View NCP1053P136_559748.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AND8099/D 5.0 V, 2.0 A Flyback Converter
Prepared by: Kristie Valdez ON Semiconductor http://onsemi.com
APPLICATION NOTE
The design of a switching power supply is an iterative process which involves many variables that have to be adjusted in order to obtain an optimized solution. However, there are trade-offs which allow for a simple low cost, low component, single sided board design method. This application note provides a simple approach to designing a converter utilizing the ON Semiconductor NCP1055 high voltage switch regulator. The easy-to-follow step-by-step procedure guides the user into designing the different blocks that constitute the power supply, mainly the input block, the power stage, the magnetics, the snubber, the output block, and the feedback loop. The circuit diagram, bill of material, and PCB layout are also included at the end of the application note. This power supply is specifically designed for a 5.0 V, 2.0 A output and a maximum duty cycle of 48%. It meets IEC and UL requirements. EMI is minimal and a 70% achievable efficiency or greater is possible. The NCP1055 is a family of monolithic high voltage switching regulators designed to work in rectified AC line sources and flyback converter applications. They are capable of providing an output power ranging from 6.0 W to 40 W with a fixed AC input of 100 V, 115 V, or 230 V and 3.0 W to 20 W with a variable AC input ranging from 85 V to 265 V. This device features an on-chip 700 V SENSEFETTM power switch circuit, an active startup regulator circuit which eliminates the need for an auxiliary bias winding on the converter transformer, fault logic with a programmable timer for converter overload protection. Protective features provide power switch current limiting, input under voltage lockout with hysteresis, thermal shutdown, and restart fault detection. For more information, please contact an ON Semiconductor sales representative or log on to www.onsemi.com. Design Parameters The first step in designing a power supply is to define and predetermine the input and output parameters. Universal Input Voltage Range:
Vin(min) + 85 VAC, Vin(max) + 265 VAC
Output Specifications:
Vout + 5.0 V " 2%, Iout + 2 A
Input Power:
Pin + Pout , an efficiency of 0.78 is a good starting est.eff
point for a flyback converter using MOSFET technology:
Pout + 5 * 2.0 + 10 W NPin + 10 + 12.82 W 0.78
DC Rail Voltages at Low Line and High Line:
Vpeak(min) + Vin(min) * 2 + 85 * 2 + 120.21 VDC Vpeak(max) + Vin(max) * 2 + 265 * 2 + 374.77 VDC
Average Input Current at Low Line:
Iin(avg) + V Pin , in(low)
where Vin(low) + Vpeak(min) * Vripple * Vdiode; Vripple + 32% Vpeak(min) Iin(avg) + 12.82 + 0.160 A 80.2
Input Peak Current:
t Ipeak + 2 * Iin(avg) * sw ton 10 ms Ipeak + 2 * 0.160 * + 0.667 A 4.8 ms
(c) Semiconductor Components Industries, LLC, 2003
1
February, 2003 - Rev. 2
Publication Order Number: AND8099/D
AND8099/D
The component losses can be evaluated and budgetized with the following formula: Ploss = Pin (1 - eff) * P% where P% is the percentage loss of the desired circuit section per total power supply loss. Usually, 35% of the losses come from the power MOSFET, 60% from the output rectifier, 5% from the magnetics, and 5% from miscellaneous sources. Estimated Power Loss = Pin - Pout = 12.82 - 10 = 2.82 W MOSFET Power Losses = 2.82 * 35% = 0.987 W Rectifier Power Losses = 2.82 * 60% = 1.692 W Circuit Description
Input Block Input Bulk Capacitor
The purpose of the input bulk capacitor C2 is to hold up the rectified line voltage and also to filter out common mode noise. It is placed between the bridge rectifier output and ground. The size of the bulk capacitor depends on peak rectified input voltage and the ripple voltage magnitude. A larger capacitor will lower the ripple voltage on the DC input line, but will induce a larger surge current when the supply is powered up. Assuming a ripple magnitude of about 32% of the peak rectified voltage at low line, Cbulk can then be calculated using:
Cbulk + + Pin (Vpeak(min)2 * Vin(low)2) fac * 12.82 + 27 mF 60 * (1202 * 80.22)
The input block of the power supply consists of a fuse, an EMI filter, a diode bridge rectifier, and an input bulk capacitor.
