SMD-04B

Optical Encoder IC

1. OVERVIEWThe SMD-04B is a high precision optical encoder ic that employs a diffraction image reflection method.
It implements an OEIC (Opto-Electric Integrated Circuit) and LED in a single package. Light emitted
from the LED is projected onto a scale, and the reflected diffraction image detected by a photodiodedetector is used to determine the relative movement between the SMD-04B and the scale. A Z-phaseorigin signal can also be output by establishing a pattern for origin detection on the scale. It also features aphotodiode detector array to reduce degradation in phase characteristics due to variations in mounting
accuracy.

2. FEATURES
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Compact, clear molded package (5.3mm×4.3mm×1.0mm)
5μm resolution (generated on A and B phases using scale with 20μm pitch pattern)
Analog output with 20μm cycle (sine wave) and Z-phase digital output
LED and OEIC fabricated in a single package
LED brightness setting and automatic brightness adjustment selectable using external pins
LED brightness auto power control function to reduce variation in analog output signal amplitude
4.5 to 5.25V supply voltage
22.0mA current consumption

3. BLOCK DIAGRAM

SMD-04B Data Sheet
DE220202-E001

2024.07
1/13

SMD-04B

Optical Encoder IC

4. PIN LAYOUT

SWL1

1

14

VSS

SWL2

2

13

NC

VDD

3

12

VA

VZ

4

11

VAB

NC

5

10

VB

NC

6

9

VBB

SWV

7

8

VREF

5. PIN DESCRIPTION
No.

Name

I/O

1

SWL1

I

LED brightness setting input 1 (with pull-up resistance)

2

SWL2

I

LED brightness setting input 2 (with pull-up resistance)

3

VDD

-

Supply voltage

4

VZ

O

Z-phase digital signal output

5

NC

-

No connection (leave open-circuit)

6

NC

-

No connection (leave open-circuit)

7

SWV

I

Reference voltage setting input

8

VREF

O

Reference voltage output

9

VBB

O

B-phase inverting analog signal (BB phase) output

10

VB

O

B-phase analog signal (B phase) output

11

VAB

O

A-phase inverting analog signal (AB phase) output

12

VA

O

A-phase analog signal (A phase) output

13

NC

-

No connection (leave open-circuit)

14

VSS

-

GroundSMD-04B Data Sheet
DE220202-E001

Function(with pull-up resistance)

2024.07
2/13

SMD-04B

Optical Encoder IC

6. ABSOLUTE MAXIMUM RATINGS
Parameter

SymbolConditions

Rating

Unit

note

Supply voltage range

VDD

Voltage between VDD and VSS-0.3 to +6.0

V*1

Input voltage range

VIN

SWL1 , SWL2 , SWV pins

-0.3 to VDD+0.3

V*1, *2

Output voltage range

VOUT

VA , VAB , VB , VBB ,VREF , VZ pins

-0.3 to VDD+0.3

V*1, *2

Storage temperature range

TSTG-30 to +85

°C

*3

-

*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: VDD in absolute value ratings refers to the recommended operating voltage VDD value.
*3: Stored separately in Nitrogen (N2) atmosphere or vacuum.

7. RECOMMENDED OPERATING CONDITIONS
VSS=0V
Parameter

SymbolConditions

MIN

TYP

MAX

Unit

Supply voltage

VDD

Between VDD and VSS terminals

4.5

-

5.25

V

Operating temperature

Ta

−30

-

85

°C

Response speed

Rt

0

-

2

m/s

* Operation outside the recommended operating conditions may adversely affect reliability. Use only
within specified ratings.

