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REFACDC009 - Reference Design

Non-Isolation Buck Converter PWM method Output 2W -12V

The BM2P129TF-EVK-002 evaluation board outputs -12V minus voltage from the input of 90Vac to 264Vac. The output current supplies up to 0.167A. BM2P109TF which is PWM method DC/DC converter IC built-in 650V MOSFET is used. The BM2P129TF contributes to low power consumption by built-in a 650V starting circuit. Built-in current detection resistor realizes compact power supply design.

  • Current mode control imposes current limitation on every cycle, providing superior performance in bandwidth and transient response.
  • The switching frequency is 100 kHz in fixed mode. At light load, frequency is reduced and high efficiency is realized.
  • Built-in frequency hopping function contributes to low EMI. Low on-resistance 9.5Ω 650V MOSFET built-in contributes to low power consumption and easy design.
  • The flywheel diode is a fast recovery diode of 1A/650V RFN1LAM6S, contributing to low power consumption.


Design Resources



Board Number Input voltage Input Frequency Output voltage Maximum output power Output current range Stand-by Power Efficiency Output ripple voltage Size Operating Temperature
BM2P129TF-EVK-002 90 to 264Vac 47 to 63Hz -12V(Typ.) 2W Iout=167mA 2 to 167mA *1 44mW Iout=0A 0.722 29mVpp *2 25mm x 45mm -10 to 65deg.C
*1 Please adjust operating time, within any parts surface temperature under 105 °C
*2 Not include spike noise

Distribution Inventory

Board Number Distributor Quantity Available
BM2P129TF-EVK-002 Mouser Electronics Inc. 2
Chip One Stop, Inc. 1
CoreStaff Co., Ltd. 1
DigiKey 1

Key Components

Board Number Part Number Product Category Datasheet Status SPICE LTspice® ? Thermal Model Symbol & Footprint 3D STEP Samacsys ECAD Library Calc Tool ROHM Solution Simulator
BM2P129TF-EVK-002 BM2P129TF AC/DC Converters ICs - Recommended - - - -
BM2P129TF-EVK-002 RFN1LAM6S Fast Recovery Diodes - Recommended - - - - -
BM2P129TF-EVK-002 RRE02VSM6S Standard Rectifier Diodes - Recommended - - - - -