iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 1/17
FEATURES
APPLICATIONS
♦ Linear Hall sensor array for magnetic pole pitch of 2.56 mm
♦ Non-sensitive to magnetic stray fields due to differential
measurement technique
♦ Interpolator with 8-bit linear resolution of 20 µm
♦ Linear speed up to 5 m/s
♦ Buffered I/O stages for signal outputs
♦ Configuration inputs for operating mode selection
♦ Analog operation modes:
- sine/cosine signals controlled to 2 Vpp
- triange or sawtooth signal with selectable amplitude
♦ Digital operation modes:
- A/B quadrature signals with Z index pulse
- Counter pulses for external binary counters
♦ Cascading of multiple iC-ML possible for chain operation
(Evaluation of independent scales x, y, z)
♦ Error signal output for detection of low magnetic field strength
♦ Additional operating modes with reduced power consumption
♦ Standby modus when not enabled
♦ Extended temperature range of -40...+125 °C
♦
♦
♦
♦
♦
♦
♦
♦
Analog and digital linear sensors
Incremental linear encoders
Pole wheel sensing
Potentiometer replacement
Contactless slider/switch
Commutation of linear motor
Absolute displacement sensing
Liquid level meter
PACKAGES
CFG3
VDD
D
NEN
A
CFG2
GND
TSSOP20
C
CFG1
B
Die-Size
4.4 mm x 1.9 mm
BLOCK DIAGRAM
VDD
VDD
CFG1
SIN
SIN
A
I/O
DIG
8 BIT
VDD
COS
CFG2
HALL SENSOR
AMP
B
I/O
GAIN
VDD
2
SIN +COS
CFG3
2
iC-ML
C
I/O
GAIN CONTROL
D
NEN
VDD
VREF
MODE
SELECT
BIAS
REFH
AMPLITUDE
ERROR
CONTROL
I/O
VPHI
DIG/R
REFL
INTERFACE
GND
Copyright © 2009 iC-Haus
http://www.ichaus.com
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 2/17
DESCRIPTION
The CMOS device iC-ML consists of four hall sensors arranged in a line and optimized to read out
magnetic tapes with 2.56 mm pole spacing. This
sensor array permits error-tolerant adjustment of the
magnetic tape, reducing assembly efforts. The integrated signal conditioning unit provides a differential
sine/cosine signal at the output.
The sensor generates one sine/cosine cycle for each
full magnetic periode of 5.12 mm, enabling the travelling distance to be clearly determined. At the same
time the internal amplitude control unit produces an
regulated output amplitude of 2 Vpp regardless of
variations in the magnetic field strength, supply voltage and temperature. Furthermore, signals are provided which enable the sensor amplitude to be assessed and also report any magnetic tape loss.
With the aid of the integrated 8-bit sine/digital converter the travelling distance within a magnetic periode is determined from the sine/cosine signals. This
is output via an incremental interface in a number
of selectable resolutions. The zero position of each
periode is indicated by an index pulse. The maximum resolution of 8-bit is maintained up to travelling
speeds of 5 m/s.
The absolute position within a magnetic periode can
be converted back to a linear analog output signal
using the internal D/A converter; here, output voltage limits can be set as required using the external
pins. Either a periodic linear signal (sawtooth) or a
delta voltage (triangle) can be provided. iC-ML can
be easily cascaded in three different modes of chain
operation so that several axes of transistion can be
scanned. The linear positions of the individual axes
can then be read via a common bus.
Used in conjunction with a magnetic tape iC-ML can
act as an linear encoder system with an integrated
magnetic scanning feature.
PACKAGES TSSOP20
PIN CONFIGURATION - TSSOP20
PIN FUNCTIONS
No. Name Function
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
T0
NEN
n.c.
GND
n.c.
CFG2
B
n.c.
A
n.c.
VTC
D
n.c.
C
CFG3
n.c.
VDD
n.c.
CFG1
VTS
Test Pin (connect to GND)
Enable Input, low active
Ground
Configuration Input 2
Bidirectional Input/Output B
Bidirectional Input/Output A
Test Pin (do not connect)
Bidirectional Input/Output D
Bidirectional Input/Output C
Configuration Input 3
+5 V Supply Voltage
Configuration Input 1
Test Pin (do not connect)
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 3/17
ABSOLUTE MAXIMUM RATINGS
Beyond these values damage may occur; device operation is not guaranteed.
Item
No.
