19-4119; Rev 1; 1/10
KIT
ATION
EVALU
BLE
AVAILA
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
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.
Features
o
Withstands 60V at BAT Supply and Hall Inputs
o
6V to 18V Operating Voltage Range
o
Provides Supply Current and Interfaces to Two
2-Wire Hall Sensors
o
Error Output with Diagnostics of Hall Inputs and
BAT Voltage
o
Protects Hall Sensors from Overvoltage by
Isolating Them from Supply Transients
o
Hall Inputs Protected from Short to Ground
o
Ramps Current to Hall Sensors at 4mA/µs
o
Output Enable Input Allows Multiplexing of
Outputs from Multiple MAX9921s
o
Hall Output Filtering
o
Hall Sensor Blanking Following Hall Sensor
Power-Up or Restart
o
Low-Power Shutdown, Controlled with OE and
DIAG Inputs
o
Operates with ±2V Ground Shifts Between Hall
Sensor and MAX9921
MAX9921
Ordering Information
PART
MAX9921AUB+T
MAX9921AUB/V+T
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
10 µMAX
10 µMAX
Applications
Door Modules
Window Lifters
Seat Movers
Electric Sunroofs
Powered Lift Gate
Controllers
Powered Running Boards
Seatbelt Buckles
+Denotes
a lead(Pb)-free/RoHS-compliant package.
T = Tape and reel.
/V denotes an automotive qualified part.
Pin Configuration appears at end of data sheet.
Typical Application Circuit
V
BAT
: 6V TO 18V OPERATING,
WITHSTANDS 60V
BATTERY
E
C
U
C
O
N
N
E
C
T
O
R
R
ISET
= 63.4kΩ, 1%
BAT
ISET
REF
GENERATION,
DIAGNOSTICS
AND
OVERVOLTAGE
DETECT
0.01μF
IN1
FILTER
0.01μF
IN2
FILTER
GND
10kΩ
0.1μF
3.3V TO 5V
N
S
REMOTE
GROUND
CONTROL
OE
ERR
V
CC
DIAG
OUT1
μP/LOGIC
CIRCUIT
N
S
REMOTE
GROUND
MAX9921
OUT2
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.
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
MAX9921
ABSOLUTE MAXIMUM RATINGS
BAT to GND............................................................-0.3V to +60V
ISET to BAT ...........................................................-2.0V to +0.3V
IN1, IN2 to GND..........-5.0V to the lower of +60V or (V
BAT
+ 1V)
DIAG, OE to GND..................................................-0.3V to +6.0V
OUT1, OUT2,
ERR
to GND....................................-0.3V to +6.0V
Short-Circuit Duration of OUT1, OUT2,
ERR
to GND
or to 5.5V (individually)............................................Continuous
Current into Any Pin Except IN1, IN2 ...............................±20mA
Current into IN1, IN2.......................................................±100mA
Continuous Power Dissipation (T
A
= +70°C)
10-Pin µMAX (derate 5.6mW/°C above +70°C) .........444.4mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DC ELECTRICAL CHARACTERISTICS
(V
BAT
= 13.6V, V
DIAG
= 0, V
OE
= 5V, IN1 = IN2 = no connection, R
ISET
= 63.4kΩ, R
PU
= 10kΩ at
ERR,
OUT1 and OUT2, T
A
= -40°C
to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
GENERAL
BAT Supply Range
V
BAT
Low for
ERR
Output Active
V
BAT
High for
ERR
Output Active
BAT Supply Current
HALL INPUTS (IN1 and IN2)
Input Current for Output High
Input Current for Output Low
Input Current Hysteresis for
High/Low Detection
Input Pullup Impedance
Input Voltage Interpreted as
Shorted to Battery
Current Range Interpreted as
Open Circuit
Current Level Interpreted as
Shorted Sensor to Ground
I
IH
I
IL
I
IN,HYS
R
PU
V
SB
I
OC
Not a sustained
R
ISET
= 63.4kΩ
condition, reverts to -
50µA when detected R
ISET
= 59.0kΩ
R
ISET
= 63.4kΩ
R
ISET
= 59.0kΩ
R
ISET
= 63.4kΩ
R
ISET
= 59.0kΩ
R
ISET
= 63.4kΩ
R
ISET
= 59.0kΩ
V
BAT
= 6V, inputs IN1, IN2 with
I
IN
= -14mA
Measured with respect to V
BAT
-2
-7.2
-7.8
0.76
0.78
50
100
+0.02
-23
mA
-25
-11.5
-12.4
mA
mA
mA
Ω
mV
mA
V
BAT
V
BL
V
BH
I
BAT
I
SD
Normal mode
Shutdown mode, V
OE
= V
DIAG
= 0V
1
6
5.2
22
1.3
1
18
V
V
V
mA
