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SVRFL2800S - 11.0

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Page 9

SVRFL2800S Series

6.2.2 Adjusting the Output Voltage (TRIM)

The output voltage set point of the converter can be adjusted using the TRIM pin. To

adjust the output up, connect the trim resistor from TRIM to OUTCOM. To adjust the

output down, connect the trim resistor from TRIM to +VOUT. The maximum trim

range is -20% and +10% from nominal. The appropriate resistor values versus the

output voltage are given in the table below. Because the TRIM pin can be sensitive to

external noise, the trim resistor should be physically located close to the SVRFL

converter with short interconnects. The TRIM pin should be left open if not used.

When adjusting the output voltage, do not exceed the rated total output power or

output current.

SVRFL283R3S

SVRFL2805S

SVRFL2812S

SVRFL2815S

+Vout (V)

Rtrim

(Ω)

+ Vout

(V)

Rtrim

(Ω)

+ Vout

(V)

Rtrim

(Ω)

+ Vout

(V)

Rtrim

(Ω)

3.60

68.3k

5.5

35k

13.2

5.8k

16.50

1.7k

3.55

85k

5.4

47.5k

13.0

10k

16.25

5k

3.50

110k

5.3

68.3k

12.8

16.2k

16.00

10k

3.45

151.7k

5.2

110k

12.6

26.6k

15.75

18.3k

3.40

235k

5.1

235k

12.4

47.3k

15.50

35k

3.35

485k

5.0

12.2

109k

15.25

85k

3.30

4.9

225k

12.0

15.00

3.25

135k

4.8

100k

11.8

454k

14.75

475k

3.20

55k

4.7

58.3k

11.6

213k

14.50

225k

3.15

28.3k

4.6

37.5k

11.4

134k

14.25

142k

3.10

15k

4.5

25k

11.2

94k

14.00

100k

3.05

7k

4.4

16.7k

11.0

70.1k

13.75

75k

3.00

1.7k

4.3

10.7k

10.8

54.3k

13.50

58.3k

4.2

6.3k

10.6

42.9k

13.25

46.4k

4.1

2.8k

10.4

34.4k

13.00

37.5k

4.0

0

10.2

27.8k

12.75

30.6k

10.0

22.5k

12.50

25k

9.8

18.2k

12.25

20.5k

9.6

14.6k

12.00

16.7k

6.2.3 Remote Sense (+S, -S)

Remote sensing compensates for voltage drops in the output pins and traces by sensing and regulating directly at the load. The remote

sense function can compensate for up to a 10% voltage drop (5% in the positive lead and 5% in the negative lead). The sum of the

TRIM up and remote sense compensation cannot exceed 10% such that the voltage at the output terminals of the converter does not

exceed 110% of the nominal output voltage. If not used, the user should connect +S to +VOUT and –S to OUTCOM at the pins of the

converter.

6.2.4 Frequency Synchronization (SYNCIN, SYNCOUT)

The SVRFL2800S Series will free run at a switching frequency of approximately 525 kHz, which has been set for optimum converter

performance. Frequency synchronization is not necessary unless required by system constraints. The SVRFL2800S Series provides a

frequency synchronization input (SYNCIN) and output (SYNCOUT), both referenced to INCOM.

The SYNCIN pin can be driven by an external clock or by the SYNCOUT pin of another SVRTR converter. The internal clock and

internal power train will operate at the frequency applied to the SYNCIN pin. The SYNCIN pin should be driven with a TTL type 5 V

square wave signal. The duty cycle of the square wave should be between 20% and 80%. The SYNCIN pin is internally capacitively-

coupled and the internal load is equivalent to 220 pF. Proper layout and circuit techniques are necessary to prevent noise from being

injected into this pin. Synchronized converters should located physically close together and share a low impedance INCOM connection.

The SYNCIN pin can be left open or connected to INCOM if not used.

+

-

+

-

2.5V

Ri

30

10K

30

Rt

+VOUT

7

+S

10

TRIM

3

-S

9

OUTCOM

8

(TRIM DOWN)

Rtrim

(TRIM UP)

Rtrim