Symbol
Parameter
G001 VDD
Supply voltage
G002 V()
Voltages at A, B, C, D, NEN, CFG1,
CFG2
G003 Imx(VDD)
Conditions
V() < VDD + 0.3 V
Unit
Min.
Max.
-0.3
6
V
-0.3
6
V
Current at VDD
-30
30
mA
G004 Imx(GND) Current at GND
-30
30
mA
G005 Imx()
Current at A, B, C, D, NEN, CFG1,
CFG2
-10
10
mA
G006 Ilu()
Pulse current (Latch-up immunity)
Pulse width < 10 µs
-100
100
mA
G007 Vd()
ESD-Voltage at all pins
HBM, 100 pF discharged over 1.5 kΩ
2
kV
G008 Ts
Storage temperature
150
°C
-40
THERMAL DATA
Operating conditions: VDD = 5 V ±10 %
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
T01
Ta
Ambient temperature
T02
Rthja
Thermal resistance chip/ambient
-40
SMD assembly, no additional cooling areas
All voltages are referenced to ground unless otherwise stated.
All currents into the device pins are positive; all currents out of the device pins are negative.
Typ.
Max.
125
°C
75
K/W
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 4/17
ELECTRICAL CHARACTERISTICS
Operating conditions: VDD = 5 V ±10 % , Tj = -40 ... 125 °C, unless otherwise noted
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Typ.
Max.
5
5.5
V
14
7
20
10
mA
mA
200
µA
General
001
002
VDD
Supply voltage
I(VDD)
Supply current
open pins, normal operation
open pins, power reduction mode (PRM)
4.5
003
I(VDD)sb
Standby supply current
NEN = VDD
004
td(VDD)on Turn on delay
VDD > 4 V, see Fig. 9
10
µs
005
td(VDD)off Turn off delay
VDD < 2.6 V
10
µs
Hall sensor array
101
Hext
Requiered external magnetic field at chip surface
strength
20
102
psens
Hall sensor array pitch
see Fig. 1
1.28
mm
103
ysens
Hall sensor array distance to
center of die
see Fig. 1
0.7
mm
104
xdis
Lateral displacement of chip to
package
in TSSOP20 package, see Fig. 2
-0.2
0.2
mm
105
ydis
Vertical displacement of chip to
package
in TSSOP20 package, see Fig. 2
-0.2
0.2
mm
106
Φdis
Angular displacement of chip with in TSSOP20 package, see Fig. 2
reference to package
-3
3
DEG
107
hsens
Distance chip surface to top of
package
in TSSOP20 package, see Fig. 2
50
100
400
kA/m
µm
Signal conditioning
201
Voff
Offset voltage
202
TC(Voff)
Temperatur coefficient of offset
voltage
203
Vdc
Output mean value
204
Ratio
Amplitude ratio of SIN / COS
205
fhc
Cut off frequency
206
t()settle
Settling time
207
V()gain
Gain output voltage
208
V()ampl
Sine/Cosine amplitude
on output, with external magnetic field amplitude of 20 kA/m
-50
50
mV
-50
50
µV/K
%VDD
45
50
55
0.95
1.00
1.05
20
to 70 % amplitude, Hext = 40 kA/m
80
150
µs
4.0
V
1.0
1.1
V
20
%
256
300
kHz
0.05
V()ampl = V()max - Vdc
0.9
kHz
Sine-to-digital converter
301
AArel
Relative angular error
302
f(OSC)
Oscillator frequency
303
TC(OSC)
Temperature coefficient of oscillator frequency
304
hys
Converter hysteresis
with reference to one periode, see Fig. 3
-20
200
-0.1
%/K
1
LSB
Configuration inputs CFG1, CFG2, CFG3
401
Vt()hi
Threshold voltage high
60
78
% VDD
402
Vt()lo
Threshold voltage low
25
40
% VDD
403
V0()
Open circuit voltage
43
57
% VDD
404
Ri()
Input resistance
45
450
kΩ
2
V
150
Enable input NEN
501
Vt()hi
Threshold voltage high
502
Vt()lo
Threshold voltage low
503
Vt()hys
Hysteresis
504
Ipu()
Pull-up current
0.8
V
Vt()hys = Vt()hi - Vt()lo
300
mV
V() = 0...VDD - 1 V
-240
-120
-25
µA
V
Digital outputs: A, B, C, D
601
Vs()hi
Saturation voltage high
Vs()hi = VDD - V(), I() = -4 mA
0.4
602
Vs()lo
Saturation voltage low
I() = 4 mA
0.4
V
603
tr()
Rise time
CL() = 50 pF
60
ns
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 5/17
ELECTRICAL CHARACTERISTICS
Operating conditions: VDD = 5 V ±10 % , Tj = -40 ... 125 °C, unless otherwise noted
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
604
tf()
Fall time
CL() = 50 pF
605
Ilk()
Leackage current
NEN = high, V() = 0 ... VDD
606
Vc()hi
Clamp voltage high
Vc()hi = V() - VDD, NEN = high, I() = 4 mA
607
Vc()lo
Clamp voltage low
NEN = high, I() = -4 mA
Typ.
