TOP246FN View Datasheet(PDF) - Power Integrations, Inc
Part Name
Description
Manufacturer
TOP246FN
Power Integrations, Inc
TOP246FN Datasheet PDF : 52 Pages
| |||
Multiple Output, 60 W, 185-265 VAC Input Power Supply
Figure 44 shows a multiple output supply typical for high end
set-top boxes or cable decoders containing high capacity hard
disks for recording. The supply delivers an output power of
45 W continuous/60 W peak (thermally limited) from an input
voltage of 185 VAC to 265 VAC. Efficiency at 45 W,
185 VAC is ≥ 75%.
The 3.3 V and 5 V outputs are regulated to ±5% without
the need for secondary linear regulators. DC stacking (the
secondary winding reference for the other output voltages is
connected to the cathode of D10 rather than the anode) is used
to minimize the voltage error for the higher voltage outputs.
Due to the high ambient operating temperature requirement
typical of a set-top box (60 °C), the TOP246Y is used to
reduce conduction losses and minimize heatsink size. Resistor
R2 sets the device current limit to 80% of typical to limit
overload power. The line sense resistor (R1) protects the
TOPSwitch-GX from line surges and transients by sensing when
the DC rail voltage rises to above 450 V. In this condition the
TOPSwitch-GX stops switching, extending the input voltage
withstand to 496 VAC, which is ideal for countries with
poor power quality. A thermistor (RT1) is used to prevent
premature failure of the fuse by limiting the inrush current (due
TOP242-250
to the relatively large size of C2). An optional MOV (RV1)
extends the differential surge protection to 6 kV from 4 kV.
Leakage inductance clamping is provided by VR1, R5 and C5,
keeping the DRAIN voltage below 700 V under all conditions.
Resistor R5 and capacitor C5 are selected such that VR1
dissipates very little power except during overload conditions.
The frequency jittering feature of TOPSwitch-GX allows the
circuit shown to meet CISPR22B with simple EMI filtering
(C1, L1 and C6) and the output grounded.
The secondaries are rectified and smoothed by D7 to D11, C7,
C9, C11, C13, C14, C16 and C17. Diode D11 for the 3.3 V
output is a Schottky diode to maximize efficiency. Diode D10
for the 5 V output is a PN type to center the 5 V output at 5 V.
The 3.3 V and 5 V output require two capacitors in parallel to
meet the ripple current requirement. Switching noise filtering
is provided by L2 to L5 and C8, C10, C12, C15 and C18.
Resistor R6 prevents peak charging of the lightly loaded 30 V
output. The outputs are regulated using a secondary reference
(U3). Both the 3.3 V and 5 V outputs are sensed via R11
and R10. Resistor R8 provides bias for U3 and R7 sets the
overall DC gain. Resistor R9, C19, R3 and C5 provide loop
compensation. A soft-finish capacitor (C20) eliminates output
overshoot.
PERFORMANCE SUMMARY
Output Power:
Regulation:
3.3 V:
5 V:
12 V:
18 V:
30 V:
Efficiency:
No Load Consumption:
45 W Cont./60 W Peak
± 5%
± 5%
± 7%
± 7%
± 8%
≥75%
0.6 W
VR1
R5
P6KE170 68 kΩ
2W
C6
2.2 nF
Y1
D1-D4
1N4007 V
C5
1 nF
400 V
D6
1N4937
R6 D7
10 Ω UF4003
D8
UF5402
C7
47 µF
50 V
D9
UF5402
C9
330 µF
25 V
C11 C13
C16
390 µF 1000 µF 1000 µF
35 V
25 V
25 V
D10
BYV32-200
D11
MBR1045
C14
1000 µF
25 V
C17
1000 µF
25 V
L2
3.3 µH
3A
L3
3.3 µH
3A
L4
3.3 µH
5A
L5
3.3 µH
5A
C15
220 µF
16 V
C18
220 µF
16 V
C8
10 µF
50 V
C10
100 µF
25 V
C12
100 µF
25 V
30 V @
0.03 A
18 V @
0.5 A
12 V @
0.6 A
5V@
3.2 A
3.3 V @
3A
RTN
L1
20 mH
0.8A
C1
0.1 µF
X1
RV1
275 V
14 mm
F1
3.15 A
J1
RT1
L
10 Ω
1.7 A
N
C2
68 µF
400 V
R1
2 MΩ
1/2 W
T1
D6
1N4148
TOPSwitch-GX
D
L
TOP246Y
CONTROL
U1
C
S
XF
C3
0.1 µF
50 V
R3
6.8 Ω
R2
9.08 kΩ
C5
47 µF
10 V
C3
1 µF
50 V
R7
150 Ω
U2
LTV817
R8
1 kΩ
R11
9.53
kΩ
R9 C19
3.3 kΩ 0.1 µF
C20
22 µF
10 V
U3
TL431
R12
10 k
R10
15.0
kΩ
PI-2693-081704
Figure 44. 60 W Multiple Output Power Supply using TOP246.
23 M
12/04
|
|
Share Link: