LCS700LG datasheet(7/30 Pages) POWERINT

7 / 30 page

Rev. G 05/15

LCS700-708

www.power.com

Figure 5. Placement of Bypass Capacitors on Signal Pins of IC.

Figure 6. Alternate Layout for LCS Footprint using Round Pads with Jumper Connecting

Two Grounds Highlighted.

Figure 7 shows a an example of preferred routing for the optocou-

pler and traces connected to the FEEDBACK pin. The optocoupler is

spaced away from the transformer, reducing noise pickup. The

optocoupler output trace (from pin 3) is also routed to increase the

distance between it and “active” components and traces, such as T1

and the hot side of capacitor C12. Resistor R20 is located close to U1

rather than optocoupler U2, so that any noise picked up on the

optocoupler trace is filtered by the combination of R20 and C4 before

it gets to the FEEDBACK pin on U1. C4 is placed directly adjacent to

the FEEDBACK pin of U1 (pin 4).

VCCH is connected to the standby supply through a high-voltage

ultrafast diode and a 2.2 W resistor connected in series. This diode

resistor network charges the VCCH bypass/storage capacitor whenever

the internal LLC low-side MOSFET is on. The resistor limits the peak

instantaneous charging current. See R6 and D1 in Figure 8.

G Pin

LCS700LG Datenblatt(PDF) 7 Page - Power Integrations, Inc.