SM3473A/B
Interpolation IC for MR Sensors
■OVERVIEW
The SM3473 is an interpolation IC for use with MR sensors. It accepts 2-phase Cos/Sin analog signals from an MR sensor, and
outputs a 2-phase incremental pulse with frequency generated by the division of the analog signal by a selectable 1, 2, 4, 8,16×
interpolation factor. The analog signal is amplified, with the amplifier gain set by an external resistor voltage divider connected
across the supply lines, before interpolation.
■FEATURES
■PIN LAYOUT
QFN16 package
（Top View)
・Interpolation factor:
1, 2, 4, 8, 16 selectable
Ver. A ： 1，2，4，8
Ver. B ： 2，4，8，16
・Input frequency: 50kHz (max)
・Supply voltage: 3.0 to 5.5V
・Operating temperature range: -20 to +85°C
・Current consumption: 2.6mA (typ @ VDD=5V)
1.0mA (typ @ VDD=3.3V)
・Input signal amplitude: 33mVpp to 600mVpp
@ VDD=5V
・Package: 16 pin QFN（size：3mm×3mm）
■ORDERING INFORMATION
Device
Package
SM3473A/B-G＊
16 pin QFN
*1. “-G” option code lead-free package
■PACKAGE DIMENSIONS
Unit: mm
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SM3473A/B
■BLOCK DIAGRAM
VDD
A(cos)
AMP
x5~x30
ANsig(-cos)
Asig(cos)
AN(-cos)
Interpolation
B(sin)
AMP
x5~x30
Buffer
DA
Buffer
DB
Output
controller
BNsig(-sin)
Bsig(sin)
BN(-sin)
GS
EX1
EX2
MODE0 MODE1
MODE2
VSS
IPSL0 IPSL1
■PIN DESCRIPTION
No.
Name
I/O
Description
1
EX1
O
Test output
2
DB
O
B-phase interpolation digital signal output
3
DA
O
A-phase interpolation digital signal output
4
IPSL1
I
Interpolation factor select input 1
5
IPSL0
I
Interpolation factor select input 0
6
MODE2
I
Mode select input 2
7
MODE1
I
Mode select input 1
8
MODE0
I
Mode select input 0
9
A
I
A-phase non-inverted input
10
AN
I
A-phase inverted input
11
B
I
B-phase non-inverted input
12
BN
I
B-phase inverted input
13
VSS
Ground
14
GS
I
Analog gain select input
15
VDD
Supply voltage
16
EX2
O
Test output
17
TP
Thermal pad. Connect to VSS or leave open.
I: Input, O: Output
The GS, IPSL1, IPSL0, MODE2, MODE1, MODE0 inputs cannot be used open-circuit because they do not have
built-in pull-down/pull-up resistors. Always apply the required voltages to these inputs.
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SM3473A/B
■ABSOLUTE MAXIMUM RATINGS
VSS=0V
Parameter
Symbol
*1
Supply voltage
*1,*3
Input voltage
*1,*3
Rating
Unit
VDD
Between VDD–VSS
−0.3 to +6.5
V
VIN
*5
−0.3 to VDD+0.3
V
*6
−0.3 to VDD+0.3
V
*6
5
mA
Tj
+150
°C
TSTG
−40 to +125
°C
VOUT
Output voltage
Output current
IOUT
*2
Junction temperature
*4
Storage temperature
Conditions
Input pins
Output pins
Output pins
*1: Parameters must not exceed ratings, not even momentarily. If a rating is exceeded, there is a risk of IC failure, deterioration in
characteristics, and decrease in reliability.
*2: Parameters should not exceed ratings. If a rating is exceeded, there is a risk of deterioration in characteristics and decrease in
reliability.
*3: VDD is the supply voltage in the recommended operating conditions.
*4: Stored separately without packing material in N2 (Nitrogen) or vacuum atmosphere.
*5: Applies to A, AN, B, BN, GS, IPSL0, IPSL1, MODE0, MODE1, and MODE2 inputs.
*6: Applies to DA, DB, EX1, and EX2 outputs.
■RECOMMENDED OPERATING CONDITIONS
VSS=0V
Parameter
Supply voltage
Symbol
VDD
Logic input voltage
VIN1
Conditions
Between VDD–VSS
IPSL0, IPSL1,
MODE0, MODE1, MODE2 pins
Analog input voltage range*1
VIN2
A, AN, B, BN pins
Input signal amplitude
VINPP
Input offset voltage*2
VOFFSET
Input signal frequency
FIN
A, AN, B, BN pins
VDD=5V, Ta=25°C
A-AN midpoint voltage offset,
B-BN midpoint voltage offset,
VDD=5V, Ta=25°C, VINPP ≥ 0.1V
A, AN, B, BN pins
MIN
3.0
TYP
5.0
MAX
5.5
Unit
V
VSS
-
VDD
V
1
-
VDD − 1
V
0.033
-
0.6
VPP
−15
-
15
mV
-
-
50
kHz
-
+85
°C
Operating temperature
Ta
−20
* Operation outside the recommended operating conditions may adversely affect reliability.
