PDF TNY268 Data sheet ( Hoja de datos )

Número de pieza TNY268
Descripción Low Power Off-line Switcher
Fabricantes Power Integrations 
Logotipo Power Integrations Logotipo

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TinySwitch®-II Family
Enhanced, Energy Efficient,
Low Power Off-line Switcher
Product Highlights
TinySwitch-II Features Reduce System Cost
• Fully integrated auto-restart for short circuit and open
loop fault protection – saves external component costs
• Built-in circuitry practically eliminates audible noise with
ordinary dip-varnished transformer
• Programmable line under-voltage detect feature prevents
power on/off glitches – saves external components
• Frequency jittering dramatically reduces EMI (~10 dB)
– minimizes EMI filter component costs
• 132 kHz operation reduces transformer size – allows use
of EF12.6 or EE13 cores for low cost and small size
• Very tight tolerances and negligible temperature variation
on key parameters eases design and lowers cost
• Lowest component count switcher solution
• Expanded scalable device family for low system cost
Better Cost/Performance over RCC & Linears
• Lower system cost than RCC, discrete PWM and other
integrated/hybrid solutions
• Cost effective replacement for bulky regulated linears
• Simple ON/OFF control – no loop compensation needed
• No bias winding – simpler, lower cost transformer
• Simple design practically eliminates rework in
EcoSmart®– Extremely Energy Efficient
• No load consumption <50 mW with bias winding and
<250 mW without bias winding at 265 VAC input
• Meets California Energy Commission (CEC), Energy
Star, and EU requirements
• Ideal for cell-phone charger and PC standby applications
High Performance at Low Cost
• High voltage powered – ideal for charger applications
• High bandwidth provides fast turn on with no overshoot
• Current limit operation rejects line frequency ripple
• Built-in current limit and thermal protection improves
TinySwitch-II integrates a 700 V power MOSFET, oscillator,
high voltage switched current source, current limit and
thermal shutdown circuitry onto a monolithic device. The
start-up and operating power are derived directly from
the voltage on the DRAIN pin, eliminating the need for
a bias winding and associated circuitry. In addition, the
UV Resistor
HV DC Input
Figure 1. Typical Standby Application.
DC Output
230 VAC ±15%
85-265 VAC
TNY263 P or G 5 W 7.5 W 3.7 W 4.7 W
TNY264 P or G 5.5 W 9 W 4 W 6 W
TNY265 P or G 8.5 W 11 W 5.5 W 7.5 W
TNY266 P or G 10 W 15 W 6 W 9.5 W
TNY267 P or G 13 W 19 W 8 W 12 W
TNY268 P or G 16 W 23 W 10 W 15 W
Table 1. Notes: 1. Minimum continuous power in a typical
non-ventilated enclosed adapter measured at 50 °C ambient.
2. Minimum practical continuous power in an open frame
design with adequate heat sinking, measured at 50 °C
ambient (See Key Applications Considerations). 3. Packages:
P: DIP-8B, G: SMD-8B. For lead-free package options, see Part
Ordering Information.
TinySwitch-II devices incorporate auto-restart, line under-
voltage sense, and frequency jittering. An innovative design
minimizes audio frequency components in the simple ON/OFF
control scheme to practically eliminate audible noise with
standard taped/varnished transformer construction. The fully
integrated auto-restart circuit safely limits output power during
fault conditions such as output short circuit or open loop,
reducing component count and secondary feedback circuitry
cost. An optional line sense resistor externally programs a line
under-voltage threshold, which eliminates power down glitches
caused by the slow discharge of input storage capacitors present
in applications such as standby supplies.The operating frequency
of 132 kHz is jittered to significantly reduce both the quasi-peak
and average EMI, minimizing filtering cost.
April 2005

1 page

TNY268 pdf
the SOURCE pin. The optocoupler LED is connected in series
with a Zener diode across the DC output voltage to be regulated.
When the output voltage exceeds the target regulation voltage
level (optocoupler LED voltage drop plus Zener voltage), the
optocoupler LED will start to conduct, pulling the EN/UV pin
low. The Zener diode can be replaced by a TL431 reference
circuit for improved accuracy.
ON/OFF Operation with Current Limit State Machine
The internal clock of the TinySwitch-II runs all the time. At
Figure 6. TinySwitch-II Operation at Near Maximum Loading.
the beginning of each clock cycle, it samples the EN/UV pin to
decide whether or not to implement a switch cycle, and based
on the sequence of samples over multiple cycles, it determines
the appropriate current limit. At high loads, when the EN/UV
pin is high (less than 240 µA out of the pin), a switching cycle
with the full current limit occurs.At lighter loads, when EN/UV
is high, a switching cycle with a reduced current limit occurs.
At near maximum load, TinySwitch-II will conduct during nearly
all of its clock cycles (Figure 6). At slightly lower load, it will
“skip” additional cycles in order to maintain voltage regulation
at the power supply output (Figure 7). At medium loads, cycles
will be skipped and the current limit will be reduced (Figure 8).
At very light loads, the current limit will be reduced even further
(Figure 9). Only a small percentage of cycles will occur to
satisfy the power consumption of the power supply.
The response time of the TinySwitch-II ON/OFF control scheme
is very fast compared to normal PWM control. This provides
tight regulation and excellent transient response.
Power Up/Down
The TinySwitch-II requires only a 0.1 µF capacitor on the
BYPASS pin. Because of its small size, the time to charge this
capacitor is kept to an absolute minimum, typically 0.6 ms. Due
to the fast nature of the ON/OFF feedback, there is no overshoot
at the power supply output. When an external resistor (2 M)
is connected from the positive DC input to the EN/UV pin, the
power MOSFETswitching will be delayed during power-up until
the DC line voltage exceeds the threshold (100 V). Figures 10
and 11 show the power-up timing waveform of TinySwitch-II
in applications with and without an external resistor (2 M)
connected to the EN/UV pin.
Figure 7. TinySwitch-II Operation at Moderately Heavy Loading.
Figure 8. TinySwitch-II Operation at Medium Loading.

