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rev.
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1 of 11
09/2010
PART NUMBER:
VPOL5A-5-SMT
DESCRIPTION:
point of load 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/EN60950-1 (E222736) certified.
1. INTRODUCTION
2. VPOL5A-5-SMTCONVERTER FEATURES
3. GENERAL DESCRIPTION
3.1 Electrical Description
3.2 Thermal Packaging and Physical Design.
4. TECHNICAL SPECIFICATIONS
5. MAIN FEATURES AND FUNCTIONS
5.1 Operating Temperature Range
5.2 Over-Temperature Protection (OTP)
5.3 Output Voltage Adjustment
5.4 Safe Operating Area (SOA)
5.5 Over Current Protection
5.6 Remote On/Off
5.7 UVLO (Under-Voltage Lockout)
6. SAFETY
6.1 Input Fusing and Safety Considerations.
7. APPLICATIONS
7.1 Layout Design Challenges.
7.2 Convection Requirements for Cooling
7.3 Thermal Considerations
7.4 Power De-Rating Curves
7.5 Efficiency vs Load Curves
7.6 Input Capacitance at the Power Module
7.7 Test Set-Up
7.8 VPOL5A-5-SMT Series Output Voltage Adustment.
7.9 Output Ripple and Noise Measurement
7.10 Output Capacitance
7.11 SMT Reflow Profile
8. MECHANICAL OUTLINE DIAGRAMS
8.1 SIP/SMT05 Mechanical Outline Diagrams
8.2 SMT Tape and Reel Dimensions
20050
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112
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97062
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fax
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w
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rev.
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2 of 11
09/2010
PART NUMBER:
VPOL5A-5-SMT
DESCRIPTION:
point of load converter
Q1
L1
+VO
1. Introduction
This application note describes the features and functions of
CUI INC’s
VPOL5A-5-SMT 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-SMT series provide precisely regulated output voltage range
from 0.75V 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
+85
synchronous rectification and drive control techniques.
The modules are fully protected against short circuit and over-
temperature conditions.
CUI INC’s
world class automated
manufacturing methods, together with an extensive testing and
qualification program, ensure that all VPOL5A-5-SMT series converters
are extremely reliable.
to
. Ultra-high efficiency operation is achieved through the use of
+VIN
C1
Q2
D1
C2
COM
COM
R1
PWM IC
ON/OFF
R trim
R2
ERR AMP
TRIM
Figure 1. Electrical Block Diagram
3.2 Thermal Packaging and Physical Design.
The VPOL5A-5-SMT 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.
2. VPOL5A-5-SMTConverter Features
High efficiency topology, typically 94% at 3.3 Vdc
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
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-SMT 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-SMT 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-
SMT 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.
20050
SW
112
th
Ave. Tualatin, Oregon
97062
phone
503.612.2300
fax
503.612.2383
www.cui.com
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product page.
rev.
page
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3 of 11
09/2010
PART NUMBER:
VPOL5A-5-SMT
DESCRIPTION:
point of load converter
4. Technical Specifications
(All specifications are typical at nominal input, full load at 25
PARAMETER
ABSOLUTE MAXIMUM RATINGS
unless otherwise noted.)
Device
Min.
Typical Max.
Units
NOTES and CONDITIONS
ALL
ALL
Input Voltage
Continuous
Operating Temp erature
See Thermal Considerations Section
Storage Temperature
0
-40
ALL
-55
3.0
5.8
+85
+125
5
2.0
1.9
0.1
5
25
30
30
35
35
35
35
10
0.1
150
5.5
Vdc
INPUT CHARACTERISTICS
Operating Input Voltage
Input Under-Voltage Lockout
Turn -On Voltag e Threshold
Turn -Off Voltag e Threshold
Lockout Hysteresis Voltage
Maximum Input Current
Vo,set
Vin-0.5 Vdc
ALL
ALL
ALL
ALL
ALL
Vdc
Vdc
Vdc
Vdc
A
Vin=0 to 5.5 Vdc , Io=Io,max.
Vo=0.75V
Vo=1.2V
Vo=1.5V
Vo=1.8V
Vo=2.0V
Vo=2.5V
Vo=3.3V
Shutdown input idle current
P-P thru 1uH inductor, 5Hz to 20MHz
No-Load Input Current
ALL
mA
Off Converter Input Current
Inrush Current (I t)
Input Reflected-Ripple Current
2
ALL
ALL
ALL
mA
As
mA
2
OUTPUT CHARACTERISTIC
Output Voltage Set Point
Output Voltage Trim Adjustment Range
Output Voltage Regulation
Load Regulation
Line Regulation
Tempera ture Coefficient
Output Voltage Ripple and Noise
Peak-to-Peak
RMS
External Capacitive Load
Operating Output Current Range
Output DC Current-Limit Inception
Shout Circuit Protection
Output Voltage =90% Nominal Output Voltage
Continuous with Hiccup Mode
Io=Io.min to Io.max
Vin=low line to high line
Ta=-40
to 85
ALL
ALL
ALL
-0.5
-0.4
-0.03
+0.5
+0.4
+0.03
%
%
%/
Vin=Nominal Vin , Io=Io.max, Tc=25
Selected by an extern al resistor
ALL
ALL
-1.5% Vo,set +1.5%
0.75
3.63
Vdc
Vdc
5Hz to 20MHz bandwidth
Full Load, 1uF ceramic and 10uF tantalum
F u l l L oa d , 1 u F c e r a m i c a n d 1 0 u F t a n t a l u m
Lo w ESR
ALL
ALL
ALL
ALL
ALL
0
6
9.5
50
20
3000
5
15
mV
mV
uF
A
A
20050
SW
112
th
Ave. Tualatin, Oregon
97062
phone
503.612.2300
fax
503.612.2383
www.cui.com
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rev.
