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RS972 2-Channel Optical Encoder Module – Infrared Low-Power Incremental Encoder

Not recommended for use in safety critical applications (e.g. ABS braking system).

Key Features

2-Channel A/B Quadrature Output

High-performance A and B quadrature channels for rotation sensing and direction detection.

Infrared LED Light Source (850 nm)

Invisible 840–860 nm infrared LED. Low forward voltage: 1.4 V min / 1.9 V max at 20 mA — unique IR sensing capability.

3.3/5 V Wide Voltage Range

Operates from 2.7 V to 5.5 V — compatible with both 3.3 V and 5 V logic systems without regulators.

Ultra-Low Power Consumption

Receiver chip draws only 2 mA typical (3 mA max) — optimized for energy-efficient and battery-powered designs.

TTL

TTL Compatible with Internal Pull-Up

TTL compatible outputs; V_OH ≥ 80% of V_CC. No external components needed.

CPR

500 & 1000 CPR / 7 LPI Options

Rotary: 500 CPR and 1000 CPR. Linear: 20, 45, 90, 150, 180, 300, 360 LPI. Optical radius = 11 mm.

C-Shape Structure

Compact C-shaped package for easy mounting on motor shafts and code discs.

°C

Wide Temperature Range -40 to +85 °C

Operating and storage temperature range from -40 °C to +85 °C for industrial environments.

Specifications

Absolute Maximum Ratings

Parameter	Symbol	Range	Unit
Storage Temperature	T_s	-40 ~ +85	°C
Operating Temperature	T_A	-40 ~ +85	°C
Supply Voltage	V_cc	-0.5 ~ 7	V
Soldering Temperature	—	≤ 260 (t ≤ 5 s)	°C
Response Frequency	f	60	kHz
Reverse Voltage	V_r	5	V

Recommended Operating Conditions

Parameter	Symbol	Condition	Range	Unit
Operating Temperature	T	—	-40 ~ +85	°C
Power Supply	V_cc	Ripple voltage < 100 mV	2.7 ~ 5.5	V

Electrical Characteristics (T_A = 25 °C, V_cc = 3.3 V or 5 V)

Parameter	Symbol	Min.	Typ.	Max.	Unit	Condition
Light Source Forward Voltage	V_f	1.4	—	1.9	V	I_f = 20 mA
Light Source Wavelength	λ_p	840	—	860	nm
Receiver Chip Operating Current	I_CC	—	2	3	mA
Low Level Output Voltage	V_OL	—	0.2	0.4	V
High Level Output Voltage	V_OH	V_CC × 0.8	V_CC	—	V
A/B Rising Edge Time	t_r	—	300	—	ns
A/B Falling Edge Time	t_f	—	20	—	ns
AB Duty Cycle	D_t	40	50	60	%
A/B Phase Difference	θ	60	90	120	°e

Mechanical Dimensions

Fig.2 — Straight Lead Without Mounting Holess

RS972 Straight Lead Without Mounting Holess Dimension Drawing

ROP = 11mm, 2-Ø1.2 mounting posts

Fig.3 — Straight Lead With Mounting Holess

RS972 Straight Lead With Mounting Holess Dimension Drawing

ROP = 11mm, 2-Ø1.2 mounting posts. Unit: mm.

Fig.4 — Bent Lead Dimension

Unit: mm.

Module Printing — RS972 Series

RS972 Module Printing

Pin Definitions

Pin	Name	Function	Direction
1	V_cc	Power Supply +3.3 V / +5 V (2.7–5.5 V)	Power Supply
2	CH A	A Channel quadrature output	Output
3	CH B	B Channel quadrature output	Output
4	GND	Ground (0 V)	Ground

Output Waveform

Fig.1 — Top View Module — Counterclockwise Rotation A/B Output Waveforms

Part Number Configuration Guide

Rotary (CPR) Ordering Code

RS 97200-A

Position	Code	Meaning	Options
1–3	RS	Series Prefix	Fixed
4–6	972	Model – 2-Channel, IR LED, 60 kHz, 3.3/5 V	Fixed
7	CPR Code	Resolution (CPR)	A = 500 CPR, B = 1000 CPR
8	Mounting	Mounting Holes	0 = Without Mounting Holess, 1 = With Mounting Holess
9	Lead Type	Lead Configuration	0 = Straight Lead, 1 = Bent Lead

Example: RS97200-A = RS972, without mounting holes, straight lead, 500 CPR.

