rev.

page

date

DESCRIPTION:

point of load converter

2 of 12

11/2007

20050

phone 503.612.2300 fax 503.612.2382

PART NUMBER:

VPOL16A-12-SIP

1. Introduction

This application note describes the features and functions of V-Infinity’s

VPOL16A-12-SIP series of Non Isolated DC-DC Converters. These are

highly efficient, reliable and compact, high power density, single output

DC/DC converters. These “Point of Load” modules serve the needs

specifically of the fixed and mobile telecommunications and computing

market, employing economical distributed Power Architectures. The

VPOL16A-12-SIP series provide precisely regulated output voltage

range from 0.75V to 5.0Vdc over a wide range of input voltage (Vi=9.0 –

14Vdc) and can operate over an ambient temperature range of –40°C

to +85°C. Ultra-high efficiency operation is achieved through the use of

synchronous rectification and drive control techniques.

The modules are fully protected against short circuit and over-

temperature conditions. V-Infinity’s world class automated

manufacturing methods, together with an extensive testing and

qualification program, ensure that all VPOL16A-12-SIP series

converters are extremely reliable.

2.

Converter

Features

High efficiency topology, typically 94% at 5.0Vdc

Industry standard footprint

Wide ambient temperature range, -40°C to +85°C

Cost efficient open frame design

Programmable output voltage via external resistor from 0.75 to

5.0Vdc

No minimum load requirement (Stable at all loads)

Remote ON/OFF

Remote sense compensation

Fixed switching frequency

Continuous short-circuit protection and over current protection

Over-temperature protection (OTP)

Monotonic Startup with pre-bias at the output.

UL/IEC/EN60950 Certified.

3. General Description

3.1 Electrical Description

A block diagram of the VPOL16A-12-SIP Series converter is shown in

Figure 1. Extremely high efficiency power conversion is achieved

through the use of synchronous rectification and drive techniques.

Essentially, the powerful VPOL16A-12-SIP series topology is based on

a non-isolated synchronous buck converter. The control loop is

optimized for unconditional stability, fast transient response and a very

tight line and load regulation. In a typical pre-bias application the

VPOL16A-12-SIP series converters do not draw any reverse current at

start-up. The output voltage can be adjusted from 0.75 to 5.0vdc, using

the TRIM pin with a external resistor. The converter can be shut down

via a remote ON/OFF input that is referenced to ground. This input is

compatible with popular logic devices; a 'positive' logic input is supplied

as standard. Positive logic implies that the converter is enabled if the

remote ON/OFF input is high (or floating), and disabled if it is low.

The converter is also protected against over-temperature conditions. If

the converter is overloaded or the ambient temperature gets too high,

the converter will shut down to protect the unit.

C1

C2

Q2

Q1

D1

L1

+VIN

COM

COM

+VO

PWM IC

R1

R2

R sense

R trim

ERR AMP

ON/OFF

TRIM

+SENSE

Figure 1. Electrical Block Diagram

3.2 Thermal Packaging and Physical Design.

The VPOL16A-12-SIP series uses a multi-layer FR4 PCB construction.

All surface mount power components are placed on one side of the

PCB, and all low-power control components are placed on the other

side. Thus, the Heat dissipation of the power components is optimized,

ensuring that control components are not thermally stressed. The

converter is an open-frame product and has no case or case pin. The

open-frame design has several advantages over encapsulated closed

devices. Among these advantages are:

Efficient Thermal Management: the heat is removed from the

heat generating components without heating more sensitive, small

signal control components.

Environmental: Lead free open-frame converters are more easily

re-cycled.

Cost Efficient: No encapsulation. Cost efficient open-frame

construction.

Reliable: Efficient cooling provided by open frame construction

offers high reliability and easy diagnostics.

VPOL16A-12-SIP