PKS603-607
C10
1 nF
250 VAC
R8
68
Ω
C11
1/2 W 330 pF
D9
1N4148
C17
4.7 nF
1 kV
D1-D4
1N4007
C4
150
µF
400 V
R15
2.2
Ω
R4
22
Ω
1/2 W
D6
FR106
D5
1N4007
t
RT1
10
Ω
O
R9
C13
47
µF
0.33
Ω
2W
16 V
Q1
2N3906
30 V @
C14
L2 220 nF
1.07 A Cont.
2.7 A Peak
5.3
µH
50 V
C5
2.2 nF
1 kV
VR1
1N4764A
100 V
1
9,10
D8
STPS3150
C12
330
µF
50 V
7,8
R3
10 kΩ
1/2 W 3
4
C6
47
µF
35 V
5
T1
EE25
VR2
1N5255B
28 V
R11
3 kΩ
R10
1.5 kΩ
RTN
L1
5.3 mH
R2
R1
1.3 MΩ 1.3 MΩ
C3
680 nF
X1
R5
2.2 MΩ
PeakSwitch
D
U1
PKS606Y
C7
100 nF
400 V
S
2
R12
1 kΩ
R7
4.7 kΩ
C15
100 nF
50 V
D10
UF4003
VR3
1N5258B
36 V
Q2
FS202DA
R6
2.4 MΩ
D7
1N4148
C16
100 nF
R14
100
Ω
R13
1 kΩ
R16
2.7 MΩ
EN/UV
BP
GND
F1
3.15 A
J1
L
PE
N
C1-C2
100 pF
250 VAC
C8
220 nF
50 V
U2
PC817X4
RTN Connected to PE via Flying Lead
C19
1 nF, 250 VAC
J3
PCB Term 18 AWG
PI-4170-060706
Figure 15. PeakSwitch PKS606Y, 32 W Continuous, 81 W Peak, Universal Input Power Supply.
Application Example
The circuit shown in Figure15 is a low cost, high efficiency,
flyback power supply designed to provide a 30 V, 1.06 A
continuous, 2.7 A peak output from universal input using the
PKS606Y.
The supply features under-voltage lockout and smart C sense with
A
fast reset. Latching overload, open loop, and hysteretic thermal
shutdown protect both the supply and load under fault conditions
while high efficiency (>80%) and very low no-load consumption
(<200 mW at 230 VAC) meets both active and standby efficiency
requirements. Output regulation is accomplished using a simple
Zener reference and opto coupler feedback.
Components C1, C2, C3, C10, C17, C19, R15, L1 and L2 provide
common mode and differential mode EMI filtering. Resistors
R1 and R2 discharge C3 when AC power is removed to prevent
electric shock from touching the AC input. Thermistor RT1
limits the peak inrush current when AC is first applied.
The rectified and filtered input voltage is applied to the primary
winding of T1. The other side of the transformer primary is
driven by the integrated MOSFET in U1. Diode D6, C5, R3,
R4, and VR1 clamp the U1 drain voltage to safe levels. Use
of a fast diode (500 ns) vs ultrafast for D6 increases power
supply efficiency by recovering some of the clamp energy. A
slow or standard recovery diode must not be used due to the
high switching frequency (a slow diode will not recover fast
enough under startup or output faults and therefore fail due
to excess dissipation). The use of a Zener in series with R3
compared to a standard RCD clamp optimizes both EMI and
energy efficiency.
Components D5, C7, and R5-6 provide AC line and under-
voltage sensing for PeakSwitch U1. By providing a separate
rectified voltage across C7 which is independent from the load
condition, rather than using the main input capacitor, allows
PeakSwitch
to distinguish the cause of loss of regulation. It
also provides fast reset when the AC input is removed, should
latching shutdown be triggered. Connecting R5 and R6 to C4
would still provide under-voltage lockout but after a fault the
user would have to wait for C4 to discharge before the supply
would reset. Resistor R16 provides a small amount of bias to
the U1 ENABLE/UNDER-VOLTAGE pin to retain the under-
voltage lockout function during brown-out conditions.
With R5 and R6 present, switching is inhibited until the current
into the EN/UV pin exceeds 25 µA. This allows the startup
voltage to be programmed within the normal operating input
voltage range, preventing glitching of the output under abnormal,
low voltage conditions and also on removal of the AC input.
Under a fault condition, for example an output short circuit or
broken feedback loop, if the line voltage is within the normal
range (>25 µA into the EN/UV pin) the PeakSwitch will latch
8
Rev. I 10/06
POWERINT [ POWER INTEGRATIONS, INC. ]
