MAX9921AUB+ Maxim Integrated Products, MAX9921AUB+ Datasheet - Page 14

• Manufacturer Part Number: MAX9921AUB+
• Description: IC SENSOR HALL EFFECT 10-MSOP
• Manufacturer: Maxim Integrated Products
• Type: Hall Effect Sensorr

Specifications of MAX9921AUB+

• Input Type: Voltage
• Output Type: Logic
• Interface: 2-Wire
• Current - Supply: 1.3mA
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Table 4. Partial List of Compatible Hall Switches
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
The MAX9921 is optimized for use with 2-wire Hall-
effect switches or with 3-wire Hall-effect switches con-
nected as 2-wire (Figure 6). When using a 3-wire Hall
sensor, the resistor R is chosen so that the current
drawn by the Hall sensor crosses the MAX9921 current
threshold when the magnetic threshold of the Hall sen-
sor is exceeded.
Table 4 shows a partial list of Hall sensors (primarily 2-
wire) that can be used with the MAX9921. The DC
Electrical Characteristics Table gives tested I
rent threshold limits for both a lower current range and
Figure 6. 3-Wire Hall-Effect Switches Configured as 2-Wire
Note: The Hall switches listed above are supported by the MAX9921 using R
14
HAL573-6
HAL556/560/566
HAL581/584
A1140/1/2/3
A1180/81/82/83
______________________________________________________________________________________
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PART
V
CC
Applications Information
Hall-Effect Sensor Selection
R
MANUFACTURER
Micronas
Micronas
Micronas
Allegro
Allegro
IN_
MAX9921
GND
IH
www.micronas.com
www.micronas.com
www.micronas.com
www.allegromicro.com
www.allegromicro.com
/I
IL
cur-
WEBSITE
a higher current range which correspond to the selec-
tion of the R
MAX9921 compatible with a wide array of 2- and 3-wire
Hall sensors.
The MAX9921 is optimized for use with external protec-
tion 0.01µF capacitors from both IN1 and IN2 to BAT.
These are essential to ensure robustness against auto-
motive transients. These capacitors may be tied to
GND instead of to BAT, but the connection to BAT is
recommended.
To ensure correct operation of the Hall sensor at low
input voltages, it is important to consider the voltage
drop of the MAX9921 with low battery voltages. This
dropout voltage can be calculated using the formula:
I
the Hall sensor and R
MAX9921, nominally 50Ω (see the Input Pullup
Resistance vs. V
Characteristics ). As an example, assume the use of a
HAL573 sensor, which draws a maximum current of
17mA. The dropout voltage is then 850mV and the
approximate minimum voltage supplied to the Hall sensor
is 6V - 0.85V = 5.15V, which is higher than the minimum
operating voltage of 3.75V specified for the HAL573.
HALL
is the maximum current which must be supplied to
ISET
= 63.4k Ω .
2-wire
2-wire
2-wire
2-wire
2-wire
ISET
V
DROPOUT
BAT
Hall Input Bypass Capacitor
resistor value. This makes the
PU
graph in the Typical Operating
is the internal resistance of the
Low-Voltage Operation
= I
HALL
COMMENT
x R
PU