Max.
60
ns
5
µA
0.3
1.6
V
-1.5
-0.3
V
2
V
-5
Digital inputs: A, B, C, D
701
Vt()hi
Threshold voltage high
702
Vt()lo
Threshold voltage low
703
Vt()hys
Hysterese
704
Ipd()
Pull-down current
0.8
V
Vt()hys = Vt()hi - Vt()lo
300
mV
V() = 1 V...VDD
10
30
50
µA
Analog outputs: A, B, C, D
801
SR
Slew Rate
802
fhc()
Cut off frequency
803
I()
Output current
804
R()eda
Input resistance DA-converter
between pin B and pin C
805
R()ada
Output resistance DA-converter
at pin A
psens
2
psens
V/µs
500
kHz
-1
6
8
1
mA
10
kΩ
100
kΩ
psens
ysens
0%
twhi()/T
50%
AArel
center of chip
Figure 1: Location of HALL sensors on die
hsens
xdis
0%
100%
20
AArel
Figure 3: Definition of relative angular error
ydis
φdis
center of chip
1
Figure 2: Position of die in TSSOP20 package
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 6/17
OPERATING CONDITIONS: Logic
Operating conditions: VDD = 5 V ±10 %, Tj = -40...125 °C, unless otherwise noted
Input level low = 0...0.45 V, high = 2.4 V...VDD, timing according Fig. 4
Item
No.
Symbol
Parameter
Conditions
Unit
Min.
Max.
Logic
I001 ts(NEN)
Setup time NEN
CLK : low → high, see Fig. 15
I002 tp(NEN)
Delay time NENO
CLK : high → low, see Fig. 15
30
ns
I003 tp(SIG1)
Delay time SIG1
CL() = 50 pF, see Fig. 15
60
µs
I004 tp(SIG2)
Delay time SIG2
CL() = 50 pF, see Fig. 15
2
µs
I005 tp(CFGx)
Setup time at CFGx, x = 1..3
see Fig. 9
4
µs
30
V
Input/Output
2.4V
2.0V
0.8V
0.45V
t
1
0
Figure 4: Reference levels for delays
ns
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 7/17
The sensor principle
In conjunction with a magnetic tape iC-ML can be used
to create a complete linear encoder system. With a
Hall sensor pitch of 1.28 mm, the iC-ML is taylored
to work with a magnetic tape having a pole pitch of
2.56 mm (5.12 mm magnetic periode). At a resolution
of 8 bit, the digital increment represents a linear distance of 20 µm. In the same way, pole wheels can also
be used together with the iC-ML.
Magnetic tapes (or pole wheels) with a smaller pitch
than 2.56 mm can be used by skewing the iC-ML with
respect to the tape direction and thus adjusting the projected sensor pitch to the tape pitch.
iC-ML has four Hall sensors which are used pairwise
to generate sine- and cosine signals. Each Hall sensor pair detects the magnetic tape at a lateral distance
of half of a magnetic periode. From the difference of
the hall voltages, each Hall sensor pair generates either the sine or the cosine signal. Due to the differential sensing, the resulting signal voltages are insensitve
to external homgenious magnetic fields and pole with
variations.
From the physical principal, the Hall sensors are also
insensitive to magnetic fields parallel to the chip surface.
Arrangement and signal outputs
Figure 5 shows the arrangement of the iC-ML to the
magnetic tape. Both chip and magnetic tape are parallel aligned to each other. The coordinate system is defined in the way that the z-coordinate is perpendicularly
to the surface of the magnetic tape and the x-direction
lies in direction of travel. The four HALL sensors are
located at the upper edge of the chip and should be
centered to the magnetic tape for optimized magnetic
sensing.
