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Copyright © 2014 Active-Semi, Inc.
ActiveQRTM is a trademark of Active-Semi.
ActiveQRTM Quasi-Resonant PWM Power Switch
FEATURES
•Integrated Power MOSFET
•CCM and Quasi-Resonant Operation
•Adjustable up to 75kHz Switching Frequency
•Integrated Patented Frequency Foldback
Technique
•Integrated Patented Line Compensation
•Built-in Soft-Start Circuit
•OCP/OLP Protection
•Line Under-Voltage, Thermal, Output Over-
voltage, Output Short Protections
•Current Sense Resistor Short Protection
•Transformer Short Winding Protection
•100mW Standby Power
•Complies with Global Energy Efficiency and
CEC Average Efficiency Standards
•SOP-8 and DIP-7 Packages
APPLICATIONS
•Power Supplies for Portable Media Player,
DSCs, Set-top boxes, DVD players, records
•Adaptors for Small home appliances
•Auxiliary Power Supply for PC,LCD TV and
PDP TV
GENERAL DESCRIPTION
ACT518 is a high performance peak current mode
PWM power switch. It applies ActiveQRTM
and frequency foldback technique to reduce EMI
and improve efficiency. Its maximum design
switching frequency is set at 75kHz. Very low
standby power, good dynamic response and
accurate voltage regulation is achieved with an
opto-coupler and the secondary side control circuit.
The Idle mode operation enables low standby
power of 100mW with small output voltage ripple.
By applying frequency foldback and ActiveQRTM
technology, The integrated power switch increases
the average system efficiency compared to
conventional solutions and exceeds the latest
ES2.0 efficiency standard with good margin.
ACT518 integrates comprehensive protection. In
case of over temperature, over voltage, short
winding, short current sense resistor, open loop an
d overload conditions, it would enter into auto
restart mode including Cycle-by-Cycle current
limiting.
ACT518 is to achieve no overshoot and very short
rise time even with big capacitive load with the built-
in fast and soft start process.
In full load condition, ACT518 is able to be
designed to work in both CCM mode and DCM
mode to meet different types of applications. Quasi-
Resonant (QR) operation mode can effectively
improve efficiency during DCM operation, and
reduce the EMI noise and further reduce the
components in input filter.
ACT518SH is for application up to 10 Watt and
ACT518DF is for application up to 18 Watt.
Figure 1:
Simplified Application Circuit
ACT518
Rev 0, 13-Jun-14
ACT518
Rev 0 , 13-Jun-14
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ActiveQRTM is a trademark of Active-Semi.
PIN CONFIGURATION
PIN DESCRIPTIONS
PART NUMBER TEMPERATURE RANGE PACKAGE PINS PACKING
METHOD TOP MARK
ACT518SH-T -40°C to 85°C SOP-8 8 TUBE & REEL ACT518SH
ACT518DF -40°C to 85°C DIP-7 7 TUBE ACT518DF
SOP-8
ACT518SH
ORDERING INFORMATION
PIN NAME DESCRIPTION
1 CS
Current Sense Pin. Connect an external resistor (RCS) between this pin and ground to set peak
current limit for the primary switch.
2 FB Feedback Pin. Connect this pin to optocouplers’s collector for output regulation.
3 VDET
Valley Detector Pin. Connect this pin to a resistor divider network from the auxiliary winding to
detect zero-crossing points for valley turn on operation.
4 VDD Power Supply. This pin provides bias power for the IC during startup and steady state operation.
5,6 GND Ground.
7,8 DRAIN MOSFET Drain Pin.
DIP-7
ACT518DF
ACT518
Rev 0 , 13-Jun-14
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ABSOLUTE MAXIMUM RATINGSc
ELECTRICAL CHARACTERISTICS
(VDD = 14V, LM = 1.3mH, RCS = 1.65, VOUT = 5V, NP = 114, NS =9, NA =23, TA = 25°C, unless otherwise specified.)
c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods.
