LOW POWER PWM CONTROLLER FOR OFF-LINE ADAPTER AP3710 · The AP3710 is a green-mode PWM controller, its main applications are low power supplies such as offline battery chargers, adapters,

LOW POWER PWM CONTROLLER FOR OFF-LINE ADAPTER AP3710

Data Sheet

1

BCD Semiconductor Manufacturing LimitedJan. 2013 Rev. 1. 4

General Description

The AP3710 is a green-mode PWM controller, its mainapplications are low power supplies such as offlinebattery chargers, adapters, STB and other auxiliarysupplies, where the needs for low no load power, lowtotal cost and high reliability are all required.

The functional blocks of AP3710 include: under volt-age lockout with low start-up current; precise voltagereference for internal comparators; PWM comparatorwith current limit control, feedback signal and band-gap input; short circuit comparator and open circuitprotection for opto-coupler.

The AP3710 operates at a fixed 60kHz switching fre-quency, its output connects to the emitter of high volt-age NPN transistor or the source of MOSFET. Innormal mode, it works as a switch to turn on or turn offthe external transistor. In failure modes like open loop,over voltage or overload due to short circuit, the chipenters into an auto restart mode controlled by the inter-nal protection unit.

The AP3710 is available in SOIC-8 and DIP-8 pack-ages.

Features

· Current Mode Control with Skip Cycle Capability · Low Start-up Current: 0.25mA· Low Operating Current: 0.45mA· Output Current Capacity: 900mA· Fixed Switching Frequency: 60kHz · Frequency Dithering for Low EMI· Under-Voltage Lockout with Hysteresis· Built-in Slope Compensation· Short Circuit Protection· Open and Short Circuit Protection for Opto-

Coupler· Maximum Input Power is 0.2W under No Load· Maximum Input Power is 1W under 0.5W Load· Low Total Cost Solution

Applications

· Adapters· Battery Chargers· Set Top Boxes· Auxiliary Supplies· DVD

Figure 1. Package Types of AP3710

SOIC-8 DIP-8


Data Sheet

2


Pin Configuration

Figure 2. Pin Configuration of AP3710 (Top View)

GND

NC

VCC

OUT

NC

VA

NC

VSEN

Pin Description

Pin Number Pin Name Function

1 GND Power supply ground

2 VCC The power supply of the IC and this terminal is also used for the feedback control

3, 6, 8 NC Not connected

4 OUT The PWM output is directly connected to the emitter of NPN transistor or the sourceof MOSFET

5 VSEN It is used for line voltage compensation, and PWM uses this to terminate the outputswitch conduction

7 VA It is used for short circuit protection, and this terminal will be pulled down to lowlevel when short circuit happens at the load side

M Package (SOIC-8)

1

2

3

4

8

7

6

5

GND

NC

VCC

OUT

NC

VA

NC

VSEN

P Package (DIP-8)

1

2

3

4

8

7

6

5


Data Sheet

3


Functional Block Diagram

Figure 3. Functional Block Diagram of AP3710

VCC OUT

GND

VSEN

VA

2

+-

OSCILLATOR

PWMCOMPARATOR

UVLOCOMPARATOR

DRIVER

1

4

+

-

FB

-

DISCHARGECOMPARATOR

+_

VREF(1.2V)

5

7

VREF(1.2V)

VREF(1.2V)

BIAS

START-UPCURRENTSOURCE

PWMCONTROL

DISCHARGELOGIC

SLOPCOMPENSATION


Data Sheet

4


Parameter Value Unit

Supply Voltage -0.3 to 6.3 V

Voltage at OUT -0.3 to 40 V

Analog Input at VSEN -0.3 to 6.3 V

Output Current at OUT Internally limited A

Power Dissipation 0.6 W

Operating Junction Temperature 150 oC

Storage Temperature -65 to 150 oC

Lead Temperature (Soldering, 10s) 300 oC

ESD (Machine Model) 250 V

ESD (Human Body Model) 3000 V

Note 1: Stresses greater than those listed under "Absolute Maximum Ratings" may cause permanent damage to the device.These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicatedunder "Recommended Operating Conditions" is not implied. Exposure to "Absolute Maximum Ratings" for extended periodsmay affect device reliability.

