Application Note Please read the Important Notice and Warnings at the end of this document Revision 1.0
www.infineon.com 2016-09-26
AN
-
REF
-
3W
-
IOT
-
COOLSET
IoT off-line isolated power supply 3 W 5 V, <13 mW
standby
SMPS based on CoolSET™ICE3RBR4765JG current mode controller
About this document
Scope and purpose
This document presents one solution for a simple, low-power, offline flyback converter based on the Infineon
ICE3RBR4765JG controller. It is an engineering report of features and performance for a 5 V 3 W solution, with
explanations covering component selection, circuit and layout design.
The ICE3RBR4765JG is an offline SMPS current mode controller from the CoolSET™jitter series, with integrated
650 V CoolMOS™MOSFETs and a startup cell.
Intended audience
This document is intended for power supply design engineers, application engineers, students, etc., who wish
to design low cost, highly reliable off-line Switched Mode Power Supply (SMPS) systems for:
•Applications related to the Internet of things (IoT)
1) Standby power supply
2) Power supply for microcontrollers
3) Power supply for standalone sensors operating on a wired/wireless interface bus
•USB-power supply embedded in a wall plug
•Intelligent wall plug switched by wireless (with relay)
•Metering application
•General Applications with small formfactor in the power range 1 W to 3 W.
Application Note 2 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
SMPS based on CoolSET™ICE3RBR4765JG current mode c
ontroller
Table of contents
Table of contents
About this document .............................................................................................................................................1
1 Introduction.......................................................................................................................................3
2 Technical specification ......................................................................................................................4
3 List of product features – ICE3RBR4765JG .........................................................................................5
4 Circuit description..............................................................................................................................6
4.1 Circuit diagram........................................................................................................................................6
4.2 Introduction.............................................................................................................................................6
4.3 Line input rectification............................................................................................................................6
4.4 Primary side EMI filter .............................................................................................................................6
4.5 Primary side snubber ..............................................................................................................................7
4.6 Power supply for CoolSET™controller...................................................................................................7
4.7 Secondary side rectification ...................................................................................................................7
4.8 Feedback loop circuit..............................................................................................................................8
5 CoolSET™ICE3RBR4765JG controller ................................................................................................9
5.1 Start up ....................................................................................................................................................9
5.2 Peak primary current control .................................................................................................................9
5.3 Active Burst Mode (ABM) ....................................................................................................................... 10
5.4 Protection modes and auto restart ......................................................................................................10
6 PCB Layout.......................................................................................................................................12
7 Bill of materials ................................................................................................................................13
8 Transformer specification................................................................................................................14
8.1 Electrical diagram .................................................................................................................................14
8.2 Electrical specification..........................................................................................................................14
8.3 Material..................................................................................................................................................14
8.4 Transformer build diagram...................................................................................................................15
8.5 Transformer design by Würth Elektronik .............................................................................................15
9 Test results.......................................................................................................................................16
9.1 Efficiency................................................................................................................................................16
9.2 No-load power consumption................................................................................................................17
9.3 Light load power consumption.............................................................................................................17
9.4 Line and load regulation ....................................................................................................................... 18
9.5 Output voltage ripple............................................................................................................................19
9.6 Thermal performance ...........................................................................................................................19
10 Waveforms .......................................................................................................................................20
10.1 Switching waveforms at steady state...................................................................................................20
10.2 Startup...................................................................................................................................................20
10.3 Output voltage ripple............................................................................................................................21
10.4 Active burst mode .................................................................................................................................22
10.5 Load transient response .......................................................................................................................23
10.6 Output voltage overshoot and undershoot .........................................................................................23
11 Conducted EMI.................................................................................................................................26
12 References .......................................................................................................................................27
Revision history ...................................................................................................................................................28
Application Note 3 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Introduction
1 Introduction
This is an engineering report for a 5 V, 3 W offline flyback power supply. This document contains the technical
specification for the power supply, a list/description of the main features, circuit and layout description as well
as the measurement results.
In this application, an Infineon ICE3RBR4765JG from the CoolSET™jitter series is used as a flyback controller.
