Datasheet

rev.
page
date
DESCRIPTION: point of load converter
2 of 10
08/2007
20050 SW 112
th
Ave. Tualatin, Oregon 97062 phone [phone] fax [phone]
PART NUMBER: VPOL5A-5-SIP
1. Introduction
This application note describes the features and functions of
VPOL5A-5-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
VPOL5A-5-SIP series provide precisely regulated output voltage range
from 0.75 V to 3.63 Vdc over a wide range of input voltage (Vi=3.0 –
5.5 Vdc) and can operate over an ambient temperature range of –40
to +85 . 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. world class
automated
manufacturing methods, together with an extensive testing and
qualification program, ensure that all VPOL5A-5-SIP series converters
are extremely reliable.
2. VPOL5A-5-SIP Converter Features
High efficiency topology, typically 94% at 3.3 Vdc
Industry standard footprint
Wide ambient temperature range, -40C to +85C
Cost efficient open frame design
Programmable output voltage via external resistor from 0.75 to
3.63 Vdc
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 VPOL5A-5-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 VPOL5A-5-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
VPOL5A-5-SIP series converters do not draw any reverse current at
start-up. The output voltage can be adjusted from 0.75 to 3.63vdc,
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 trim
ERR AMP
ON/OFF TRIM
Figure 1. Electrical Block Diagram
3.2 Thermal Packaging and Physical Design.
The VPOL5A-5-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 The
rmal 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 easil
y
recycled.
Cost Efficient: No encapsulation. Cost efficient open-frame
construction.
Reliable: Efficient cooling provided by open frame construction
offers high reliability and easy diagnostics.
CUI INC’s
CUI INC’s
For more information, please visit the product page.