NCP1060, 12 Vout, 2W Off-line Buck Regulator

DN05080/D
Design Note – DN05080/D
NCP1060, 12 Vout, 2W Off-line Buck Regulator
Device
Application
Input Voltage
NCP1060
Smart Meters,
Electric Meters,
White Goods
85 to 265 V
Output Voltage
Output Ripple
Typical Current
Max Current
Min Current
PFC (Yes/No)
Efficiency
Inrush Limiting / Fuse
Operating Temp. Range
Cooling Method /
Supply Orientation
Signal Level Control
Topology
Up to 2 W at
12 Vout
Off-Line 100 kHz
Buck
I/O
Isolation
Non-isolated
Output Specification
4 to 16 Vdc depending on selected Z1 zener value
Less than 1%
100 to 150 mA for 12Vout
160 mA
0 mA
No
See plots below
External fuse required
0 to +50°C (dependent on IC1 cooling)
Convection
None
Circuit Description
This design note describes a very simple, low
power, constant voltage output buck power
converter intended for powering electronics
for power goods, electrical meters and
industrial equipment where isolation from the
AC mains is not required. The switching
element
in
the
converter
is
ON
Semiconductor’s
NCP106x
series
of
monolithic switchers. In this reference design,
the NCP1060 is utilized with a 60 kHz
switching frequency and a maximum output
current of 150 mA.
This buck circuit utilizes a simple charge
pump or “bootstrap” type of voltage sensing
and regulation scheme composed of D2, C1.
This simple sensing technique eliminates the
use of an optocoupler in the feedback loop.
Thanks an on chip voltage reference and
error amplifier no external active components
are necessary for regulation. Just simple
resistor divider composed of R2, R5 and R6
to bring portion of external voltage to FB pin.
This helps to achieve load regulation +/-5%
September 2015, Rev.0
Output
Power
over the loads 100% down to 1% of maximum
rated load. Below 1% the output voltage will
rise to the value of the overvoltage clamping
zener diode D4 across the output. For a 12 V
output a typical value for zener diode will be
15 V and at no load the output will be
clamped at this level.
The sensed voltage produced on C5 is also
used to power the NCP106x controller
through D1 once converter has started. This
auxiliary Vcc to run the chip improves the
overall efficiency of the circuit and prevents
the controller from running in DSS mode
under normal load conditions.
Although this is low power output converter,
full bridge rectifier is used, to lower input peak
current. C4, L2 and C5 form a conducted EMI
filter.
The 1.2 mH buck output inductor is available
in several surface mount or through hole
configurations from multiple vendor. This
inductor should be designed to handle high
voltage.
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DN05080/D
Schematic
Figure 1 – Buck converter schematic
Output Regulation
Figure 2 – Output voltage dependency on output current
September 2015, Rev.0
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DN05080/D
Typical Efficiency versus Load for 110 V and 230 V
Figure 3 – Efficiency of the Buck Converter
Output Ripple – 150 mA load, 230 Vac Input
Figure 4 – Output Voltage Ripple at Full Load
September 2015, Rev.0
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DN05080/D
References:
ON Semiconductor Application Notes: AND8318, AND8328
ON Semiconductor Design Notes: DN05014, DN06011, DN06052, DN05058
ON Semiconductor NCP1060 High-Voltage Switcher for low Power offline SMPS.
PC Board:
Figure 5 - components position on PCB (top side)
Figure 6 - components position on PCB (bottom side)
September 2015, Rev.0
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DN05080/D
Figure 7 – PCB’s bottom side
Table 1– Bill of materials
Designator
Quantity
Value
Tolerance
Footprint
Manufacturer
Manufacturer Part
Number
CAPACITOR
ELECTROLYTIC
CAPACITOR
150 nF
220 μF / 35
V
10%
0805
THROUGH
HOLE
Kemet
C0805C154K5RACTU
100 nF
2.2 uF /
450 V
10 μF / 25
V
10%
39 nF
10%
NU
Description
C1
1
C2
1
C3, C7
2
C4, C5
2
C6
1
CAPACITOR
ELECTROLYTIC
CAPACITOR
ELECTROLYTIC
CAPACITOR
C8, C9
2
CAPACITOR
CX1
1
CAPACITOR X2
D1
1
DIODE
D2, D3
2
D4
Koshin
KZH-35V221MG4
0805
THROUGH
HOLE
THROUGH
HOLE
Kemet
United ChemiCon
C0805C104K5RACTU
Koshin
KLH025V100ME3
Kemet
C0805C393K5RACTU
-
0805
THROUGH
HOLE
-
MMSD4148
-
SOD123
DIODE
MURA160
-
SMA
1
ZENER DIODE
MMSZ15
5%
SOD123
D5, D6, D7, D8
4
DIODE
MRA4007
-
SMA
IC1
1
SWITCHER
NCP1060
-
SOIC10
L1
1
INDUCTOR
1.2 mH
10%
L2
1
INDUCTOR
1.0 mH
10%
(L,N,+12V,GND)
4
TERMINAL PIN
1.0 mm
-
R1
1
VARISTOR
820572711
-
SMD/SMT
THROUGH
HOLE
THROUGH
HOLE
THROUGH
HOLE
ON
Semiconductor
ON
Semiconductor
ON
Semiconductor
ON
Semiconductor
ON
Semiconductor
Würth
Elektronik
Würth
Elektronik
R2
1
RESISTOR
33 kΩ
1%
0805
R3
1
RESISTOR
20 Ω
5%
0613
R4
1
RESISTOR
NU
-
0805
R5
1
RESISTOR
13 kΩ
1%
0805
R6
1
RESISTOR
220 kΩ
1%
0805
September 2015, Rev.0
20%
20%
20%
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Ettinger
Würth
Elektronik
Rohm
Semiconductor
VIshay BC
Components
Rohm
Semiconductor
Rohm
Semiconductor
EKMG451ELL2R2MJC5S
MMSD4148T1G
MURA160T3G
MMSZ15T1G
MRA4007T3G
NCP1060AD060R2G
768775312
768772102
13.14.119
820572711
MCR10ERTF3302
AC03000002009JAC00
MCR10ERTF1302
MCR10ERTF2203
5
DN05080/D
Figure 8 – PCB’s top side
Figure 9 – PCB’s bottom side
1
© 2015 ON Semiconductor.
Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor
does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to
assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated
with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its
products at any time, without notice.
Design note created by Jaromír Uherek, e-mail: mailto:[email protected]
September 2015, Rev.0
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