SIP
Features and Benefits
1 2
3
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
..........................................
28 V
Reverse-Supply Voltage, V
RCC
........................
–18 V
Magnetic Flux Density, B .........................Unlimited
Operating Temperature
Ambient, T
A
, Range E..................
–40ºC to 85ºC
Ambient, T
A
, Range L................
–40ºC to 150ºC
Maximum Junction, T
J(max)
........................165ºC
Storage Temperature, T
S
..................
–65ºC to 170ºC
Chopper stabilization
– Superior temperature stability
– Extremely low switchpoint drift
– Insensitive to physical stress
Reverse battery protection
Solid-state reliability
Small size
Robust EMC capability
High ESD ratings (HBM)
A1242-DS
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