Use only within specified ratings.
*1 Analog signal input voltage range VIN2 definition
*2 Offset voltage VOFFSET definition
A, AN (B, BN) ± 7.5mV
→ Absolute value (width) of 15 mV
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SM3473A/B
■ELECTRICAL CHARACTERISTICS
●Analog Circuit Electrical Characteristics
VDD=3.0 to 5.5V, VSS=0V, Ta= −20 to +85°C unless otherwise noted
Parameter
Pins
Symbol
Conditions
Operating current
consumption
VDD
Standby current
VDD
Logic input voltage
Logic input current
IPSL0
IPSL1
MODE0
MODE1
MODE2
IPSL0
IPSL1
MODE0
MODE1
MODE2
Output voltage
DA,DB
Rise/Fall time
DA,DB
MIN
TYP
MAX
IDD1
VDD=5V, no load
-
2.6
6
IDD2
VDD=3V, no load
-
1.2
4
ISTB
MODE2=MODE1=VDD,
Ta=25°C
−1
-
1
-
VDD
Unit
mA
0.7VDD
VIH
μA
V
VIL
IIH
VIN=VDD, Ta=25°C
VSS
-
0.3VDD
−1
-
1
μA
IIL
VIN=VSS, Ta=25°C
VOH
IOUT= -1.5mA
VOL
IOUT= 1.5mA
CL=20pF,
0.2VDD to 0.8VDD
Tr/Tf
−1
-
1
VDD−0.4
-
-
VDD
-
0.3
-
-
10
V
ns
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SM3473A/B
●Interpolation Accuracy Characteristics
Parameter
Angular error
Symbol
ARAL
Conditions
VDD=5V, 8x interpolation (Ver. A) /
16x interpolation (Ver. B), minimum gain (GS: GND),
Input frequency: 5kHz, sine wave input,
Input amplitude: Single-ended input 1.2Vp-p
(equivalent to 0.6Vp-p differential input),
A/B phase difference: 90° or −90°,
Input period conversion, max – min
MIN
TYP
MAX
Unit
0
-
3
deg.
*ARAL definition described below.
ARAL angular error
The angular error expresses the variation (max – min) of the phase difference between DA and DB edges relative to the ideal phase
difference.
For example, for ×8 interpolation, 8 cycles of square wave output occur within 1 input cycle. If 1 output cycle is further divided by 4 by
the DA and DB edges, the ideal phase difference between DA and DB edges is calculated by the following equation where 360° represents
1 input cycle.
360°
= 11.25°
8× 4
If the actual DA-DB phase difference between adjacent waveform edges (edges 0 and 1, 1 and 2, and so on) is 11° of the input cycle, then
the angular error at that point would be -0.25°. The angular error during 1 input cycle can then be calculated by multiplying by the
interpolation factor × 4. The ARAL angular error is the difference between the maximum and minimum values of the angular error over 1
input cycle.
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SM3473A/B
■FUNCTIONAL DESCRIPTION
●Amplifier Circuit
The amplifier circuit amplifies the 2-phase analog displacement detection signal (phase A and phase B) from a sensor.
The gain of the amplifier circuit is selected by the input voltage on GS, derived using a resistor voltage divider.
●Analog Signal Gain Selection
Use the following diagram and table to determine the input voltage on the GS input.
Input amplitude
[mVp-p]
200
to
*
IC mounting board
GS
Determine the R1 and R2 resistance values to match the output
amplitude of the magnetic sensor to be used.
For R1=Open and R2=0, the GS pin is shorted to GND. Similarly, for
R1=0 and R2=Open, the GS pin is connected to VDD.
R1 and R2 in the table are constructed using E12 series values. Use
resistance values a power of 10 (10x) times the values in the table, as
required, for the resistor voltage divider.
Also, use resistors with a value tolerance of 1% or lower.
For an amplitude of 200mVp-p or higher (marked with * in the table),
short the GS pin to GND. However, note that the amplifier has a gain of 5
even at the lowest amplification setting, so make sure that the signal
amplitude after amplification does not exceed |VDD-2V| [Vp-p].
For example, if VDD=5V, the input amplitude is 600mVp-p.
0.6Vp-p × 5 [gain] = 3Vp-p ⇔5V (VDD) - 2V = 3Vp-p
*
192
to
200
183
175
167
158
150
to
to
to
to
to
192
183
175
167
158
142
to
150
133
to
142
125
to
133
117
to
125
108
to
117
100
to
108
92
to
100
83
75
67
58
50
to
to
to
to
to
92
83
75
67
58
42
to
50
33
to
42
Resistance ratio
R1
R2
Open
0
22
1.2
33
1.8
33
3.9
6.8
1.2
33
8.2
10
3.3
2.7
1.2
2.2
1.2
3.3
1.8
1.5
1
1.8
1.2
2.7
1.8
3.3
2.2
2.2
1.8
3.3
2.7
1
1
1.8
2.2
2.7
3.3
1
1.5
1.2
1.8
1.8
2.7
2.2
3.3
1.2
2.2
1.8
3.3
1.2
2.7
3.3
10
8.2
33
1.2
6.8
3.9
33
1.2
22
1.8
33
0
Open
If phase A/B are single-ended inputs, the input amplitude column
values become doubled.