SMD-04B Data Sheet
DE220202-E001

2024.07
3/13

SMD-04B

Optical Encoder IC

8. ELECTRICAL CHARACTERISTICS
8.1. DC Characteristics
VDD = 5V ,VSS = 0V , Ta = 27C unless otherwise noted

Parameter

SymbolConditions

MIN

TYP

MAX

Current consumption 1

IDD1

SWL1 = H , SWL2 = H

-

10

16

Current consumption 2

IDD2

SWL1 = H , SWL2 = L

-

14.2

22

Current consumption 3

IDD3

SWL1 = L , SWL2 = H

-

22

32

Current consumption 4

IDD4SWL1 = L , SWL2 = L

-

5

9

Reference voltage 1

Vref1

SWV=H

1.1

1.45

1.8

Reference voltage 2

Vref2

SWV=L

1.8

2.25

2.7

A-phasesignal offset voltage

VAO

AB-phasesignal offset voltage

VABO

B-phasesignal offset voltage

VBO

BB-phasesignal offset voltage

VBBO

Output voltage
fluctuation 1

VD1

Output voltage
fluctuation 2

VD2

Output voltage
fluctuation 3

VD3

Output voltage
fluctuation 4

VD4

HIGH-level
input voltage

VIH

LOW-level
input voltage

Unit

Pins

mA

VDD

V

VREF

VA

SWL1 = L , SWL2 = L
Variation from VREF

VAB
-0.15

-

0.15

V
VB
VBB

Difference between
0µA and 50µA
sink current
Difference between
0µA and 50µA
sink current
Difference between
0µA and 50µA
sink current
Difference between
0µA and 50µA
sink current

0

-

30

-30

-

0

0

-

150

mV

VA
VAB
VB
VBB

mV

VREF

-150

-

0

-

0.8*VDD

-

VDD

V

VIL

-

0

-

0.2*VDDV

HIGH-level
input current

IIH

VIN=VDD

-1

-

1

µA

LOW-level
input current

IIL

VIN=VSS

-20

-1

µA

Z-phase signal
HIGH-level voltage

VOH

Iout=0.5mA,
SWV=L

0.8*VDD

-

VDD

V

VZ

Z-phase signal
LOW-level voltage

VOL

Iout=-0.5mA

0-0.2*VDDV

VZ

SMD-04B Data Sheet
DE220202-E001

2024.07
4/13

SWL1
SWL2
SWV

SMD-04B

Optical Encoder IC

8.2. Analog Characteristics
VDD = 5V ,Parameter

SymbolA-phase output
signal amplitude

VAP-P

AB-phase output
signal amplitude

VABP-P

B-phase output
signal amplitude

VBP-P

BB-phase output
signal amplitude

VBBP-P

A-phase - B-phasedifferenceDP

Conditions

VSS = 0V , Ta = 27C unless otherwise noted
MIN

TYP

MAX

Unit

Pins
VA

SWL1 = L , SWL2 = H
Standard scale conditions
Value of peak to peak

VAB
0.8

1.2

1.92

V
VB
VBB

Standard scale conditions

Standard scale conditions
Z-phase signal
WZ
output width
T = 20 μm※1
*1: “T” indicates the width of a single VA and VB cycle.

80

90

100

°

VA,VB

0.17T

0.5T

0.7T

μm

VZ

VB

VBO

VBP-P center
VBP-P

Vref1 (or Vref2)
VAP-P
VAP-P center

VAO
20μm
VA

VAO and VBO indicate the difference between the VA and VB center line and Vref1 (or Vref2), respectively.

Wz
VZ

Vref1 (or Vref2)

VA

SMD-04B Data Sheet
DE220202-E001

T

2024.07
5/13

SMD-04B

Optical Encoder IC

8.3. AC Characteristics
VDD = 5V ,VSS = 0V , Ta = 27C unless otherwise noted

Parameter

SymbolConditions

MIN

TYP

MAX

Unit

Pins

Z-phase output signal
rise timetr

SWV = L , CL = 15 pF
0.1VDD → 0.9VDD

-

-

100

ns

VZ

Z-phase output signal
fall timetf

SWV = L , CL = 15 pF
0.9VDD → 0.1VDD

-

-

100

ns

VZ

8.4. Standard Scale Conditions
Electrical characteristics established under the following conditions.
Parameter

Conditions

Unit

Reflecting surface reflectance50%

Non-reflecting surface reflectance10%20μm pitch,(10μm Cr line/10μm space)-Z-phase pattern

