Rev. F 01/10

5

LNK603-606/613-616

www.powerint.com

istic and frequency control for constant current (CC) regulation.

The feedback resistors (R5 and R6) were selected using

standard 1% resistor values to center both the nominal output

voltage and constant current regulation thresholds.

Key Application Considerations

Output Power Table

The data sheet maximum output power table (Table 1) repre-

sents the maximum practical continuous output power level

that can be obtained under the following assumed conditions:

1. The minimum DC input voltage is 90 V or higher at 85 VAC

input. The value of the input capacitance should be large

enough to meet these criteria for AC input designs.

2. Secondary output of 5 V with a Schottky rectifier diode.

3. Assumed efficiency of 70%.

4. Discontinuous mode operation (K

5. The part is board mounted with SOURCE pins soldered to a

sufficient area of copper to keep the SOURCE pin tempera-

ture at or below 90 °C.

6. Ambient temperature of 50 °C for open frame designs and

an internal enclosure temperature of 60 °C for adapter

designs.

Note: Higher output power are achievable if an output CC

tolerance >±10% is acceptable, allowing the device to be

operated at a higher SOURCE pin temperature.

Output Tolerance

LinkSwitch-II provides an overall output tolerance (including line,

component variation and temperature) of ±5% for the output

voltage in CV operation and ±10% for the output current during

CC operation over a junction temperature range of 0 °C to 100 °C

for the P/G package. For the D package (SO8) additional CC

variance may occur due to stress caused by the manufacturing

flow (i.e. solder-wave immersion or IR reflow). A sample power

supply build is recommended to verify production tolerances for

each design.

BYPASS Pin Capacitor Selection

For LinkSwitch-II 60x Family of Devices (without output

cable voltage drop compensation)

A 1

mF BYPASS pin capacitor is recommended. The capacitor

voltage rating should be greater than 7 V. The capacitor’s

dielectric material is not important but tolerance of capacitor

should be ≤ ±50%. The capacitor must be physically located

close to the LinkSwitch-II BYPASS pin.

For LinkSwitch-II 61x Family of Devices (with output cable

voltage drop compensation)

The amount of output cable compensation can be selected with

the value of the BYPASS pin capacitor. A value of 1

mF selects

the standard cable compensation. A 10

mF capacitor selects

the enhanced cable compensation. Table 2 shows the amount

of compensation for each LinkSwitch-II device and capacitor

value. The capacitor can be either ceramic or electrolytic but

tolerance and temperature variation should be ≤ ±50%.

The output voltage that is entered into PIXls design spreadsheet

is the voltage at the end of the output cable when the power

supply is delivering maximum power. The output voltage at the

terminals of the supply is the value measured at the end of the

cable multiplied by the output voltage change factor.

LinkSwitch-II Layout Considerations

Circuit Board Layout

LinkSwitch-II is a highly integrated power supply solution that

integrates on a single die, both, the controller and the high

voltage MOSFET. The presence of high switching currents and

voltages together with analog signals makes it especially

important to follow good PCB design practice to ensure stable

and trouble free operation of the power supply. See Figure 5 for

a recommended circuit board layout for LinkSwitch-II.

When designing a printed circuit board for the LinkSwitch-II

based power supply, it is important to follow the following

guidelines:

Single Point Grounding

Use a single point (Kelvin) connection at the negative terminal of

the input filter capacitor for the LinkSwitch-II SOURCE pin and

bias winding return. This improves surge capabilities by

returning surge currents from the bias winding directly to the

input filter capacitor.

Bypass Capacitor

The BYPASS pin capacitor should be located as close as

possible to the SOURCE and BYPASS pins.

Feedback Resistors

Place the feedback resistors directly at the FEEDBACK pin of

the LinkSwitch-II device. This minimizes noise coupling.

Thermal Considerations

The copper area connected to the SOURCE pins provides the

LinkSwitch-II heat sink. A good estimate is that the LinkSwitch-II

will dissipate 10% of the output power. Provide enough copper

area to keep the SOURCE pin temperature below 90 °C. Higher

temperatures are allowable only if an output current (CC)

tolerance above ±10% is acceptable. In this case a maximum

SOURCE pin temperature below 110 °C is recommended to

provide margin for part to part R

LinkSwitch-II Output Cable Voltage Drop Compensation

Device

BYPASS Pin

Capacitor Value

Output Voltage

Change Factor

LNK613

1

mF

1.035

10

mF

1.055

LNK614

1

mF

1.045

10

mF

1.065

LNK615

1

mF

1.050

10

mF

1.070

LNK616

1

mF

1.060

10

mF

1.090

Table 2. Cable Compensation Change Factor vs Device and BYPASS Pin

Capacitor Value.