Absolute Maximum Ratings (Note 1)

Package Switching Frequency

Temperature Range

Part Number Marking IDPacking Type

Lead Free Green Lead Free Green

SOIC-8 60kHz -40 to 85oCAP3710M-E1 AP3710M-G1 3710M-E1 3710M-G1 Tube

AP3710MTR-E1 AP3710MTR-G1 3710M-E1 3710M-G1 Tape & Reel

DIP-8 60kHz -40 to 85oC AP3710P-E1 AP3710P-G1 AP3710P-E1 AP3710P-G1 Tube

BCD Semiconductor's Pb-free products, as designated with "E1" suffix in the part number, are RoHS compliant. Products with"G1" suffix are available in green packages.

Ordering Information

Circuit Type

Package

E1: Lead Free

AP3710 -

TR: Tape and ReelBlank: TubeM: SOIC-8

P: DIP-8

G1: Green


Data Sheet

5


Parameter Symbol Conditions Min Typ Max Unit

UVLO SECTION

Turn on Threshold Voltage VCC (on) 5.30 5.60 5.90 V

Turn off Threshold Voltage VCC (off) 3.4 3.65 3.90 V

Discharge Voltage VDIS 2.7 2.9 3.1 V

STANDBY CURRENT SECTION

Start-up Current IST VCC=4V 0.25 0.4mA

Operating Current ICC(opr) 0.45 0.7

VCC Zener Voltage VZ ICC=10mA 6.5 7 7.5 V

Dynamic Impedance RVCC VCC=3.8 to 4.8V (Note 2) 10 18 30 kΩ

INTERNAL OSCILLATOR

Switching Frequency FSW (Note 3) 50 60 70 kHz

Frequency Dithering ±2 ±3.5 ±5 kHz

Temperature Stability -40 to 85oC 5 %

DRIVE OUTPUT SECTION

OUT Turn-on Voltage VOUT(on) 7.6 9.3 11 V

OUT Turn-off Voltage VOUT(off) 5.7 6.8 7.9 V

Rise Time TR CL=1nF, 15Ω pull-up 60ns

Fall Time TF CL=1nF, 15Ω pull-up 30

Maximum Duty Cycle DMAX VCC(off) + 0.2V 68 75 82%

Minimum Duty Cycle VCC=VCC (on)-0.2V 3 5

Driver OUT On-Resistance ROUT IOUT=0.7A 3 5 Ω

Switch Off Current (OUT) Driver off, VOUT=10V 20 40 µA

Effective Current Limit ILIM VCC=VCC(off)+0.5V 800 900 mA

OUT Current Coefficient GA -0.6 A/V

CURRENT SECTION

Maximum Input Signal VSEN 0.9 1.0 1.1 V

VCC=4V, TJ=25oC, unless otherwise specified.

Electrical Characteristics

Note 2: Guaranteed by design, not tested in production.Note 3: The fixed oscillation frequency, the frequency jittering is not included.


Data Sheet

6


Electrical Characteristics (Continued)

Figure 4. The Test Circuit for Current Limit

+

+

AP3710

+_ VIN =10V

R100Ω/3W C1

100µF/50V

1N5819

L70µH

27V Zener

C2100µF/50V

C32200pF

OUT

VCC

GND

VCC=VCC(off)+0.5V


Data Sheet

7


Figure 7. Start-up Current vs. VCC Voltage Figure 8. Switching Frequency vs. Ambient Temperature

Typical Performance Characteristics

Figure 5. Operating Current vs. Ambient Temperature Figure 6. Start-up Current vs. Ambient Temperature

-40 -20 0 20 40 60 80 100 120

320

360

400

440

480

520

560

600

640

680

Ope

ratin

g C

urre

nt (µ

A)

Ambient Temperature (oC)-40 -20 0 20 40 60 80 100 120

120

160

200

240

280

320

360

400

Sta

rt-up

Cur

rent

(µA)

Ambient Temperature (oC)

1 2 3 4 50

100

200

300

400

500

Sta

rt-up

Cur

rent

(µA

)

VCC Voltage (V)

-40 -20 0 20 40 60 80 100 120

56

58

60

62

64

66

68

70

Switc

hing

Fre

quen

cy (K

Hz)