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
I
SC
2
_______________________________________________________________________________________
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
DC ELECTRICAL CHARACTERISTICS (continued)
(V
BAT
= 13.6V, V
DIAG
= 0, V
OE
= 5V, IN1 = IN2 = no connection, R
ISET
= 63.4kΩ, R
PU
= 10kΩ at
ERR,
OUT1 and OUT2, T
A
= -40°C
to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
PARAMETER
Output Voltage Low (ERR, OUT1,
OUT2)
Three-State Output Current (ERR,
OUT1, OUT2)
Input-Voltage High (DIAG, OE)
Input-Voltage Low (DIAG, OE)
Input Resistance to GND (DIAG, OE)
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC I/O (OUT1, OUT2,
ERR,
DIAG, and OE)
V
OL
I
OZ
V
IH
V
IL
R
IN
50
80
Sink current = 1mA
V
OE
= 0V, 0
≤
V
OUT_
≤
5V
2.1
0.8
0.4
±1
V
µA
V
V
kΩ
MAX9921
AC TIMING CHARACTERISTICS
(V
BAT
= 13.6V, V
DIAG
= 0, V
OE
= 5V, IN1 = IN2 = no connection, R
ISET
= 63.4kΩ, R
PU
= 10kΩ at
ERR,
OUT1 and OUT2, T
A
= -40°C
to +125°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Notes 1, 2, and 4)
PARAMETER
IN1, IN2 Blanking Time at Hall
Switch Power-Up
IN1, IN2 Current Ramp Rate
After Turn-On
Delay from IN_ to OUT_ (Filter
Delay)
Delay from IN_ Fault to
ERR
Delay from DIAG High to
OUT_ and
ERR
Delay from DIAG Low to OUT_
and
ERR
Delay Difference Between
Rising and Falling Edges for
Both Channels
Delay Difference Between
Channels
Maximum Frequency on Hall
Inputs
IN_ Pulse Length Rejected by
Filter to OUT_
SYMBOL
t
BL
t
RAMP
t
DEL
t
ERR
t
DLH
t
DHL
CONDITIONS
I
IH
= -11.5mA to GND, time from V
IN_
=
500mV until OUT_ high, C
L
= 20pF (Note 3)
V
IN
= GND
From I
IH
to I
IL
or from I
IL
to I
IH
, C
L
= 20pF,
Figure 1
From I
IL
to I
SC
or from I
IH
to I
OC,
falling edge
only, C
L
= 20pF, Figure 1
Rising edge of DIAG to falling or rising edge
of outputs, C
L
= 20pF, Figure 1
Falling edge of DIAG to falling or rising edge
of outputs, C
L
= 20pF, Figure 1
C
HALL-BYPASS
= 0.01µF, I
IH
= -11.5mA and
I
IL
= -7.2mA, C
L
= 20pF
C
HALL-BYPASS
= 0.01µF, I
IH
= -11.5mA and
I
IL
= -7.2mA, C
L
= 20pF
C
HALL-BYPASS
= 0.01µF, I
IH
= -11.5mA and
I
IL
= -7.2mA, C
L
= 20pF
Figure 2
50
5.5
MIN
50
3.8
6.5
31
350
1.6
TYP
MAX
140
UNITS
µs
mA/µs
µs
ns
ns
µs
t
DM
20
ns
t
CC
f
MAX
P
R
100
ns
kHz
µs
Note 1:
All DC specifications are 100% tested at T
A
= +25°C. AC specifications and specifications over -40°C to +125°C are guar-
anteed by design.
Note 2:
C
L
is external load capacitance on the outputs for test only.
Note 3:
These blanking times apply when the MAX9921 is operating in normal mode. Blanking times following power-up or startup
from shutdown mode are 20µs longer.
Note 4:
The following AC parameters change with the value of R
ISET
: t
BL
, t
RAMP
, t
DEL
, f
MAX
, and P
R
. The typ values given are for
R
ISET
= 63.4kΩ. The parameters t
RAMP
and f
MAX
increase 8%, and t
DEL
and P
R
decrease 8% with R
ISET
= 59.0kΩ. The lim-
its for tBL and fMAX apply for both resistor values.
_______________________________________________________________________________________
3
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
MAX9921
Timing Diagrams
APPROX. 50mA
RETRY
SHORT CIRCUIT
14mA
IN 1
7mA
HALL SENSOR OPEN CIRCUIT
t
DEL
5V
OUT1
0V
4mA/μs
0mA
5V
OUT2
0V
t
ERR
5V
ERR
0V
t
ERR
5V
DIAG
0V
Figure 1. Timing Diagram
4
_______________________________________________________________________________________
Dual, 2-Wire Hall-Effect Sensor Interface
with Diagnostics
Timing Diagrams (continued)
MAX9921
P
R
P
R
14mA
IN_
7mA
0mA
5V
OUT_
0V
t
DEL
t
DEL
Figure 2. Hall Input Pulse Rejection
_______________________________________________________________________________________
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