Page 1
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/1 Page 1 of 8
Applications
• Distributed power architectures
• Telecommunications equipment
• LAN/WAN applications
• Data processing applications
Features
• Cost-effective single board design
• Low profile – 11 mm height
• Input/output isolation: 1500VDC, basic
insulation
• High efficiency
• Output back-drive protection
• Start-up into high capacitive load
• Low conducted and radiated EMI
• Output overcurrent protection
• Output overvoltage protection
• Overtemperature protection
• Remote sense
• Set point accuracy ± 1%
• Remote on/off (primary referenced), positive
or negative logic
• Output voltage trim adjust, positive or
negative
• UL 1950 Recognition, CSA 22.2 No. 950-95
certification, TUV IEC950
Description
The new QLS30 series of single-output DC/DC converters features single board, multi-layer construction
and an SMT design that is highly reliable due to the low component count and minimal manufacturing touch
time. The QLS30 series uses fewer components than any other equivalently rated single board converter.
The converters can deliver a maximum of 30 Amps with a typical efficiency of 85%. The QLS provides
superior thermal performance, with minimal derating. The QLS30ZB model converter can deliver 22.8
amperes at 1.8 volt output in ambient conditions of 65°C and 200 LFM. This full featured, low profile
converter offers input undervoltage lockout, overload, overvoltage and overtemperature protection. Interface
features include remote on/off, remote sense and output voltage trim.
Selection Chart
Model Input
voltage
VDC
Input
current,
max
ADC
Output
voltage
Vout,
VDC
Output rated
current
I
rated,
ADC
Output
Ripple/Noise,
mV p-p
Typical
Efficiency
@ I
rated,
%
QLS30ZB 36-75 1.5 1.8 30 100 86
QLS30ZA 36-75 1.3 1.5 30 100 85
QLS30ZY 36-75 1.1 1.2 30 100 84
This product is intended for integration into end-use equipment. All the required procedures for CE marking of end-use equipment
should be followed
.
Page 2
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/1 Page 2 of 8
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings may cause performance degradation, adversely effect
long-term reliability and cause permanent damage to the converter.
Parameter Conditions/Description Min Max Units
Input voltage Continuous
Transient, 100mS
75
100
VDC
VDC
Operating Temperature At 100% load -40 100
°C
Storage Temperature -40 125
°C
ON/OFF Control Voltage Referenced to -Vin 50 VDC
Environmental and Mechanical Specifications
All specifications apply over specified input voltage, output load and temperature range, unless otherwise
noted.
Parameter Conditions/Description Min Nom Max Units
Shock Halfsine wave, 3 axes 50 g
Sinusoidal Vibration GR-63-Core, Section 5.A.2 1
Weight 1.2/35 Oz/g
Water Washing Standard process Yes
MTBF Per Bellcore TR-NWT-000332 1,980 kHrs
Isolation Specifications
All specifications apply over specified input voltage, output load and temperature range, unless otherwise
noted.
Parameter Conditions/Description Min Nom Max Units
Insulation Safety Rating Basic
Isolation Voltage 1500 VDC
Isolation Resistance 10 MOhm
Isolation Capacitance 1800 pF
Input Specifications
All specifications apply over specified input voltage, output load and temperature range, unless otherwise
noted.
Parameter Conditions/Description Min Nom Max Units
Input Voltage Continuous 36 48 75 VDC
Turn-On Input Voltage Ramping Up 33 VDC
Turn-Off Input Voltage Ramping Down 32 VDC
Turn-On Time To Output Regulation Band
100% Resistive Load
510mS
Input Reflected Ripple Current Full Load, 12uH source
inductance
50 mA p-p
Inrush Transient Vin=Vin.max 0.1 A2s
Page 3
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/1 Page 3 of 8
Output Specifications
All specifications apply over specified input voltage, output load and temperature range, unless otherwise
noted.
