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InnoSwitch3-TN

Product catalog summary

Product Overview
The InnoSwitch3-TN family is a high-efficiency off-line CV/CC QR flyback switcher IC designed for both isolated and non-isolated applications. It integrates a 725 V primary MOSFET, synchronous rectification, and secondary-side control, making it suitable for auxiliary power supplies in appliances and industrial systems.

Key Features

Multi-mode Quasi Resonant (QR) / CCM flyback controller.
Integrated FluxLink™ feedback for reliable synchronous rectification.
High efficiency across load range with up to 90% full load efficiency.
EcoSmart™ technology for energy efficiency, with less than 5 mW no-load at 230 VAC.
Advanced protection features including output over-voltage protection (OVP) and thermal shutdown.
Compliance with global safety standards such as UL1577 and TUV (EN62368-1).

Applications
Ideal for auxiliary supplies in appliances and industrial systems, the InnoSwitch3-TN family supports designs with positive and negative output rails.

Technical Specifications

Output power ranges from 10 W to 21 W depending on the model and input voltage.
Reinforced insulation with isolation voltage >4000 VAC.
Compact MinSOP-16A package reduces PCB area.

Functional Description
The IC combines a high-voltage power MOSFET switch with primary and secondary controllers. It uses a magneto-inductive coupling feedback scheme via FluxLink for accurate switching information transmission. The primary controller operates in QR, CCM, and DCM modes, while the secondary controller manages voltage and current regulation.

Design Considerations

Output power is dependent on design parameters such as input voltage and efficiency.
Primary-side overvoltage protection is achieved through an internal protection mechanism triggered by a threshold current into the PRIMARY BYPASS pin.

Example Application
A dual output power supply design for HVAC applications is provided, featuring a low component count and high efficiency. The design includes a bridge rectifier, pi-filter for EMI attenuation, and synchronous rectification for the 5 V output.

Specifications and Procedures
The document outlines the use of the InnoSwitch3-TN IC for power supply design, emphasizing the importance of a blocking diode to prevent reverse current and the calculation of a series resistor to manage overvoltage. The IC can start in self-powered mode, but a bias winding is necessary for sustained operation. Optimization of external components like the primary snubber and transformer is crucial for reducing no-load consumption.

Component Selection
For the primary-side circuit, a 0.47 mF capacitor is recommended for decoupling, with a preference for ceramic capacitors due to their compact size and stability. The bias winding should develop 7 V at minimum load to ensure low no-load power consumption. A glass passivated diode is suggested for its low junction capacitance.

For the secondary-side circuit, a 2.2 mF ceramic capacitor is recommended for the SECONDARY BYPASS pin. A 47 W resistor ensures sufficient IC supply current. The SR FET should be directly connected to the SYNCHRONOUS RECTIFIER DRIVE pin for efficiency, with a Schottky diode used for higher efficiency.

Overvoltage Protection and Snubber Circuit
The primary-side controller uses the bias winding voltage for overvoltage protection, with a Zener diode recommended for fault detection. A snubber circuit is advised to prevent voltage spikes, with RCDZ clamps offering high efficiency.

Output Capacitor and Feedback Circuit
Low ESR aluminum electrolytic capacitors are suitable, with aluminum-polymer capacitors gaining popularity. The output voltage feedback circuit should maintain a COMP pin voltage of 1.265 V.

Recommendations for Circuit Board Layout
Single-point grounding and strategic placement of bypass capacitors are crucial. The primary loop area should be minimized, and thermal considerations addressed by maximizing copper area for heat dissipation. The Y capacitor should be placed to route surge currents away from the IC.

EMI Reduction
Minimizing loop areas and appropriate component placement are key strategies for reducing EMI. A small capacitor in parallel to the clamp diode can further aid in EMI reduction.

Electromagnetic Interference (EMI) Reduction Techniques

Utilize a resistor in series with the bias winding and common mode chokes at the power supply input to reduce radiated EMI.
Shield windings on the transformer can achieve similar performance to common mode chokes and improve EMI margins.
Adjusting SR switch RC snubber component values and using a pi-filter in the input rectifier circuit can help reduce EMI.
A 1 mF ceramic capacitor at the power supply output aids in reducing radiated EMI.

Transformer Design Recommendations

Ensure the power supply delivers rated power at the lowest input voltage, with a recommended filter capacitor of at least 2 mF/W.
Set the switching frequency between 25 kHz to 95 kHz, with considerations for primary inductance and peak current tolerances.
Adjust the reflected output voltage (VOR) to maintain KP = 0.8 for universal input and KP = 1 for high-line-only conditions.

