INN3676C-H606-TL — 36W Off-Line CV/CC Flyback Switcher with Integrated SR and FluxLink (InSOP-24D)

What Are the Technical Specifications of INN3676C?

The two halves of one chip: the primary side switches the transformer; the secondary side regulates and drives the SR FET. FluxLink in the middle is what deletes the optocoupler from your BOM.

Key numbers that matter: Per the Power Integrations InnoSwitch3-EP datasheet, 75kHz is the recommended full-load switching frequency for this part. Average switching frequency must stay below 110kHz — exceed it and overload protection forces auto-restart.

The input filter needs at least 2µF per watt of capacitance (3µF/W for margin) to keep the DC bus above 70V at low line.

When Should You Use (and NOT Use) the INN3676C?

✅ Use INN3676C when:

• 20–40W adapters and chargers. The CV/CC regulation pairs cleanly with a USB-PD or QC protocol IC on the secondary side, and the integrated SR driver removes the output diode loss.
• Efficiency standards apply. DoE Level VI and CoC v5 average-efficiency limits are the reason this family exists. 94% peak plus <30mW standby clears them with margin.
• You want the optocoupler gone. FluxLink deletes the opto, the TL431, and their compensation network from the BOM — fewer aging parts, fewer failure modes.
• Appliance, utility-meter, or industrial auxiliary supplies needing wide input and a long-life feedback path.

❌ Don't use INN3676C when:

• Your supply is under ~10W. A LinkSwitch-XT LNK364DN or LinkSwitch-LP LNK562DN does the job at a fraction of the cost.
• Isolation isn't needed. For a non-isolated buck off the rectified line, an LNK306-class part is the cheaper, simpler route.
• You're above 40W open frame. Step up to the INN3677C (45W) or move to a two-stage design.
• Absolute minimum BOM cost is the only spec. A UC3842-class controller plus optocoupler is still cheaper at very high volume — the InnoSwitch3-EP premium buys efficiency and parts count, not the lowest unit price.

What Are the Alternatives to INN3676C?

INN3676C vs INN3677C — the upgrade decision in one rule. If your adapter budget lands between 36W and 45W open frame, take the INN3677C — running a 36W part at its ceiling leaves no headroom for line sag and component tolerance. Same package, same design effort, roughly the same BOM.

The InnoSwitch3-EP power ladder at 85–265VAC open frame: the INN3676C sits one step below the family's 40W ceiling — the same FluxLink and SR feature set scales from 10W to 40W across six part numbers.

INN3676C vs LinkSwitch — when the smaller family is the honest choice. Below 10W the InnoSwitch3-EP's SR driver and CCM headroom are wasted silicon. The LinkSwitch parts run the same topologies at their own power levels without the FluxLink tax.

What Are the Typical Applications of INN3676C?

USB-PD and QC wall adapters (20–40W): Add a protocol controller and a USB-C connector and the INN3676C does the power stage. The built-in CC mode handles the constant-current segments the protocol asks for, and the SR drive keeps secondary loss low where efficiency is measured.

The complete 20–40W PD chain in six blocks: the INN3676C covers the transformer, its own secondary controller, and the SR MOSFET drive — the protocol controller is the only other IC you add.

Appliance control supplies: Washing machines, dishwashers, and similar white goods need an isolated rail that survives brownouts and wide line swings. The INN3676C's 85–265VAC input range and auto-restart fault response cover both.

Utility meters and smart-grid equipment: The <30mW no-load spec matters most here — a meter supply is idle for most of its life. FluxLink also removes the optocoupler CTR drift that slowly de-rates long-life designs.

Industrial auxiliary and bias supplies: For drives, PLCs, and instrumentation, the INN3676C provides an isolated 12V/24V rail with reinforced isolation already certified — the HIPOT test is done at the factory, not in your EMC lab.

Multi-output supplies — with one caveat. A real cross-regulation trap exists here: under heavily unbalanced loads the QR controller can misread discontinuous mode and hold switching frequency back, sagging all outputs (documented on the Power Integrations community forum). Design the transformer coupling tightly and validate worst-case load steps.

