Data sheet
AM512BD01_04
Issue 4, 14
th
January 2009
AM512B –
Angular magnetic encoder IC
Features
Contactless angular position encoding over 360°
Ideal for harsh environments due to magnetic
sensing
Complete system-on-chip solution
9 bit absolute encoder
Output options:
Incremental
Parallel
Serial SSI
Analogue linear
Factory optimized linearity
High rotational speed up to 30,000 rpm
5 V power supply
Low power consumption. 20 mA typical.
Extended operating temperature range
(-40 °C to +125 °C)
SMD package LQFP44
RoHS compliant (lead free)
Applications
Non-contact position or velocity
measurements:
Motor motion control
Flow measurement
Robotics
Camera positioning
Front panel switches
Workshop equipment
Mobility aids
Potentiometer replacement
General description
The AM512B is a compact solution for angular
position sensing. The IC senses the angular
position of a permanent magnet placed above
the chip. The permanent magnet must be
diametrically polarized and of cylindrical shape.
The AM512B uses Hall sensor technology to
detect the magnetic flux density distribution at
the surface of the silicon. Hall sensors are
placed in a circular array around the center of
the IC and deliver a voltage representation of
the magnetic field distribution.
The sine and cosine voltage outputs from the
sensor array vary with magnet position. The
sine and cosine signals are then converted to
absolute angle position with a fast nine bit flash
interpolator.
The absolute angle position value from the
interpolator is output either through a parallel
binary interface, a serial SSI interface or a linear
voltage output. The relative changes of the
angle position are also output as incremental
A QUAD B encoder signals. The resolution of
incremental output is 512 counts per turn.
Fig. 1: AM512B with magnet
© 2009 RLS d.o.o.
A
associate company
Data sheet
AM512BD01_04
Issue 4, 14
th
January 2009
Index
Pin description............................................................................................................................3
Absolute maximum ratings .........................................................................................................5
Operating range conditions ........................................................................................................5
Digital outputs ............................................................................................................................5
Digital inputs...............................................................................................................................5
CW or CCW rotation of the magnet............................................................................................5
Sinusoidal analogue output for monitoring .................................................................................6
Binary synchronous serial output SSI.........................................................................................7
Binary parallel output..................................................................................................................8
Incremental output......................................................................................................................8
Linear voltage output..................................................................................................................9
Hysteresis ................................................................................................................................11
Position delay...........................................................................................................................11
Nonlinearity ..............................................................................................................................11
Recommended magnet ............................................................................................................13
Magnet position ........................................................................................................................14
Mounting instructions ...............................................................................................................14
Magnet quality and the nonlinearity error .................................................................................15
Error signal...............................................................................................................................16
Typical applications ..................................................................................................................17
Characteristics .........................................................................................................................18
LQFP44 package dimensions ..................................................................................................19
Ordering information.................................................................................................................20
Sample kits...............................................................................................................................21