Linear (LPI) Ordering Code

RS 97200-36

Position	Code	Meaning	Options
1–3	RS	Series Prefix	Fixed
4–6	972	Model	Fixed
7	LPI Code	Linear Resolution	02 = 20, 09 = 90, 15 = 150, 18 = 180, 30 = 300, 36 = 360, 45 = 45 LPI
8	Mounting	Mounting Holes	0 = Without, 1 = With
9	Lead Type	Lead Configuration	0 = Straight Lead, 1 = Bent Lead

RS97X Series: RS970 (3-Ch, 200 kHz, Red LED) RS971 (2-Ch, 3.3/5 V, Red LED) RS972 (2-Ch, 3.3/5 V, IR LED)

Applications

Printers Plotters Servo Motors Factory Automation

Frequently Asked Questions

What makes the RS972 unique compared to the RS970 and RS971?

The RS972 uses an infrared (IR) LED light source at 840–860 nm, whereas both the RS970 and RS971 use visible red LEDs (650–660 nm). This makes the RS972 ideal for applications requiring invisible sensing, reduced ambient visible-light interference, or compatibility with IR-transparent code discs and optical paths.

What is the forward voltage of the RS972's IR LED?

The IR LED forward voltage is 1.4 V minimum to 1.9 V maximum at I_f = 20 mA. This is significantly lower than the red LED versions (1.9–2.3 V), contributing to the RS972's lower overall power consumption in the emitter circuit.

What are the CPR and LPI options for the RS972?

The RS972 offers 500 CPR and 1000 CPR rotary resolution options. For linear sensing, it supports 7 LPI options: 20, 45, 90, 150, 180, 300, and 360 LPI. The optical radius (ROP) is 11 mm.

Does the RS972 work with 3.3 V microcontrollers?

Yes. The RS972 operates from 2.7 V to 5.5 V, making it natively compatible with both 3.3 V and 5 V logic. The TTL-compatible output with V_OH ≥ 80% of V_CC ensures reliable 3.3 V logic detection without any level-shifting circuitry.

How much current does the RS972 consume?

The receiver chip draws only 2 mA typical (3 mA maximum). Combined with the IR LED's low forward voltage, the RS972 is the most power-efficient option in the RS97X family, ideal for battery-powered or energy-harvesting encoder applications.

Can the RS972 infrared encoder be used in bright ambient light?

Yes. The 850 nm IR wavelength is outside the visible spectrum and is less susceptible to interference from ambient visible light sources (such as fluorescent or LED room lighting). This makes the RS972 particularly suitable for environments with high ambient visible light where red-LED encoders may experience reduced signal-to-noise ratio.

Is the RS972 recommended for safety-critical systems?

No. The RS972 is not recommended for use in safety critical applications including ABS braking systems, life support equipment, or aerospace flight controls. It is designed for general industrial automation, office automation, and commercial equipment.

Interested in the RS972 for Your IR Sensing Application?

Contact EPOCH for samples, technical support, and volume pricing on the RS972 infrared encoder module.

Request a Quote

Legal Disclaimer: The information provided in this datasheet is for reference purposes only. EPOCH Electronic reserves the right to change specifications without prior notice. Products are not authorized for use in safety-critical applications including but not limited to life support, ABS braking, and aerospace systems. All dimensions and electrical parameters are based on datasheet revision A2. Actual performance may vary depending on operating conditions and code disc quality. Verify all specifications with the official EPOCH datasheet before design-in.

Ordering Information

Ordering Information / Part Number

RS972 series is available in a variety of options, and the specific CPR selection is as follows, based on the optical radius (ROP) = 11mm.

RS972 Series Optical Encoder Modules Ordering Information

RS972 series linear type by LPI options are as follows.

RS972 Optical Encoder Modules linear type by LPI options

Module Printing

RS972 Series Optical Encoder Modules Module Printing

Packaging Information

Item	Description	QTY/Tube	Tubes/Carton	G.W	N.W	QTY/Carton	Package Size
RS97 Series	RS97 Series Optical Encoder Modules （With Mounting Holes）	25 pcs	60 tubes	5.78 kgs	2.4 kgs	1500 pcs	620310225 (mm)
	RS97 Series Optical Encoder Modules （With Mounting Holes）	25 pcs	10 tubes	1.01 kgs	0.4 kgs	250 pcs	6004870 (mm)
	RS97 Series Optical Encoder Modules （Without Mounting Holes）	50 pcs	60 tubes	7.88 kgs	4.5 kgs	3000 pcs	620310225 (mm)
		50 pcs	10 tubes	1.36 kgs	0.75 kgs	500 pcs	6004870 (mm)

Material Weight Schedule

Material	Optical Encoder Module （With Mounting Holes）	Optical Encoder Module （Without Mounting Holes）	Tube	Carton
Weight	1.6g/pc	1.5g/pc	45g/pc	680g/160g
QTY/Carton	1,500pcs /250pcs	3,000pcs /500pcs	60 tubes/10 tubes	1pc
Weight/Carton	2,400g/400g	4,500g/750g	2,700g/450g	680g/160g
	5,780g/1500pcs 1,010g/250pcs	7,880g/3,000pcs 1,360g/500pcs