MC34703 View Datasheet(PDF) - Freescale Semiconductor

Part Name

Description

Manufacturer

MC34703

10A+ Switch-Mode Power Supply with LDO Regulator

Freescale Semiconductor 

PIN CONNECTIONS

Table 1. 34703 Pin Definitions (continued)

A functional description of each pin can be found in the Functional Pin Description section beginning on page 15.

Pin Number Pin Name Pin Function Formal Name

Definition

4

VIN1

Input

Input Voltage 1

The input supply pin for the integrated circuit. The internal circuits of the

IC are supplied through this pin.

5

SCL

Input

Serial Clock

I2C bus pin. Serial clock.

6

FREQ

Input

Oscillator Frequency The switcher oscillator frequency can be adjusted by connecting an

external resistor RF to the FREQ pin. The default switching frequency

(FREQ pin left open or tied to VDDI) is ~300 kHz.

7

ADDR

Input

Address

I2C address selection. This pin can be either left open, tied to VDDI, or

grounded through a 10 kΩ resistor.

8

RESET

Output

Reset

The Reset pin indicates to the external circuitry when one of the

regulators protection features has been activated. Note, since it is an

open drain output it has to be pulled up to some supply voltage (e.g., the

output of the LDO) by an external resistor.

9

LCMP

Input

Linear Compensation Linear regulator compensation pin.

10

ISNS

Input

Current Sense

Current sense pin of the LDO to provide overcurrent protection of the

linear regulator’s external power MOSFET. The voltage drop over the

LDO current sense resistor RS is sensed between the ISNS and the LDO

pins. The LDO current limit can be adjusted by selecting the proper value

of the current sense resistor RS.

11

LDO

Input

Linear Regulator Input pin of the linear regulator power sequence and current limit control

circuits.

12

VBD

Output

Boost Voltage Drain Drain of the internal boost regulator's switching power MOSFET.

13

VBST

Input

Boost Voltage Sense Note, this pin must be connected to VBST (pin 1) and is not intended to

SENSE

provide power to external circuitry.

14

EN1

Input

Enable Pin 1

Enable 1 Input. The combination of the logic state of the Enable 1 and

Enable 2 inputs determine operation mode and type of power sequencing

of the IC.

15

SDA

Input/Output

Serial Data

I2C bus pin. Serial data.

16

CLKSYN Input/Output Clock Sync Input/ Oscillator synchronization input pin or oscillator output pin. The CLKSYN

Oscillator Output pin can be configured either as an oscillator output when the CLKSEL pin

is left open or it can be used as a synchronization input when the CLKSEL

pin is grounded.

17

VDDI

Passive

Vdd Filter

Internal supply voltage capacitor pin. A ceramic low ESR 1.0 µF capacitor

in parallel with a ceramic 100nF capacitor should be connected from this

pin to ground. The VDDI power supply voltage is for internal use only; do

not use externally.

18

GND

Signal

Ground

Analog ground of the IC.

19

RT

Passive

Reset Timer

This pin allows programming the Power-ON Reset delay by means of an

external RC network.

20

LDRV

Output

LDO Gate Drive LDO gate drive of the external pass N-channel MOSFET.

21

LFB

Input

LDO Feedback

Linear regulator feedback pin.

22

VOUT

Output Output Voltage Power This pin must be directly connected to the output voltage of the buck

Sequencing Control converter. This pin controls the buck regulators output voltage (Vout) in

accordance with the power sequencing control mode set by EN1 and

EN2.

23

INV

Input

Error Amp

Buck Controller Error Amplifier inverting input.

24

COMP

Input

Switcher

Buck converter compensation pin.

Compensation

34703

4

Analog Integrated Circuit Device Data

Freescale Semiconductor

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