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SM3473A/B
●Interpolation Circuit
The interpolation circuit converts the analog input signal amplified by the amplifier circuit to binary using a resistor voltage divider
comparator, and outputs 2-phase digital signals using logic signal processing. The comparator has a hysteresis of approximately
45mV.
●Interpolation Factor Selection
The interpolation factor is determined by the High/Low voltage combination applied to the IPSL0 and IPSL1 pins.
The interpolation factor settings are shown in the following table.
Ver. A
Ver. B
IPSL1
IPSL0
Interpolation
factor
IPSL1
IPSL0
Interpolation
factor
0
0
8
0
0
16
0
1
4
0
1
8
1
0
2
1
0
4
1
1
1
1
1
2
●Operating Mode Selection (MODE pins)
The MODE pins are used to switch the internal node of the device for monitoring signals, and to switch to power-down mode.
The output on the output pins (DA, DB, EX1, EX2) are controlled by the High/Low combination on the MODE pins.
The mode switching settings are shown in the following table.
MODE2
MODE1
MODE0
Operating mode
DA
DB
EX1
EX2
0
0
0
Normal operating mode (digital output)
dig_A
dig_B
Hi-Z
Hi-Z
0
0
1
EX_OR output ON
dig_A
dig_B
exor(da,db)
Hi-Z
0
1
0
Output tied "L"
L
L
Hi-Z
Hi-Z
0
1
1
Output tied "H"
H
H
Hi-Z
Hi-Z
1
0
0
dig_A
dig_B
ana_A
ana_B
1
0
1
ana_AN
ana_BN
ana_A
ana_B
1
1
0
1
1
1
Hi-Z
Hi-Z
Hi-Z
Hi-Z
Simultaneous analog output mode
(Non-inverted output)
Analog output mode
(Inverted / Non-inverted output)
Power-down mode
In the table, dig_A/dig_B indicates the interpolation output, and ana_A/ana_AN/ana_B/ana_BN indicate the analog signal outputs
after signal amplification.
The analog output mode is used to check the analog waveform after internal amplification. It can be used for debugging during
prototyping, for example.
In power-down mode, the internal circuits stop and the current consumption falls below 1µA. Power-down mode is selected by
setting MODE2 and MODE1 to the same potential as VDD; the state of MODE0 has no effect.
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SM3473A/B
●Timing Diagrams
1x interpolation CW
1x interpolation CCW
2x interpolation CW
2x interpolation CCW
4x interpolation CW
4x interpolation CCW
8x interpolation CW
8x interpolation CCW
16x interpolation CW
16x interpolation CCW
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SM3473A/B
■TYPICAL APPLICATION CIRCUIT
Power-down mode not used
Sensor output amplitude: 120mVp-p
8x interpolation (Ver. A) / 16x interpolation (Ver. B)
MR sensor
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SM3473A/B
Please pay your attention to the following points at time of using the products shown in this document.
1. The products shown in this document (hereinafter ”Products”) are designed and manufactured to the generally accepted standards of
reliability as expected for use in general electronic and electrical equipment, such as personal equipment, machine tools and
measurement equipment. The Products are not designed and manufactured to be used in any other special equipment requiring
extremely high level of reliability and safety, such as aerospace equipment, nuclear power control equipment, medical equipment,
transportation equipment, disaster prevention equipment, security equipment. The Products are not designed and manufactured to be
used for the apparatus that exerts harmful influence on the human lives due to the defects, failure or malfunction of the Products.
If you wish to use the Products in that apparatus, please contact our sales section in advance.
In the event that the Products are used in such apparatus without our prior approval, we assume no responsibility whatsoever for any
damages resulting from the use of that apparatus.
2. NPC reserves the right to change the specifications of the Products in order to improve the characteristics or reliability thereof.
3. The information described in this document is presented only as a guide for using the Products. No responsibility is assumed by us for any
infringements of patents or other rights of the third parties which may result from its use. No license is granted by implication or otherwise
under any patents or other rights of the third parties. Then, we assume no responsibility whatsoever for any damages resulting from that
infringements.
4. The constant of each circuit shown in this document is described as an example, and it is not guaranteed about its value of the mass
production products.
5. In the case of that the Products in this document falls under the foreign exchange and foreign trade control law or other applicable laws and
regulations, approval of the export to be based on those laws and regulations are necessary. Customers are requested appropriately take
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SEIKO NPC CORPORATION
1-9-9, Hatchobori, Chuo-ku,
Tokyo 104-0032, Japan
Telephone: +81-3-5541-6501
Facsimile: +81-3-5541-6510
http://www.npc.co.jp/
Email:sales@npc.co.jp
ND16007-E-00 2016.07
SEIKO NPC CORPORATION - 10