TNY284DG-TL — 5W Isolated Flyback Switcher IC, <30mW No-Load (SO-8C)

What Are the Technical Specifications of TNY284DG-TL?

Key numbers that matter: 132kHz switching means roughly half the primary inductance of 66kHz LinkSwitch designs — smaller transformer, same power. The 725V MOSFET gives 25V extra breakdown margin over TinySwitch-III. ON/OFF control keeps efficiency flat from 10% to 100% load. No PWM sag at light load.

When Should You Use (and NOT Use) the TNY284DG-TL?

✅ Use TNY284DG-TL when:

• You need an isolated flyback supply up to 5W. USB chargers, appliance standby rails, smart home hubs — anything where the output must be galvanically isolated from the mains and total power is under 5–6W.
• Standby power is the design's KPI. The <30mW no-load figure (with bias winding) hits every regulation: DOE Level VI, EU CoC Tier 2, California Title 20. For products that spend 95% of their life in standby, this is the spec that matters.
• You're upgrading from TinySwitch-III (TNY274). Same SO-8C footprint, same flyback topology, but 725V MOSFET, half the no-load consumption, and line-compensated overload protection that keeps max power flat across 85–265VAC instead of doubling at high line.
• Cost-sensitive designs that still need global compliance. The ON/OFF control eliminates loop compensation components. Self-biasing from the DRAIN pin means no auxiliary bias winding or startup resistor chain.

❌ Don't use TNY284DG-TL when:

• You need more than 5–6W adapter power. At 8.5W open-frame or 11W peak, the TNY284 is at its thermal limit. Step up to TNY285 (6W adapter) or TNY286 (7.5W adapter) in the same SO-8C package.
• You want to use the increased current limit feature. The TNY284's MOSFET physically cannot handle BP/M = 10µF (increased mode). Start at TNY285 for all three current limit options.
• You don't need isolation. If the load can float at line potential, a non-isolated buck with LNK306 costs less and needs fewer components. Flyback isolation adds a transformer, optocoupler, and TL431.
• You need CC/CV output for battery charging. TinySwitch-4 is a fixed-voltage controller. For lithium chargers with primary-side CC/CV regulation, use LinkSwitch-II (LNK623–626).

TNY284 vs TNY285 vs TNY286 — How Do They Compare?

The TinySwitch-4 family scales from 5W to 15W in the same SO-8C footprint. The differences are MOSFET die size and current limit options, not pinout or feature set.

So which one? TNY284 hits the sweet spot for USB chargers, smart plugs, and appliance standby — 5W and under. TNY285 adds 40% more power. TNY286 reaches 9W.

Common trap: Setting BP/M = 10µF on a TNY284. The MOSFET doesn't support extended power mode. You'll get low output and erratic switching.

Pin Functions at a Glance

What Are the Typical Applications of TNY284DG-TL?

Smart plug / smart home standby supply (5V/1A). A TinySwitch-4 flyback with a USB output is the reference architecture inside millions of smart plugs, Wi-Fi relays, and home automation hubs. The <30mW standby means the supply itself draws less than the Wi-Fi module it powers.

Appliance auxiliary supply (12V/300mA). Washing machines, fridges, and AC units all need a low-voltage rail for the MCU, display, and sensors. The TNY284 produces an isolated 12V rail floating safely above the chassis. Line-compensated overload protection prevents brownout failures — the MCU still gets full power when mains sags.

PC standby / ATX auxiliary supply (5VSB). The always-on 5V standby rail in desktop PSUs is a natural fit for TinySwitch-4. With <30mW no-load, the standby supply meets ErP Lot 6 before the main converter even starts. For ATX supplies needing 2–3A standby, step up to TNY288 or larger.

Analog meter / DIN-rail supply (3.3V/500mA). Industrial panel meters and DIN-rail modules need an isolated supply from 230VAC that fits in a 25mm-wide housing. The TNY284 + EFD15 or EE13 transformer stays under 12mm height — critical for compact DIN-rail form factors.

What Are the Alternatives to TNY284DG-TL?

TNY284 vs TNY274 — worth the upgrade? The TNY274 has been the workhorse for a decade. TinySwitch-4 adds 25V MOSFET headroom, halves no-load, and adds line-compensated overload — max output flat across 85–265VAC instead of 2:1. For new designs, start with TNY284. For existing ones, it's a drop-in upgrade.

TNY284 vs LNK623 — flyback for voltage, or flyback for current? TinySwitch-4 is a fixed-voltage controller — regulate with TL431 + optocoupler. LinkSwitch-II does primary-side regulation, no optocoupler. But it targets CC/CV charging and LED driving, not precision voltage rails. For clean 5V or 12V, TinySwitch-4 gives tighter regulation.