Parameter Conditions/Description Min Nom Max Units
Output Voltage Setpoint Accuracy Vin=Vin.nom, Full Load -1 1 %Vout
Output Current*
See selection chart for I
rated
10 100
%I
rated
Line Regulation
Vin.min to Vin.max, I
rated
0.2 %Vout
Load Regulation Vin=Vin.nom, 10% to
100%I
rated
0.2 %Vout
Total output voltage regulation Over all input voltage, load,
and temperature conditions
-2 2 %Vout
Remote Sense Headroom 0.5 VDC
Dynamic Regulation
Peak Deviation
Settling Time
50-75% load step change
to 1% error band
6
500
%Vout
µS
Admissible Load Capacitance
I
rated
, Nom Vin
20,000
µF
Output Current Limit Threshold** Vout=0.97Vout.nom 110 140
%I
rated
Switching Frequency 300 kHz
Overvoltage Protection,
Non Latching
Over all input voltage and
load conditions
120 140 %Vout
Trim Range
I
rated
, Vin=Vnom
90 110 %Vout
* At Iout<Iout.min, the output may contain low frequency component that exceeds ripple specifications.
** Overcurrent protection is non-latching with auto recovery.
Feature Specifications
All specifications apply over specified input voltage, output load and temperature range, unless otherwise
noted.
Parameter Conditions/Description Min Nom Max Units
Shutdown (ON/OFF)
Negative Logic
Converter ON
Source Current
Converter OFF
Open Circuit Voltage
Positive Logic
Converter ON
Open Circuit Voltage
Converter OFF
Source Current
On/Off signal is low – converter is ON
ON/OFF pin is connected to -Vin
ON/OFF pin is floating
On/Off signal is low –converter is OFF
ON/OFF pin is floating
ON/OFF pin is connected to -Vin
-1.0
3.5
3.5
-1.0
2.1
2.5
2.0
1.8
150
5
50
5
1.8
1
VDC
mADC
VDC
VDC
VDC
VDC
VDC
mADC
Overtemperature
Protection
Average Board Temperature 105
°C
Page 4
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/01 Page 4 of 8
Characteristic Curves
50
55
60
65
70
75
80
85
90
95
0 3 6 9 12 15 18 21 24 27 30
Output current, A
Efficiency, %
36V 48V 75V
Fig. 1 QLS30ZB Efficiency vs. Output Load
50
55
60
65
70
75
80
85
90
0 3 6 9 12 15 18 21 24 27 30
Output current, A
Efficiency, %
36V 48V 75V
Fig. 2 QLS30ZA Efficiency vs. Output Load
50
55
60
65
70
75
80
85
90
95
0 3 6 9 12151821242730
Output current, A
EFFICIENCY%
36V 48V 75V
Fig. 3 QLS30ZY Efficiency vs. Output Load
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
0 10203040506070
Input Voltage, VDC
Input Current, ADC
Fig. 4 QLS30ZB Input Characteristic
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 10203040506070
Input voltage, VDC
Input current, ADC
Fig. 5 QLS30ZA Input Characteristic
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 10203040506070
Input voltage, VDC
Input current, ADC
Fig. 6 QLS30ZY Input Characteristic
Page 5
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/01 Page 5 of 8
Typical Application
Figure 7 below shows the recommended
connections for the QLS30 series converter.
+Vo
+Sense
Trim
-Sense
-Vo-Vi
+Vi
On/Off
Fuse
C1 C2 C3
QLS30ZX
Fig.7 Typical application of QLS30 series
The QLS30 series converters do not require any
external components for proper operation.
However, if the distribution of the input voltage to
the converter contains significant inductance, the
capacitor C1 may be required to enhance
performance of the converter. A minimum of a
33μF electrolytic capacitor with the ESR<0.7Ω is
recommended for the QLS30 series.
Refer to the “Inrush Current Control Application
Note” on www.power-one.com for suggestions on
how to limit the magnitude of the inrush current.
For output decoupling we recommend to use a
10μF tantalum and a 1μF ceramic capacitors
connected directly across the output pins of the
converter. Note that the capacitors do not
substitute the filtering required by the load.
Shutdown Feature Description
The ON/OFF pin in the QLS30 series converters
functions as a normal soft shutdown. It is
referenced to the –Vin pin (see Figure 7). With
positive logic, when the ON/OFF pin is pulled low,
the output is turned off and the unit goes into a
very low input power mode.
With negative logic, when the ON/OFF pin is
pulled low, the unit is turned on. An open collector
switch is recommended to control the voltage
between the ON/OFF pin and the -Vin pin of the
converter. The ON/OFF pin is pulled up
internally, so no external voltage source is
required. The user should avoid connecting a
resistor between the ON/OFF pin and the +Vin
pin.
When the ON/OFF pin is used to achieve remote
control, the user must take care to insure that the
pin reference for the control is really the -Vin pin.
The control signal must not be referenced ahead
of EMI filtering, or remotely from the unit.
