Part Number: SD4938
Function: Current Mode PWM Controller with 150V MOSFET
Package: SOP-8 Type
Manufacturer: Hangzhou Silan Microelectronics ( www.silan.com.cn )
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Description
SD4938 is an offline current-mode PWM controller with an integrated 150V power MOSFET designed for switch-mode power supply (SMPS) applications. It incorporates a high-voltage startup circuit, burst mode operation for low standby power, frequency reduction at light loads, and soft-start functionality to improve efficiency and reliability. Comprehensive protection features—including overcurrent, overvoltage, undervoltage, overload, and overtemperature protection with automatic restart—make the SD4938 well suited for compact AC/DC power supplies and industrial power conversion systems.
Features
- Current-mode PWM controller with integrated 150V power MOSFET
- Input voltage range: 20V to 150V
- Integrated high-voltage self-startup circuit
- Adjustable output voltage options: 12V, 15V, and 18V
- Maximum output current: 0.5A
- Burst mode operation for ultra-low standby power consumption
- Frequency reduction at light load for improved efficiency
- Soft-start function to reduce startup stress
- Automatic restart after fault recovery
- Available in SOP-8 package
Pinout
Typical Circuit Usage
- Offline flyback power supplies
- Industrial AC/DC converters
- PoE auxiliary power supplies
- Electric bicycle power modules
- Power supplies for electric tools
- Balance wheel (self-balancing scooter) controllers
- Battery charging power supplies
- Embedded SMPS modules
Absolute Maximum Ratings
| Parameter | Symbol | Rating | Unit |
|---|---|---|---|
| High Voltage Input (Drain to Source) | VHV,MAX | 155 | V |
| Power Supply Voltage (VDD to Source) | VDD,MAX | 30 | V |
| Power Dissipation | PD | 0.8 | W |
| Thermal Resistance (Junction to Ambient) | θJA | 140 | °C/W |
| Thermal Resistance (Junction to Case) | θJC | 28 | °C/W |
| Operating Junction Temperature | TJ | 150 | °C |
| Operating Ambient Temperature | Tamb | −40 to +125 | °C |
| Storage Temperature | TSTG | −55 to +150 | °C |
How to Choose This Part
- Select the SD4938 for compact offline SMPS designs requiring an integrated high-voltage MOSFET.
- Suitable for power supplies operating from 20V to 150V input.
- Recommended when low standby power is important due to its burst mode operation.
- Choose this device for applications requiring comprehensive fault protection with automatic restart.
- Ideal for flyback converters delivering approximately 12V, 15V, or 18V outputs up to 0.5A.
- Appropriate for industrial and consumer power conversion products requiring a minimal external component count.
Applications
- Balance wheel
- Offline flyback converters
- Power over Ethernet (PoE) equipment
- Electric bicycles (E-bike)
- Self-balancing scooters
SD4938 Datasheet PDF Download