Figure 6: Sensing of a pole wheel at the surface using iC-ML
Figure 5: Arrangement of iC-ML to the magnetic
tape
Magnet wheels are scanned depending upon their direction of magnetization either on the surface or at the
periphery. The sensing radius must be chosen accordingly to match the magnetic pitch to the sensor pitch.
For further consideration, the reference position of the
chip is selected in such a way that the x-position of the
outmost left hall sensor coincides with the zero point
of the magnetic tape, which is located at the center of
an arbritrally chosen north pole of the magnetic tape.
Then, as shown in figure 8, the corresponding output
signals in the analog operation mode (S-Sensor) will
be available as a function of the lateral shift xd . The
electrical signals exhibit the same periodicity as the
magnetic field of the magnetic tape, showing extremes
at the poles (Vcos) or at the pole gaps (Vsin).
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 8/17
this vector rotates counterclockwise (mathematically
positive rotation), whereas if the tape is moved in positive x-direction (with respect to the chip), the vector
rotates clockwise (mathematically negative rotation).
Figure 7: Sensing of a pole wheel at the peripherie
using iC-ML
When the Vcos and Vsin signals are displayed as a
Lissajou figure, a rotating vector is defined. If the chip
is moved in positive x-direction with respect to the tape,
Figure 8: Signal outputs Vsin und Vcos
Programming the configuration
iC-ML has 28 modes of operation (see tables on the
following pages). After the device has been switched
on or "woken up" from standby mode by a low signal at pin NEN the levels at the configuration inputs
CFG1 to CFG3 are assessed. These three-level inputs can be connected to GND (low), left open (open)
or connected to VDD (high). For correct identification,
a setup time of at least tp(CFGx) = 4 µs must be maintained between programming the configuration and activating the device. While the device is active changes
in signal at the configuration inputs are ignored.
If several iC-MLs are connected in series in chain operation (see the description of functions on page 12)
it must be ensured that the NEN input of the devices
is switched to low during the various clock cycles and
that the programming default does thus not lie within
the active phase of the devices.
In standby all ports are switched to tristate, i.e. high
impedance. Only in chain operation modes port D is
active high so that the devices arranged further behind
can also be deactivated.
4V
VDD
NEN
iC-ML active
iC-ML active
CFGx
td(VDD)on
tp(CFGx)
tp(CFGx)
Figure 9: Programming the configuration
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 9/17
Operating modes
Mode
NEN CFG1 CFG2
Analog
low
low
S-Sensor low
D-Sensor low open low
D-Sensor low high low
Linear output
R-Sensor low
low open
low open open
low high open
low high open
Chain-Mode
low high
AB-Chain low
D-Chain
low open high
S-Chain
low high high
Incr. ABZ
ABZ 8-1
low
low
low
ABZ 8-0
low open low
ABZ 7-1
low
low open
ABZ 7-0
low open open
ABZ 6-1
low
low high
ABZ 6-0
low open high
ABZ 8-1
low
low
low
ABZ 8-0
low open low
ABZ 7-1
low
low open
ABZ 7-0
low open open
ABZ 6-1
low
low high
ABZ 6-0
low open high
Incr. CLK
CLK 8
low high low
CLK 6
low high high
DIR 8
low high low
DIR 6
low high high
Test (for iC-Haus use only)
low high open
Test
Standby
high
x
x
1
CFG3
Port A
Port B
Port C
Port D
Res. Comments
low
low
low
PSIN
PSIN
PSIN
VREF
NSIN
NSIN
PCOS
PCOS
PCOS
GAIN
NCOS
NCOS
PRM
low
low
low
high
VTRI
VTRI
VSAW
VSAW
REFH
REFH
REFH
REFH
MSB
MSB
REFL
REFL
NERR
GAIN
NERR
GAIN
8
8
8
8
low
low
low
A
PSIN/NSIN
PSIN/VREF
CLK
CLK
CLK
B
PCOS/NCOS
PCOS/GAIN
NENO
NENO
NENO
8
open
open
open
open
open
open
high
high
high
high
high
high
A
A
A
A
A
A
A
A
A
A
A
A
B
B
B
B
B
B
B
B
B
B
B
B
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
8
8
7
7
6
6
8
8
7
7
6
6
open
open
high
high
NCLKUP
NCLKUP
NCLK
NCLK
NCLKDN
NCLKDN
DIR
DIR
NCLR
NCLR
NCLR
NCLR
NERR
NERR
NERR
NERR
8
6
8
6
open
x
AB=1
AB=0
AB=1
AB=0
AB=1
AB=0
AB=1, PRM
AB=0, PRM
AB=1, PRM
AB=0, PRM
AB=1, PRM
AB=0, PRM
Test
TRI
TRI
TRI
TRI1
In chain operation port D is active high so that the backend devices can also be deactivated.