PARAMETER VALUE UNIT
DRAIN to GND -0.3 to + 650 V
FB, CS, VDET to GND -0.3 to + 6 V
VDD to GND -0.3 to + 28 V
Continuous Drain Current, TC=25˚C SOP-8 2 A
DIP-7 4 A
SOP-8 1.1 A
DIP-7 2.9 A
Maximum Power Dissipation SOP-8 0.95 W
DIP-7 1.5 W
Junction to Ambient Thermal Resistance (JA) SOP-8 105 ˚C/W
DIP-7 80 ˚C/W
Operating Junction Temperature -40 to 125 ˚C
Storage Temperature -55 to 150 ˚C
Lead Temperature (Soldering, 10 sec) 300 ˚C
Continuous Drain Current, TC=100˚C
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
Supply
VDD Turn-On Voltage VDDON V
DD Rising from 0V 11.3 12.3 13.3 V
VDD Turn-Off Voltage VDDOFF V
DD Falling after Turn-on 6.7 7.4 8.1 V
VDD Over Voltage Protection VDDOVP V
DD Rising from 0V 25 V
Start Up Supply Current IDDST V
DD = 10V, before VDD Turn-on 8 15 µA
IDD Supply Current IDD VDD = 15V, after VDD Turn-on ,FB
floating 0.6 mA
IDD Supply Current at Standby IDDSTBY FB = 1.3V 0.4 mA
IDD Supply Current at Fault IDDFAULT Fault mode, FB Floating 250 µA
Feedback
FB Pull up Resistor RFB 15 k
CS to FB Gain ACS 3 V/V
VFB at Max Peak Current 3 + VBE V
FB Threshold to Stop Switching VFBBM1 1.32 V
FB Threshold to Start Switching VFBBM2 1.41 V
Output Overload Threshold 4.2 V
OverLoad/Over Voltage Blanking
Time TOVBLANK 320 ms
ACT518
Rev 0 , 13-Jun-14
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ActiveQRTM is a trademark of Active-Semi.
PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT
Power Mosfet
Drain Source Breakdown Voltage BVDSS V
GS=0V,ID=250uA 650 V
Drain On Resistor RDSON
VGS=10V,ID=1A,SOP-8 5.1
VGS=10V,ID=2A,DIP-7 3.6
Current Limit
CS Current Limit Threshold VCSLIM 0.91 0.96 1.01 V
Leading Edge Blanking Time TCSBLANK 240 300 360 ns
Oscillator
Maximum Switching Frequency fMAX 75 kHz
Switching Frequency Foldback fMIN FB = 2.3V+VBE f
MAX/3 kHz
Maximum Duty Cycle DMAX 65 75 %
Valley Detection
ZCD Threshold Voltage VDETTH 100 mV
Valley Detection Time Window
After valley detection time
window, if no valley de-
tected, forcedly turn-on
main switch
3.5 µs
VDET Leakage Current 1 µA
Protection
CS Short Waiting Time 2 µs
CS Short Detection Threshold 0.115 V
CS Open Threshold Voltage 1.73 V
Abnormal OCP Blanking Time 150 ns
Thermal Shutdown Temperature 135 ˚C
Line UVLO IVDETUVLO 0.1 mA
Line OVP IVDETOVP 2 mA
VDET Over Voltage Protection VDETVOOVP 2.448 2.72 2.992 V
VDET Vo Short Threshold VDETVOshort 0.406 0.58 0.754 V
ELECTRICAL CHARACTERISTICS CONT’D
(VDD = 14V, LM = 1.3mH, RCS = 1.65, VOUT = 5V, NP = 114, NS =9, NA =23, TA = 25°C, unless otherwise specified.)
ACT518
Rev 0 , 13-Jun-14
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ActiveQRTM is a trademark of Active-Semi.
FUNCTIONAL BLOCK DIAGRAM
ACT518
Rev 0 , 13-Jun-14
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Copyright © 2014 Active-Semi, Inc.
ActiveQRTM is a trademark of Active-Semi.
ACT518 is a high performance peak current mode
PWM integrated power IC. It includes the most
advance features that are required in the adaptor
applications up to 12 Watt. Unique fast startup,
frequency foldback, QR switching technique,
accurate peak current line compensation, Idle
mode, short winding protection, OCP, OTP, OVP
and UVLO are included in the controller.
Startup
Startup current of ACT518 is designed to be very
low so that VDD could be charged to VDDON
threshold level and device starts up quickly. A large
value startup resistor can therefore be used to
minimize the power loss yet reliable startup in
application. For a typical AC/DC adaptor with
universal input range design, two 1M, 1/8 W
startup resistors could be used together with a VDD
capacitor(4.7uF) to provide a fast startup and yet
low power dissipation design solution.
During startup period, the IC begins to operate with
minimum Ippk to minimize the switching stresses
for the main switch, output diode and transformers.
And then, the IC operates at maximum power
output to achieve fast rise time. After this, VOUT
reaches about 90% VOUT , the IC operates with a
‘soft-landing’ mode(decrease Ippk) to avoid output
overshoot.
Constant Voltage (CV) Mode Operation
In constant voltage operation, the ACT518
regulates its output voltage through secondary side
control circuit . The output voltage information is
sensed at FB pin through OPTO coupling. The error
signal at FB pin is amplified through TL431 and
OPTO circuit. When the secondary output voltage is
above regulation, the error amplifier output voltage
decreases to reduce the switch current. When the
secondary output voltage is below regulation, the
error amplifier output voltage increases to ramp up
the switch current to bring the secondary output
back to regulation. The output regulation voltage is
determined by the following relationship:
where RF1 (R13) and RF2 (R14) are top and bottom
feedback resistor of the TL431.
