TOP243G Power Integrations, TOP243G Datasheet - Page 21

• Manufacturer Part Number: TOP243G
• Description: IC OFFLINE SWIT OVP UVLO HV 8SMD
• Manufacturer: Power Integrations
• Series: TOPSwitch®-GXr

Specifications of TOP243G

• Output Isolation: Isolated
• Frequency Range: 66 ~ 132kHz
• Voltage - Output: 700V
• Power (watts): 25W
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 8-SMD Gull Wing, 7 Leads
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Figure 41. 30 W Power Supply using External Current Limit Programming and Line Sensing for UV and OV.
Application Examples
A High Efficiency, 30 W, Universal Input Power Supply
The circuit shown in Figure 41 takes advantage of several of
the TOPSwitch-GX features to reduce system cost and power
supply size and to improve efficiency. This design delivers
30 W at 12 V, from an 85 to 265 VAC input, at an ambient of
50 °C, in an open frame configuration. A nominal efficiency
of 80% at full load is achieved using TOP244Y.
The current limit is externally set by resistors R1 and R2 to a
value just above the low line operating peak DRAIN current
of approximately 70% of the default current limit. This allows
use of a smaller transformer core size and/or higher transformer
primary inductance for a given output power, reducing
TOPSwitch-GX power dissipation, while at the same time
avoiding transformer core saturation during startup and output
transient conditions. The resistors R1 & R2 provide a signal
that reduces the current limit with increasing line voltage, which
in turn limits the maximum overload power at high input line
voltage. This function in combination with the built-in soft-
start feature of TOPSwitch-GX, allows the use of a low cost
RCD clamp (R3, C3 and D1) with a higher reflected voltage,
by safely limiting the TOPSwitch-GX drain voltage, with
adequate margin under worst case conditions. Resistor R4
PERFORMANCE SUMMARY
Output Power:
Regulation:
Efficiency:
Ripple:
250 VAC
100 nF
CX1
J1
N
L
20 mH
L1
3.15 A
F1
600 V
BR1
2A
30 W
4%
79%
50 mV pk-pk
68 F
400 V
C1
4.7 nF
TOP244Y
4.7 M
1 kV
9.09 k
1/2 W
1/2 W
2 M
C3
R4
R1
UF4005
R2
D1
U1
D
S
68 k
2 W
CONTROL
CONTROL
R3
X
2.2 nF
CY1
L
F
TOPSwitch-GX
C
T1
47 F
10 V
C5
provides line sensing, setting UV at 100 VDC and OV at
450 VDC. The extended maximum duty cycle feature of
TOPSwitch-GX (guaranteed minimum value of 75% vs. 64%
for TOPSwitch-II) allows the use of a smaller input capacitor
(C1). The extended maximum duty cycle and the higher
reflected voltage possible with the RCD clamp also permit the
use of a higher primary to secondary turns ratio for T1 which
reduces the peak reverse voltage experienced by the secondary
rectifier D8. As a result a 60 V Schottky rectifier can be used
for up to 15 V outputs, which greatly improves power supply
efficiency. The frequency reduction feature of the
TOPSwitch-GX eliminates the need for any dummy loading
for regulation at no load and reduces the no load/standby
consumption of the power supply. Frequency jitter provides
improved margin for conducted EMI meeting the CISPR 22
(FCC B) specification.
Output regulation is achieved by using a simple Zener sense
circuit for low cost. The output voltage is determined by the
Zener diode (VR2) voltage and the voltage drops across the
optocoupler (U2) LED and resistor R6. Resistor R8 provides
bias current to Zener VR2 for typical regulation of ±5% at the
12 V output level, over line and load and component
variations.
6.8
R5
MBR1060
1 nF
C14
D8
150
1N4148
R15
D2
0.1 F
560 F
35 V
C6
C10
560 F
35 V
C11
150
R6
3.3 H
VR2
1N5240C
10 V, 2%
TOP242-250
L3
LTV817A
150
U2
R8
220 F
35 V
C12
PI-2657-040501
1/02
G
12 V
@ 2.5 A
RTN
21