Dual Output Off-Line Non-isolated Fly-back Power Solution
AP3917B 12V/20mA+3.8V20mA EV3 Board User
’s Guide
AP3917B EV3 Page 2 of 17 06-21-2019
Rev 1.0 www.diodes.com
Chapter1 Induction
1.1 General Description
AP3917B is an off-line universal AC Voltage input step-down regulator that provides accurate constant voltage (CV), outstanding
low standby power, light loading efficiency and dynamics performance. The chip supports non-isolated buck and buck-boost
topology, and also isolated and non-isolated flyback topology. The main applications are for cost-effective home appliance
power.
Working with a single winding inductor and integrating a 650V MOSFET when used in buck topology, the BOM cost is very low.
The AP3917B EV3 Evaluation Board contains two outputs specifications: 12V20mA and 3.8V20mA, with both non-isolations
flyback. The two outputs share a three-winding transformer. The feedback circuitry samples 3.
8V output. The user’s guide
provides good design example for dual output power applications in home appliance power.
1.2 AP3917B Key Features
Universal 85V to 264V V
AC
Input
Internal MOSFET 650V (Rds(on) 10
Ω max. @25
℃
)
Maximum output Current: 170mA typ.@5V output
Low Standby Power Consumption
High Light Loading Efficiency and average efficiency can meet DOE IV and CoC V5 Tier
2
Frequency Modulation to suppress EMI to meet EN55032 and FCC part 15 class B
Rich Protection including: OTP, OLP, OLD,SCP
Extremely low system component count.
Totally Lead-free & Fully RoHS Compliant (SO-7)
Halogen and Antimony Free. “Green” Device
1.3 Applications
Non-Isolated Home Appliances including: AC Fans, Rice Cooker, Air conditioner, Coffee Machines, Soy Milk Machines, ect.
Auxiliary Power to IoT Devices.
1.4 Board Picture
Fig.1-1, Top View
Fig. 1-2, Bottom View