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PDF ACT412 Data sheet ( Hoja de datos )
| Número de pieza | ACT412 | |
| Descripción | Quasi-Resonant PWM Controller | |
| Fabricantes | Active-Semi | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de ACT412 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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ACT412
Rev 1, 30-Oct-13
ActivePSRTM Quasi-Resonant PWM Controller
FEATURES
• Patented Primary Side Regulation
Technology
• Quasi-Resonant Operation
• Adjustable up to 120kHz Switching
Frequency
• +/-5% Output Voltage Regulation
• Constant Power Operation Mode for Fast
Start-up and Motor Drive Applications
• Integrated Line and Primary Inductance
Compensation
• Built-in Soft-Start Circuit
• Line Under-Voltage, Thermal, Output Over-
voltage, Output Short Protections
• Current Sense Resistor Short Protection
• Transformer Short Winding Protection
• Less than 100mW Standby Power
• Complies with Global Energy Efficiency and
CEC Average Efficiency Standards
• Tiny SOT23-6 Packages
mode including cycle-by-cycle current limiting.
ACT412 is to achieve no overshoot and very short
rise time even with big capacitive load (10000µF)
with the built-in fast and soft start process, .
The Quasi-Resonant (QR) operation mode can
effectively improve efficiency, reduce the EMI noise
and further reduce the components in input filter.
ACT412 is idea for application up to 36 Watt.
Figure 1:
Simplified Application Circuit
APPLICATIONS
• AC/DC Adaptors/Chargers for E-Shaver,
Motor Driver, ADSL, Network Power, Cell
Phone
• Big Capacitive Load Application
GENERAL DESCRIPTION
The ACT412 is a high performance peak current
mode PWM controller which applies ActivePSRTM
and ActiveQRTM technology. ACT412 achieves
accurate voltage regulation without the need of an
opto-coupler or reference device.
The ACT412 is designed to achieve less than
100mW Standby Power. By applying frequency fold
back and ActiveQRTM technology, ACT412
exceeds the latest ES2.0 efficiency standard.
ACT412 integrates comprehensive protection. In
case of over temperature, over voltage, short
winding, short current sense resistor, open loop
and overload conditions, it would enter auto restart
Innovative PowerTM
-1-
Active-Semi Proprietary―For Authorized Recipients and Customers
ActivePSRTM is a trademark of Active-Semi.
www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
1 page  
ACT412
Rev 1, 30-Oct-13
ELECTRICAL CHARACTERISTICS CONT’D
(VDD = 18V, LM = 0.5mH, RCS = 0.75Ω, VOUT = 13V, NP = 68, NS =12, NA = 17, TA = 25°C, unless otherwise specified,12V0.4A applica-
tion)
PARAMETER
Protection
CS Short Waiting Time
CS Short Detection Threshold
CS Open Threshold Voltage
Abnormal OCP Blanking Time
Inductance Short CS Threshold Voltage
Thermal Shutdown Temperature
Thermal Hysteresis
Vo Short Detection Threshold
Line UVLO
Line UVLO Hysteresis
Line OVP
VFB Over Voltage Protection
Valley Detection
Valley Detection Time Window
SYMBOL TEST CONDITIONS
VFBUVLO
IFBUVLO
IFBOVP
VCOMP = 0.45V
MIN
2
TYP MAX UNIT
2.25 3
µs
0.1 0.15
V
1.75 V
190 ns
1.75 V
135 ˚C
20 ˚C
0.28 V
0.2 mA
20 µA
2.4 mA
3V
3.3 µs
Innovative PowerTM
-5-
Active-Semi Proprietary―For Authorized Recipients and Customers
ActivePSRTM is a trademark of Active-Semi.
www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
5 Page 
ACT412
Rev 1, 30-Oct-13
TYPICAL APPLICATION CONT’D
An EE16 core is selected for the transformer. From
the manufacture’s catalogue recommendation, the
core with an effective area AE is 19.2mm2 .The turn
of the primary winding is:
NP
≥ Ilim × Lp _ max
AE × Bmax
=
0.75
19.2 ×
× 0.00073
3000 ×10 −10
= 95T
(13)
Ilim = 2 × Ip _ FL = 2 × 375 mA ≈ 750 mA
The turns of secondary and auxiliary winding
can be derived accordingly:
(14)
Ns
= Np /
Np
NS
= 95
/ 5 .53
≈ 17 T
NA
=
NA
NS
× Ns
= 1 .4 × 17
≈ 24 T
(15)
Determining the value of the current sense resistor
(R9) uses the peak current in the design. Since the
ACT412 internal current limit is set to 1V, the
design of the current sense resistor is given by:
R CS
= V CS
I lim
=1
0 .75
≈ 1 .3 .Ω
(16)
The voltage feedback resistors are selected
according to frequency at full load. The design
frequency at full load is given by:
fs
=
Np
Ns
×
R fb 1 × R fb 2
R fb 1 + R fb 2
×
Lp
VO + VD
×
V cs
R cs
× K f _ sw
(17)
The design Vo is given by:
down the turn ratio and inductance.
N p = 68T ,Ns = 12T ,N A = 17 T ,Lp = 0.5 mH
(21)
PCB Layout Guideline
Good PCB layout is critical to have optimal
performance. Decoupling capacitor (C4) and
feedback resistor (R5/R6) should be placed close to
VDD and FB pin respectively. There are two main
power path loops. One is formed by C1/C2, primary
winding, Mosfet transistor and current sense
resistor (R9). The other is secondary winding,
rectifier D8 and output capacitors (C5/C6). Keep
these loop areas as small as possible. Connecting
high current ground returns, the input capacitor
ground lead, and the ACT412 GND pin to a single
point (star ground configuration).
Vo
=
(1 +
Rfb1
Rfb 2
)× Ns
Na
× VFB
− VD
(18)
Where k is IC constant and K=0.0000065, then we
can get the value:
R fb1 = 45 .3 K , R fb 2 = 6 .9 K
(19)
When selecting the output capacitor, a low
ESR electrolytic capacitor is recommended to
minimize ripple from the current ripple. The
approximate equation for the output capacitance
value is given by:
COUT
= IOUT
f ×Vsw RIPPLE
= 1.8
110k ×50mV
= 327μF
(20)
Two 330µF electrolytic capacitors are used to keep
the ripple small.
In fact, consider of transformer production, we scale
Innovative PowerTM
- 11 -
Active-Semi Proprietary―For Authorized Recipients and Customers
ActivePSRTM is a trademark of Active-Semi.
www.active-semi.com
Copyright © 2013 Active-Semi, Inc.
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet ACT412.PDF ] | |
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