TOP266KG Power Integrations, TOP266KG Datasheet - Page 19

• Manufacturer Part Number: TOP266KG
• Description: IC OFFLINE SWITCHER 39W 58W
• Manufacturer: Power Integrations
• Series: TOPSwitch®-JXr

Specifications of TOP266KG

• Output Isolation: Isolated
• Frequency Range: 66 ~ 132kHz
• Voltage - Output: 725V
• Power (watts): 39W
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 12-BSOP (0.350", 8.89mm Width) Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 596-1399

TOPSwitch-HX vs. TOPSwitch-JX
6. Power levels shown in the power table for the V package
The provided peak power depends on the current limit for the
respective device.
TOP264-271 Selection
Selecting the optimum TOP264-271 depends upon required
maximum output power, efficiency, heat sinking constraints,
system requirements and cost goals. With the option to
externally reduce current limit, TOP264-271 may be used for
lower power applications where higher efficiency is needed or
minimal heat sinking is available.
Input Capacitor
The input capacitor must be chosen to provide the minimum
DC voltage required for the TOP264-271 converter to maintain
regulation at the lowest specified input voltage and maximum
output power. Since TOP264-271 has a high DC
optimized dual slope line feed forward for ripple rejection, it is
possible to use a smaller input capacitor. For TOP264-271, a
capacitance of 2 mF per watt is possible for universal input with
an appropriately designed transformer.
Primary Clamp and Output Reflected Voltage V
A primary clamp is necessary to limit the peak TOP264-271 drain
to source voltage. A Zener clamp requires few parts and takes
up little board space. For good efficiency, the clamp Zener
should be selected to be at least 1.5 times the output reflected
voltage V
short. When using a Zener clamp in a universal input application,
a V
tolerances and temperature variations of the Zener. This will
ensure efficient operation of the clamp circuit and will also keep
the maximum drain voltage below the rated breakdown voltage
of the TOP264-271 MOSFET. A high V
advantage of the wider DC
RCDZ) clamp provides tighter clamp voltage tolerance than a
Table 3.
www.powerint.com
Function
CONTROL current I
0% duty cycle
eDIP-12 / eSOP-12
packages
Breakdown voltage BV
Fast AC reset
OR
device assume 6.45 cm
in an enclosed adapter, or 19.4 cm
of less than 135 V is recommended to allow for the absolute
OR
Comparison Between TOPSwitch-HX and TOPSwitch-JX.
, as this keeps the leakage spike conduction time
C(OFF)
DSS
at
MAX
2
TOPSwitch-HX
of 610 g/m
I
(TOP256-258)
I
Not available
Min. 700 V at T
3 external transistor circuits
using the V pin
C(OFF)
B
of TOP264-271. An RCD (or
= External bias current
= I
B
+ 3.4 mA
OR
2
2
in an open frame.
is required to take full
copper heat sink area
J
= 25 °C
MAX
OR
limit and an
TOPSwitch-JX
I
(TOP266-268)
Available
Min. 725 V at T
1 external transistor circuit
using the X pin
C(OFF)
= I
B
+ 1.6 mA
Zener clamp and allows a V
dissipation can be minimized by reducing the external current
limit as a function of input line voltage (see Figure 19). The RCD
clamp is more cost effective than the Zener clamp but requires
more careful design (see Quick Design Checklist).
Output Diode
The output diode is selected for peak inverse voltage, output
current, and thermal conditions in the application (including heat
sinking, air circulation, etc.). The higher DC
along with an appropriate transformer turns ratio, can allow the
use of a 80 V Schottky diode for higher efficiency on output
voltages as high as 15 V.
Bias Winding Capacitor
Due to the low frequency operation at no-load, a bias winding
capacitance of 10 mF minimum is recommended. Ensure a
minimum bias winding voltage of >9 V at zero load for correct
operation and output voltage regulation.
Soft-Start
Generally, a power supply experiences maximum stress at
start-up before the feedback loop achieves regulation. For a
period of 17 ms, the on-chip soft-start linearly increases the
drain peak current and switching frequency from their low
starting values to their respective maximum values. This
causes the output voltage to rise in an orderly manner, allowing
time for the feedback loop to take control of the duty cycle.
This reduces the stress on the TOP264-271 MOSFET, clamp
circuit and output diode(s), and helps prevent transformer
saturation during start-up. Also, soft-start limits the amount of
output voltage overshoot and, in many applications, eliminates
the need for a soft-finish capacitor. Note that as soon as the
loop closes the soft-start function ceases even if this is prior to
the end of the 17 ms soft-start period.
EMI
The frequency jitter feature modulates the switching frequency
over a narrow band as a means to reduce conducted EMI peaks
associated with the harmonics of the fundamental switching
J
= 25 °C
•
•
•
•
•
•
•
•
TOPSwitch-JX Advantages
Reduced CONTROL current
Better no-load performance (<0.1 W)
Better standby performance
66/132 kHz frequency option for DIP style heat sink
less designs
Better thermal performance for increased power
capability over DIP-8 / SMD-8 packages
Simplifies meeting customer derating requirements
(e.g. 80%)
Extended line surge withstand
Saves 5 components
OR
as high as 150 V. RCD clamp
TOP264-271
MAX
of TOP264-271,
Rev. C 11/10
19