No Load Idle Mode
In no load standby mode, the feedback voltage falls
below VFBBM2 and reaches VFBBM1, ACT518 stop
switching. After it stops, as a result of a feedback
reaction, the feedback voltage increases. When the
feedback voltage reaches VFBBM2, ACT518 start
switching again. Feedback voltage drops again and
output voltage starts to bounds back and forward
with very small output ripple. ACT518 leaves Idle
mode when load is added strong enough to pull
feedback voltage exceed VFBBM2.
Figure 2:
Idle Mode
Primary Inductor Current Limit
Compensation
The ACT518 integrates a primary inductor peak
current limit compensation circuit to achieve
constant OLP over wide line and wide inductance.
Frequency Foldback
When the load drops to 75% of full load level,
ACT518 starts to reduce the switching frequency,
which is proportional to the load current ,to improve
the efficiency of the converter.
ACT518’s load adaptive switching frequency
enables applications to meet all latest green energy
standards. The actual minimum average switching
frequency is programmable with output
capacitance, feedback circuit and dummy load
(while still meeting standby power).
Valley Switching
ACT518 employed valley switching from no load to
heavy load to reduce switching loss and EMI. In
discontinuous mode operation, the resonant voltage
between inductance and parasitic capacitance on
MOSFET source pin is coupled by auxiliary winding
and reflected on VDET pin through feedback
network R6, R7. Internally, the VDET pin is
connected to an zero-crossing detector to generate
the switch turn on signal when the conditions are
met.
FUNCTIONAL DESCRIPTION
(1)
)
R
R
1(VV 2F
1F
431TL_REFOUTCV +×=
Ip
Vo
Vfb
t
Ip_FL
Ilim
Vfb_fl
Vfb_olp
2A
Vfbbm1
Io
12V
Vfbbm2
0A
ACT518
Rev 0 , 13-Jun-14
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ActiveQRTM is a trademark of Active-Semi.
Figure 3:
Valley Switching
Protection Features
The ACT518 provides full protection functions. The
following table summarizes all protection functions.
Auto-Restart Operation
ACT518 will enter into auto-restart mode when a
fault is identified. There is a startup phase in the
auto-restart mode. After this startup phase the
conditions are checked whether the failure is still
present. Normal operation proceeds once the
failure mode is removed. Otherwise, new startup
phase will be initiated again.
To reduce the power loss during fault mode, the
startup delay control is implemented. The startup
delay time increases over lines.
FUNCTIONAL DESCRIPTION CONT’D
PROTECTION
FUNCTIONS
FAILURE
CONDITION
PROTECTION
MODE
VDD Over Voltage VDD > 25V
(4 duty cycle) Auto Restart
VVDET Over Volt-
age/No Voltage
VVD > 2.72V or
No switching
for 4 cycles
Auto Restart
Over Temperature T > 135˚C Auto Restart
Short Winding/
Short Diode
VCS > 1.72V Auto Restart
Over Load/Open
Loop
IPK = ILIMIT or
VFB = 3.5V + VBE
for 320ms
Auto Restart
Output Short
Circuit VDET < 0.58V Auto Restart
VDD Under Volt-
age VDD < 7.4V Auto Restart
Vdrain_gnd
t
DC voltage
T
TonPossible V alley tur n on
V
ACT518
Rev 0 , 13-Jun-14
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ActiveQRTM is a trademark of Active-Semi.
Figure 4:
Universal VAC Input, 5V/2A Output Adaptor
ACT518
Rev 0 , 13-Jun-14
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ActiveQRTM is a trademark of Active-Semi.