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TNY268 arduino
2. A secondary output of 5 V with a Schottky rectifier diode.
3. Assumed efficiency of 77% (TNY267 & TNY268),
75% (TNY265 &TNY266) and 73% (TNY263 &TNY264).
4. The parts are board mounted with SOURCE pins soldered
to sufficient area of copper to keep the die temperature at
or below 100 °C.
In addition to the thermal environment (sealed enclosure,
ventilated, open frame, etc.), the maximum power capability
of TinySwitch-II in a given application depends on transformer
core size and design (continuous or discontinuous), efficiency,
minimum specified input voltage, input storage capacitance,
output voltage, output diode forward drop, etc., and can be
different from the values shown in Table 1.
Audible Noise
The TinySwitch-II practically eliminates any transformer audio
noise using simple ordinary varnished transformer construction.
No gluing of the cores is needed. The audio noise reduction
is accomplished by the TinySwitch-II controller reducing the
current limit in discrete steps as the load is reduced. This
minimizes the flux density in the transformer when switching
at audio frequencies.
Worst Case EMI & Efficiency Measurement
Since identical TinySwitch-II supplies may operate at several
different frequencies under the same load and line conditions,
care must be taken to ensure that measurements are made under
worst case conditions.When measuring efficiency or EMI verify
that the TinySwitch-II is operating at maximum frequency and
that measurements are made at both low and high line input
voltages to ensure the worst case result is obtained.
Single Point Grounding
Use a single point ground connection at the SOURCE pin for
the BYPASS pin capacitor and the Input Filter Capacitor
(see Figure 17).
Primary Loop Area
The area of the primary loop that connects the input filter
capacitor, transformer primary and TinySwitch-II together
should be kept as small as possible.
Primary Clamp Circuit
A clamp is used to limit peak voltage on the DRAIN pin at
turn-off. This can be achieved by using an RCD clamp (as
shown in Figure 14). A Zener and diode clamp (200 V) across
the primary or a single 550 V Zener clamp from DRAIN to
SOURCE can also be used. In all cases care should be taken
to minimize the circuit path from the clamp components to the
transformer and TinySwitch-II.
Thermal Considerations
Copper underneath the TinySwitch-II acts not only as a single
point ground, but also as a heatsink. The hatched areas shown
in Figure 17 should be maximized for good heat sinking of
TinySwitch-II and the same applies to the output diode.
EN/UV pin
If a line under-voltage detect resistor is used then the resistor
should be mounted as close as possible to the EN/UV pin to
minimize noise pick up.
The voltage rating of a resistor should be considered for the under-
voltage detect (Figure 15: R2, R3) resistors. For 1/4 W resistors,
the voltage rating is typically 200 V continuous, whereas for
1/2 W resistors the rating is typically 400 V continuous.
The placement of the Y-capacitor should be directly from the
primary bulk capacitor positive rail to the common/return
terminal on the secondary side. Such placement will maximize
the EMI benefit of the Y-capacitor and avoid problems in
common-mode surge testing.
It is important to maintain the minimum circuit path from
the optocoupler transistor to the TinySwitch-II EN/UV and
SOURCE pins to minimize noise coupling.
The EN/UV pin connection to the optocoupler should be kept
to an absolute minimum (less than 12.7 mm or 0.5 in.), and
this connection should be kept away from the DRAIN pin
(minimum of 5.1 mm or 0.2 in.).
Output Diode
winding, the output diode and the output filter capacitor, should
be minimized. See Figure 17 for optimized layout. In addition,
sufficient copper area should be provided at the anode and
cathode terminals of the diode for adequate heatsinking.
Input and Output Filter Capacitors
There are constrictions in the traces connected to the input and
output filter capacitors. These constrictions are present for two
reasons. The first is to force all the high frequency currents
to flow through the capacitor (if the trace were wide then it
could flow around the capacitor). Secondly, the constrictions
minimize the heat transferred from the TinySwitch-II to the input
filter capacitor and from the secondary diode to the output filter
capacitor. The common/return (the negative output terminal
in Figure 17) terminal of the output filter capacitor should be
connected with a short, low impedance path to the secondary
winding. In addition, the common/return output connection
should be taken directly from the secondary winding pin and
not from the Y-capacitor connection point.

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