CNY17-X CNY17F-X Photocoupler Datasheet - 6-Pin DIP Package - Isolation 5000Vrms - CTR 40-320% - English Technical Document

1. Product Overview

The CNY17-X and CNY17F-X series are families of 6-pin Dual In-line Package (DIP) photocouplers, also known as optocouplers or optoisolators. Each device consists of a gallium arsenide infrared light-emitting diode (LED) optically coupled to a silicon NPN phototransistor. The primary function is to provide electrical isolation between two circuits while allowing signal transmission via light. The key distinction between the two series is the availability of an external base connection (pin 6) in the CNY17-X, which is absent (No Connection) in the CNY17F-X series, the latter offering reduced noise susceptibility.

1.1 Core Advantages and Target Market

These devices are designed for applications requiring reliable signal isolation. Their core advantages include a high isolation voltage of 5000 V_rms, a compact DIP form factor suitable for through-hole mounting, and selected current transfer ratio (CTR) groupings for design consistency. They are approved by major international safety standards bodies (UL, cUL, VDE, SEMKO, etc.), making them suitable for a wide range of industrial, consumer, and power supply applications where safety and noise immunity are critical.

2. In-Depth Technical Parameter Analysis

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the stress limits beyond which permanent damage to the device may occur. These are not recommended operating conditions.

• Input (LED Side): The maximum continuous forward current (I_F) is 60 mA. A short-duration (10 µs) peak forward current (I_FM) of 1 A is permissible. The maximum reverse voltage (V_R) across the LED is 6 V. The input power dissipation (P_D) is 100 mW at 25°C, derating by 3.8 mW/°C above 100°C.
• Output (Phototransistor Side): The collector-emitter voltage (V_CEO) and collector-base voltage (V_CBO, for CNY17-X only) are rated at 80 V. The emitter-collector (V_ECO) and emitter-base (V_EBO) voltages are 7 V. The output power dissipation (P_C) is 150 mW at 25°C, derating by 9.0 mW/°C above 100°C.
• Device Total: The total device power dissipation (P_TOT) must not exceed 200 mW.
• Isolation & Environment: The isolation voltage (V_ISO) is 5000 V_rms (AC for 1 minute). The operating temperature range (T_OPR) is -55°C to +110°C. The maximum soldering temperature is 260°C for 10 seconds.

2.2 Electro-Optical Characteristics

These parameters define the device's performance under typical operating conditions (T_a = 25°C unless specified).

2.2.1 Input Characteristics (Infrared LED)

• Forward Voltage (V_F): Maximum 1.65 V at I_F = 60 mA. This is the voltage drop across the LED when conducting.
• Reverse Current (I_R): Maximum 10 µA at V_R = 6 V. This is the leakage current when the LED is reverse-biased.
• Input Capacitance (C_in): Typical 18 pF. This affects high-frequency switching performance on the input side.

2.2.2 Output Characteristics (Phototransistor)

• Dark Currents: With the LED off (I_F=0), leakage currents exist. I_CEO (collector-emitter) is typically 50 nA at V_CE=10V. I_CBO (collector-base, CNY17-X only) is max 20 nA at V_CB=10V.
• Breakdown Voltages: BV_CEO and BV_CBO are min 80 V. BV_ECO is min 7 V.
• Output Capacitance (C_CE): Typical 8 pF. This affects the output switching speed.

2.3 Transfer Characteristics

These are the most critical parameters for signal coupling applications.

• Current Transfer Ratio (CTR): This is the ratio of output collector current (I_C) to input LED forward current (I_F), expressed as a percentage. The devices are grouped into four distinct CTR ranges:
  • CNY17-1 / CNY17F-1: CTR = 40% to 80% (at I_F=10mA, V_CE=5V)
  • CNY17-2 / CNY17F-2: CTR = 63% to 125%
  • CNY17-3 / CNY17F-3: CTR = 100% to 200%
  • CNY17-4 / CNY17F-4: CTR = 160% to 320%
• CTR at Low Current: At I_F = 1mA, the minimum CTR is specified (e.g., 13% for -1 grade, 56% for -4 grade), which is important for low-power or analog sensing applications.
• Saturation Voltage (V_CE(sat)): Maximum 0.3 V at I_F=10mA, I_C=2.5mA. This is the voltage across the transistor when it is fully "on."
• Isolation Resistance (R_IO): Minimum 10¹¹ Ω. This indicates the extremely high DC resistance between the input and output sides.
• Input-Output Capacitance (C_IO): Typical 0.5 pF. This small capacitance is key to achieving high common-mode transient immunity (CMTI).

2.4 Switching Characteristics

Dynamic performance is defined by turn-on/off and rise/fall times, which depend on test conditions.