Fuse
Select the closest standard capacitor of 33 mF with low ESR. Aluminum electrolytics are preferred because of their sturdiness and high reliability. Power Stage At the heart of the power stage is the ON Semiconductor NCP1055. The NCP1055 is a high voltage switching regulator that uses a fixed-frequency, duty cycle controlled oscillator. Rectified AC line voltage is applied to the startup circuit Pin 5 through the primary winding of the transformer. The circuit then routes current to the supply capacitor C5 which is typically connected to Pin 1. A switching cycle begins when the oscillator charges and discharges an on chip timing capacitor which generates a square wave signal used to pulse width modulate the power switch circuit. The control input pin is monitoring source or sink current drawn by an optocoupler. When the power supply output is greater than the reference voltage, the optocoupler begins to conduct pulling on the control input. The output of the control input is then sampled continuously during ton and has the ability to either turn the power switch circuit on or off at any time within ton. Magnetics Calculations The next step is the design of the flyback transformer. The design of the magnetics block is the most important and delicate part of the whole design process because it will determine how well the power supply will perform. The flyback-mode transformer functions by first conducting current in the primary winding, thus storing energy in the core of the transformer. The core energy is then transferred to the secondary winding when the primary side is turned off. The core and bobbin are standard EFD20 sizes.
The fuse F1 is protecting the circuit from current surges occurring at turn on. In this application, F1 is rated for 2.0 A, 125 VAC.
EMI Filter
The EMI filter is suppressing common mode and differential mode noise and is very dependent upon board layout, component selection, etc. An X capacitor C1 and a common mode choke L1 are placed across the AC lines to attenuate differential mode noise, see Figure 1. The EMI inductor is slowing down any transient voltage surge to reduce high frequency noise. Both the capacitor and choke should be placed before the diode bridge and as close to the AC line input as possible to minimize RFI.
Diode Bridge Rectifier
In order to choose the right diode bridge rectifier, the values of the forward and surge currents and DC blocking voltage must be considered. The surge current can reach values up to five times that of the average input rms current. It is therefore necessary to select a rectifier capable of handling such large currents. DC Blocking Voltage is calculated at high line:
VR w Vpeak(max) + Vin(max) * 2 + 375 VDC
Forward Current:
IF w 1.5 * Iin(avg) + 1.5 * 0.160 + 0.240 A
Surge Current:
IFSM w 5 * IF + 5 * 0.240 + 1.2 A
http://onsemi.com
2
AND8099/D
In order for the regulator to operate in discontinuous mode under worse case conditions and to maximize power, the maximum on time is 48% of the full period, therefore the the maximum primary inductance is calculated based on a maximum duty cycle of 48%. Using a larger inductance than calculated will cause the power supply output to fall out of regulation.
Lpri + Lpri + Vin(low) * max Ipeak * fop , where
to high frequency noise. Since i + C * dv, increasing the
dt
capacitance will also reduce the magnitude of the voltage ripple. The snubber and ringing damper act together to protect the IC from voltage transients greater than 700 V and reduce radiated noise. Output Block The output consists of a diode rectifier, a pi-filter, and a voltage regulator. For a flyback converter with an output voltage less than 7.5 V, a Schottky rectifier provides the maximum efficiency and is therefore the best choice. The Schottky rectifier used is the ON Semiconductor 1N5822, in which VR = 40 V, IF = 3.0 A, and VF = 0.525 V. The main purpose of this rectifier is to take the secondary voltage and convert it to a DC voltage. The following equations are used in selecting the Schottky rectifier: Maximum reverse peak voltage (calculated at high line):
N VRout u Vout ) Vpeak(max) * sec Npri VRout u 5 ) 375 * 1 + 33.85 V 13
max is the maximum duty cycle
80.2 * 0.48 + 0.577 mH 0.667 * 100 * 103
Primary flyback voltage:
VFB + Vin(low) * ton toff -6 + 80.2 * 4.8 * 10 -6 5.2 * 10
+ 74.03 V, where ton is 4.8 ms Primary to secondary turns ratio:
Npri VFB + + 74.03 + 13.4 [ 13 turns 5 ) 0.525 N sec Vout ) VF
By rearranging the above equation and solving for Nsec yields 1 turn. Energy entering the core during on-time (when the power switch is conducting):
Estored + Lpri * Ipeak2 , where the stored energy is 2
For discontinuous mode, the maximum forward peak current can be approximated using:
IFout + 4 * Iout + 8 A
measured in Joules.