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 10/17
Analog modes of operation
Mode
Analog
S-Sensor
D-Sensor
D-Sensor
NEN CFG1 CFG2 CFG3
low
low
low
low
open
high
low
low
low
low
low
low
Port A
Port B
Port C
Port D
Res. Comment
PSIN
PSIN
PSIN
VREF
NSIN
NSIN
PCOS
PCOS
PCOS
GAIN
NCOS
NCOS
PRM
In the analog modes of operation the amplified Hall
voltages are available at the output ports. The sine/
cosine output signals are controlled to have stable amplitudes of 1 V and referenced to a DC value equivalent
to half of the supply voltage (VREF). Due to the internal signal conditioning unit, no special adjustment is
required. An externally connected interpolator can be
used if further trimming of the output signals is desired.
5
Signal GAIN allows conclusions to be drawn as to the
operating point of the sensor. This is influenced by
the amplitude of the magnetic field, the sensor supply
voltage and temperature. The higher the GAIN potential, the greater the necessary amplification of the Hall
voltages; the external magnetic field is smaller. Besides recording the direction of magnetization of the
permanent magnet the distance between the magnet
and sensor may also be assessed using the GAIN signal. If the gain is insufficient to boost the Hall voltages
to 2 Vss the amplitude control reaches its upper limit
and the output amplitude becomes smaller.
4
Voltage [V]
PSIN
NCOS
The GAIN signal can be used to adjust the permanent
magnet. If the central point of both the magnet and
sensor iC-ML are the same the GAIN signal has no
harmonics. A misaligned sensor must readjust the operating point depending on the angle; the GAIN signal
varies in amplitude. To adjust the sensor to the magnetic tape this must be shifted along its y- and z-axis
so that the GAIN signal has to readjust as little as possible.
3
VREF
2
PCOS
NSIN
1
GAIN
0
0
100
200
300
400
500
600
700
Time [µs]
Figure 10: Analog mode output signals after switching on the device
S sensor mode
After the device has been activated via NEN = low the
sensor is set to its operating point. All signals are referenced to half the supply voltage (VREF). In S sensor mode this potential is available at port B. Ports A
and C output the sine and cosine Hall voltages set to
2 Vss. The angle can be calculated from the relation of
the sine voltage (difference in voltage PSIN to VREF)
to the cosine voltage (difference in voltage PCOS to
VREF). The device supplies an angle which remains
non-ambiguous over a 360° rotation of the permanent
magnet.
D sensor mode
In D sensor mode differential sine (pin A and pin B) and
cosine (pin C and pin D) signals are supplied at the output; as opposed to S sensor mode inverted Hall signals
are now also available at the ports. The advantage of
this mode of operation is the doubled signal amplitude
of the differential Hall voltages and the lack of dependence on reference voltage VREF. The angle is now
calculated via the ratio of the difference between PSIN
and NSIN and between PCOS and NCOS.
D sensor mode is also available with a reduced power
consumption (PRM or Power Reduced Mode). In this
mode the Hall sensor is supplied with current less frequently, reducing the power consumption. Here it must
be observed that the maximum rotating frequency also
drops by a factor of 2.
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 11/17
Resistor modes of operation
Port A
Port B
Port C
Port D
VTRI
VTRI
VSAW
VSAW
REFH
REFH
REFH
REFH
MSB
MSB
REFL
REFL
NERR
GAIN
NERR
GAIN
Resistor modes of operation
In R sensor mode the taps of an integrated resistive
divider are selected depending on the angular position
("potentiometer replacement"). The value of the absolut angular position acts as a "wiper" and selects one
of the 256 taps on the resistor chain.
Res. Comments
8
8
8
8
5
REFH
4
Voltage [V]
Mode
NEN CFG1 CFG2 CFG3
Linear output
low open low
R-Sensor low
low open open low
low high open low
low high open high
3
VSAW
2
REFL
1
0
0
45
90
135
180
225
270
315
360
405
450
Angle [°]
Figure 11: Potentiometer equivalents for resistor
mode operations
Figure 12: R-Sensor mode with sawtooth output
voltage VSAW
5
Modes of operation with a triangular voltage VTRI
avoids the discontinuity at the zero angular position.
