SLM2100

Transformer design for SLM2100 flyback converter: (1) Core selection - use EE16 or EE19 ferrite core for 12-24W applications. (2) Primary inductance - calculate based on switching frequency (65kHz typical) and power level. Lp = (Vin_min × D_max)² / (2 × Pout × fsw × Krf), where Krf is ripple factor (0.5-1.0). (3) Turns ratio - Np/Ns = (Vin_min × D_max) / (Vout + Vf) / (1-D_max). (4) Wire gauge - use litz wire or multiple strands for primary to reduce skin effect. (5) Air gap - typically 0.1-0.3mm for energy storage. (6) Safety - maintain 6mm creepage/clearance for reinforced insulation. Silan provides reference designs with transformer specifications. For custom designs, use Silan's transformer design spreadsheet or contact FAE.

Use Silan reference design transformers; contact FAE for custom specifications.

The SLM2100 operates at fixed 65kHz switching frequency with frequency modulation for EMI reduction: (1) Base frequency - 65kHz provides good balance of transformer size, EMI, and efficiency. (2) Frequency jitter - ±4kHz modulation at 250Hz rate spreads EMI spectrum and reduces peak emissions. (3) Transformer design - design for 65kHz operation with proper core material (PC40 or equivalent). (4) EMI filter - 65kHz is below CISPR conducted EMI start frequency (150kHz), simplifying filter design. (5) Audible noise - 65kHz is above audible range, preventing transformer acoustic noise. The fixed frequency simplifies design compared to quasi-resonant controllers. Burst mode operation at light loads reduces effective frequency to minimize standby losses.

Fixed 65kHz with jitter; no external frequency adjustment needed.

Achieving low standby power (<100mW) with SLM2100: (1) Burst mode - SLM2100 automatically enters burst mode at light loads, switching on/off in bursts to reduce losses. (2) Startup resistor - use high-value startup resistor (2-5MΩ) to minimize continuous loss. (3) Vcc supply - use auxiliary winding instead of startup resistor after startup. (4) Feedback optocoupler - use high-CTR optocoupler to reduce LED current. (5) Snubber - optimize snubber for minimal loss while maintaining clamping. (6) Transformer - use low-core-loss ferrite and optimized winding. (7) Measured results - typical designs achieve 50-80mW standby at 230VAC with no load. For <75mW target (EuP Lot 6), careful component selection and layout are required.

Use burst mode and optimize startup circuit; expect 50-100mW standby power.

SLM2100 comprehensive protection features: (1) Overvoltage protection (OVP) - shuts down if Vout exceeds threshold, prevents damage to load. (2) Overload protection (OLP) - limits power if output is overloaded for sustained period. (3) Overcurrent protection (OCP) - cycle-by-cycle current limiting protects MOSFET and transformer. (4) Thermal protection - shuts down if die temperature exceeds 150°C, auto-restarts when cooled. (5) Leading edge blanking - prevents false triggering from switching noise. (6) Soft start - gradually increases current limit at startup to prevent stress. (7) Short circuit protection - hiccup mode operation during sustained shorts. These protections ensure safe operation under all fault conditions and improve system reliability.

All protections built-in; no external components needed for basic protection.

The SLM2100 is designed for optocoupler feedback for accurate output regulation. Primary-side regulation (PSR) without optocoupler: (1) Not directly supported - SLM2100 requires optocoupler for feedback. (2) Alternative - consider Silan's SLM2115 which supports PSR using auxiliary winding voltage sensing. (3) PSR advantages - eliminates optocoupler, reducing cost and improving reliability. (4) PSR limitations - regulation accuracy typically ±5% vs ±1% with optocoupler. (5) Load regulation - PSR has poorer cross-regulation in multi-output supplies. For applications requiring tight regulation (<±3%) or multiple outputs, use optocoupler feedback with SLM2100. For cost-sensitive single-output applications with moderate regulation requirements, consider PSR-capable alternatives.

Use optocoupler feedback with SLM2100; consider SLM2115 for PSR applications.

EMI design considerations for SLM2100 flyback converters: (1) Frequency jitter - built-in ±4kHz jitter spreads EMI spectrum and reduces peaks by 5-10dB. (2) Input filter - use common mode choke and X/Y capacitors at AC input. 10-100nF X-capacitor typical. (3) Snubber - proper RCD snubber reduces voltage spikes and associated EMI. (4) Layout - minimize loop areas in high di/dt paths (input capacitor, primary winding, MOSFET). (5) Shielding - consider shielded transformer or copper foil shield for conducted EMI. (6) Output filter - add small LC filter on output if ripple affects load. (7) Grounding - use single-point ground connection, separate power and signal grounds. Typical designs pass CISPR22/EN55022 Class B with proper filtering. Pre-compliance testing recommended during development.

Follow Silan reference design filter; pre-test for EMI compliance early.