• Condition 1 (V_CC=10V, I_C=2mA, R_L=100Ω):
  • Turn-on time (t_on): Typical 10 µs, Max 12 µs.
  • Turn-off time (t_off): Typical 9 µs, Max 12 µs.
  • Rise time (t_r): Typical 6 µs, Max 10 µs.
  • Fall time (t_f): Typical 8 µs, Max 10 µs.
• Condition 2 (V_CC=5V, I_F=10mA, R_L=75Ω):
  • Rise time (t_r): Typical 2 µs, Max 10 µs.
  • Fall time (t_f): Typical 3 µs, Max 10 µs.

3. Grading System Explanation

The primary grading for these photocouplers is based on the Current Transfer Ratio (CTR). The four grades (1, 2, 3, 4) offer progressively higher minimum and maximum CTR values. This allows designers to select a device that matches their required signal gain and provides consistency in production batches. For example, a digital input circuit requiring a strong, well-defined signal might use a -3 or -4 grade, while a circuit sensitive to variations might specify a tighter, lower-gain -1 grade.

4. Performance Curve Analysis

The datasheet references "Typical Electro-Optical Characteristics Curves." While the specific graphs are not detailed in the provided text, typical curves for such devices include:

• CTR vs. Forward Current (I_F): Shows how the transfer ratio changes with LED drive current, usually peaking at a specific current.
• CTR vs. Temperature: Illustrates the decrease in CTR as ambient temperature increases, which is critical for high-temperature operation.
• Collector Current (I_C) vs. Collector-Emitter Voltage (V_CE): The output characteristics of the phototransistor, showing the saturation region and the active region.
• Forward Voltage (V_F) vs. Forward Current (I_F): The IV characteristic of the infrared LED.

These curves are essential for understanding device behavior under non-standard conditions and for optimizing circuit design.

5. Mechanical and Package Information

The devices are offered in a standard 6-pin DIP package with several lead form options.

5.1 Package Dimensions and Options

• Standard DIP: The default through-hole package.
• Option M: Features a "wide lead bend" providing 0.4 inch (approx. 10.16 mm) lead spacing for compatibility with wider PCB footprints.
• Option S: Surface mount lead form. Designed for reflow soldering processes.
• Option S1: Surface mount lead form with a "low profile" for applications with height restrictions.

Detailed dimensioned drawings (in mm) are provided for each option, specifying body size, pin length, pin spacing, and seating plane.

5.2 Pin Configuration and Polarity

Clear pin identification is crucial for correct installation.

• CNY17-X (with base pin):
  1. Anode (LED +)
  2. Cathode (LED -)
  3. No Connection
  4. Emitter (Phototransistor)
  5. Collector (Phototransistor)
  6. Base (Phototransistor, external connection)
• CNY17F-X (without base pin):
  1. Anode (LED +)
  2. Cathode (LED -)
  3. No Connection
  4. Emitter (Phototransistor)
  5. Collector (Phototransistor)
  6. No Connection

6. Soldering and Assembly Guidelines

The datasheet specifies a maximum soldering temperature of 260°C for 10 seconds. This is typically for wave or hand soldering of the through-hole leads. For surface mount options (S, S1), standard infrared or convection reflow profiles with a peak temperature not exceeding 260°C should be used. Precautions should be taken to avoid excessive mechanical stress on the package during handling. Storage should be in a dry, anti-static environment within the specified temperature range of -55°C to +125°C.

7. Packaging and Ordering Information

7.1 Model Numbering Rule

The part number follows the format: CNY17-XY(Z)-V or CNY17F-XY(Z)-V

• X: Part number / CTR grade (1, 2, 3, or 4).
• Y: Lead form option (S, S1, M, or none for Standard DIP).
• Z: Tape and reel option (TA, TB, or none). Applies only to S and S1 options.
• V: Optional VDE approval marking.

7.2 Packaging Specifications

• Tube Packaging: Standard DIP and Option M are supplied in tubes containing 65 units each.
• Tape and Reel: Options S and S1 are available on tape and reel. Both TA and TB options contain 1000 units per reel.

8. Application Recommendations

8.1 Typical Application Circuits

The datasheet lists common uses: Power supply regulators (for feedback isolation), digital logic inputs (for level shifting and noise isolation), and microprocessor inputs (for interfacing with noisy external signals). A specific test circuit for switching times is shown (Figure 11), which includes an input current-limiting resistor (R_IN), an optional base-emitter resistor for the CNY17-X (R_BE), and a collector load resistor (R_L).

