34704 datasheet(5/54 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

34704

PIN CONNECTIONS

A/B

PVIN3

Power

REG3 power supply input

voltage

This is the connection to the drain of the high side switch FET.

Input decoupling /filtering is required for proper REG3 operation.

Use a 10uf decoupling capacitor for better performance.

A/B

SW3

Output

REG3 switching node

The inductor is connected between this pin and the regulated

REG3 output.

A/B

VOUT3

Output

REG3 output voltage

return pin

This is the discharge path of REG3 output voltage.

A/B

FB3

Input

REG3 voltage feedback

input for voltage

regulation/programming

Connect the feedback resistor divider to this pin.

A/B

Input

Soft start time

The soft start time for all regulators can be adjusted by

connecting this pin to an external resistor divider between VDDI

and AGND pins.

A/B

FREQ

Input

Oscillator frequency

The oscillator frequency can be adjusted by connecting this pin

to an external resistor divider between VDDI and AGND pins.

This pin sets FSW1 value.

A/B

FB8

Input

REG8 voltage feedback

input for voltage

regulation/programming

Connect the feedback resistor divider to this pin.

A/B

BT8

Passive

REG8 bootstrap capacitor

input pin

Connect a 0.01

μF capacitor between this pin and SW8 pin to

enhance the gate of the Synchronous Power MOSFET.

A/B

VOUT8

Output

REG8 regulated output

voltage pin

Connect this pin directly to the load directly and to the output

filter as close to the pin as possible.

A/B

SW8

Output

REG8 switching node

The inductor is connected between this pin and the VIN pin.

A/B

SW1

Output

REG1 switching node

The inductor is connected between this pin and the VIN Pin.

A/B

Passive

REG1 regulated output

voltage before the cutoff

switch

REG1 regulated output voltage before the cut-off switch. This

supplies the internal circuits and the gate drive

23(1)

VOUT1

Output

REG1 regulated output

voltage pin.

Connect this pin directly to the load directly and to the output

filter as close to the pin as possible.

NC0

No Connect

Pin 23 is not connected.

A/B

BT1

Passive

REG1 bootstrap capacitor

input pin

Connect a 1.0

μF capacitor between this pin and SW1 pin to

enhance the gate of the Switch Power MOSFET.

A/B

SCL

Input/Output

I2C serial interface clock

input

I2C serial interface clock input.

A/B

SDA

Input/Output

I2C serial interface data

input

I2C serial interface data input.

A/B

RST

Open Drain

Power reset output signal

(Microprocessor Reset)

This is an open drain output and must be pulled up by an

external resistor to a supply voltage like VIN.

COMP7

Passive

REG7 compensation

network connection

REG7 compensation network connection.

NC1

No Connect

Pin 28 is not connected

VREF7

Output

REG7 resistor feedback

network reference voltage

Connect this pin to the bottom of the feedback resistor divider.

NC2

No Connect

Pin 29 is not connected

Table 2. 34704 Pin Definitions (continued)

A functional description of each pin can be found in the Functional Pin Description section beginning on page 17.

Pin Number Device Pin Name Pin Function

Formal Name

Definition

34704 Datasheet(PDF) 5 Page - Freescale Semiconductor, Inc

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