30μm Cr line-

Gap (ΔGap)

0.5

mm

Yaw angle (Δθy)
Roll angle (Δθr)
Pitch angle (Δθp)

0

°

Scale
Incremental pattern

Mounting

SMD-04B Data Sheet
DE220202-E001

2024.07
6/13

SMD-04B

Optical Encoder IC

9. FUNCTIONAL DESCRIPTIONThe SMD-04B projects visible LED light with a center wavelength of 650nm through a slit and onto ascale with a 20μm pitch pattern (10μm line/10μm space), and detects the relative movement between the
ic and the scale by receiving a diffracted image of the reflected light using a photodiode detector. It
outputs analog signals (sine wave) with 20μm period comprising an A-phase (VA) and B-phase (VB) thatare 90° out of phase. It can also output a Z-phase digital signal formed using a 30μm reflective pattern at
one location on the 20μm pitch scale. The Z-phase signal is output when the A-phase is HIGH (VA>Vref1(or Vref2)).
To enable the Z-phase signal, set the LED brightness switching function to APC as described in section
9.1.

9.1. LED Brightness Switching Function
The SMD-04B has a function that adjusts the variation in signal amplitude by adjusting the LED
brightness. The signal amplitude can be adjusted by changing the LED current to control the LED
brightness as shown in the following table.
For details about APC adjustment, see section 9.2.
SWL1

H

L

SWL2

H

L

H

L

A,B-phase analog signal amplitude

×1.0

×1.8

APC

OFF

9.2. LED Auto Power Control (APC) Brightness Adjustment Function
The SMD-04B has a built-in APC (Auto Power Control), LED brightness automatic adjustment function.
It detects the light reflected from the scale using the photodiode detector, and controls the LED current toadjust the brightness.
In addition to reducing the fluctuation in amplitude of the A-phase (VA) and B-phase (VB) signals due
to fluctuations in LED brightness, it also reduces the temperature dependency of the signal amplitude bycompensating for changes in LED brightness due to temperature variations.

9.3. Reference Voltage Switching Function
The SMD-04B has a function for switching the reference voltage (Vref) by changing the setting of theSWV pin. Set the reference voltage according to the required input conditions of the following stage
circuit.
When used with SWV=H, the VZ pin becomes an open-drain output.

SMD-04B Data Sheet
DE220202-E001

2024.07
7/13

SMD-04B

Optical Encoder IC

10. Scale Mounting Conditions
The optical center of the encoder ic is offset from the physical center by 0.77 mm in the verticaldirection (ΔY in the diagram below) and 0.0mm in the horizontal direction (ΔX in the diagram below). If
using a linear scale, you only need to take the offset in the scale width direction (ΔY) into account. If
using a rotary scale, the offset in the horizontal direction (ΔX) must also be taken into account.
The optimum optical conditions of the product will vary depending on the mounting conditions.
Conduct careful evaluation to meet requirements. In particular, the effects on amplitude and phasedifference due to mounting conditions are larger if using a small diameter rotary scale than if using alinear scale. Provision of separate mounting adjustments is recommended to achieve better productperformance.
Roll angle Δθr
Scale

Yaw angle ΔθyAlignment center
between ic andscale

IC (this product)

Gap
Δθp

ΔGap

Pitch angle
Alignment center between ic and scale
IC center
Center in scale width direction+SW

Scale vertical offset ΔY−SW

IC center

Scale horizontal offset ΔX[Reference data]
Parameter
Scale
Mounting

SMD-04B Data Sheet
DE220202-E001

Conditions

Unit

Scale width (±SW)±1 (min.)mm

Scale vertical offset (ΔY)

0.77

mm

Scale horizontal offset (ΔX)

0.0

mm

2024.07
8/13

SMD-04B

Optical Encoder IC

11. TYPICAL CHARACTERISTICS* NPC standard scale and mounting conditions

11.1. Mounting Characteristics

Amplitude v. Gap (ΔGap)

Phase difference v. Gap (ΔGap)