Data Sheet

8


-40 -20 0 20 40 60 80 100 1202.70

2.75

2.80

2.85

2.90

2.95

3.00

3.05

3.10

Dis

char

ge V

olta

ge (V

)


Figure 11. On Resistance vs. Ambient Temperature Figure 12. Turn on Voltage vs. Ambient Temperature

Typical Performance Characteristics (Continued)

Figure 9. Normalized Current Limit Figure 10. Discharge Voltage vs. Ambient Temperature

-40 -20 0 20 40 60 80 100 1200.80

0.85

0.90

0.95

1.00

1.05

1.10

N

orm

aliz

ed C

urre

nt L

imit


vs. Ambient Temperature

-40 -20 0 20 40 60 80 100 1205.0

5.1

5.2

5.3

5.4

5.5

Turn

on

Thre

shol

d Vo

ltage

(V)


-40 -20 0 20 40 60 80 100 1202.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

On

Res

ista

nce

(Ω)



Data Sheet

9


Function Description1. UVLO and Start up CircuitThe AP3710's turn on threshold voltage is 5.6V and itsturn off threshold voltage is 3.65V, so the UVLOhysteresis voltage is 1.95V, which helps AP3710 todraw adequate energy to supply VCC terminal duringstart-up. Please see Figure 13 for UVLO chart.

The VCC terminal in Figure 3 is used for both biassupply and feedback control. When AP3710 ispowered on, the start-up current source turns on and itcan not turn off until VCC level increases to itsthreshold value and PWM pulse is produced.

In start-up section of typical application shown byFigure 14, the rectified line voltage VIN charges thecapacitor C4 through start-up resistor R2+R3 until Q1is turned on so OUT terminal can directly driveexternal Q1, a MOSFET inside AP3710 is connectedin series with the Q1.

Once the start-up is set up, the auxiliary bias windingwill supply the VCC terminal enough operatingcurrent. The start-up sequence is shown in Figure 15.

VCC: Supply Voltage (V)

Turn onTurn off

ICC

: Sup

ply

Cur

rent

(µA)

5.63.65

Figure 13. 5.6/3.65V UVLO Threshold of AP3710

Figure 14. The Start-up Circuit of Typical Application

Figure 15. Power up Waveforms

U3PC817

+

OUT

VCC

GND

U1AP3710

+

Q1APT13003

D6

R6

C4

C5

C6

R7

D6

R5

R16

R14C7R16

VSEN

VA

R13

VINRectified AC VO

R2+R3

U2AZ431

R8


Data Sheet

10


2. VCC/Feedback ControlIn Figure 14, an opto-coupler and secondary constantvoltage consists of voltage feedback network. Voltagefeedback loop consists of shunt regulator AZ431 andFB/VCC terminal of AP3710. When load is heavy, thevoltage on VCC terminal will decrease to enlarge dutycycle; on the contrary, if load drops, the voltage onVCC will increase to reduce duty cycle.

3. Skip Cycle Mode Operation The AP3710 enters skip cycle mode when load powerdrops below a given level, and this is performed bysensing the VCC voltage level, i.e., the heavier loadpower, the lower VCC voltage level. In normaloperation, the VCC terminal indicates a peakinductance current under certain load power. If theload power decreases, VCC voltage level increases toask for less peak current. When it reaches adetermined value, the IC prevents the current fromdecreasing further down and starts to blank the outputpulses, the IC then enters the skip cycle modeoperation. Figure 16 is the sketch for the two operationmode.

4. Slope Compensation The AP3710 is current mode PWM controller, and itregulates peak inductance current by its currentcontrol loop. It is known that a continuous conductionmode SMPS may induce noise and harmonicoscillation on current sense or feedback signal, andthis is especially serious when duty cycle exceeds50%. The internal slope compensation of AP3710 canimprove power supply stability by increasing thecurrent slope.

5. Current Limit ControlThe AP3710 employs current mode control toimprove transient response and voltage stability. InFigure 3, the external inductor current through theOUT pin is converted to a voltage by an internalresistor, and this voltage will participate to controlduty cycle and peak inductor current.

6. Frequency DitheringFrequency dithering is performed by periodicallyspreading a single switching frequency into adjacentfrequency band, so the peak energy is spread. Thistechnique can improve EMI performance by reducingboth quasi peak and average EMI emissions.

