LNK353/354
®
LinkSwitch-HF Family
Enhanced, Energy Efficient, Low Power
Off-Line Switcher IC
Product Highlights
Features Optimized for Lowest System Cost
• Fully integrated auto-restart for short-circuit and open
loop protection
• Self-biased supply – saves transformer auxiliary winding
and associated bias supply components
• Tight tolerances and negligible temperature variation on
key parameters eases design and lowers cost
• High maximum switching frequency allows very low
flux density transformer designs, practically eliminating
audible noise
• Frequency jittering greatly reduces EMI
• Packages with large creepage to high voltage pin
• Lowest component count switcher solution
Much Better Performance over Linear/RCC
• Lower system cost than RCC, discrete PWM and other
integrated solutions
• Universal input range allows worldwide operation
• Simple ON/OFF control – no loop compensation needed
• No bias winding – simpler, lower cost transformer
• High frequency switching – smaller and lower cost
transformer
• Very low component count – higher reliability and single
side printed circuit board
• High bandwidth provides fast turn on with no overshoot
and excellent transient load response
• Current limit operation rejects line frequency ripple
• Built-in current limit and hysteretic thermal shutdown
protection
®
EcoSmart – Extremely Energy Efficient
• No-load consumption <300 mW without bias winding at
265 VAC input
• Meets California Energy Commission (CEC), Energy
Star, and EU requirements
Applications
• Chargers for cell/cordless phones, PDAs, digital cameras,
MP3/portable audio devices, shavers etc.
• Standby and auxiliary supplies
Description
LinkSwitch-HF integrates a 700 V power MOSFET, oscillator,
simple ON/OFF control scheme, a high voltage switched current
+
DC
Output
Wide Range
HV DC Input
D
LinkSwitch-HF
+
FB
BP
S
PI-3855-022704
Figure 1. Typical Standby Application.
OUTPUT POWER TABLE
PRODUCT(3)
230 VAC ±15%
Adapter(1)
85-265 VAC
Open
Open
Adapter(1)
Frame(2)
Frame(2)
LNK353 P or G
3W
4W
LNK354 P or G
3.5 W
5W
2.5 W(4)
3W
(4)
3W
4.5 W
Table 1. Notes: 1. Typical continuous power in a non-ventilated
enclosed adapter measured at 50 °C ambient. 2. Maximum practical
continuous power in an open frame design with adequate heat
sinking, measured at 50 °C ambient. 3. Packages: P: DIP-8B,
G: SMD-8B. For lead-free package options, see Part Ordering
Information. 4. For designs without a Y capacitor, the available power
may be lower (see Key Applications Considerations).
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 DRAIN pin,
eliminating the need for a bias winding and associated circuitry.
The 200 kHz maximum switching frequency allows very
low flux transformer designs, practically eliminating audible
noise with the simple ON/OFF control scheme using standard
varnished transformer construction. Efficient operation at this
high switching frequency is achieved due to the optimized
switching characteristics and small capacitances of the integrated
power MOSFET. 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. The internal oscillator frequency is
jittered to significantly reduce both the quasi-peak and average
EMI, minimizing filtering cost.
February 2005