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4 of 11
09/2010
PART NUMBER:
VPOL5A-5-SMT
DESCRIPTION:
point of load converter
PARAMETER
DYNAMIC CHARACTERISTICS
Output Voltage Transient Response
Error Brand
Setting Time (within 1% Vout nominal)
NOTES and CONDITIONS
Device
Min.
Typical Max.
Units
50% Step Load Change, di/dt=0.1A/us
50% Step Load Change, di/dt=0.1A/us
ALL
ALL
200
200
mV
us
EFFICIENCY
Vo=0.75V
Vo=1.2V
Vo=1.5V
Vo=1.8V
Vo=2.0V
Vo=2.5V
Vo=3.3V
Non-isolation
79
85
87
89
90
92
94
0
100% Load
ALL
%
ISOLATION CHARACTERISTICS
Input to Output
ALL
Vdc
FEATURE CHARACTERISTICS
Switching Frequency
On/Off Control, Positive Logic Remote On/Off
Logic Low (Module Off)
Logic High (Module On)
On/Off Control, Negative Logic Remote On/Off
Logic Low (Module On)
Logic High (Module Off)
On/Off Current (for both remote on/off logic)
Leakage Current (for both remote on/off logic)
Turn -On Delay and Rise Time
Turn -On Delay Time, From On/Off Control
Turn -On Delay Time, From I nput
Output Voltage Rise Time
Over Temperature Protection
ALL
Standard Model
or Open Circuit
or Open Circuit
Ion/off at Von/off =0.0V
Logic High, Von/off=14V
Von/off to 10 %Vo,set
Vin,min. to 10%V o,set
10%Vo,set to 90 %Vo,set
Suffix “N” Model
ALL
AL L
AL L
ALL
ALL
ALL
per MIL-HDBK-
2
2
4.5
120
0
2.8
0
Vin
0.4
Vin
1
1
300
0.4
KHz
Vdc
Vdc
Vdc
Vdc
mA
mA
ms
ms
ms
GENERAL SPECIFICATIONS
MTBF
Weight
Dimensions
SIP packages
SMT packages
Io=100%of Io.max;Ta=25
217F
ALL
ALL
0.9x0.4x0.22 inc hes (22.9x10.16x5.6 mm)
0.8x0.45x0.24 inches(20.3x11. 43x6.09 mm)
1.5
2.3
M hours
grams
20050
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112
th
Ave. Tualatin, Oregon
97062
phone
503.612.2300
fax
503.612.2383
www.cui.com
For more information, please visit the
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rev.
page
date
5 of 11
09/2010
PART NUMBER:
VPOL5A-5-SMT
DESCRIPTION:
point of load converter
5. Main Features and Functions
5.1 Operating Temperature Range
CUI INC’s VPOL5A-5-SMT series converters highly efficient converter
design has resulted in its ability to operate over a wide ambient
temperature environment ( -40
to 85 ). Due consideration must be
given to the de-rating curves when ascertaining maximum power that can
be drawn from the converter. The maximum power drawn is influenced
by a number of factors, such as:
Input voltage range.
Output load current.
Air velocity (forced or natural convection).
Mounting orientation of converter PCB with respect to the Airflow.
Motherboard PCB design, especially ground and power planes.
These can be effective heat sinks for the converter.
5.4 Safe Operating Area (SOA)
Figure 2 provides a graphical representation of the Safe Operating Area
(SOA) of the converter. This representation assumes ambient operating
conditions such as airflow are met as per thermal guidelines provided in
Sections 7.2 and 7.3.
Vo
Vo,nom
VOLTAGE (V)
Safe Operating Area
5.2 Over-Temperature Protection (OTP)
The VPOL5A-5-SMT Series converters are equipped with non-latching
over-temperature protection. A te mperature sensor monitors the
temperature of the hot spot (typically, top switch). If the temperature
exceeds a threshold of 120 C (typical) the converter will shut down,
disabling the output. When the temperature has decreased the converter
will automatically restart.
The over-temperature condition can be induced by a variety of reasons
such as external overload condition or a system fan failure.
Io,max Io,CL Io
CURRENT (A)
Figure 2. Maximum Output Current Safe Operating Area
5.5 Over Current Protection
All different voltage models have a full continuous short-circuit protection.
The unit will auto recover once the short circuit is removed. To provide
protection in a fault condition, the unit is equipped with internal over-
current protection. The unit operates normally once the fault condition is
removed. The power module will supply up to 150% of rated current. In
the event of an over current converter will go into a hiccup mode
protection.
5.3 Output Voltage Adjustment
Section 7.8 describes in detail as to how to trim the output voltage with
respect to its set point. The output voltage on all models is trimmable in
the range 0.75 – 3.63 Vdc.
5.6 Remote On/Off
The remote on/off input feature of the converter allows external circuitry
to turn the converter ON or OFF. Active-high remote on/off is available
as standard. The VPOL5A-5-SMT series converters are turned on if the
remote on/off pin is high, or left open or floating. Setting the pin low will
turn the converter ‘Off’. The signal level of the remote on/off input is
defined with respect to ground. If not using the remote on/off pin, leave
the pin open (module will be on). The part number suffix “N” is Negative
remote on/off version. The unit is guaranteed OFF over the full
temperature range if this voltage level exceeds 2.8 Vdc. The converters
are turned on If the on/off pin input is low or left open. The recommended
SMTremote on/off drive circuit as shown as figure 3, 4.
20050
SW
112
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Ave. Tualatin, Oregon
97062
phone
503.612.2300
fax
503.612.2383
www.cui.com
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