Why Buy INN3676C from ICMASS?

The whole PI family on one order. An adapter BOM rarely stops at the switcher — it needs the rectifier bridge, the SR MOSFET, the output capacitors, and often an LNK-series standby rail. We stock the InnoSwitch3, LinkSwitch, TinySwitch, and TOPSwitch families together, so one shipment covers the design.

Genuine parts, verified lot. Power Integrations ICs are a common counterfeit target because they're easy to remark and hard to spot on a quick test. We source this family from authorized channels and can provide lot traceability on request.

Cross-reference support. Not sure whether the design wants an INN3676C, an INN3677C, or a TOP265KG? Tell us your power level, isolation requirement, and efficiency target — we'll narrow it to the right part number.

Shenzhen warehouse, global DHL/FedEx. Same-day shipping for orders placed before 15:00 CST. International delivery in 5–10 days.

Frequently Asked Questions About INN3676C

Q1: Does the INN3676C need an optocoupler?

A: No — FluxLink replaces it. The secondary controller senses output voltage and current and sends commands to the primary through a magnetically coupled data link. The optocoupler, TL431, and their compensation parts all leave the BOM.

Q2: Why do all my outputs sag when one rail is loaded hard?

A: Unbalanced multi-output loading can trigger false discontinuous-mode detection in QR mode. A Power Integrations community thread documents exactly this: with one secondary rail loaded heavier than the main output, the main rectifier current drops to zero early, the controller enters QR mode, and the 20µs valley-wait caps the switching frequency — all outputs sag. Tight transformer coupling and worst-case load testing are the fix.

Q3: What switching frequency should I design for?

A: 75kHz at full load, and keep the average below 110kHz. The datasheet recommends 75kHz as the loss-balance sweet spot for this part size. If average switching frequency climbs past 110kHz, the overload protection interprets it as a fault and forces auto-restart.

Q4: Why does my supply hiccup under heavy load?

A: Usually insufficient input capacitance. Below 2µF per watt the DC bus sags under 70V at low line, the controller runs out of headroom, and the supply auto-restarts. 3µF/W provides margin against capacitor tolerance and aging.

Q5: Can I drop an INN3676C into an existing opto-feedback TOP/TNY design?

A: Not directly — it's a redesign, not a swap. The transformer must be re-specified (the secondary side now carries a controller and SR MOSFET), and the opto/431 compensation network disappears. What you gain: higher efficiency, no opto aging, and fewer parts.

Q6: Is the INN3676C pin-compatible with INN3675C or INN3677C?

A: Yes, within the InnoSwitch3-EP family the InSOP-24D parts share the same pinout. Power scaling between 25W, 36W, and 45W is a part-number change with the same board. Transformer and current-limit components still need re-checking per the new rating.

Q7: What does the integrated SR driver actually do?

A: It drives an external synchronous-rectifier MOSFET on the secondary side. You supply the SR FET (a 100V-class part, sized for output current) and the INN3676C handles timing and gate drive, so the output rectifier's diode drop becomes a low-R_DS(on) channel.

Q8: What efficiency and standby should I expect?

A: Up to 94% at full load and under 30mW no-load. Those are the numbers that clear DoE Level VI and CoC v5 average-efficiency limits with margin — which is the practical reason to choose this part over a conventional opto design.

Q9: Does the secondary side need a separate SR controller IC?

A: No — the SR drive logic is inside the INN3676C's secondary controller. One external MOSFET and its gate resistors are the entire secondary power stage. This is the parts-count difference versus a controller-plus-SR-controller design.

Q10: Can the INN3676C do USB-PD without extra chips?

A: The power stage, yes — the protocol, no. CV/CC regulation is built in, but the USB-PD handshake lives in a separate protocol IC. That's standard: every PD adapter is switcher + protocol controller + connector, and the INN3676C is the switcher half.