Sales Information

Phone:(425) 353-3010

Fax: (425) 353-4030

SVRFL2800S - 11.0

E-mail: vptsales@vptpower.com

Web: www.vptpower.com

Page 10

SVRFL2800S Series

The SYNCOUT pin provides a 5 V quasi-square wave output at either the SYNCIN frequency or the free-running frequency if SYNCIN

is not used. The SYNCOUT of a SVRFL can be connected to the SYNCIN pin of a second SVRFL to synchronize its switching

frequency to that of the first SVRFL. Similarly, the SYNCOUT of the second SVRFL can be connected to SYNCIN of a third SVRFL.

Subsequent SVRFL converters can be connected in this daisy chain arrangement as shown in the figure. SYNCOUT should be left

open if not used.

6.2.5 Parallel Operation (SHARE)

The SVRFL2800S Series provides a SHARE function for active current sharing among paralleled modules. To enable load sharing,

connect a single wire between the SHARE pins of all parallel modules. The SHARE pin can be noise sensitive. Paralleled converters

should be located physically close to one another and share a low impedance OUTCOM connection. A symmetrical layout of the output

traces will improve share accuracy. Frequency synchronization is not required for parallel operation. The SHARE pin should be left

open if not used.

6.3 PROTECTION FEATURES

6.3.1 Input Undervoltage Lockout

The SVRFL2800S Series provides input undervoltage lockout protection. For input voltages below the turn-on voltage, the converter will

remain off, drawing minimal current from the source. When the input voltage exceeds the turn-on voltage, the converter will start. The

lockout circuit is designed to tolerate slow ramping input voltage waveforms. VPT’s proprietary magnetic feedback technology provides

bias voltage to all secondary control circuits and control amplifiers before the output starts, ensuring a well-controlled start up

sequence.

2

INCOM

4

INH1

1

28VIN

7

+VOUT

8

OUTCOM

LOAD

+

-

28Vdc

12

28VOUT

7

OUTCOM

1 28VIN

6 INCOM

CASE

-S

9

+S

10

SYNCIN

6

28VIN

2

28VIN

3

INCOM

4

INCOM

5

28VOUT 11

28VOUT 10

OUTCOM 9

OUTCOM 8

SVRME28 EMI FILTER

SVRFL2800S DC-DC CONVERTER

CASE

5

SYNCOUT

11

SHARE

2

INCOM

4

INH1

1

28VIN

7

+VOUT

8

OUTCOM

-S 9

+S

10

SYNCIN

6

SVRFL2800S DC-DC CONVERTER

CASE

5

SYNCOUT

11

SHARE

2

INCOM

4

INH1

1

28VIN

7

+VOUT

8

OUTCOM

-S

9

+S

10

SYNCIN

6

SVRFL2800S DC-DC CONVERTER

CASE

11

SHARE