© 2009 RLS d.o.o.
A
associate company
2
Data sheet
AM512BD01_04
Issue 4, 14
th
January 2009
Pin description
Pin description
Pin nr. Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
*
Prog
Prg
Error
Cos
Sin
NC
NC
D8
D7/Data
D6/Vout
D5
BP
Vss
D4
D3/A
D2/Ri
Vdd
D1/B
D0
CS
Clock
BP
Vss
RefN
Vdd
Vss
DL
NC
Vss
Vss
Vss
Vdd
Vdd
BP
RefP
Agnd
Agndi
Ihal
NC
Iboh
R25
PS
Vss
BP
PS = Low
(parallel output)
OTP setup input. Connect to Vss *
OTP setup input. Do not connect *
Output for monitoring
Cosine analogue output for monitoring
and filtering
Sine analogue output for monitoring and
filtering
Not used, must leave unconnected
Not used, must leave unconnected
D8 (MSB) bit of parallel outputs
D7 bit of parallel outputs
D6 bit of parallel outputs
D5 bit of parallel outputs
Back plane – connect to Vss
Power supply 0 V
D4 bit of parallel outputs
D3 bit of parallel outputs
D2 bit of parallel outputs
Power supply +5 V
D1 bit of parallel outputs
D0 (LSB) bit of parallel outputs
Chip select. If high then digital output pins
are in high impedance
Not used, must leave unconnected
Back plane – connect to Vss
Power supply 0 V
Not used, connect to Vss
Power supply +5 V
Power supply 0 V
Data latch (active high)
Not used, must leave unconnected
Power supply 0 V
Power supply 0 V
Power supply 0 V
Power supply +5 V
Power supply +5 V
Back plane – connect to Vss
Not used, connect to Vdd
Analogue reference
Analogue reference input
Input for hall sensor bias current (18K to
Vdd)
Not used
Input for amplifier bias current (82K to
Vss)
Input for setting Agnd voltage (open = 3/5
Vdd, low = 1/2 Vdd)
Output mode selection
Power supply 0 V
Back plane – connect to Vss
PS = High
(serial, incremental and linear output)
OTP setup input. Connect to Vss *
OTP setup input. Do not connect *
Output for monitoring
Cosine analogue output for monitoring
and filtering
Sine analogue output for monitoring and
filtering
Not used, must leave unconnected
Not used, must leave unconnected
Not used, must leave unconnected
Data output for SSI
Linear voltage output
Not used, must leave unconnected
Back plane – connect to Vss
Power supply 0 V
Not used, must leave unconnected
Incremental output A
Incremental output Ri
Power supply +5 V
Incremental output B
Not used, must leave unconnected
Chip select. If high then digital output pins
are in high impedance
Clock input for SSI
Back plane – connect to Vss
Power supply 0 V
Input to define a minimum value of Vout
range
Power supply +5 V
Power supply 0 V
Data latch (active high)
Not used, must leave unconnected
Power supply 0 V
Power supply 0 V
Power supply 0 V
Power supply +5 V
Power supply +5 V
Back plane – connect to Vss
Input to define a maximum value of Vout
range
Analogue reference
Analogue reference input
Input for hall sensor bias current (18K to
Vdd)
Not used
Input for amplifier bias current (82K to
Vss)
Input for setting Agnd voltage (open = 3/5
Vdd, low = 1/2 Vdd)
Output mode selection
Power supply 0 V
Back plane – connect to Vss
Fig. 2: Pin description
Table on the left shows the
description for each pin of the
standard LQFP44 package.
The AM512B has two output
modes: parallel output mode
and serial, incremental, linear
output mode. The desired
operational mode can be
selected by pin PS. When the
mode is changed, functions of
some pins are changed.
Each AM512B is factory optimized to achieve optimum performance. The information is stored in
PROM.
© 2009 RLS d.o.o.
A
associate company
3
Data sheet
AM512BD01_04
Issue 4, 14
th
January 2009
Pins 1 and 2
are used for OTP (One Time Programming) of the chip. The OTP is carried out at the factory
and defines the behavior and accuracy of the AM512B. In operation pin 1 (Prog) must be connected to V
ss
and pin 2 (Prg) must be unconnected.
Pin 3
(Error) is an analogue output signal. It can be used for monitoring the alignment between the AM512B
and the magnet. See the “Error signal” section on page 15 for detailed information.
Pins 4 and 5
are Cosine and Sine output signals for monitoring and filtering. A low-pass filter can be made
with an external capacitor as there is a built-in 10 kΩ serial resistor. Recommended value for filtering is a
10 nF capacitor connected to V
ss
. When a 10 nF capacitor is used for filtering the position information is
delayed by an additional 10 µs. See the “Position delay” section on page 11 for detailed information.
Pins 6, 7, 28 and 39
are not connected internally. They can be left unterminated.
Pins 8, 9, 10, 11, 14, 15, 16, 18, 19
are output pins. The function of each pin is changed when the output
mode is changed. See the “Pin description” table on page 3.
Pins 12, 22, 34, 44
are back plane pins which must be connected to V
ss
.
Pins 13, 17, 23, 25, 26, 29, 30, 31, 32, 33, 43
are power supply pins. All pins must be connected.
Pin 20
(CS) is a digital input with an internal pull-down resistor. When high, all digital output pins (D8-D0)
are set to high impedance mode. This function can be used when several AM512B devices are used in
parallel mode.
Pin 21
(Clock) is a digital input for serial SSI communication. See the “Binary synchronous serial output SSI”
section on page 7 for detailed information.