The controller has a built-in 650 V CoolMOS™as the main switching component, as well as the startup cell. The
reference design board operates in Discontinuous Conduction Mode (DCM), running at 65 kHz switching
frequency. The output is a single 5 V / 600 mA, generated by secondary side regulation. Active Burst Mode (ABM)
operation provides very low standby power consumption (less than 13 mW over input voltage range 180 Vac ~
265Vac). Low EMI is achieved by built-in frequency jitter and soft start operation.
Figure 1 Top and bottom side of the reference design board
Application Note 4 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Technical spe
cification
2 Technical specification
Table 1 Power supply technical specification
Input voltage 180 Vac~265 Vac
Line frequency 50 Hz, 60 Hz
Output voltage 5 V
±
5%
Rated output current 600 mA
Rated output power 3 W
Efficiency 79% @ 230 Vac, full load
Output voltage ripple (max.) <80 mVpp
No load power consumption @Vin:
180Vac ~ 265Vac
<13 mW
Power consumption at 10 mA load <100 mW
Device dimensions 50 mm x 23.5 mm x 14 mm (L x W x H)
Isolation Reinforced isolation between primary and secondary side
Application Note 5 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
List of product features
–
ICE3RBR4765JG
3 List of product features – ICE3RBR4765JG
Table 2 List of features
650 V avalanche rugged CoolMOS™with built-in startup cell
Active Burst Mode (ABM) for lowest standby power
65 kHz internally fixed switching frequency
Auto restart protection mode for overload, open loop, VCC undervoltage, overtemperature and VCC
overvoltage
Built-in soft start
Fast load jump response in Active Burst Mode (ABM)
Internal PWM leading edge blanking
Built-in frequency jitter feature and soft driving for low EMI
BiCMOS technology provides wide VCC range
Application Note 6 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Circuit description
4 Circuit description
4.1 Circuit diagram
Figure 2 Schematic diagram for 5 V, 3 W power supply
4.2 Introduction
Key features of this application are the circuit simplicity, very small form factor and very low no-load power
consumption, with regard to the performance and stable operation in all conditions. In order to fit into a very
small form factor, the larger components are selected based on a maximum height as well as having the
smallest PCB footprint. The very low power consumption with no-load is achieved by addressing critical
components that continuously draw power, as well as the controller power consumption that depends
significantly on its supply voltage.
4.3 Line input rectification
The input voltage range is 180 Vac~265 Vac, and the converter is supplied by two wires without a protective
ground connection. This application does not cover the low input voltage range from 85 Vac, mainly due to the
need for a large bulk capacitor in the primary side.
Line input rectification circuit contains the fuse F1, the series resistor R1, the varistor V1 and the standard
bridge rectifier BR1. F1 is a slow blow 500 mA fuse in a radial case. The varistor is used as a surge and
overvoltage protector. Resistor R1 limits the inrush current and reduces the EMI.
4.4 Primary side EMI filter
The rectified input voltage is filtered by capacitors C1 and C2. L1 is the EMI suppressor for any high frequency
spikes in the primary current. Capacitors C1 and C2 are ceramic 1uF 450 V devices in an SMD package, selected
Application Note 7 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Circuit description
particularly for the small package size. With an input voltage of 180 Vac and a full load, C1 and C2 will discharge
to approximately 180 V. The maximum value of the rectified voltage is 375 V for a 265 Vac input.
4.5 Primary side snubber
When the CoolMOS™MOSFET turns off, a high drain voltage spike occurs - caused by the transformer leakage
inductance. These oscillations are damped by the RC snubber. D1 is a high voltage ultrafast diode with a very
short recovery time. C4 is selected based on the oscillation period and the voltage overshoot on the CoolMOS™
MOSFET drain. R2's value and its power rating depend on the maximum peak current through the primary
inductance and the CoolMOS™MOSFET voltage overshoot. The design margin for the CoolMOS™MOSFET drain
to source voltage must be maintained at all operating points. The snubber also suppresses radiated EMI.
4.6 Power supply for CoolSET™controller
When the input voltage is applied, the IC starts to charge its VCC capacitor through the built-in startup cell. The
startup cell is activated if the VCC voltage is below the undervoltage threshold level of 10.5 V. VCC charge current
is controlled to 0.9 mA by the startup cell. The startup cell remains active until the VCC voltage exceeds the on-
threshold of 18 V, when the chip starts to operate and the startup cell is turned off. By implementing hysteresis
for the startup VCC voltage, an uncontrolled ringing when switching on is avoided.