ITEM REFERENCE DESCRIPTION QTY MANUFACTURER
1 U1 IC, ACT518, SOP-8 1 Active-Semi
2 C1,C2 Capacitor, Electrolytic, 10µF/400V, 10 × 14mm 1 KSC
3 C3 Capacitor, Ceramic,1000pF/500V,0805,SMD 1 POE
4 C4 Capacitor, Electrolytic, 6.8µF/35V, 5 × 11mm 1 KSC
5 C7,C6 Capacitor, Electrolytic, 470µF/10V, 10 × 11.5mm 2 KSC
6 C8 Capacitor, Ceramic, 0.33µF/50V,0805,SMD 1 POE
7 C9 Capacitor, Ceramic,100pF/100V,0805,SMD 1 POE
8 C5 Capacitor, Ceramic,1000pF/50V,0805,SMD 1 POE
9 BD1 Diode, Rectifier ,1000V1A, MB6S, DO-4 1 Good-Ark
10 D2,D4 Diode, Ultra Fast, RS1M,1000V/1.0A, SMD 2 Good-Ark
11 D3 Diode, Schottky, 45V/10A, SB1045S, DO-201 1 Good-Ark
12 L1 DM Inductor, 1.5mH, DR5 1 SoKa
13 Bead1,2 T6*2*3, R5 2 SoKa
14 L2 DM Inductor, 10µH, DR5 1 SoKa
15 PCB1 PCB, L*W*T = 48.5291.6mm, Cem-1, Rev:A 1 Jintong
16 F1 Fusible, 1A/250V 1 TY-OHM
17 R1,2 Chip Resistor, 1M, 0805, 5% 2 TY-OHM
18 R3 Carbon Resistor, 750k, 1206, 5% 1 TY-OHM
19 R11 Chip Resistor, 1.5k, 0805, 5% 1 TY-OHM
20 R4,5,9 Chip Resistor, 22, 0805, 5% 3 TY-OHM
21 R6 Chip Resistor, 51.1k, 0805, 1% 1 TY-OHM
22 R7 Chip Resistor, 11.1k, 0805, 1% 1 TY-OHM
23 R8 Chip Resistor, 1.65, 1206, 1% 1 TY-OHM
24 R9 Chip Resistor, 0.87,1W, 1% 1 TY-OHM
25 R10 Chip Resistor, 200, 0805, 5% 1 TY-OHM
26 R12 Chip Resistor, 3.3k, 0805, 5% 1 TY-OHM
27 R13 Chip Resistor, 10.5, 0805, 1% 1 TY-OHM
28 R14 Chip Resistor, 10k, 0805, 1% 1 TY-OHM
29 R17 Chip Resistor, 12k, 0805, 5% 1 TY-OHM
30 T1 Transformer, LP = 1.3mH, EE16 1
31 NTC Thermistor, SC053 1 TY-OHM
32 TVS Varistor, 10471 1 TY-OHM
33 CY1 Y capacitance, 2200pF/400V,Y1 1 SEC
34 U2 Opto-coupler, PC817C CTR = 200% 1 Sharp
35 U3 Voltage Regulator, TL431A, VREF = 2.5V 1 ST
Table 1:
ACT518 5V10W Bill of Materials
ACT518
Rev 0 , 13-Jun-14
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TYPICAL PERFORMANCE CHARACTERISTICS
ACT518-001
VDD ON/OFF Voltage vs. Temperature
13.5
12.5
11.5
10.5
9.5
8.5
7.5
6.5
VDDON and VDDOFF (V)
Temperature (°C)
0 40 12080
VDDOFF
ACT518-002
Startup Supply Current vs. Temperature
8
7
6
9
Startup Supply Current (µA)
ACT518-003
Supply Current at Idle/Fault Mode vs.
Temperature
Supply Current (mA)
0.4
0.3
0.2
ACT518-004
Maximum Switching Frequency vs.
Temperature
90
70
60
80
Maximum Switching Frequency (KHz)
ACT518-005
VCS Voltage vs. Temperature
VCS Voltage (V)
1.0
0.9
0.8
0.7
0.6
ACT518-006
VFB Threshold Voltage vs. Temperature
VFB Threshold Voltage (V)
4
3
2
1
0
5
VDDON
Temperature (°C)
0 20 60 40 80 100 120
Stop Switching
Start Switching
Idle Mode
Fault Mode
Temperature (°C)
0 20 60 40 80 100 120
Temperature (°C)
0 20 60 40 80 100 120
Temperature (°C)
0 20 60 40 80 100 120
Temperature (°C)
0 20 60 40 80 100 120
OLP
ACT518
Rev 0 , 13-Jun-14
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PACKAGE OUTLINE
SOP-8 PACKAGE OUTLINE AND DIMENSIONS
ACT518
Rev 0 , 13-Jun-14
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Copyright © 2014 Active-Semi, Inc.
ActiveQRTM is a trademark of Active-Semi.
Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each
product to make sure that it is suitable for th eir applicatio ns. Active-Se mi products are not inten ded or aut horized for use
as critical components in life-support devices or systems. Active-Semi, Inc. does not assume any liability arising out of
the use of any product or circuit described in this datasheet, nor does it convey any patent license.
Active-Semi and its logo are trademarks of Active-Semi, Inc. F or more info rmation on this and other products, contact
sales@active-semi.com or visit http://www.active-semi.com.
is a registered trademark of Active-Semi.
DIP-7 PACKAGE OUTLINE AND DIMENSIONS
PACKAGE OUTLINE
