DIODES AP3917B Power Switchers User Guide

DIODES AP3917B Power Switchers

Induction

General Description
AP3917B is an off-line universal AC Voltage input step-down regulator that provides an 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.

AP3917B Key Features

• Universal 85V to 264V VAC Input
• Internal MOSFET 650V (Rds(on) 10Ω 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

Applications

• Non-Isolated Home Appliances including: AC Fans, Rice Cooker, Air conditioner, Coffee Machines, Soy Milk Machines, ect.
• Auxiliary Power to IoT Devices.

Board Picture

system performance
The system performance included in and output characters, specifications, EMC, protection, ect.

input characters
Input AC voltage rating| 100V/60Hz| 115/230| 240V/50Hz|

Two wire, no PE

Input AC voltage range| 85V/60Hz| –| 264V/50Hz
Input AC frequency range| 47Hz| 50/60| 63Hz
Output characters
Output voltage 1| 11.1V| 12.0V| 12.9V| Test at board terminal
Output voltage 1| 3.61V| 3.8V| 3.99V
loading current 1| 0| –| 20mA| mA
loading current 2| 4| –| 20mA
performance specifications
Standby power| –| | 12mW| @230V/50Hz
Efficiency| –| 74.32%/72.98%| –| @full load, 115V/230V
Ripple & Noise| 12V| –| 192mV| 220mV|

@full load

3.8V| –| 101mV| 150mV
Start up time| –| 16.8ms| 20ms| @full load, 85V/60Hz
EMC test
ESD test| Air| ±15kV| –| –|

@full load condition

contract| ±8kV| –| –
Surge Test| ±0.5kV| –| –| Differential mode, 2ohm, 1.2/50us
Conduction EMI| 110V| 6dB margin| –| –| FCC Part 15 Class B
230V| 6dB margin| –| –| EN55032
Protection function
SCP test| –| –| –| OK
OLP test| –| –| –| OK
OTP test| 135℃| 150℃| 165℃| OK

Environment

• Operation temperature: -20℃~85℃
• Operation Humidity: 20%~90% R.H.
• Storage temperature: 0~40℃
• Storage Humidity: 0%~95% R.H.

Schematic and bill of material

Schematic

Bill of Material

Table 3-1, bill of material

10

|

D1

| S1MWF-7, slow type diode, mark F9|

SOD123-FL

|

1

|

Diodes

11| D2| ES1J, 1A/600V, Trr 35ns| SMA| 1| Diodes
12| D3| APD260, Schottky diode, 2A/60V| DO-41| 1| Diodes
13| L1| 2.2mH,choke inductor| DIP, 0406| 1| Deloop

14

|

T1

|

EE8.3, Horizontal

| DIP, 3+3Pin,

Horizontal

|

1

|

Deloop

15| R1| 24.7k, thick film| SMD 0805, 1%| 1| Panasonic
16| R2| 13.0k, thick film| SMD 0805, 1%| 1| Panasonic
17| R3| 330k, thick film| SMD 0805, 5%| 1| Panasonic
18| R4| 27k, thick film| SMD 0805, 5%| 1| Panasonic
19| U1| AP3917B| SO-7| 1| Diodes
total| 19pcs

Transformer Specification

Electrical Diagram

• Bobbin: EE8.3, 3+3Pin, Horizontal
• Core: PC40, Ae=7mm2

Transformer Instructions

Note: the transformer needs to be varnished. Put the transformer in the varnish for 30min, then remove it to the oven at 90℃ for at least 6 hours.

Electrical Specifications

Evaluation Board Connections

PCB Layout

Circuit Description

Input EMI Filtering
The input stage is composed of fusible resistor RF1, bridge diodes (BD1), Capacitors C1 and inductor L1. Resistor RF1 is a flame proof, fusible, wire- wound resistor. It limits inrush current to safe levels for bridge diodes, provides differential mode noise reduction and acts as an input fuse in the event of short circuit. Inductor L1 and Capacitor C1 constitute a LC filter, which can smooth the input voltage and improve EMI conduction.

Control IC
AP3917B co-packages a 650V power MOSFET and control circuitry into a cost- effective SO-8 package. The device gets its start-up current from DRAIN pin with a small capacitor C3 connect to BP pin when AC source is applied.

Flyback block
The flyback system which coupled in a transformer contains two output, 12V and 3.8V. The 3.8V output winding and 12V output winding are in series, so if the turn ratio of 12V winding to 3.8V winding approximate to 12/3.8, the output voltage can be fixed to 12V and 3.8V.

Output Rectification
During the ON time of U1, current ramps in the main inductance of transformer T1 until the current reaches to the Ipk. During the OFF time the inductor current ramps down via diodes D2 and D3. D2 andD3 must be ultra-fast diode or schottky diode (Trr<50ns or lower). Capacitor C3/C5 should be selected to have an adequate ripple margin.