Figure 3 Power management of the IC
In order to achieve the lowest power consumption, VCC is set as low as possible within a defined range. Due to
the tolerance of the IC, especially the undervoltage lockout level (which can be as high as 11.2 V), a safe margin
for VCC is taken into account when the transformer auxiliary winding is determined. Capacitors C6 and C7 are
selected to be sufficient to keep VCC above this safe margin during the discharge phase, when the IC is not in a
steady state. The VCC capacitance must not be unnecessarily large with respect to the startup time. In steady
state conditions VCC is stable as the IC is supplied from the auxiliary winding.
4.7 Secondary side rectification
The secondary side rectification circuit is a simple diode rectifier with filter capacitors. Diode D3 is a Schottky
type, selected to meet the current and reverse voltage requirements. Its low forward voltage reduces the power
loss in D3, and therefore lowers its temperature and improves the overall efficiency.
Application Note 8 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Circuit description
Selection of output capacitors C9 and C10 directly affects the output voltage ripple, standby power
consumption and the repetition time period during active burst mode. In general, large output capacitors
reduce the output voltage ripple and increase the repetition time period which, in turn, reduces the standby
power consumption. However, too large an output capacitance leads to a very slow Vout discharge at extremely
light load or open load. If VCC discharges and triggers the UVLO before the IC enters active burst mode, the IC
may be trapped in an endless auto restart mode and never enters active burst mode.
The output voltage ripple is reduced by selecting an ultra low-ESR capacitor. Typically, capacitors with ultra
low ESR have relatively high leakage current that increases standby power consumption significantly. By
combining one ultra low-ESR capacitor and one regular capacitor, maximum output voltage ripple is less than
80 mVpp and the standby power consumption is less than 13 mW.
4.8 Feedback loop circuit
The major requirement for the feedback loop is to match the dynamically varying load and provide stable
system control. The output voltage is sensed using an LMV431 precision shunt regulator (1% initial tolerance,
1.24 V reference voltage), which has a low operating current (55 µA). Resistors R7 and R8 set the output voltage
to 5 V. The resistance of R7 and R8 should be selected to be as large as possible to reduce the standby power
consumption while not being so large that they affect control stability. R4 determines the optocoupler (U2)
diode current - this is important for fast transient response and as well for standby power consumption.
Optocoupler U2 is selected based on its Current Transfer Ratio (CTR) and low input current while ensuring the
package permits a suitable creepage distance.
In terms of component selection, the feedback loop circuitry is the most complicated to calculate as the open
load power consumption must be very low. Additionally, output voltage regulation, load transient response,
stability, output voltage ripple and burst mode repetition time depend on the feedback loop. Therefore, most
component values in the feedback loop are determined by testing.
Application Note 9 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
CoolSET™
ICE3RBR4765JG controller
5 CoolSET™ICE3RBR4765JG controller
The ICE3RBR4765JG controller belongs to the CoolSET™jitter series and includes built-in features for soft start,
blanking window, frequency jitter, active burst mode, propagation delay compensation, modulated gate
driving and auto-restart when protection features are triggered.
Figure 4 Pin configuration PG-DSO-12
For full details about the ICE3RBR4765JG controller, see [1].
5.1 Start up
The built-in startup cell is sufficient for the ICE3RBR4765JG to start without external startup resistors. The
startup cell connects the drain pin to the VCC pin of the IC and charges the external capacitors to 18 V when the
IC starts switching. At this point, the VCC pin is supplied from the auxiliary winding.
In the startup phase, the IC provides a soft start function to gradually increase the primary current by
increasing the duty cycle in 32 steps. The soft start phase finishes 20 ms after the IC is switched on (VCC exceeds
18 V).
In addition to start up, the soft start function is also activated at a restart attempt during auto restart. This
means that the converter transfers a significant amount of energy to the secondary side every time the IC
restarts. As a consequence, when the output is open and the input voltage is interrupted significant output
voltage overshoot can occur if the feedback loop response is not sufficiently fast, as the converter is charging
the output capacitors even though the output voltage is close to Vout nominal.