Function Description (Continued)

Figure 17. Frequency Dither Influences the Switching Cycle

Normal PWM Waveform

Cycle SkipWaveform

Figure 16. Skip Cycle and Normal PWM Waveform

t0


Data Sheet

11


Function Description (Continued)7. Short Circuit ProtectionInternal short circuit control can protect a SMPS frombeing damaged when short circuit at its outputhappens.

In Figure 18, when VCC drops below its turn offthreshold value, the UVLO comparator's output willcontrol the Discharge Logic to pull VA terminal to lowlevel, and the low level is kept before the VCC voltagedrops below the threshold value of discharge compara-tor. Then the system will re-startup from C4 chargingagain and the same process will repeat indefinitely.The long start-up period makes the input power lowenough to ensure the whole system in safety underoutput short circuit condition.

Figure 18. Short Circuit Protection Block

DischargeLogic

DischargeComparator

FromUVLO

VA

VREF1.2V

FromVCC


Data Sheet

12


Typical Application

Figure 19. 12V/1A Adapter

++

J1AC 85-264V

D1-D4

C1

L3

C8 C9

12V/1A

U3

++

C2

VO+

VO-

+

OUT

VCC

GND

U1

+

Q1D6

R6

C4

C5

C6

R7

D5

R5

D8ZD2

R16

C7R15

D7

C3R4

R2

L2

R1

T1EE16

F1

R11

VSEN

VA

R13

U2

C11

L4

R3

R9

R14

R8

C10


Data Sheet

13


Bill of Materials for Figure 19

Designator Part Type Designator Part Type

R1 Resistor, NTC Resistor, 5Ω C1, C2 Electrolytic Capacitor, 10 µF/400V, φ10

R2, R3 Resistor, 1MΩ, 1206 C3 Capacitor, 2200pF, d=5mm

R4 Resistor, 68kΩ, 1206 C4, C5 Capacitor, 10µF, d=4.5mm

R5 Resistor, 3Ω, 0805 C6 Capacitor, 22nF, 0805

R6 Resistor, 200Ω, 0805 C7 Capacitor, 0.47µF, 0805

R7 Resistor, 2kΩ, 0805 C8 Electrolytic Capacitor, 1000µF

R8 Resistor, 5.1MΩ, SIP C9 Electrolytic Capacitor, 220µF

R9, R15, R16 Resistor, 3kΩ, 0805 C10 Y Capacitor, 2200pF

R11 Resistor, 15 Ω, 1206 C11 Capacitor, 1nF, 0805

R13 Resistor, 1kΩ, 0805 L2 Inductor, 300µH/0.3A

R14 Resistor, 11.4kΩ, 0805 L4 Inductor, 100µH/1A

T1 Transformer, EE-20

D1 to D4 Diode, 1N4007, DO-41 ZD2 Zener, 13V/1W

D5, D6 Diode, 1N4148, LL-34 Q1 Transistor, APT13003E, TO-126

D7 Diode, FR107, DO-15 U1 IC, AP3710

D8 Diode, 3100, DO-201 U3 Opto-coupler, PC817, DIP-4


Data Sheet

14


Mechanical Dimensions

Unit: mm(inch)SOIC-8

φ

0°8°

1°5°

R0.150(0.006)

R0.

150(

0.00

6)

1.000(0.039)

0.330(0.013)0.510(0.020)

1.350(0.053)1.750(0.069)

0.100(0.004)0.300(0.012)

0.900(0.035)

0.800(0.031)

0.200(0.008)

3.800(0.150)4.000(0.157)

7°

7°

20:1D

1.270(0.050) TYP

0.190(0.007)0.250(0.010)

8°

D 5.800(0.228)6.200(0.244)

0.675(0.027)0.725(0.029)

0.320(0.013)

8°

0.450(0.017)0.800(0.031)

4.700(0.185)5.100(0.201)

Note: Eject hole, oriented hole and mold mark is optional.


