
LNK304-306
LinkSwitch-TN Family
Lowest Component Count, Energy Efficient
Off-Line Switcher IC
Figure 1. Typical Buck Converter Application (See Application
Examples Section for Other Circuit Configurations).
Product Highlights
Cost Effective Linear/Cap Dropper Replacement
Lowest cost and component count buck converter solution
Fully integrated auto-restart for short-circuit and open
loop fault protection - saves external component costs
66 kHz operation with accurate current limit - allows low
cost off-the-shelf 1 mH inductor for up to 120 mA output
current
Tight tolerances and negligible temperature variation
High breakdown voltage of 700 V provides excellent
input surge withstand
Frequency jittering dramatically reduces EMI (~10 dB) -
minimizes EMI filter cost
High thermal shutdown temperature (+135
°C minimum)
Much Higher Performance over Discrete Buck and
Passive Solutions
Supports buck, buck-boost and flyback topologies
System level thermal overload, output short-circuit and
open control loop protection
Excellent line and load regulation even with typical
configuration
High bandwidth provides fast turn-on with no overshoot
Current limit operation rejects line ripple
Universal input voltage range (85 VAC to 265 VAC)
Built-in current limit and hysteretic thermal protection
Higher efficiency than passive solutions
Higher power factor than capacitor-fed solutions
Entirely manufacturable in SMD
EcoSmart – Extremely Energy Efficient
Consumes typically only 50/80 mW in self-powered buck
topology at 115/230 VAC input with no load (opto feedback)
Consumes typically only 7/12 mW in flyback topology
with external bias at 115/230 VAC input with no load
Meets Blue Angel, Energy Star, and EU requirements
Applications
Appliances and timers
LED drivers and industrial controls
Description
LinkSwitch-TN is specifically designed to replace all linear and
capacitor-fed (cap dropper) non-isolated power supplies in the
under 360 mA output current range at equal system cost while
offering much higher performance and energy efficiency.
PRODUCT(4)
MDCM(2)
OUTPUT CURRENT TABLE(1)
Table 1. Notes: 1. Typical output current in a non-isolated buck converter.
Output power capability depends on respective output voltage. See Key
Applications Considerations Section for complete description of
assumptions, including fully discontinuous conduction mode (DCM)
operation. 2. Mostly discontinuous conduction mode. 3. Continuous
conduction mode. 4. Packages: P: DIP-8B, G: SMD-8B. Please see
ordering information.
230 VAC
±15%
MDCM(2)
85-265 VAC
120 mA 170 mA 120 mA 170 mA
175 mA 280 mA 175 mA 280 mA
225 mA 360 mA 225 mA 360 mA
LNK304P or G
LNK305P or G
LNK306P or G
LinkSwitch-TN devices integrate a 700 V power MOSFET,
oscillator, simple On/Off control scheme, a high voltage switched
current source, frequency jittering, cycle-by-cycle current limit
and thermal shutdown circuitry onto a monolithic IC. The start-
up and operating power are derived directly from the voltage on
the DRAIN pin, eliminating the need for a bias supply and
associated circuitry in buck or flyback converters. The fully
integrated auto-restart circuit safely limits output power during
fault conditions such as short-circuit or open loop, reducing
component count and system-level load protection cost. A local
supply provided by the IC allows use of a non-safety graded
optocoupler acting as a level shifter to further enhance line and
load regulation performance in buck and buck-boost converters,
if required.
CCM(3)
January 2004
DC
Output
Wide Range
HV DC Input
PI-3492-111903
+
FB
BP
S
D
LinkSwitch-TN