Signal MSB can be used to differentiate between the
first and second half rotation. The delta voltage is limited by thresholds REFH and GND. As in VSAW mode
both GAIN and NERR signals are available.
REFH
4
Voltage [V]
In modes with a sawtooth voltage VSAW at port A
the angle is converted into a linear voltage which lies
within thresholds REFH and REFL at ports B and C
(see Figure 12). The integrated resistor chain is directly available at the ports so that thresholds REFH
and REFL can also be reversed. Depending on the
selected mode either a GAIN signal or a NERR error
signal are present at port D to monitor the amplitude.
If the amplitude is at least 70 %, NERR is high; should
the amplitude sink to below 50 % of the set amplitude,
NERR switches to active low.
3
2
VTRI
1
0
0
MSB
45
90
135
180
225
270
315
360
405
450
Angle [°]
Figure 13: R-Sensor mode with triangular output
voltage VTRI
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 12/17
AB chain, D chain and S chain modes
Mode
NEN
Chain operation
AB chain low
D chain
low
S chain
low
CFG1 CFG2 CFG3
low
open
high
high
high
high
low
low
low
Port A
Port B
Port C
Port D
A
PSIN/NSIN
PSIN/VREF
CLK
CLK
CLK
B
PCOS/NCOS
PCOS/GAIN
NENO
NENO
NENO
Res. Comments
8
CLK
ML 0
ML 1
CLK
NEN(0)
ML 2
CLK
NEN(1)
NEN NENO
iC-ML
CLK
NEN(2)
NEN NENO
NEN(3)
NEN NENO
iC-ML
iC-ML
A
A
A
C
C
C
A
C
Figure 14: Chain modes for iC-ML
CLK
ts(NEN)
NEN(0)
tp(NEN0)
NEN(1)
tp(SIG1) tp(SIG2)
ts(NEN)
B
PCOS0
NCOS0
ML 0 active
PCOS1
NCOS1
ML 1 active
PCOS2
NSIN2
NCOS2
ML 2 active
Figure 15: Signal patterns in D chain mode
TRISTATE
PSIN2
TRISTATE
NSIN1
TRISTATE
PSIN1
TRISTATE
NSIN0
TRISTATE
PSIN0
TRISTATE
A
TRISTATE
NEN(3)
TRISTATE
NEN(2)
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 13/17
In the various chain modes multiple iC-MLs can be arranged in a chain (see Figure 14) where all of the devices are connected by a shared CLK line (pin B). The
NEN input is evaluated synchronously with the rising
CLK edge. If the NEN input is switched to low, the
device is active during the following CLK cycle(s). To
allow the devices to be cascaded a delayed enable signal is generated at output pin NENO (pin D) with which
the follow-on device can be activated. If the NEN input of the first device in the chain is reset to high, all
devices in the chain are deactivated. Bus lines A (pin
A) and C (pin C) are activated by tristate output stages
which are high impedance when NEN is high and CLK
is low and also following the second rising CLK edge.
AB chain mode
In AB chain mode two A/B digital incremental signals
are generated at ports A and C. The two square-wave
signals are phase shifted at either +90° or -90°, depending on the direction of rotation. Following a CLK
pulse the next device in the chain is enabled. Here the
falling CLK edge deactivates the current device (e.g.
ML 1 in Figure 14) and activates the next device in the
chain (ML 2) with a low signal at its NEN input. After
a device has been activated the two bus lines A (port
A) and B (port C) are first switched to low (see Figure
15). This is then followed by the incremental signals
being output, starting at the zero position. In the event
of error the bus lines remain low.
second clock pulse deactivates the current device and
activates the following device in the chain with a low
signal at its NEN input.
S chain mode
In S chain mode the non-inverted sine (port A) and cosine (port C) signals are presented to the bus during
the first clock pulse, with the signals VREF (port A)
and GAIN (port C) following on the positive CLK edge
of the next pulse. Each device is thus active for two
clock pulses. The falling CLK edge in the second clock
pulse deactivates the current device and activates the
following device in the chain with a low signal at its
NEN input.
The sine and cosine signals can be assessed using
signal VREF. Signal GAIN (pin D) indicates iC-ML’s internal amplification (see Electrical Characteristics No.
207) and can be used to estimate the signal amplitude
of the internal Hall sensor. The GAIN signal can also
be used to adjust the rotary axis of the magnet to the
center of the chip.
