34716 datasheet(19/25 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34716

TYPICAL APPLICATIONS

CONFIGURING THE OUTPUT VOLTAGE:

Channel 1 of the 34716 is a general purpose DC-DC

converter, the resistor divider to the -INV1 node is

responsible for setting the output voltage, according to the

following equation:

Where VREF is the internal VBG=0.7V.

Channel 2 is a DDR specific voltage power supply, and the

output voltage is given by the equation:

Where VREFIN is equal to VDDQ.

SWITCHING FREQUENCY CONFIGURATION

The switching frequency will have a value of 1.0 MHz by

connecting the FREQ terminal to the GND. If the smallest

frequency value of 200 KHz is desired, then connect the

FREQ terminal to VDDI. To program the switching frequency

to another value, an external resistor divider will be

connected to the FREQ terminal to achieve the voltages

given by Table 5.

Table 5.

Frequency Selection Table

SOFT START ADJUSTMENT

Table 6 shows the voltage that should be applied to the

ILIM1 terminal to get the desired desired sort start timing on

channel 1 only.

Table 6. Soft Start Configurations

Figure 9. Resistor divider for Frequency and Soft Start

adjustment

FREQUENCY

VOLTAGE APPLIED TO PIN FREQ

200

2.341 – 2.500

253

2.185 - 2.340

307

2.029 - 2.184

360

1.873 - 2.028

413

1.717 – 1.872

466

1.561 – 1.716

520

1.405 - 1.560

573

1.249 - 1.404

627

1.093 - 1.248

⎟

⎠

⎞

⎜

⎝

⎛

REF

OUT

REFIN

680

0.936 - 1.092

733

0.781 - 0.936

787

0.625 - 0.780

840

0.469 - 0.624

893

0.313 - 0.468

947

0.157 - 0.312

1000

0.000 - 0.156

SOFT START [MS]

VOLTAGE APPLIED TO ILIM

3.2

1.19 - 1.49V

1.6

1.50 - 1.81V

0.8

1.82 - 2.13V

0.4

2.14 - 2.50V

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