Estored + 0.577 * 10 + 1.28
- 3 * 0.6672 2 - 4 Joules 10
One can double check if the power capability of the transformer is large enough to supply enough power to the output with the following equation:
Pin(core) + Lpri * Ipeak2 * fop u Pout 2 10- 4 * 100 kHz + 12.8 W u Pout
Diode D6 along with C7, C8, C9, L2, and C11 rectify the transformer secondary and filter the output in order to provide a tightly regulated DC output . Capacitor C7, C8 and C9 are placed in parallel in order to reduce ESR. In addition, the voltage rating of C7, C8 and C9 should be high enough for them to withstand the voltage spikes and the output voltage. L2 and C11 form a low pass filter that attenuates high frequency noise. Output filter capacitor:
Cout + Iout(max) * Toff(max) , where Toff(max) Vripple(desired) + min * 1 fop
1 100 * 10 3
Pin(core) + 1.28 + 10 W
and Vripple(desired) + 40 mV
Cout + 8 * 0.52 * 0.040 + 1040 mF
Input Snubber Because of the high dv/dt characteristic of the power transistor drain voltage and of the transformer leakage inductance, voltage spikes and ringing occur at the drain when the power switch is turned off. Resistor R1, C3, D5 compromise an RCD snubber. In parallel to the primary winding are R2 and C4 which compromise an RC ringing damper which slows down the dv/dt and reduces the peak voltage therefore decreasing the ringing due
Output filter choke (designed for a break frequency of 4.0 kHz):
L+ 1 2*p*f* C 2 , where C + C11 + 330 mF and f
is the corner frequency.
2 + 4.8 mH
L+
1 2 * p * 4k * 330 mF
http://onsemi.com
3
AND8099/D
Feedback Loop The feedback loop is composed of an optocoupler, a shunt regulator, a compensation capacitor and a resistor divider. The optocoupler isolates the AC input from the DC output. As a shunt regulator, the ON Semiconductor TL431 is used to regulate the output voltage. This monolithic voltage reference is programmable from Vref to 36 V using two external resistors. It exhibits a wide current range of 1.0 mA to 100 mA and is an excellent replacement for Zener diodes. The reference voltage of the TL431 is set at 2.5 V, for a 5.0 V output voltage, by a resistor divider R5 and R6 (low tolerance, 2.0 kW resistors). The TL431 monitors the 5.0 V output voltage and compares the divided down voltage to its 2.5 V internal reference. A small increase in the output voltage will cause the shunt regulator to start conducting, thus sinking current through the optocoupler's LED. In turn, the optocoupler transistor becomes forward biased and starts driving current into the control input pin of the NCP1055. The power switch duty cycle is then adjusted accordingly. A compensation capacitor C10 of 0.1 mF is placed between the cathode and the reference pin of the TL431 for improved stability. The resistor R3 limits the current going through the optocoupler to a safe level and prevents damage to the optocoupler.
5.0 V, 2.0 A F1 2.0 A
D1 C3 220 p D2 L1 C1 0.1 10 mH + D4 C2 33 D5 D3 R1 91 k C4 47 p R2 2.2 k
T1
D6
L2 5.0 mH + C7 + C8 + C9 330 330 330 R3 47 R4 1.0 k IC2 C10 0.1 IC3 C6 100 p + C11 330 + R6 2.0 k
Vin 85-265 VAC
C12 1.0
R5 2.0 k
8
7
6 3
NCP1055P100
1 2 4
5
C5 10
+
C13 1n
X
Figure 1. Circuit Diagram
http://onsemi.com
4
AND8099/D
Table 1. Bill of Materials