8.2 Design Considerations

• LED Current Limiting: Always use a series resistor to limit I_F to the desired value, typically between 1 mA and 20 mA for a balance of speed, CTR, and power.
• Load Resistor (R_L): The value of R_L on the collector affects switching speed, output swing, and power consumption. A smaller R_L gives faster fall times but reduces output voltage swing.
• Noise Immunity (CNY17F-X): The CNY17F-X series, with no external base connection, is less susceptible to noise injection into the phototransistor's base, making it preferable in electrically noisy environments.
• Speed vs. Current Trade-off: Higher I_F generally improves switching speed but increases power dissipation. Refer to the switching time specifications under different test conditions.
• CTR Degradation: CTR can decrease over the lifetime of the device, especially at high operating temperatures and currents. Derate the design accordingly for long-term reliability.

9. Technical Comparison

The key differentiator within this family is the presence (CNY17-X) or absence (CNY17F-X) of the external base pin. The CNY17-X offers more design flexibility; the base pin can be left open, connected to the emitter via a resistor (to improve speed by sweeping out stored charge), or used in specific biasing configurations. The CNY17F-X offers superior noise immunity as the phototransistor base is completely internal and inaccessible, which is a significant advantage in high-noise industrial environments. Both series share identical isolation, voltage, and CTR specifications.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the main difference between grades -1, -2, -3, and -4?

A: The difference is the guaranteed range of the Current Transfer Ratio (CTR). Grade -4 has the highest gain (160-320%), while grade -1 has the lowest (40-80%). Choose based on the required signal amplification in your circuit.

Q: When should I use the CNY17F-X instead of the CNY17-X?

A: Use the CNY17F-X when operating in environments with significant electrical noise (e.g., motor drives, industrial controls). The lack of an external base connection makes it inherently less susceptible to electromagnetic interference (EMI) coupling into the sensitive base region.

Q: How do I calculate the input series resistor for the LED?

A: Use Ohm's Law: R_IN = (V_{CC_IN} - V_F) / I_F. Assume V_F ≈ 1.2V typical (max 1.65V). For example, with a 5V supply and desired I_F of 10mA: R_IN = (5V - 1.2V) / 0.01A = 380Ω. Use a standard 390Ω resistor.

Q: Can I use this for AC signal isolation?

A: Yes, but with limitations. The phototransistor output is unidirectional (DC). To transmit AC signals, you typically need two photocouplers (one for each half-cycle) or additional circuitry to bias the output into its linear region for analog transmission, though linearity is not a specified parameter for this device.

11. Practical Design Example

Scenario: Isolating a 3.3V microcontroller GPIO pin from a 24V industrial sensor signal.

1. Device Selection: Choose CNY17F-3 for good gain (100-200% CTR) and high noise immunity.
2. Input Side (Microcontroller): GPIO pin drives the LED via a current-limiting resistor. With V_{GPIO_HIGH} ≈ 3.3V and target I_F = 5mA: R_IN = (3.3V - 1.2V) / 0.005A = 420Ω. Use 430Ω.
3. Output Side (Sensor Interface): Connect the phototransistor collector to the 24V supply via a pull-up resistor (R_L). The emitter connects to ground. Choose R_L to ensure the output saturates when on and provides a valid logic high when off. With I_C ≈ CTR * I_F = 150% * 5mA = 7.5mA (typical), and desired output logic high of ~20V when off: R_L ≤ (24V - 20V) / (I_CEO). With I_CEO max ~50nA, almost any value works for leakage. For switching speed, a 10kΩ resistor is a common starting point. The output (collector node) now provides an isolated, inverted copy of the input signal.

12. Operating Principle

A photocoupler operates by converting an electrical signal into light, transmitting it across an electrically insulating barrier, and then converting the light back into an electrical signal. In the CNY17-X/F-X series, an electrical current (I_F) flows through the infrared LED, causing it to emit photons. These photons pass through a transparent insulating mold compound and strike the base region of the silicon phototransistor. The photon energy generates electron-hole pairs in the base, creating a base current that turns on the transistor, allowing a collector current (I_C) to flow. The ratio I_C/I_F is the CTR. No electrical connection exists between the input and output, providing galvanic isolation determined by the mold compound's dielectric strength and the internal pin spacing (creepage >7.6mm).

13. Technology Trends

Photocoupler technology continues to evolve. While traditional phototransistor-based couplers like the CNY17 series remain popular for cost-effective, general-purpose isolation, trends are moving towards:

Higher Speed: Development of faster couplers using photodiode and integrated amplifier (e.g., digital isolators) for multi-Mbps data transmission.

Higher Integration: Combining multiple isolation channels or integrating isolation with other functions like gate drivers or ADC interfaces in a single package.

Improved Reliability & Lifetime: Focus on materials and designs that minimize CTR degradation over time and temperature.

Miniaturization: Migration to smaller surface-mount packages (SOIC, SSOP) with the same or better isolation ratings. The CNY17 series' S and S1 options reflect this trend towards surface-mount assembly.