8

DCP0115

®

up to 10

µs. Making the gate open drain will re-enable the

DCP0115. However, there is a trade-off in using this function;

the DCP0115 quiescent current may increase and the on-chip

oscillator may run slower. This degradation in performance is

dependent on the external CMOS gate capacitance, therefore

the smaller the capacitance, the lower the performance de-

output, which has a low output capacitance, offers the lowest

reduction in performance.

DECOUPLING

Ripple Reduction

The high switching frequency of 400kHz allows simple

filtering. To reduce ripple, it is recommended that 0.47

µF

outputs should both be decoupled to pin 5. In applications

where power is supplied over long lines and output loading

is high, or, there is significant inductance at the output, it

may be necessary to use a 2.2

µF capacitor on the input to

insure startup.

There is no restriction on the size of the output capacitor used

to reduce ripple. The DCP0115 will start into any capacitive

load. Low ESR capacitors will give the best reduction.

EXTERNAL SYNCHRONIZATION

The DCP0115 can be synchronized externally if required

using a simple external interface. Figure 4 shows a universal

pins are used to select external synchronization or self-

synchronization.

This interface can also be used to stop (disable) the DCP0115.

FIGURE 4. Universal Interface.

CTL

FUNCTION

1

1

External Sync

—

0

Self-Sync

0

1

Device Stop

FIGURE 3. DCP011515 Fully Loaded.

DCP0115xxx

1

2

5

6

7

14

8

V

CC

0V

0V

+V

OUT

–V

OUT

SYNC

I/O

1A

I/O

1B

U1

CONT

C

3

470nF

C

6

470nF

(One Per

DC/DC)

DCP0105xxx

1

2

5

6

7

14

8

V

CC

0V

0V

+V

OUT

SYNC

R

1

33k

Ω

R

2

33k

Ω

DCP0105xxx

1

2

5

6

7

14

8

V

CC

0V

0V

+V

OUT

SYNC

C

4

470nF

+5V

+5V

0V

+Out 2

0V

+Out 3

I/O

1A

U3

CONT

I/O

1A

I/O

1B

U4

CONT

I/O

1A

I/O

1B

U5

CONT

SYNC ON

FREQ IN

CTL

R

3

33k

Ω

0V

0V

0V

0V

C

5

470nF

+15V

0V

4066

C

1

470nF

C

2

470nF

+15V

0V

+Out 1

–Out 1

+5V

1

2

5

6

7

V

S

0V

0V

+V

Out

–V

Out

C

1

0.47µF

+15V

C

3

0.47µF

R

3

820

Ω

R

4

1k

Ω

C

2

0.47µF

R

1

820

Ω

R

2

1k

Ω

DCP0115