
10
C
4/03
TNY264/266-268
Key Application Considerations
TinySwitch-II
vs.
TinySwitch
Table 2 compares the features and performance differences
between the TNY254 device of the
TinySwitch
family with the
TinySwitch-II
family of devices. Many of the new features
Table 2. Comparison Between TinySwitch and TinySwitch-II.
*Not available.
** See typical performance curves.
Function
TinySwitch
TinySwitch-II
TNY264/266-268
TinySwitch-II
Advantages
TNY254
Switching Frequency 44 kHz
±
10% (@25
°
C) 132 kHz
±
6% (@25
°
C) Smaller transformer for low cost
and Tolerance
Temperature Variation +8%
+2%
(0 - 100
°
C)**
Active Frequency Jitter
N/A*
±
4 kHz
Ease of design
Manufacturability
Optimum design for lower cost
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
Line UV Detect
N/A*
Single resistor
programmable
Prevents power on/off glitches
Current Limit Tolerance
Temperature Variation
(0 - 100
°
C)**
Auto-Restart
±
11% (@25
°
C)
-8%
±
7% (@25
°
C)
0%
Increases power capability and
simplifies design for high volume
manufacturing
N/A*
6% effective on-time
Limits output short-circuit current to
less than full 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
0.037” / 0.94 mm
0.137” / 3.48 mm
Greater immunity to arcing as a
result of dust, debris or other
contaminants build-up
Design
Output Power
Table 1 (front page) shows the practical maximum 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
μ
F/W for universal input and 1
μ
F/W
for 230 or 115 VAC with doubler input.
eliminate the need for or reduce the cost of circuit components.
Other features simplify the design and enhance performance.