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dc1807af

DEMO MANUAL DC1807A

QUICK START PROCEDURE

Rail Tracking

Demonstrationcircuit1807Aissetupforindependentturn-on

determined by the TRK/SS2 cap at C47. The turn-on of one

rail will not affect the other for the original demo board.

TRACK 2 DIVIDER

TRK/SS2 CAPACITOR

CONFIGURATION

R36

R34

R37

C47

Soft Start Without Tracking

0Ω

OPEN

OPEN

0.1μF

0Ω

10.0kΩ

20.0kΩ

OPEN

External Coincident Tracking

17.8kΩ

OPEN

20.0kΩ

OPEN

to track an external signal. It can also be modified to allow

signal. Tables 2 and 3 cover the rail tracking options for

each rail, with the –B version used as an example.

Single Output/Dual Phase Operation

A single output/dual phase converter may be preferred

for high output current applications. The benefits of sin-

gle output/dual phase operation is lower ripple current

through the input and output capacitors, improved load

step response and simplified thermal design. To implement

single output / dual phase operation, make the following

modifications:

per pads near J3 and J5 at the edge of the board. Use

a piece of heavy copper foil.

2. Tie ITH1 to ITH2 by stuffing 0 at R49. Turn on the power

at the input.

3. Tie VFB1 to VFB2 by stuffing 0 at R50.

4. Tie TRK/SS1 to TRK/SS2 by stuffing 0 at R52.

5. Tie RUN1 to RUN2 by stuffing 0 at R55.

6. Remove the redundant ITH compensation network and

VFB divider.

Figure 2. Measuring Output Voltage Ripple

TRACK 1 DIVIDER

TRK/SS1 CAPACITOR

CONFIGURATION

R3

R2

C2

Soft Start Without Tracking

0Ω

OPEN

0.1μF

External Coincident Tracking

17.8kΩ

20.0kΩ

OPEN