MC34713 查看數據表（PDF） - Freescale Semiconductor

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MC34713

5.0 A 1.0 MHz Fully Integrated Single Switch-Mode Power Supply

Freescale Semiconductor 

FUNCTIONAL DESCRIPTION

INTRODUCTION

FUNCTIONAL DESCRIPTION

INTRODUCTION

Advanced microprocessor-based systems require

compact, efficient, and accurate point-of-load (PoL) power

supplies. These PoL supply high current and fast transient

response capability while maintaining regulation accuracy.

Voltage monitoring (power sequencing) and increased

operating frequency are also key features for PoL power

supplies.

PoL power supplies are non-isolated DC to DC converters

that are physically located near their load (on the same

printed circuit board) and take their input supply from an

intermediate bus. Their close proximity to the load allows for

higher efficiency, localized protection, and minimum

distribution losses. Their compact design and low

component-count also reduces overall system cost.

The 34713 is a PoL single-output power supply that

embodies an integrated solution that’s both highly cost-

effective and reliable. It utilizes a voltage-mode synchronous

buck switching converter topology with integrated low

RDS(ON) (45 mΩ) N-channel power MOSFETs for high-

efficiency operation. It provides an output voltage with an

accuracy of less than ±2.0 %, capable of supplying up to

5.0 A of continuous current. Its power sequencing/tracking

abilities makes it ideal for systems with multiple related

supply rails. It has an adjustable switching frequency, thus

permitting greater design flexibility and optimization over a

wide range of operating conditions, and can operate at up to

1.0 MHz to significantly reduce the external components size

and cost. It also features an over-current limit control, and

protects against output overvoltage, undervoltage, and

overtemperature conditions. It also protects the system from

short circuit events and incorporates a power-good output

signal to alert the host MCU should a fault occur.

Operation can be enabled or disabled by controlling the

SD pin, which offers power sequencing capabilities.

By monolithically integrating the control and supervisory

circuitry along with power-FETs, the 34713 offers a complete,

compact, cost-effective, and simple solution to satisfy the

PoL needs of today’s systems.

FUNCTIONAL PIN DESCRIPTION

REFERENCE VOLTAGE INPUT (VREFIN)

The 34713 will track the voltage applied at this pin.

FREQUENCY ADJUSTMENT INPUT (FREQ)

The buck converter switching frequency can be adjusted

by connecting this pin to an external resistor divider between

VDDI and GND pins. The default switching frequency (FREQ

pin connected to ground, GND) is set at 1.0 MHz.

SOFT START ADJUSTMENT INPUT (ILIM)

Soft start timing can be adjusted by applying an external

voltage between 1.25 and VDDI on this pin.

SIGNAL GROUND (GND)

Analog ground of the IC. Internal analog signals are

referenced to this pin voltage.

INTERNAL SUPPLY VOLTAGE OUTPUT (VDDI)

This is the output of the internal bias voltage regulator.

Connect a 1.0 µF, 6 V low ESR ceramic filter capacitor

between this pin and the GND pin. Filtering any spikes on this

output is essential to the internal circuitry stable operation.

OUTPUT VOLTAGE DISCHARGE PATH (VOUT)

Output voltage of the Buck Converter is connected to this

pin. it only serves as the output discharge path once the SD

signal is asserted.

ERROR AMPLIFIER INVERTING INPUT (INV)

Buck converter error amplifier inverting input. Connect the

output voltage feedback network to this pin.

COMPENSATION INPUT (COMP)

Buck converter external compensation network connects

to this pin. Use a type III compensation network.

INPUT SUPPLY VOLTAGE (VIN)

IC power supply input voltage. Input filtering is required for

the device to operate properly.

POWER GROUND (PGND)

Buck converter and discharge MOSFET power ground. It

is the source of the buck converter low-side power MOSFET.

SWITCHING NODE (SW)

Buck converter switching node. This pin is connected to

the output inductor.

POWER INPUT VOLTAGE (PVIN)

Buck converter power input voltage. This is the drain of the

buck converter high-side power MOSFET.

BOOTSTRAP INPUT (BOOT)

Bootstrap capacitor input pin. Connect a capacitor (as

discussed on page 17) between this pin and the SW pin to

enhance the gate of the high-side Power MOSFET during

switching.

Analog Integrated Circuit Device Data

Freescale Semiconductor

34713

9

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