Ref. IC1 IC2 IC3 D1-4 D5 D6 T1 L1 L2 C1 C2 C3 C4 C5 C6 C7-9, C11 C10 C12 C13 R1 R2 R3 R4 R5, R6 F1 J1-2 J1 2 Component Value IC, 680 mA, 100 kHz, DIP8 Optocoupler, Dip 2.5 V Shunt Reg., TO-92 1.0 A, 800 V, Gen. Purp. 1.0 A, 600 V, Ultra Fast 3.0 A, 40 V, Schottky Flyback Transformer Choke, Common Mode, 10 mH Choke, Power, 5.0 mH 0.1 mF, Film, Radial 33 mF, 400 V, Radial 220 pF, 1.0 kV, 10%, Disc 47 pF, 1.0 kV, 10%, Disc 10 mF, 16 V, 20%, Radial 100 pF, 1.0 kV, 10%, Disc 330 mF, 10 V, Radial 0.1 mF, 50 V, Cer., Radial, 10% 1.0 mF, 35 V, Tant., Radial, 10% 0.001 mF, 50 V, Cer., Radial, 10% 91 kW, 1.0 W 2.2 kW, 1/2 W, 5% 47 W, 1/4 W, 5% 1.0 kW, 1/4 W, 5% 2.0 kW, 1/4 W, 1% 2.0 A, axial Term. Block Pos Term Block, 2 Pos., Plug and Header Qty. 1 1 1 4 1 1 1 1 1 1 1 1 1 1 1 4 1 1 1 1 1 1 1 2 1 1 Part Number NCP1055P100 SFH615A-4 TL431AILP 1N4006 MUR160TR 1N5822 31592 40479 40480 XSC275V104-M15S 400V33-HS NCD221K1KVY5F NCD470K1KVSL 16V10 NCD101K1KVY5FAB2 10V330-HOSS SR215C104KAA 105X9050 SR211C102KAA MO-1-91K-5TR 1/2W-2.2K-5B 1/4W-47R-5 1/4W-1K-5B CCF-55-2001FTR 251002TR1 1757242 1757019 1786404 J3-4 J3 4 Term. Block, Pos., Inv. Term Block 2 Pos Inv Plug and Header 1 1786174 Phoenix Contact Phoenix Contact Manufacturer ON Semiconductor Isocom ON Semiconductor ON Semiconductor ON Semiconductor ON Semiconductor Midcom Midcom Midcom Nissei United Chem-Con NIC Components NIC Components United Chem-Con NIC Components United Chem-Con AVX AVX AVX SEI SEI SEI SEI SEI LittleFuse
http://onsemi.com
5
AND8099/D
Table 2. Converter Test Data and Results
Test Line Regulation Load Regulation Conditions Vin = 85 VAC; Iout = 2.0 A Vin = 265 VAC; Iout = 2.0 A Vin = 85 VAC; Iout = 0 = 0.200 A = 1.0 A = 2.0 A Vin = 110 VAC; Iout = 0 = 0.200 A = 1.0 A = 2.0 A Vin = 230 VAC; Iout = 0 = 0.200 A = 1.0 A = 2.0 A Vin = 265 VAC; Iout = 0 = 0.200 A = 1.0 A = 2.0 A Vin = 85 VAC Vout = 4.971 V Vout = 4.982 V Vout = = = = Vout = = = = Vout = = = = Vout = = = = 4.994 V 4.991 V 4.985 V 4.971 V 4.993 V 4.991 V 4.986 V 4.976 V 4.993 V 4.991V 4.987V 4.981V 4.994 V 4.991 V 4.987 V 4.982 V Data Results D 11 mV
D 23 mV
D 17 mV
D 12 mV
D 12 mV
Efficiency
Vout = 4.971 V; Iout = 2.0 A; Pout = 9.942, Pin = 13.64 W Vout = 4.976 V; Iout = 2.0 A; Pout = 9.952, Pin = 13.41 W Vout = 4.981 V; Iout = 2.0 A; Pout = 9.942, Pin = 13.47 W Vout = 4.982 V; Iout = 2.0 A; Pout = 9.964, Pin = 13.67 W
72.8 %
= 110 VAC
74.2 %
= 230 VAC
73.8 %
= 265 VAC Output Ripple Voltage Vin = 85 VAC; Iout = 2.0 A Vin = 265 VAC; Iout = 2.0 A
72.8 % 100 mVp-p 230 mVp-p
http://onsemi.com
6
AND8099/D
Figure 2. PCB Metal Layer
Figure 3. PCB Silk Screen
http://onsemi.com
7
AND8099/D
References 1. Brown, Marty, Power Supply Cookbook, Butterworth-Heinemann, 1994. 2. Pressman, Abraham I., Switching Power Supply Design, Second Edition, McGraw-Hill, 1998. 3. Motorola, Inc., Handling EMI in Switch Mode Power Supply Design, AN-SMPS-EMI, Motorola, Inc., 1998.
SENSEFET is a trademark of Semiconductor Components Industries, LLC (SCILLC)
ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
PUBLICATION ORDERING INFORMATION
Literature Fulfillment: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada Email: ONlit@hibbertco.com N. American Technical Support: 800-282-9855 Toll Free USA/Canada JAPAN: ON Semiconductor, Japan Customer Focus Center 2-9-1 Kamimeguro, Meguro-ku, Tokyo, Japan 153-0051 Phone: 81-3-5773-3850 ON Semiconductor Website: http://onsemi.com For additional information, please contact your local Sales Representative.
http://onsemi.com
8
AND8099/D
This datasheet has been download from: www..com Datasheets for electronics components.

▲Up To Search▲

Price & Availability of NCP1053P136

	To Download NCP1053P136 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .