PI3301-X1 datasheet(21/26 Pages) VICOR

21 / 26 page

vicorpower.com

Rev 1.3

Cool-Power®

800 735.6200

09/2015

Page 21 of 26

PI33XX-X1

Application Description

Output Voltage Trim

The PI33XX-X1 family of Buck Regulators provides

four common output voltages: 1.0V, 1.8V, 2.5V, and

3.3V. A post-package trim step is implemented to

offset any resistor divider network errors ensuring

maximum output accuracy. With a single resistor

connected from the ADJ pin to SGND or REM, each

device’s output can be varied above or below the

nominal set voltage (with the exception of the

PI3311-X1 which can only be above the set voltage

of 1V).

Device

Output Voltage

Set

Range

PI3311-X1-LGIZ

1.0V

1.0 to 1.4V

PI3318-X1-LGIZ

1.8V

1.4 to 2.0V

PI3312-X1-LGIZ

2.5V

2.0 to 3.1

PI3301-X1-LGIZ

3.3V

2.3 to 4.1

Table 3 - PI33XX-X1 family output voltage ranges

The remote pin (REM) should always be connected

the VOUT pin, if not used, to prevent an output

voltage offset. Figure 4 shows the internal feedback

voltage divider network.

Figure 4 - Internal resistor divider network

R1,

R2, and R4 are all internal 1.0 % resistors and

R_low and R_high are external resistors for which

the designer can add to modify VOUT to a desired

output.

The internal resistor value for each

regulator is listed below in Table 4.

Device

PI3311-X1-LGIZ

Open

100

PI3318-X1-LGIZ

0.806k

1.0k

100

PI3312-X1-LGIZ

1.5k

1.0k

100

PI3301-X1-LGIZ

2.61k

1.13k

100

Table 4 - PI33XX-X1 Internal divider values

choosing an output voltage value within the

ranges stated in Table 3, VOUT can simply be

adjusted up or down by selecting the proper R_high

or R_low value, respectively.

The following

equations can be used to calculate R_high and R_low

values:

(

)

(

)

( )

(

)

(

)

( )

If,

for example, a 4.0V output is needed, the user

should choose the regulator with a trim range

covering 4.0V from Table 3. For this example, the

PI3301 is selected (3.3V set voltage). First step

would be to use Equation (1) to calculate R_high

since the required output voltage is higher than the

regulator set voltage. The resistor-divider network

values for the PI3301 are can be found in Table 4 and

are R1=2.61kΩ and R2=1.13kΩ. Inserting these

values in to Equation (1), R_high is calculated as

follows:

(

)

(

)

Resistor R-high would be connected as in Figure 4 to

achieve the 4.0V regulator output. No R_low resistor

would be used since in this example the trim is

above the regulator set voltage.

The PI3311-X1 output voltage can only be trimmed

higher than the factory 1V setting. The following

ADJ

REM

VOUT

SGND

R_low

R_high

1.0Vdc

PI3301-X1 Datasheet(PDF) 21 Page - Vicor Corporation

PI3301-X1 Datasheet(HTML) 21 Page - Vicor Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Datasheet Download

Link URL