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PDF MAX9921 Data sheet ( Hoja de datos )
| Número de pieza | MAX9921 | |
| Descripción | 2-Wire Hall-Effect Sensor Interface | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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19-4119; Rev 0; 6/08
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
www.datasheet4u.com
General Description
The MAX9921 provides a single chip solution to interface
two 2-wire Hall-effect sensors to a low-voltage micro-
processor (µP). This device supplies and monitors the cur-
rent drawn by two Hall-effect sensors, filters the sensed
current level, and outputs the corresponding logic level.
The MAX9921 includes input diagnostics and fault pro-
tection. These features allow the device to determine fault
conditions such as open inputs, inputs shorted to the bat-
tery, and inputs shorted to ground. If the MAX9921
detects any of these conditions at either IN1 or IN2, the
device shuts off the current to the corresponding input.
The MAX9921 protects the Hall sensors from supply tran-
sients up to 60V at the BAT supply. Normal operating
supply voltage ranges from 6V to 18V. If the battery volt-
age is out of range, the MAX9921 shuts off the current to
the Hall sensors.
The MAX9921 provides an 80µs blanking time following
Hall sensor power-up or restart. The open-drain logic
outputs are compatible with logic levels up to 5.5V.
The MAX9921 is available in a small 10-pin µMAX®
package and is specified over the -40°C to +125°C
automotive temperature range.
Applications
Door Modules
Window Lifters
Seat Movers
Electric Sunroofs
Powered Lift Gate
Controllers
Powered Running Boards
Seatbelt Buckles
Features
♦ Withstands 60V at BAT Supply and Hall Inputs
♦ 6V to 18V Operating Voltage Range
♦ Provides Supply Current and Interfaces to Two
2-Wire Hall Sensors
♦ Error Output with Diagnostics of Hall Inputs and
BAT Voltage
♦ Protects Hall Sensors from Overvoltage by
Isolating them from Supply Transients
♦ Hall Inputs Protected from Short to Ground
♦ Ramps Current to Hall Sensors at 4mA/µs
♦ Output Enable Input Allows Multiplexing of
Outputs from Multiple MAX9921s
♦ Hall Output Filtering
♦ Hall Sensor Blanking Following Hall Sensor
Power-Up and Restart
♦ Low-Power Shutdown, Controlled with OE and
DIAG Inputs
♦ Operates with ±2V Ground Shifts Between Hall
Sensor and MAX9921
Ordering Information
PART
TEMP RANGE
MAX9921AUB+T -40°C to +125°C
+Denotes a lead-free package.
T = Tape and reel.
PIN-PACKAGE
10 µMAX
Pin Configuration appears at end of data sheet.
Typical Application Circuit
VBAT: 6V TO 18V OPERATING,
WITHSTANDS 60V
RISET = 63.4kΩ, 1%
0.1μF
3.3V TO 5V
BATTERY
N
S
REMOTE
GROUND
N
S
REMOTE
GROUND
ISET
E
C
U
C
O
N
N
0.01μF
E IN1
C
T 0.01μF
O IN2
R
BAT
REF
GENERATION,
DIAGNOSTICS
AND
OVERVOLTAGE
DETECT
CONTROL
FILTER
FILTER
GND
MAX9921
OE
ERR
DIAG
OUT1
OUT2
10kΩ
VCC
μP/LOGIC
CIRCUIT
GND
µMAX is a registered trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1 page  
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
www.datasheet4u.com
Timing Diagrams (continued)
PR
14mA
IN_
7mA
0mA
PR
OUT_
5V
0V
Figure 2. Hall Input Pulse Rejection
tDEL
tDEL
_______________________________________________________________________________________ 5
5 Page 
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
www.daTtaashbeleet4u2.c.omDiagnostic Truth Table (Diagnostic Mode)
INPUT
DIAG
ERR
OUTPUT
OUT1
OUT2
DIAGNOSIS
1 0 0 0 No fault
1 0 0 1 IN1 open circuit, or IN1 open circuit and fault on IN2
1 0 1 0 IN1 shorted to battery, or IN1 shorted to battery and fault on IN2
1 0 1 1 IN1 shorted to ground, or IN1 shorted to ground and fault on IN2
1
1
0
0
VBAT out of range, or power-up or restart and blanking cycle (dominant
fault masks all other faults)
1 1 0 1 IN2 open circuit
1 1 1 0 IN2 shorted to battery
1 1 1 1 IN2 shorted to ground
Hall Sensor Protection from Supply Transients
If the VBAT voltage is lower than 6V or exceeds 18V,
IN1 and IN2 shut off current to both Hall sensors and
ERR, OUT1, and OUT2 go low. When VBAT returns to
the proper range, both IN1 and IN2 restart, following a
blanking cycle.
Hall Inputs Open Condition
If either IN1 or IN2 is open (IIN < 2mA), the correspond-
ing input shuts off current to the Hall sensor. If IN1 or
IN2 is loaded, it exits the open input fault condition and
restarts the corresponding Hall input, following a blank-
ing cycle.
Hall Input Shorted to Battery
If either IN1 or IN2 is shorted to the battery (VIN > VBAT
+ 100mV), the MAX9921 shuts off current to the corre-
sponding Hall sensor. In this case, if IN1 or IN2 is more
than 1V above VBAT, it may back-drive current into
BAT. In such a condition, the current level in the Hall
input should not exceed 100mA. Therefore, all the
MAX9921s together can share a separate reverse-
polarity protection diode to avoid powering up other cir-
cuitry sharing a common diode (Figure 4).
BATTERY
REVERSE-POLARITY DIODE
FOR MAX9921s
RISET
RISET
REVERSE-POLARITY DIODE
FOR OTHER CIRCUITRY
MAX9921
BAT DIAG
ISET OE
IN1 ERR
IN2 OUT1
GND OUT2
MAX9921
BAT DIAG
ISET OE
IN1 ERR
IN2 OUT1
GND OUT2
BAT
OTHER
CIRCUITRY
GND
Figure 4. Several MAX9921s Connected to a Common Reverse-Polarity Diode
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MAX9921.PDF ] | |
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