Pin 24
(RefN) is a reference voltage input for minimum value of the linear output voltage (V
out
).
Pin 27
(DL) is a digital input with an internal pull-down resistor. The pin is used to latch (freeze) all 9 bits of
information. It is used only for parallel output mode. When serial output mode is selected, the signal has no
effect.
DL
Low
High
Function (parallel output mode)
Parallel output is constantly refreshed
Parallel output information is latched
Pin 35
(RefP) is a reference voltage input for maximum value of the linear output voltage (V
out
).
Pin 36
(Agnd) is a buffered analogue reference output. It is a reference voltage for analogue sinusoidal
signals. It is used by the interpolator and for analogue signal outputs.
Pin 37
(Agndi) is an internally generated reference voltage. It is generated with a V
dd
/V
ss
resistor divider.
The resistors values are 20 kΩ and 30 kΩ. The reference voltage is 3 V typically (3/5 of power supply
voltage). Agndi must be connected to an external 100 nF capacitor. The reference voltage value can be
changed to 1/2 of supply voltage by connecting the pin 41 (R25) to V
ss
.
Pin 38
(Ihal) is used to define the system sensitivity. When a resistor (R
Ihal
) is connected from pin 38 (Ihal) to
V
dd
a hall sensor bias current is defined. Recommended value for R
Ihal
is 18 kΩ. The value of R
Ihal
can be
altered to adjust the sensitivity. See the R
Ihal
/Signal amplitude characteristic chart (Figure 32, page 18).
Pin 40
(Iboh) is used to define the amplifiers bias current. When a resistor (R
Iboh
) is connected between pin
40 (Iboh) and V
ss
amplifiers bias current is defined. The value R
Iboh
must be 82 kΩ.
Pin 41
(R25) is used for setting the voltage level of Agnd (open = 3/5 V
dd
, low = 1/2 V
dd
).
Pin 42
(PS) is a digital input pin with an internal pull-down resistor for selecting the output operation mode.
PS
Low
High
Output mode
Parallel output mode
Serial, incremental and linear output mode
© 2009 RLS d.o.o.
A
associate company
4
Data sheet
AM512BD01_04
Issue 4, 14
th
January 2009
Absolute maximum ratings
Ambient temperature T
A
= 22 °C unless otherwise noted.
Parameter
Symbol
Min.
Supply voltage
V
dd
-0.3
Input pin voltage
V
in
-0.3
Input current (latch-up immunity)
I
scr
Electrostatic discharge
ESD
Junction temperature
T
j
Storage temperature range
T
st
-65
Humidity non-condensing
H
5
* Human Body Model
Max.
7
V
dd
+ 0.7
50
2
160
170
85
Unit
V
V
mA
kV
°C
°C
%
Note
*
Operating range conditions
Parameter
Operating temperature range
Supply voltage
Supply current
Input frequency
Power-up time
Symbol
T
o
V
dd
I
dd
f
in
t
p
Min.
-40
4.75
18
Typ.
5
20
Max.
125
5.25
35
500
10
Unit
°C
V
mA
Hz
ms
Note
*
**
***
*
Supply current is changed if some external components are changed. Typ. figure is for
recommended values; it does not include output drive currents.
** Input frequency is the magnet rotational speed.
*** Time between power-on and valid output data.
Digital outputs
Parameter
High level output voltage
Low level output voltage
* I
H
is high level current.
** I
L
is low level current.
Symbol
V
OH
V
OL
Min.
4
V
ss
Max.
V
dd
1
Unit
V
V
Note
At I
H
< 3 mA*
At I
L
< 3 mA**
Digital inputs
Parameter
High level input voltage
Low level input voltage
Symbol
V
IH
V
IL
Min.
3.5
V
ss
Max.
V
dd
1.5
Unit
V
V
Note
CW or CCW rotation of the magnet
The arrow in Figure 3 shows clockwise (CW) rotation of the
magnet. The picture is a top view of the magnet placed
above the AM512B. CCW is counter clockwise rotation.
1
AM512B
Fig. 3: CW rotation of the magnet
© 2009 RLS d.o.o.
A
associate company
5
NXP MCU
