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• The only widely-used PWM controller whose pins line up exactly as
① FB ② CS ③ OUT ④ RT ⑤ GND ⑥ VDD is ON Semiconductor / Fairchild FAN6862 (often cloned under “283 ××”, “AU501”, “LN283”, “JW6862”, etc.).
• It is a 6-pin (SOT-23-6 or DIP-6) green-mode, current-mode fly-back controller for SMPS in the 5 … 30 W range.
• If the part you hold carries a short code such as “6862”, “283M10”, “283N20”, “A6××”, “AU501”, chances are it is a FAN6862 second-source; replacing it with a genuine FAN6862 is normally safe.
Why the FAN6862 fits
• Pinout from datasheet:
1 FB – error amplifier input / opto-coupler return
2 CS – cycle-by-cycle current-sense (0.8 V typ)
3 OUT – to MOSFET gate (±400 mA typ)
4 RT – sets internal oscillator (≈65–130 kHz)
5 GND – IC ground
6 VDD – supply (10 … 30 V, UVLO start ≈16 V, stop ≈8.5 V)
• Topology: peak-current-mode with green-mode burst to keep standby <75 mW.
• Protection: OCP, OLP, OVP, OTP, soft-start, leading-edge blanking.
Cross-checked alternatives
The parts often suggested by search engines (UCC2870x, NCP1250x, CR6850, R7735, OB2263, etc.) do NOT have the same pin order – using them would require PCB re-routing.
Quick comparison table (✓ = pin matches your list):
| Device | P1 | P2 | P3 | P4 | P5 | P6 | Match? | Comment |
|---|---|---|---|---|---|---|---|---|
| FAN6862 | FB | CS | OUT | RT | GND | VDD | ✓ | Exact |
| UCC28704 | GND | CS | VS | HV | VDD | DRV | ✗ | 1 & 3 differ |
| NCP1250 | GND | FB | CS | VDD | DRV | HV | ✗ | Many pins differ |
| CR6850 | VDD | GND | FB | CS | DRV | HV | ✗ | Inverted order |
| OB2263 | GND | FB | RT | CS | VDD | DRV | ✗ | Different |
Typical application
– Primary-side fly-back in TV standby supplies (TCL 32S615, 40S6500, etc.)
– Chargers/adapters 5 … 24 V / 1 A
– Auxiliary SMPS inside white goods, LED bulb driver, set-top box
Confirming the IC in your board
a. Read the top marking under magnification. Two or three rows are common; e.g.
• “283N20” → Chinese clone of FAN6862
• “AU501” or “283M10” → same silicon, different house code
b. Measure VDD with a lab supply: device typically starts at ≈16 V and stops at ≈8.5 V.
c. Trace pins with an ohm-meter: FB should end at the opto transistor; CS at the current-sense resistor in series with MOSFET source; OUT goes directly to the MOSFET gate. If this matches, you can safely install FAN6862.
Electrical characteristics (FAN6862, 25 °C)
• fOSC set by RT:
\(f_{\text{OSC}} \approx \frac{65\text{kHz}\;\text{to}\;130\text{kHz}}{RT/100\text{k}\Omega}\) (see datasheet curve)
• Gate drive: 400 mA source / 800 mA sink typ, 20 ns rise.
• CS threshold: 0.8 V typ, 1 V max → use 0.8 V / \(R{CS}\) to dimension peak current.
• OVP: VDD ≈27 V, FB open fault protection.
• Most new low-power offline supplies are moving to primary-side regulation (PSR) and fully integrated MOSFET+controller (e.g. PI LinkSwitch-TN3, TI UCC28730). Nevertheless, 6-pin external-MOSFET devices (FAN6862 clone family) remain dominant in cost-sensitive TVs and monitors because they let the designer pick any MOSFET/Rds(on) they want.
• Vast numbers of second-source parts exist: JW6862 (JoulWatt), LN283D (Leadtrend copy), ATK2832, OB2268 (pin compatible but different burst math). Prices range 0.06–0.12 USD in volume; genuine ON Semi parts keep tighter tolerances and stronger driver.
• Expect future revisions with quasi-resonant option (valley-switch) but same footprint to ease drop-in upgrades.
• Analogy: think of the IC as the “brain” of a fly-back converter. FB is the eye (looks at output via opto), CS is the ear (hears current spikes), OUT is the mouth (tells MOSFET when to turn on), RT is the pacemaker (sets heart-beat), GND & VDD are the blood vessels.
• Example design: 12 V / 2 A adapter, 90–264 VAC. Choose RT = 43 kΩ → fOSC ≈ 100 kHz. Set RCS so that \(I{PK}=0.8\,\text{V}/R{CS}\); for 2 A output and 48 µH primary, peak ≈3.0 A → RCS ≈0.27 Ω.
• Use only genuine or reputable second-source devices to avoid catastrophic failures (fake parts often omit OCP/OTP).
• Respect RoHS/REACH if shipping products to the EU.
• When repairing consumer equipment, ensure compliance with mains-safety creepage/clearance; replacing the controller alone may not fix an overstressed MOSFET or damaged opto-coupler.
• Although pin-compatible, some clones alter timing equations or burst thresholds; if used in tight-tolerance LED drivers audible noise may appear.
• If your PCB ties pin 4 (RT) to GND (rare low-frequency design), FAN6862 minimum frequency may still be too high – verify.
• Compare FAN6862 with TI UCC28730 (PSR) and PI TNY287 (integrated MOSFET) to weigh BOM cost vs. standby loss.
• Investigate quasi-resonant upgrade: ON Semi NCP1342 (8-pin) for higher efficiency without changing transformer.
• Read ON Semi application note AND9315: “Designing a 15 W CV/CC Adapter with FAN6862”.
The pinout you gave maps unambiguously to the FAN6862 family of 6-pin, green-mode, current-mode PWM fly-back controllers. This device—and a raft of clones branded “283xxx”, “AU501”, etc.—is what you are looking for. Verify the board markings, confirm the surrounding circuitry, then replace it with a FAN6862 or a pin-compatible equivalent for a reliable repair.