How Much Does the TNY284DG-TL Cost and Is It in Stock?

Contact ICMASS for a same-day quote. The TNY284 is an active production part with stable availability. It sits in a competitive price band with the TNY274 — typically 10–15% more than the older part, which you're paying for the higher-voltage MOSFET and lower standby consumption.

Why Buy TNY284DG-TL from ICMASS?

Full TinySwitch-4 family in one shipment. We stock TNY284 through TNY290 across SO-8C and DIP packages. If your prototype starts at 5W with a TNY284 and you later need 12W with a TNY287, we have both — same day.

Flyback design support that saves you a board spin. Tell us your input range, output voltage, and load. We'll tell you if the TNY284 is the right size, what transformer core works, and whether reduced ILIMIT mode keeps you in thermal budget. Real design feedback, not a datasheet re-read.

Complete BOM in one place. The TNY284 needs a flyback transformer, an optocoupler (PC817 or similar), a TL431 reference, an output Schottky, and a handful of passives. We stock every part in the typical TinySwitch-4 reference design — one shipment, one invoice.

Shenzhen warehouse, global shipping. Orders placed before 15:00 CST ship same day. DHL/FedEx international delivery in 5–10 days.

Frequently Asked Questions About TNY284DG-TL

Q1: Can I drop a TNY284 into a board designed for TNY274?

A: Yes — same pinout, same SO-8C footprint, same flyback topology. The TNY284 is the direct upgrade path from TinySwitch-III. The higher 725V MOSFET actually improves reliability in designs where leakage inductance spikes push near the 700V limit. One change to check: the BP/M pin capacitor. TinySwitch-III uses a fixed 100nF on the BP pin; TinySwitch-4 uses the same 100nF for standard mode. If your existing design has 100nF, it's a drop-in.

Q2: Why is my TNY284 output voltage low and switching frequency erratic?

A: The most common cause: BP/M capacitor set to 10µF. On TNY285 and above, 10µF selects increased current limit mode. On the TNY284, this mode doesn't exist — the MOSFET can't handle it. The result is low output voltage and switching dropping to 6–60kHz. Replace BP/M capacitor with 100nF (standard) or 1µF (reduced). PI Expert sometimes defaults to 10µF incorrectly — double-check this value.

Q3: Does the TNY284 brown-out detection actually work?

A: Brown-IN works. Brown-OUT is unreliable without external help. The EN/UV pin accurately detects when mains voltage drops below the threshold at startup. But once the supply is running, it may not shut down until the mains falls far below the expected threshold. For reliable brown-out, you'll need an external circuit pulling the BP/M pin below 4.9V when mains drops.

Q4: How much no-load power does TNY284 actually draw?

A: Under 30mW with a bias winding; around 100–150mW without one. The bias winding powers the IC during normal operation instead of drawing from the internal DRAIN-pin current source. The difference matters: at 30mW, the supply meets every global standard. At 150mW, you're marginal for the strictest tiers. For always-plugged-in products, add the bias winding.

Q5: TNY284DG vs TNY284PG vs TNY284KG — which package?

A: DG (SO-8C) for surface-mount, PG (DIP-8C) for through-hole, KG (eSOP-12) for best thermals. Same die in all three. The SO-8C fits automated assembly. The DIP is easier to hand-solder and sits higher off the board for natural convection. The eSOP-12 has an exposed thermal pad and handles ~15–20% more power before hitting thermal limit.

Q6: Can TNY284 work without an optocoupler?

A: No — TinySwitch-4 needs secondary-side feedback for voltage regulation. The EN/UV pin is controlled by an optocoupler transistor pulling current from the pin to disable switching cycles. Without an optocoupler and voltage reference (TL431 or Zener) on the secondary side, output voltage is unregulated. For primary-side regulation without an optocoupler, use LinkSwitch-II.

Q7: What transformer size for a 5V/1A TNY284 flyback?

A: EE13 or EFD15 core is typical. At 132kHz, the primary inductance is in the 1–2mH range. The higher frequency lets you use a smaller core than 66kHz designs. For a 5V/1A output, an EE13 with ~1.5mH primary and a 6–8 turn secondary works. PI Expert or PI Xls Designer will give you the exact numbers for your input range.

Q8: Does TNY284 need a heatsink?

A: Not at 5W with adequate PCB copper. The SOURCE pins solder to a copper pour that acts as the heatsink. At 5W adapter power from 230VAC, 200mm² of copper keeps junction temperature around 85–95°C. At 8.5W open-frame or in high-ambient (50°C+), consider the eSOP-12 (KG) package with its exposed pad.