5.2 Peak primary current control
The primary current is sensed by the external shunt resistors, R3 and R13. This signal is amplified and then
compared with the feedback signal for cycle by cycle peak current limit operation. If the amplified current
sense signal exceeds the feedback signal, the on-time Ton of the driver is closed.
Resistors R3 and R13 determine the maximum peak current of the integrated CoolMOS™MOSFET and, as a
result, the maximum output power is limited. Overload protection is triggered if the current sense voltage
exceeds the threshold Vcsth=1.03 V. Integrated propagation delay compensation reduces the influence of the AC
input voltage on the maximum output power. Leading edge blanking is integrated to protect the current limit
from distortions caused by leading edge spikes.
Application Note 10 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
CoolSET™ICE3RBR4765JG controller
Figure 5 Current mode
In active burst mode, the peak primary current limit is reduced to VCS=0.34 V. Thus, the conduction loss and
audible noise is reduced.
5.3 Active Burst Mode (ABM)
The system enters ABM under low load conditions. With ABM, the efficiency increases significantly at light load
while still maintaining a low ripple on VOUT and a fast response on step changes in load. The significant feature is
the extremely low standby power consumption: <13 mW at 180 Vac~265 Vac.
The system will enter ABM if the feedback signal falls and remains below 1.35 V for the 20 ms blanking time.
This time window prevents ABM being entered due to large step changes in load. When ABM is entered, the
current consumption of the IC is reduced to approximately 450 µA. During ABM, VCC must be kept above the
undervoltage lockout level of 10.5 V to prevent the startup cell from switching on and the IC from restarting.
The feedback signal is a sawtooth between 3.5 V when the IC starts switching and 3.0 V when the IC stops
switching. The feedback signal will increase immediately if there is a step change in load. The system will exit
the ABM when the feedback signal exceeds 4.0 V.
5.4 Protection modes and auto restart
The IC provides an auto restart mode as a protection feature to prevent damage of the device. Table 3 shows
possible system failures, conditions and corresponding protection modes.
Application Note 11 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
CoolSET™ICE3RBR4765JG controller
Table 3 System failures and protection modes
Protection function Failure condition Protection mode
VCC overvoltage 1. VVCC > 20.5 V & FB > 4 V & during soft start period & last for 30
μs
2. VVCC > 25.5 V & last for (120+30) μs (inactive during burst
mode)
Auto restart
Overtemperature
(controller junction)
TJ> 140°C & last for 30 µs Auto restart
Overload/open loop VFB > 4 V & last for 20 ms & VBA > 4.0 V & last for 30 μs
(extended blanking time counted from charging VBA from 0.9 V
to 4.0 V )
Auto restart
VCC Undervoltage/short
optocoupler
VVCC < 10.5 V & last for 10 ms + 30 μs Auto restart
Auto restart enable VBA < 0.33 V & last for 30 μs Auto restart
When the system enters the auto restart mode, the IC will be off. At this point switching stops and VCC starts to
drop. When VCC reaches the turn-off threshold of 10.5 V, the startup cell will turn on and start to charge VCC up to
the turn-on threshold of 18 V, allowing the IC to turn on again. After the startup phase, if the fault condition still
exists, the IC will enter auto restart mode once again, otherwise the system will resume normal operation.
Application Note 12 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
PCB Layout
6 PCB Layout
The printed circuit board (PCB) is dual layer, double sided, and manufactured with the standard 1.5 mm
thickness and 1oz copper. Between the primary and secondary side, the creepage distance is created according
to requirements for reinforced isolation. The overall PCB size is 50 mm x 23.5 mm.