Data Sheet

15


Mechanical Dimensions (Continued)

DIP-8 Unit: mm(inch)

4°

6°

R0.750(0.030)

0.254(0.010)TYP

0.130(0.005)MIN

8.200(0.323)9.400(0.370)

0.204(0.008)0.360(0.014)

7.620(0.300)TYP

4°

6°5°

0.700(0.028)

9.000(0.354)9.600(0.378)

3.710(0.146)4.310(0.170)

3.000(0.118)3.600(0.142)

0.360(0.014)0.560(0.022)

2.540(0.100) TYP

6.200(0.244)6.600(0.260)

3.200(0.126)3.600(0.142)

0.510(0.020)MIN

Φ3.000(0.118)Depth

0.100(0.004)0.200(0.008)

1.524(0.060) TYP

Note: Eject hole, oriented hole and mold mark is optional.

IMPORTANT NOTICE

BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifi-cations herein. BCD Semiconductor Manufacturing Limited does not assume any responsibility for use of any its products for anyparticular purpose, nor does BCD Semiconductor Manufacturing Limited assume any liability arising out of the application or useof any its products or circuits. BCD Semiconductor Manufacturing Limited does not convey any license under its patent rights orother rights nor the rights of others.

- Wafer FabShanghai SIM-BCD Semiconductor Manufacturing Limited800, Yi Shan Road, Shanghai 200233, ChinaTel: +86-21-6485 1491, Fax: +86-21-5450 0008

BCD Semiconductor Manufacturing LimitedMAIN SITE

REGIONAL SALES OFFICEShenzhen OfficeShanghai SIM-BCD Semiconductor Manufacturing Co., Ltd. Shenzhen OfficeAdvanced Analog Circuits (Shanghai) Corporation Shenzhen OfficeRoom E, 5F, Noble Center, No.1006, 3rd Fuzhong Road, Futian District, Shenzhen 518026, China Tel: +86-755-8826 7951Fax: +86-755-8826 7865

Taiwan OfficeBCD Semiconductor (Taiwan) Company Limited4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei, TaiwanTel: +886-2-2656 2808Fax: +886-2-2656 2806

USA OfficeBCD Semiconductor Corporation30920 Huntwood Ave. Hayward,CA 94544, U.S.ATel : +1-510-324-2988Fax: +1-510-324-2788

- IC Design GroupAdvanced Analog Circuits (Shanghai) Corporation8F, Zone B, 900, Yi Shan Road, Shanghai 200233, ChinaTel: +86-21-6495 9539, Fax: +86-21-6485 9673

BCD Semiconductor Manufacturing Limited

http://www.bcdsemi.com

BCD Semiconductor Manufacturing Limited

IMPORTANT NOTICE

BCD Semiconductor Manufacturing Limited reserves the right to make changes without further notice to any products or specifi-cations herein. BCD Semiconductor Manufacturing Limited does not assume any responsibility for use of any its products for anyparticular purpose, nor does BCD Semiconductor Manufacturing Limited assume any liability arising out of the application or useof any its products or circuits. BCD Semiconductor Manufacturing Limited does not convey any license under its patent rights orother rights nor the rights of others.

- Wafer FabShanghai SIM-BCD Semiconductor Manufacturing Co., Ltd.800 Yi Shan Road, Shanghai 200233, ChinaTel: +86-21-6485 1491, Fax: +86-21-5450 0008

MAIN SITE

REGIONAL SALES OFFICEShenzhen OfficeShanghai SIM-BCD Semiconductor Manufacturing Co., Ltd., Shenzhen OfficeUnit A Room 1203, Skyworth Bldg., Gaoxin Ave.1.S., Nanshan District, Shenzhen,China Tel: +86-755-8826 7951Fax: +86-755-8826 7865

Taiwan OfficeBCD Semiconductor (Taiwan) Company Limited4F, 298-1, Rui Guang Road, Nei-Hu District, Taipei, TaiwanTel: +886-2-2656 2808Fax: +886-2-2656 2806

USA OfficeBCD Semiconductor Corp.30920 Huntwood Ave. Hayward,CA 94544, USATel : +1-510-324-2988Fax: +1-510-324-2788

- HeadquartersBCD Semiconductor Manufacturing LimitedNo. 1600, Zi Xing Road, Shanghai ZiZhu Science-based Industrial Park, 200241, ChinaTel: +86-21-24162266, Fax: +86-21-24162277

Documents

LOW POWER PWM CONTROLLER FOR OFF-LINE ADAPTER AP3710 · The AP3710 is a green-mode PWM controller, its main applications are low power supplies such as offline battery chargers, adapters,