NEN
CLK
NENO
D chain mode
In D chain mode differential sine and cosine signals
are generated at ports A and C. During the first clock
pulse signals PSIN and PCOS are presented to the
bus; during the second pulse signals NSIN and NCOS
are on the bus (see Figure 15). In this mode each
device is thus active for two clock pulses. During the
first clock pulse the non-inverted sine (port A) and cosine (port C) signals are first presented to the bus, with
the inverted signals following on the positive CLK edge
during the second pulse. The falling CLK edge in the
Voltage [V]
5
4
A
3
C
2
1
0
0
100
200
300
400
500
600
700
Time [µs]
Figure 16: Bus signals and control signals in S
chain mode
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 14/17
Incremental ABZ modes
Mode
NEN
Incr. ABZ
ABZ 8-1 low
ABZ 8-0 low
ABZ 7-1 low
ABZ 7-0 low
ABZ 6-1 low
ABZ 6-0 low
ABZ 8-1 low
ABZ 8-0 low
ABZ 7-1 low
ABZ 7-0 low
ABZ 6-1 low
ABZ 6-0 low
CFG1 CFG2 CFG3
low
open
low
open
low
open
low
open
low
open
low
open
low
low
open
open
high
high
low
low
open
open
high
high
open
open
open
open
open
open
high
high
high
high
high
high
Port A
Port B
Port C
Port D
A
A
A
A
A
A
A
A
A
A
A
A
B
B
B
B
B
B
B
B
B
B
B
B
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
Z
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
NERR
iC-ML has an 8-bit sine/digital converter which can
convert the sine/cosine sensor signals into a digitized
angle. This angle is made available at the ports as an
incremental value. Signal Z is always high when the
angle is 0°; otherwise the signal is low. In all incremental modes of operation error signal NERR is available
so that the plausibility of the counter value can be verified. At an amplitude which is less than 50 % of the set
amplitude the error signal switches to low; at an amplitude greater than 70 % the error signal is reset, i.e. set
to high.
Three different quantities regarding the number of
edges per rotation of the magnet can be selected.
These are a resolution of 6 bits (64 edges per rotation), 7 bits (128 edges) or 8 bits (256 edges). The
conversion process is count-safe, i. e. the output of all
edges up to the current angle position is guaranteed as
long as the input frequency is less than the maximum
possible rotation.
All incremental resolutions also have a reduced power
consumption mode(PRM). In this mode the Hall sensor is supplied with current intermittently, reducing the
power consumption. Here it must be noted that the
maximum input frequency drops by a factor of 2.
Res. Comments
8
8
7
7
6
6
8
8
7
7
6
6
AB=1
AB=0
AB=1
AB=0
AB=1
AB=0
AB=1, PRM
AB=0, PRM
AB=1, PRM
AB=0, PRM
AB=1, PRM
AB=0, PRM
sensor via NEN at low the sensor looks for its operating point. If 70 % of the set amplitude is achieved the
error signal is reset. An error status during this phase
is also signaled when signals A and B are high and Z
low. In an error-free state Z is always high at zero position. iC-ML continues to search for its operating point
by outputting the position of the external magnetic field
at maximum count frequency via the incremental interface. Once the actual position has been obtained
the device follows a changed input signal in real time.
The edge frequency is thus 256 times the frequency of
periodical movement of the magnetic tape at a set resolution of 8 bits. If a (rising) edge reaches B before a
(rising) edge A, this means that the counter value has
risen. If the edge reaches A before B, however, this
indicates that the absolute value is lower.
NEN
NERR
A
A distinction can be made between the various modes
of operation by studying the level of the AB signals on
the Z pulse. In mode AB = 1 signals A and B are both
high, as is Z at an angle of 0°. In mode AB = 0, however, both signals A and B are low when the Z signal
is high.
B
Z
Time [us]
Firstly, the behavior of the sensor on switching on the
device is described when the magnetic tape moves in
the +x-direction (Figure 17). After switching on the
Figure 17: Incremental signals after switching on
the device, counting up
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 15/17
angle between 0° and 180° the device counts up to
the operating point; if this angle is between 180° and
360°, it first counts down. Starting when the device is
switched on all edges are output until the absolute position is reached. The setup has to wait until a certain
time has elapsed; this is dependent on the selected
resolution and is the settling time of the sensor until the
error bit is deleted plus the time needed to count up or
down to the absolute position. With a resolution of 8
bits and an angle of 180°, for example, this period constitutes 100 µs sensor settling time plus 128 times 4 µs
until the absolute position has been pinpointed. The
absolute position is thus available after a maximum of
612 µs has elapsed.