Design Optimization Considerations

Higher VOR allows increased power delivery and reduces voltage stress on output diodes and SR switches but may increase leakage inductance and secondary-side losses.
KP values close to 0.9 at minimum DC bus voltage are recommended for efficiency, though they may increase primary-side switch temperature.

Core Type and Safety Margin

Use low-loss cores to reduce thermal challenges and ensure appropriate safety margins for isolation.
For universal input designs, a total safety margin of 6.2 mm is typically required.

Primary Layers and Flux Density

Primary layers should be between 1 and 3, with a starting point of ≥200 Cmils/Amp for current density.
A maximum operating flux density of 3800 gauss is recommended to prevent core saturation under start-up or short-circuit conditions.

Quick Design Checklist

Verify maximum drain voltage and current, ensuring they do not exceed specified limits under worst-case conditions.
Conduct thermal checks to ensure temperature limits are not exceeded, allowing for part-to-part variations.

Absolute Maximum Ratings

Includes specific voltage, current, and temperature limits for various pins and components.

Thermal Resistance and Control Functions

Details on thermal resistance and control functions such as jitter frequency and maximum on-time.

Output and Circuit Protection Parameters

Specifications for ON-state resistance, drain leakage current, breakdown voltage, and thermal shutdown.

Synchronous Rectifier Specifications

Includes SR pin drive voltage, rise and fall times, and output pull-up/down resistance.

Overview
The document provides technical specifications and guidelines for the InnoSwitch3-TN series by Power Integrations. It includes detailed information on package characteristics, electrical ratings, and safety standards.

Specifications
The InnoSwitch3-TN series features a MinSOP-16A package with specific dimensions and coplanarity requirements. The primary-side current rating is 1.3 A, and the power rating is 1.35 W at 25°C. The secondary-side power rating is 0.125 W with a current rating of 3.5 A.

Package Characteristics
The package has a minimum clearance and creepage of 9.48 mm, with a distance through insulation greater than 0.4 mm. It supports a maximum RMS working isolation voltage of 512 VRMS and a maximum transient peak isolation voltage of 8 kVPK.

Safety and Standards
The product complies with UL1577 and IEC 60747-17 standards. It has a high isolation resistance and is tested for partial discharge under various conditions. The climatic category is 40/125/21.

Ordering Information
The document outlines the part ordering information, including the series number, package identifier, and features code. The MSL rating for the parts is 3.

ESD and Latch-Up
The device withstands latch-up at 125°C and has ESD protection according to ANSI/ESDA/JEDEC standards, withstanding up to ±2000 V for the Human Body Model.

Features
The InnoSwitch3-TN series includes internal feedback resistors, selectable current limit, and auto-restart for fault responses. It also features over-temperature protection with hysteretic control.

Legal and Contact Information
The document includes legal disclaimers, patent information, and contact details for Power Integrations' worldwide sales support locations.

Catalog excerpts

InnoSwitch3-TN Family High Efficiency Off-line CV/CC QR Flyback Switcher IC with Integrated 725 V Primary MOSFET, Synchronous Rectification and Integrated Secondary-Side Control Product Highlights Ideal for Isolated and Non-Isolated Applications The InnoSwitch™3-TN family dramatically increases the efficiency of auxiliary power supplies used in appliances, consumer products and industrial applications. Ideal for both isolated and non-isolated designs, this advanced flyback controller can achieve up to 90% full load efficiency, flat efficiency across the load range and very low no-load consumption. The InnoSwitch3-TN may be used as an accurate 5 V single-output power supply, with two positive rails or with both positive and negative rails. • Flybacks with positive and negative output rails • Incorporates a multi-mode Quasi Resonant (QR) / CCM flyback controller, 725 V primary MOSFET, secondary voltage and current sensing, SR driver • Integrated FluxLink™ feedback • Compact package reduces PCB area • High efficiency across load range • Accurate CV/CC independent of transformer design or external components • Easily meets 20% regulation limit on 5 V output during zero load to full-load transients The 725 V primary MOSFET, primary and secondary flyback controllers are coupled using the proprietary FluxLink communications channel. Safety-rated FluxLink communication ensures reliable synchronous rectification and accurate output CV and CC. Comprehensive safety features include output over-current protection and over-temperature protection. The small MinSOP package and a low number of external components make the InnoSwitch3-TN ICs ideal for compact designs. EcoSmart™ – Energy Efficient • Less than 5 mW no-load at 230 VAC • Enables designs that easily meet global energy efficiency regulations • Achieves up to 90% full load efficiency Advanced Protection / Safety Features Integrated output OVP Open-gate detection for SR FET Hysteretic thermal shutdown Overload power limited <15 W (5 V and <3 A) • Using accurate internal CC (constant-current) limit Figure 2. Compact MinSOP-16A M Package. Full Safety and Regulatory Compliance Maximum Output Power Table • Reinforced insulation with isolation voltage >4000 VAC • 100% production Hipot testing • UL1577, TUV (EN62368-1), CQC (GB4943.1) safety approved. VDE 0884-17 (EN60747-17) pending approval • Enables designs that have “class A” performance criteria for EN61000-4 suite of test standards, including EN61000-4-2, 4-3 (30 V/m), 4-4, 4-5, 4-6, 4-8 (100 A/m) and 4-9 (1000 A/m) Table 1. Output Power Table. Notes: 1. Minimum peak power capability. 2. Max output power is dependent on the design. Limit package temperature to <125 ºC. 3. Assumes internal output current sensing is disabled (IS-GND pins shorted) 4. Package: MinSOP-16A. • Halogen free and RoHS compliant • Auxiliary supplies in appliances and industrial systems Positive and Negative Output Dual Positive Output Green Package Figure 1. Power Supply Configuration Examples using InnoSwitch3-TN. www.power.com This Product is Covered by Patent