Amplitude v Yaw angle (Δθy)

Phase difference v. Yaw angle (Δθy)

Amplitude v. Roll angle (Δθr)

Phase difference v. Roll angle (Δθr)

Amplitude v. Pitch angle (Δθp)

Phase difference v. Pitch angle (Δθp)

SMD-04B Data Sheet
DE220202-E001

2024.07
9/13

SMD-04B

Optical Encoder IC

11.2. Temperature Characteristic

Amplitude v. Temperature (Ta)11.3. Frequency Response

Amplitude v. Frequency

SMD-04B Data Sheet
DE220202-E001

2024.07
10/13

SMD-04B

Optical Encoder IC

12. PACKAGE DIMENSIONSTop view(Unit : mm)

5.3±0.1

0.4

LED

(0.3)

Side view2

4.3±0.1

0.6×6=3.6

Light cutwallGold(Au)
electrodes

OEIC

IC center

1.0±0.15

Side view1
Epoxy resin
Glass-epoxy substrate

0.6×6=3.6

0.3±0.075

Bottom view

0.6

SMD-04B Data Sheet
DE220202-E001

2024.07
11/13

SMD-04B

Optical Encoder IC

13. USAGE NOTE
Keep this product and the wiring emerging from this product (specifically the analog signal wiring) as
far away as possible from the wiring for the drive actuator. The susceptibility of the encoder ic signal tonoise will increase the closer the wiring is positioned. Chattering of the digital signal may occur withincreasing noise, adversely affecting position detection accuracy.
To reduce the effects of noise, connect capacitors to the VDD and VSS lines of the product as shown below.

0.1μF(Mounted as close
to ic as possible)

1.SWL1

14.VSS

2.SWL2

13.NC

3.VDD

12.VA

4.VZ

10μF
(Regulator circuit)
5.0±0.25V

SMD-04B Data Sheet
DE220202-E001

SMD-04B 11.VAB

5.NC

10.VB

6.NC

9.VBB

7.SWV

8.VREF2024.07
12/13

SMD-04B

Optical Encoder IC

14. USAGE AND PRECAUTIONSThis product is designed and manufactured to the generally accepted standards of reliability as expected for use ingeneral electronic and electrical equipment, such as personal equipment, machine tools, and measurement
equipment. This product is not designed and manufactured to be used in any other special equipment requiringextremely high level of reliability and safety, such as aerospace equipment, nuclear power control equipment, medical
equipment, transportation equipment, disaster prevention equipment, security equipment.
If you wish to use this product in equipment requiring extremely high level of reliability, please contact our sales
department or representative in advance.
In the event that this product is used in such equipment, please take scrupulous care and apply fail-safe techniques
including redundancy and malfunction prevention in order to prevent damage to life, health, property, or infrastructureetc. in case there is some malfunction in the product.

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 aerospaceequipment, 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 thatexerts 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 orreliability 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 orother applicable laws and regulations, approval of the export to be based on those laws and regulations are necessary.
Customers are requested appropriately take steps to obtain required permissions or approvals from appropriate
government agencies.
6. When exporting customer’s products that use the Products, customers must comply with the "Foreign Exchange andForeign Trade Act" and other export-related laws and regulations, and follow the necessary procedures inaccordance with those laws and regulations. Do not use the Products in equipment whose sale is prohibited byexport-related laws and regulations ("JP Foreign Exchange and Foreign Trade Act" and "US Export Administration
Regulations", etc.). In addition, please do not sell the Products to users who are expected to use it for the above
equipment or companies in its supply chain. If a user who uses module parts and equipment using the Products is acompany suspected of violating human rights, please do not sell the above parts and equipment to that user.

SEIKO NPC CORPORATION
2-9-4, Taito, Taito-ku,
Tokyo 110-0016, Japan
Telephone: +81-3-6747-5300
Facsimile: +81-3-6747-5303
https://www.npc.co.jp/
Email:sales@npc.co.jp

SMD-04B Data Sheet
DE220202-E001

2024.0713/13