A3212
MICROPOWER, ULTRA-SENSITIVE
HALL-EFFECT SWITCH
The A3212 integrated circuit is an ultra-sensitive, pole independent Hall-effect
switch with a latched digital output. This sensor is especially suited for opera-
tion in battery-operated, hand-held equipment such as cellular and cordless
telephones, pagers, and palmtop computers. A 2.5 volt to 3.5 volt operation and a
unique clocking scheme reduce the average operating power requirements to less
than 15
µW
with a 2.75 volt supply.
Unlike other Hall-effect switches, either a north or south pole of sufficient
strength will turn the output on; in the absence of a magnetic field, the output
is off. The polarity independence and minimal power requirement allow these
devices to easily replace reed switches for superior reliability and ease of manu-
facturing, while eliminating the requirement for signal conditioning.
Improved stability is made possible through chopper stabilization (dynamic off-
set cancellation), which reduces the residual offset voltage normally caused by
device overmolding, temperature dependencies, and thermal stress.
This device includes on a single silicon chip a Hall-voltage generator, small-sig-
nal amplifier, chopper stabilization, a latch, and a MOSFET output. Advanced
BiCMOS processing is used to take advantage of low-voltage and low-power
requirements, component matching, very low input-offset errors, and small com-
ponent geometries.
Four package styles provide magnetically optimized solutions for most appli-
cations. Miniature low-profile surface-mount package types
EH
and
EL
(0.75 and 0.50 mm nominal height) are leadless,
LH
is a leaded low-profile
SMD, and
UA
is a three-lead SIP for through-hole mounting. Each package is
available in a lead (Pb) free version (suffix,
–T)
with 100% matte tin plated lead-
frame. EL package for limited release, engineering samples available.
FEATURES
■
■
■
■
Micropower Operation
Operation with North or South Pole
2.5 V to 3.5 V Battery Operation
Chopper Stabilized
Superior Temperature Stability
Extremely Low Switch-Point Drift
Insensitive to Physical Stress
ESD Protected to 5 kV
Solid-State Reliability
Small Size
Easily Manufacturable with Magnet Pole Independence
Data Sheet
27622.61G
2 x 2 mm MLPD
Package A3212EELLT-T
Approximate actual size
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
DD
..............................
5 V
Magnetic Flux Density, B ..........
Unlimited
Output Off Voltage, V
OUT
......................
5 V
Output Current, I
OUT
...........................
1 mA
Junction Temperature, T
J
................
+170°C
Operating Temperature, T
A
Range 'E-' ....................
-40°C to +85°C
Range 'L-' ..................
-40°C to +150°C
Storage Temperature Range,
T
S
..............................
-65°C to +170°C
Caution: These CMOS devices have input
static protection (Class 3) but are still sus-
ceptible to damage if exposed to extremely
high static electrical charges.
■
■
■
■
A3212
MICROPOWER,
ULTRA-SENSITIVE
HALL-EFFECT SWITCH
ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless
otherwise specified).
Limits
Characteristic
Supply Voltage Range
Output Leakage Current
Output On Voltage
Awake Time
Period
Duty Cycle
Chopping Frequency
Supply Current
Symbol
V
DD
I
OFF
V
OUT
t
awake
t
period
d.c.
f
C
I
DD(EN)
I
DD(DIS)
I
DD(AVG)
Chip awake (enabled)
Chip asleep (disabled)
V
DD
= 2.75 V
V
DD
= 3.5 V
Test Conditions
Operating
1
V
OUT
= 3.5 V, B
RPN
< B < B
RPS
I
OUT
= 1 mA, V
DD
= 2.75 V
Min.
2.5
–
–
–
–
–
–
–
–
–
–
Typ.
2.75
<1.0
100
45
45
0.1
340
–
–
5.1
6.7
Max.
3.5
1.0
300
90
90
–
–
2.0
8.0
10
10
Units
V
µA
mV
µs
ms
%
kHz
mA
µA
µA
µA
NOTES: 1. Operate and release points will vary with supply voltage.
2. B
OPx
= operate point (output turns on); B
RPx
= release point (output turns off).
3. Typical Data is at T
A
= +25°C and V
DD
= 2.75 V and is for design information only.
MAGNETIC CHARACTERISTICS over operating voltage and temperature range (unless
otherwise specified).
Limits
Characteristic
Operate Points
Symbol
B
OPS
B
OPN
Release Points
B
RPS
B
RPN
Hysteresis
B
hys
Test Conditions
South pole to branded side
North pole to branded side
South pole to branded side
North pole to branded side
|B
OPx
- B
RPx
|
Min.
–
-55
10
–
–
Typ.
37
-40
31
-34
5.9
Max.
55
–
–
-10
–
Units
G
G
G
G
G
NOTES: 1. Negative flux densities are defined as less than zero (algebraic convention), i.e., -50 G is less than +10 G.
2. B
OPx
= operate point (output turns on); B
RPx
= release point (output turns off).
3. Typical Data is at T
A
= +25°C and V
DD
= 2.75 V and is for design information only.
4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT).
4
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