NEN
NERR
A
B
Z
Time [us]
Figure 18: Incremental signals after switching on
the device, counting down
Always starting at zero position, the device begins
searching for the absolute position, locating it as
quickly as possible. If this positon corresponds to an
By way of example Figure 18 illustrates how the incremental interface behaves when the device first counts
down to the absolute position and the magnetic tape
then moves forwards, with the sensor following with the
relevant sequence. The Z signal is synchronous with
A and B at low.
Incremental CLK modes
Mode NEN CFG1 CFG2
Inkr. CLK
CLK 8 low high low
CLK 6 low high high
DIR 8 low high low
DIR 6 low high high
CFG3
Port A
Port B
Port C
Port D
open
open
high
high
NCLKUP
NCLKUP
NCLK
NCLK
NCLKDN
NCLKDN
DIR
DIR
NCLR
NCLR
NCLR
NCLR
NERR
NERR
NERR
NERR
CLK-INC mode
In CLK-INC mode two different count signals are
provided for the countup and countdown sequences.
Depending on the direction of rotation either signal
NCLKUP (pin A) is pulsed when the device counts
up or signal NCLKDN (pin B) when the device counts
down. In each case the remaining signal is high. The
zero angle is displayed by the NCLR index track which
can serve as an asynchronous reset for an external
counter.
Figure 19 demonstrates how iC-ML behaves in CLKINC mode, firstly when it counts up from the zero position and then, following a change in the direction of
movement, when it counts back down to zero position.
This mode permits the operation of external binary
counter modules (such as 74HC/HCT193, for example), with signal NCLR (pin C) being used to reset the
counter. With a rising edge of clock signal NCLKUP
and a high at NCLKDN the counter status is incre-
Res. Comments
8
6
8
6
mented; with a rising edge of clock signal NCLKDN
and a high at NCLKUP the counter status is decremented. Two 4-bit counters can be cascaded here to
create a full 8-bit counter.
NCLUP
NCLDN
NCLR
Time [us]
Figure 19: CLK-INC mode
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 16/17
DATA INPUT
VDD
P0
CFG1
NCLUP
CPU
CFG2
NCLDN
CPD
iC-ML
CFG3
NCLR
NEN
NERR
P1
P2
P3
74HCT193
CPU
TCD
CPD
MR
NPL
NPL
Q0
Q1
Q2
P0
TCU
Q3
P1
P2
P3
TCU
74HCT193
Q0
the value of the DIR signal. A low at DIR triggers a
countup; a high causes the setup to count down. Figure 17 shows a countup sequence followed by a countdown sequence, both across the zero position.
TCD
MR
Q1
Q2
Q3
RESET
GND
CLK
OUTPUT
Figure 20: iC-ML with binary counter 74HCT193
DIR
DIR-INC mode
In DIR-INC mode a change in angle for both directions
of rotation generates an output pulse for signal CLK
(pin A). Signal DIR (pin B) gives the direction of rotation. This mode permits the operation of external
binary counter modules (such as 74HC/HCT191, for
example), with signal NCLR (pin C) being used to reset the external counter. With a rising edge at CLK the
counter status is counted up or down, depending on
NCLR
Time [us]
Figure 21: DIR-INC mode
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As a general rule our developments, IPs, principle circuitry and range of Integrated Circuits are suitable and specifically designed for appropriate use in technical
applications, such as in devices, systems and any kind of technical equipment, in so far as they do not infringe existing patent rights. In principle the range of
use is limitless in a technical sense and refers to the products listed in the inventory of goods compiled for the 2008 and following export trade statistics issued
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We understand suitable application of our published designs to be state-of-the-art technology which can no longer be classed as inventive under the stipulations
of patent law. Our explicit application notes are to be treated only as mere examples of the many possible and extremely advantageous uses our products can
be put to.
iC-ML
HALL Position Sensor / Encoder
Rev A3, Page 17/17
ORDERING INFORMATION
Type
Package
Order Designation
iC-ML
iC-ML evaluation board
TSSOP20
iC-ML TSSOP20
iC-ML EVAL ML1D
For technical support, information about prices and terms of delivery please contact:
iC-Haus GmbH
Am Kuemmerling 18
D-55294 Bodenheim
GERMANY
Tel.: +49 (61 35) 92 92-0
Fax: +49 (61 35) 92 92-192
Web: http://www.ichaus.com
E-Mail: [email protected]
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