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PRIMARY BYPASS (BPP) PRIMARY BYPASS REGULATOR RECEIVER CONTROLLER CONTROL LOGIC From Secondary Controller FluxLink THERMAL SHUTDOWN Power Switch Figure 3. Primary Controller Block Diagram. SYNC RECTIFIER DRIVE (SR) VOUT REGULATOR 4.4 V VOUT FEEDBACK DRIVER OSCILLATOR/ TIMER Figure 4. Secondary Controller Block Diagram.

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InnoSwitch3-TN Pin Functional Description ISENSE (IS) Pin (Pin 1) Connection to the power supply output terminals. Internal current sense is connected between this pin and the SECONDARY GROUND pin. SECONDARY GROUND (GND) Pin (Pin 2) Ground connection for the secondary IC. COMPENSATION (COMP) Pin (Pin 3) This pin is connected to internal feedback network. This pin should be left open. SECONDARY BYPASS (BPS) Pin (Pin 4) It is the connection point for an external bypass capacitor for the secondary IC supply. SYNCHRONOUS RECTIFIER DRIVE (SR) Pin (Pin 5) Connection to gate terminal of external SR...

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Figure 6. Schematic RDK-710, 5 V, 1.4 A and 12 V, 0.5 A for HVAC (Heating, Ventilation and Air-Conditioning) Application. The circuit shown in Figure 6 is a low component count 5 V, 1.4 A and 12 V, 0.4 A dual output power supply using the INN3074M IC. This dual output design features a highly efficient design satisfying cross regulation requirements without a post-regulator. Bridge rectifier BR1 rectifies the AC input supply. Capacitors C1 and C2 provide filtering of the rectified AC input and together with inductor L1 form a pi-filter to attenuate differential mode EMI. Y capacitor C6 connected...

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InnoSwitch3-TN the power switch is turned off when the voltage drop across the switch falls below 0 V. Secondary-side control of the primary-side power switch avoids any possibility of cross conduction of the two switches and provides extremely reliable synchronous rectification. The secondary-side of the IC is self-powered from either the secondary winding forward voltage or the output voltage. Capacitor C7 connected to the SECONDARY BYPASS pin of InnoSwitch3-TN IC U1, provides decoupling for the internal circuitry. Total output current is monitored by an internal sense resistor between the...

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InnoSwitch3-TN aluminum capacitor of at least 22 mF with a voltage rating 1.2 times greater than the highest voltage developed across the capacitor is recommended. Highest voltage is typically developed across this capacitor when the supply is operated at the highest rated output voltage and load with the lowest input AC supply voltage. Primary Sensed OVP (Overvoltage Protection) The voltage developed across the output of the bias winding tracks the power supply output voltage. Though not precise, a reasonably accurate detection of the amplitude of the output voltage can be achieved by the primary-side...

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InnoSwitch3-TN rated with a 12 V, 0.4 A output. The SR FET driver uses the SECONDARY BYPASS pin for its supply rail, and this voltage is typically 4.4 V. A FET with a high threshold voltage is therefore not suitable; FETs with a threshold voltage of 1.5 V to 2.5 V are ideal. There is a slight delay between the commencement of the flyback cycle and the turn-on of the SR FET. During this time, the body diode of the SR FET conducts. If an external parallel Schottky diode is used, this current mostly flows through the Schottky diode. Once the InnoSwitch3-TN IC detects end of the flyback cycle, voltage...

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InnoSwitch3-TN

InnoSwitch3-TN

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