Output Feedback
The voltage across C4/C5 is quite smooth, so the divider R1 and R2 can reflect the output voltage. The output voltage dividend by R1 and R2 was sent to feedback pin to regulate the 3.8V output voltage, thus regulate the 12V output voltage. A small capacitor C7 about several hundreds of pF was used to prevent sharp noise of sampling circuit.

Quick Start Guide

1. The evaluation board is preset at 12V/20mA+3.8V20mA from output.
2. Ensure that the AC source is switched OFF or disconnected before doing connection.
3. Connect the AC line wires of power supply to “L and N” on the left side of the board.
4. Turn on the AC main switch.
5. Measure output terminals to ensure correct output voltages of Vo1 and Vo2 respectively.

Input & Output Characteristics

Input Standby Power
The standby power and output voltage was tested after 10min burning. The voltage data was tested at the PCB terminal. All the data was tested at room temperature.

Table 5-1, standby power and no load output voltage

Efficiency
The efficiency data was tested after 10min burning, and it was tested at the PCB terminal. All the data was tested at room temperature. 12V and 3.8V full load, input voltage range from 85V/60Hz to 265V/50Hz.

Table 5-2, Full load efficiency VS Vin data

Line Regulation
The line regulation data was tested after 10min burning. The voltage data was tested at the PCB terminal. All the data was tested at room temperature. 3.8V and 12V full load, Vin ranges from 85V to 264V.

Table 5-3, line and load regulation data

Load Regulation
The load regulation data was tested after 10min burning. The voltage data was tested at the PCB terminal. All the data was tested at room temperature. The load of Vo1 and Vo2 terminals both ranges from 10% to 100%.

Table 5-4, Vo1 and Vo2 output voltage

12.157
115V/60Hz| 3.788| 11.585| 3.784| 3.777| 3.774| 11.932| 3.772| 12.052| 3.766| 12.157
230V/50Hz| 3.786| 11.572| 3.781| 11.757| 3.774| 11.922| 3.769| 12.047| 3.764| 12.147
265V/50Hz| 3.785| 11.572| 3.780| 11.755| 3.774| 11.922| 3.768| 12.045| 3.763| 12.147

Key Performance test

Start up performance
The start-up time was measured with differential probe clipping on the input AC source, and the common low-voltage probe clipping on the output terminal. Before start-up, the buck cap should be discharged.

Table 5-5, start up performance

Turn on Waveforms
CH1: Vin; CH2: 3.8V output; CH3:12V output

Voltage Stress
The voltage tested below was between the source and the drain pin of IC. The test need use differential probe. The Vak voltage is tested between the anode and cathode of flyback diode D2/D3.

Table 5-6, MOSFET drain-source and flyback diodes Vak voltage stress

CH1: Vds/Vak2; CH2: Vak1

Output Ripple & Noise
The ripple and noise was tested at PCB terminal, using coaxial cable (1:1). The bandwidth was limited to 20MHz. A 10uF electrolytic capacitor and a 104 ceramic capacitor should be paralleled to the output terminal.

Table 5-7, ripple & noise

3.8V full load, 12V full load

| 85V/60Hz| 96| 184| Fig. 23
115V/50Hz| 96| 184| –
230V/50Hz| 101| 192| –
264V/60Hz| 101| 190| Fig. 24

Dynamic Response
The dynamic response output voltage was tested at the PCB terminal, and the bandwidth was limited to 20MHz. The loading is set 0mA as low load and 20mA as high load, and last for 0.1s respectively. The ramp is set at 40mA/us.

Conditions

|

Vin

| Output voltage(V)|

Figures

---|---|---|---
Vo1| Vo2
Max (V)| Min (V)| Max (V)| Min (V)
12V full load, 3.8V loading 0~100%| 85V/60Hz| 4.16| 3.62| 12.94| 8.65| Fig. 27
115V/60Hz| 4.10| 3.65| 12.87| 8.52| –
230V/50Hz| 4.06| 3.65| 12.87| 8.71| –
264V/50Hz| 4.10| 3.65| 12.94| 8.31| Fig. 28
3.8V full load, 12V loading 0~100%| 85V/60Hz| 3.98| 3.63| 15.01| 12.00| Fig. 29
115V/60Hz| 3.95| 3.63| 15.01| 11.94| –
230V/50Hz| 4.02| 3.63| 15.01| 11.94| –
264V/50Hz| 4.02| 3.63| 15.07| 11.94| Fig. 30

CH3:12V output; CH2:3.8V output

Protection (SCP) test
The SCP test was measured under the condition of output cable terminal short circuit.

Table 5-9, the short circuit protection test

Thermal Test
The thermal test was under room temperature after burning 1 hour. The board has no case, and using thermal imager to observe the surface temperature of IC .

System EMI Scan
The power supply passed EN55022 Class B (for 230V input) and FCC part 15 (for 110V input) EMI requirements with more than 6dB margin.

Conduction EMI test of 230V@full load
The test result can pass EN55022 Class B limitation with more than 6dB margin .

Conduction EMI test of 110V@full load
The test result can pass FCC part 15 limitation with more than 6dB margin.

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