Figure 6 Layout top
Figure 7 Layout bottom
Application Note 13 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Bill of materials
7 Bill of materials
Table 4 Bill of materials
Component
designator
Description Manufacturer Manufacturer part number
BR1 Bridge rectifier, 600 V, 0.5 A, TO-269AA Vishay MB6S-E3/45
C1, C2 Capacitor ceramic, 1
µ
F, 450 V, 1812 TDK CKG45NX7T2W105M500JH
C4 Capacitor ceramic, 2200 pF, 250V, 0805 Murata GRJ21AR72E222KWJ1D
C5 Capacitor ceramic, 1 nF, 50 V, 0805 standard capacitor
C6 Capacitor ceramic, 4.7
µ
F, 50 V, 1206 standard capacitor
C7 Capacitor electrolytic, 33
µ
F, 35 V, SMD Panasonic EEE-FT1V330AR
C8 Capacitor ceramic, 1000 pF, 250 V, X1/Y1 Murata DE1E3KX102MA4BN01F
C9 Capacitor electrolytic, 180
µ
F, 6.3 V, SMD Würth Elektronik 875105144007
C10 Capacitor electrolytic, 330
µ
F, 6.3 V, SMD Panasonic EEEFT0J331AP
C11 Capacitor ceramic, 10
µ
F, 25 V, 1206 Würth Elektronik 885012108021
C12 Capacitor ceramic, 33 nF, 50 V, 0805 standard capacitor
D1 Diode ultrafast, 600 V, 1 A, DO-214AC STMicroelectronics STTH1R06A
D2 Diode ultrafast, 200 V, 1 A, DO-214AC Fairchild ES1D
D3 Diode Schottky, 60 V, 2 A, DO-214AA Vishay SS26-E3/52T
F1 Fuse slow blow, 250 V, 0.5 A, TH Multicomp MST 500MA 250V
L1 Inductor, 68µH, 320mA, 3816 Würth Elektronik 744031680
R1 Resistor, 10
Ω
, 300 V, 2010 Vishay CRCW201010R0FKEF
R2 Resistor, 330 k
Ω
, 200 V, 1%, 1206 standard resistor
R3 Resistor, 6.8
Ω
, 1%, 1206 standard resistor
R4 Resistor, 3.3 k
Ω
, 1%, 0805 standard resistor
R6 Resistor, 1 M
Ω
, 1%, 0805 standard resistor
R7 Resistor, 102 k
Ω
, 1%, 0805 standard resistor
R8 Resistor, 33 k
Ω
, 1%, 0805 standard resistor
R13 Resistor, 12
Ω
, 1%, 1206 standard resistor
TR1 Transformer, 2.2 mH, EE13/7/4 Würth Elektronik 750817018
U1 IC, ICE3RBR4765JG, PG-DSO-12 Infineon ICE3RBR4765JG
U2 Optocoupler, VOL618A, LSOP 4 Vishay VOL618A-3X001T
U3 IC, LMV431, SOT-23-3 Texas Instruments LMV431AIMF/NOPB
V1 Varistor, CU3225K300G2 Epcos B72650M0301K072
Application Note 14 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Tr
ansformer specification
8 Transformer specification
8.1 Electrical diagram
Figure 8 Transformer electrical diagram
8.2 Electrical specification
Table 5 Transformer electrical specification
Primary inductance Pins 1-3, measured when all other
windings are open
2.2 mH
Number of primary turns Pins 1-3 126
Number of secondary turns Pins 7-8 10
Number of auxiliary turns Pins 4-5 24
8.3 Material
Table 6 Transformer material
Core EE13/7/4, N87 material, air gap 0.099 mm
Coil former EE13/7/4, SMD 9 pins, for reinforced insulation
Wire for primary winding 0.13 mm dia., heavy polyurethane insulated wire
Wire for secondary winding 0.4 mm dia., PFA insulated wire
Wire for auxiliary winding 0.18 mm dia., heavy polyurethane insulated wire
Insulation tape Polyester film tape
Application Note 15 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Transformer specification
8.4 Transformer build diagram
Figure 9 Transformer build diagram
8.5 Transformer design by Würth Elektronik
Figure 10 Transformer design by Würth Elektronik
Application Note 16 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Test results
9 Test results
9.1 Efficiency
Efficiency measurements are performed at room temperature in steady state. The line frequency is 50 Hz.
