TNY263-268
Key Application Considerations
TinySwitch-II vs. TinySwitch
Table 2 compares the features and performance differences
between the TNY254 device of the TinySwitch-II family with
the TinySwitch-II family of devices. Many of the new features
eliminate the need for or reduce the cost of circuit components.
Other features simplify the design and enhance performance.
Design
Output Power
Table 1 (front page) shows the practical continuous output
power levels that can be obtained under the following
conditions:
1. The minimum DC input voltage is 90 V or higher for
85 VAC input, or 240 V or higher for 230 VAC input or
115 VAC input with a voltage doubler. This corresponds to
a filter capacitor of 3
μF/W
for universal input and 1
μF/W
for 230 VAC or 115 VAC with doubler input.
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
TinySwitch-II vs. TinySwitch
Function
Switching Frequency and
Tolerance
Temperature Variation
(0-100
°C)**
Active Frequency Jitter
TinySwitch
TNY254
44 kHz ±10% (at 25
°C)
+8%
TinySwitch-II
TNY263-268
132 kHz ±6% (at 25
°C)
+2%)
•
•
•
•
TinySwitch-II
Advantages
Smaller transformer for low cost
Ease of design
Manufacturability
Optimum design for lower cost
N/A*
±4 kHz
•
Lower EMI minimizing filter
component costs
Transformer Audible Noise
Reduction
N/A*
Yes–built into controller
•
Practically eliminates audible noise with ordinary dip
varnished transformer – no special
construction or gluing required
N/A*
Single resistor
programmable
±7% (at 25
°C)
0%)
•
Prevents power on/off glitches
Line UV Detect
Current Limit Tolerance
Temperature Variation
(0-100
°C)**
Auto-Restart
±11% (at 25
°C)
-8%
•
Increases power capability and
simplifies design for high volume
manufacturing
•
Limits output short-circuit current to less than full
N/A*
6% effective on-time
load current
•
No output diode size penalty
•
Protects load in open loop fault conditions
•
No additional components required
BYPASS Pin Zener Clamp
N/A*
Internally clamped to 6.3 V
•
Allows TinySwitch-II to be powered from a low
voltage bias winding to improve efficiency and to
reduce on-chip power dissipation
DRAIN Creepage at Package
*Not available.
Table 2.
0.037 in. / 0.94 mm
0.137 in. / 3.48 mm
•
Greater immunity to arcing as a result of dust,
debris or other contaminants build-up
** See typical performance curves.
Comparison Between TinySwitch and TinySwitch-II.
10
Rev. H 02/09
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