EP1551 Evaluation Board Manual

Rev.01

3/7

Adjusting the Main Step-Up Output Voltage

The main step-up output (OUTSU 3.35V) can be adjusted from 2.7V to 5.5V using the following procedure:

1) Short JP8 to MAIN pin.

2) Cut the PC board trace that shorts the pads of R12 (located on the solder side of the PC board).

3) Select a value for R15 between 10kΩ and 100kΩ.

4) Solve for Vout:

⎟

⎠

⎞

⎜

⎝

⎛ +

=

12

15

1

25

.

1

R

R

V

V

out

5) Install R12 and R15.

Adjusting the Step-Down Output Voltage

The step-down output voltage (OUTSD 1.5V) can be set from 1.25V to VOUTSU using the following

procedure:

1) Short JP7 to MAIN pin.

2) Cut the PC board trace that shorts the pads of R13 (located on the solder side of the PC board).

3) Select a value for R16 between 10kΩ and 100kΩ.

4) Solve for Vout:

⎟

⎠

⎞

⎜

⎝

⎛ +

=

13

16

1

25

.

1

R

R

V

V

out

5) Install R13 and R16.

Adjusting the Step-Up Output Voltage

OUT1 (5V) can be set to any voltage above 1.25V. Note that OUT1 rises above its regulation voltage if the

input voltage is greater than what OUT1 is set to. Use the following procedure to set VOUT1:

1) Short JP6 to MAIN pin.

2) Cut the PC board trace that shorts the pads of R9 (located on the solder side of the PC board).

3) Select a value for R11 between 10kΩ and 100kΩ.

4) Solve for Vout:

⎟

⎠

⎞

⎜

⎝

⎛ +

=

9

11

1

25

.

1

R

R

V

V

out

5) Install R9 and R11.