Figure 11 Efficiency versus input voltage
Figure 12 Efficiency versus output power
60%
65%
70%
75%
80%
85%
180 190 200 210 220 230 240 250 260 270
Efficiency [%]
AC Line Input Voltage [Vac]
Efficiency versus AC Line Input Voltage
Average Efficiency(25%,50%,75%,100%) Full load Efficiency
60%
65%
70%
75%
80%
85%
25% 50% 75% 100%
Efficiency [%]
Output Power [%]
Efficiency versus Output Power
Vin=230Vac
Application Note 17 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Test results
9.2 No-load power consumption
Figure 13 No-load input power consumption versus input voltage
Power consumption without load is measured with the power analyzer YOKOGAWA WT3000, using the
integration function for the duration of one minute.
9.3 Light load power consumption
Figure 14 Power consumption versus input voltage when POUT=50 mW
10,0
10,5
11,0
11,5
12,0
180 210 240 270
Standby Power [mW]
AC Line Input Voltage [Vac]
Standby Power versus AC Line Input
Voltage
Standby Power
86
88
90
92
94
96
180 210 240 270
Input Power [mW]
AC Line Input Voltage [Vac]
Input Power versus AC Line Input Voltage
Pout = 50mW
Application Note 18 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Test results
9.4 Line and load regulation
Figure 15 Line regulation at full load
Figure 16 Load regulation at Vin=230 Vac
4,95
4,96
4,97
4,98
4,99
5
180 190 200 210 220 230 240 250 260 270
Output Voltage [V]
AC Line Input Voltage [Vac]
Line Regulation
Vout @ full load
4,95
4,96
4,97
4,98
4,99
5
25% 50% 75% 100%
Output Voltage [V
OUtput Power [%]
Load Regulation
Vin = 230Vac
Application Note 19 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Test results
9.5 Output voltage ripple
Figure 17 Output voltage ripple
Maximum output voltage ripple is 70 mVpp.
9.6 Thermal performance
The thermal photos were taken with a FLIR T600 thermal camera, after the board ran at full load for 45 minutes.
Figure 18 Thermal picture – top and bottom side
The hottest component is the diode D3, with a temperature of 54°C. The controller temperature is 49°C.
Ambient temperature is 25°C.
25
30
35
40
45
50
55
60
65
70
0 0,1 0,2 0,3 0,4 0,5 0,6
Output Voltage ripple [Vpp]
Output current [A]
Output voltage ripple
Vout ripple @ 180Vac Vout ripple @ 230Vac Vout ripple @ 265Vac
Application Note 20 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Waveforms
10 Waveforms
10.1 Switching waveforms at steady state
CH1: Vdrain CH2: Vcs
Figure 19 CoolMOS™drain and source voltage waveforms @230 Vac and full load
10.2 Startup
Startup waveforms are captured @230 Vac and full load (resistive load).
CH1: Vdrain CH2: VCC
Figure 20 Drain voltage and VCC voltage startup profile
Application Note 21 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Waveforms
GREY: no load startup GREEN: full load startup
Figure 21 Output voltage startup profile
10.3 Output voltage ripple
Figure 22 Output voltage ripple @230 Vac and full load
Application Note 22 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Waveforms
10.4 Active burst mode
CH1: Vdrain CH2: VCC CH3: Vfb CH4: Vout
Figure 23 No load active burst mode @180 Vac
CH1: Vdrain CH2: VCC CH3: Vfb CH4: Vout
Figure 24 Active burst mode @180 Vac when Iout=10 mA
Application Note 23 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Waveforms
10.5 Load transient response
CH1: Vout CH4: Iout
Figure 25 Load transient response
The load is switching between 50% and 100% with a 10 ms period. Slew rate is 0.2 A/µs.
10.6 Output voltage overshoot and undershoot
Test setup: Vin 230Vac; E-load: Chroma 63103A, CC mode, slew rate 0.2 A/µs.
Figure 26 shows the Vout overshoot and undershoot when the load changes from full load to open load and vice
versa. When the full load changes to open load, the Vout overshoot is 5.16 V. Vout undershoot is 4.81 V when the
load jumps from open to full load.
NB: the waveforms in this section were measured with a YOKOGAWA DLM4058 Oscilloscope. Please refer to
YOKOGAWA's user manual for the DC accuracy.
CH1: Vout CH3: VCC CH4: Iout
Figure 26 Output voltage overshoot and undershoot due to load transition
Application Note 24 Revision 1.0
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IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Waveforms
Some demo boards may demonstrate Vout dual overshoots as shown in Figure 27. The first Vout overshoot is due
to the load jump from full load to open load. When the first Vout overshoot happens, VFB is kept low and there is
no PWM switching activity. Vout and VCC start discharging. VCC capacitor C7 and output capactiors C9 / C10 are
Aluminum electrolytic capacitors with ±20% capacitance tolerance. In extreme case, C7’s tolerance is -20%,
while both C9 and C10 have tolerance of +20%. VCC discharges (much) faster than Vout, so that VCC triggers the
UVLO (10.5V) before the IC enters active burst mode. Therefore, the IC enters auto restart. A second Vout
overshoot happens when Vcc is charged up to 18 V and the IC starts switching. The maximum Vout is detected at
the second overshoot: 5.23V.
CH1: Vout CH3: VCC CH4: Iout CH5: VFB CH6: Vdrain
Figure 27 Output voltage dual overshoots due to load transition
Figure 28 and Figure 29 show the output voltage overshoot if a short AC line interruption occurs. With an open
load, the overshoot is large as the device restarts and the startup procedure charges the output capacitors
which are not yet discharged (CH4 Vout). This overshoot can be reduced by making the feedback loop faster, but
it will affect the power consumption at no load. Vout overshoot level is 5.19 V.
CH1: Vout CH2: VCC CH4: Iout
Application Note 25 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Waveforms
Figure 28 Output voltage overshoot due to AC line voltage interruption (no load)
With a 10 mA load, when the AC source is removed, Vout (Vout) discharges quickly to a low level. When the AC
source is connected again, typically no overshoot was observed at Vout.
CH1: Vout CH2: VCC CH4: Iout
Figure 29 Output voltage overshoot due to AC line voltage interruption (Iout=10 mA)
Application Note 26 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
Conducted EMI
11 Conducted EMI
Conducted EMI was measured according to test standard EN55022 class B, at Vin=230 Vac and full load.
Figure 30 Line
Figure 31 Neutral
Application Note 27 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
References
12 References
[1] Infineon Technologies, Datasheet ICE3RBR4765JG “Fixed-Frequency, 650 V CoolSET™in DS0-12 Package”
[2] Infineon Technologies, Application Note 10 W 12 V SMPS Evaluation Board with CoolSET®-F3R
ICE3BR4765JG
Application Note 28 Revision 1.0
2016-09-26
IoT off-line isolated power supply 3 W 5 V, <13 mW standby
SMPS based on CoolSET™ICE3RBR4765JG current mode control
ler
Revision history
Revision history
Major changes since the last revision
Page or Reference Description of change
First version
Trademarks of Infineon Technologies AG
µHVIC™, µIPM™, µPFC™, AU-
ConvertIR™, AURIX™, C166™, CanPAK™, CIPOS™, CIPURSE™, CoolDP™, CoolGaN™, COOLiR™, CoolMOS™, CoolSET™, CoolSiC™,
DAVE™, DI-POL™, DirectFET™, DrBlade™, EasyPIM™, EconoBRIDGE™, EconoDUAL™, EconoPACK™, EconoPIM™, EiceDRIVER™,
eupec™, FCOS™, GaNpowIR™,
HEXFET™, HITFET™, HybridPACK™, iMOTION™, IRAM™, ISOFACE™, IsoPACK™, LEDrivIR™, LITIX™, MIPAQ™, ModSTACK™, my-
d™, NovalithIC™, OPTIGA™,
OptiMOS™, ORIGA™, PowIRaudio™, PowIRStage™, PrimePACK™, PrimeSTACK™, PROFET™, PRO-SIL™, RASIC™
, REAL3™, SmartLEWIS™, SOLID FLASH™,
SPOC™, StrongIRFET™, SupIRBuck™, TEMPFET™, TRENCHSTOP™, TriCore™, UHVIC™, XHP™, XMC™
Trademarks updated November 2015
Other Trademarks
All referenced product or service names and trademarks are the property of their respective owners.
Edition 2016-09-26
AN-REF-3W-IOT-COOLSET
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Infineon Technologies AG
81726 Munich, Germany
© 2016 Infineon Technologies AG.
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