Optically coupling the information and locating the
optical coupler directly at the module will solve
any of these problems.
Note:
If the ON/OFF pin is not used, it can be left
floating (positive logic), or connected to the -Vin
pin (negative logic).
Output Voltage Trim
The trim feature allows the user to adjust the
output voltage from the nominal. This can be used
to accommodate a different requirement or to do
production margin testing. There are two
variances available in the QLS30 series.
Negative Trim (No suffix)
The QLS30 negative trim units trim up with a
resistor from the TRIM pin to the –Sense pin and
trim down with a resistor from the TRIM pin to the
+Sense pin, as shown in Fig.8.
The negative trim schematic is shown in Figure 8.
Fig.8 QLS30 series negative trim schematic
The general equation (1) for changing the output
voltage on the negative trim modules is invariant,
but the constants in the equation change due to
different internal values.
Page 6
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/01 Page 6 of 8
kΩ (1)
where A and B are constants from the table
below, and ΔV is the absolute value of the desired
change in the output voltage in Volts.
Model Trim up Trim down
ABA B
QLS30ZB 0.57 1 0.2711 1.4676
QLS30ZA 0.283 0.121 0.065 0.352
QLS30ZY 0.5928 3.01 0.5686 2.0422
Inductrial Standard Positive Trim (suffix –T)
The -T option units trim up with a resistor from the
TRIM pin to the +Sense pin and trim down with a
resistor from the TRIM pin to the –Sense pin as
shown in the Figure 9.
Fig.9 QLS30 series positive trim schematic
The equations below determine the trim resistor
value required to achieve a ΔV change in the
output voltage.
∆
∆+
−
∆
∆+
=
%
%2100
%225.1
%)100(
11.5
V
V
V
VVout
R
UP
,kΩ
−
∆
=
2
%
100
11.5
V
R
DOWN
, kΩ
For QLS30ZY use the following equations.
∆
∆+
=
%225.1
%)100(
11.5
V
VVout
R
UP
,KΩ
−
∆
=
2
1
%2
100
11.5
V
R
DOWN
,KΩ
where ΔV% is the output voltage change
expressed in percents of the nominal output
voltage, Vout.
Notes:
1. When the output voltage is trimmed up, the
output power from the converter must not
exceed its maximum rating. The power is
determined by measuring the output voltage
on the output pins, and multiplying it by the
output current.
2. In order to avoid creating apparent load
regulation degradation, it is important that the
trim resistors are connected directly to the
remote sense pins, and not to the load or to
traces going to the load.
3. The QLS30 series converters will trim down
further than the 10% limit. In general, this is
permissible. The user must confirm that the
results are acceptable in the application.
Safety Considerations
The QLS30 series converters feature 1500 Volt
DC isolation from input to output. The input to
output resistance is greater than 10MOhm.
These converters are provided with Basic
insulation between input and output circuits
according to all IEC60950 based standards.
Nevertheless, if the system using the converter
needs to receive safety agency approval, certain
rules must be followed in the design of the
system. In particular, all of the creepage and
clearance requirements of the end-use safety
requirements must be observed. These
documents include UL60950, CSA60950-00 and
EN60950, although other additional requirements
may be needed for user’s specific applications.
The QLS30 series converters have no internal
fuse. An external fuse must be provided to
protect the system from catastrophic failure, as
illustrated in Figure 7. The fuse with a rating of
4A or less is recommended. The user can select
a lower rating fuse based upon the highest inrush
transient at the maximum input voltage and the
maximum input current of the converter at the
minimum input voltage. Both input traces and the
,
V
VBA
R
TRIM
∆
∆×−
=
Page 7
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/01 Page 7 of 8
chassis ground trace (if applicable) must be
capable of conducting a current of 1.5 times the
value of the fuse without opening. The fuse must
not be placed in the grounded input line, if any.
In order for the output of the QLS30 series
converter to be considered as SELV (Safety Extra
Low Voltage) or TNV-1, according to all IEC60950
based standards, one of the following
requirements must be met in the system design:
• If the voltage source feeding the module is
SELV or TNV-2, the output of the converter
may be grounded or ungrounded.
• If the voltage source feeding the module is
ELV, the output of the converter may be
considered SELV only if the output is
grounded per the requirements of the
standard.
• If the voltage source feeding the module is a
Hazardous Voltage Secondary Circuit, the
voltage source feeding the module must be
provided with at least Basic insulation
between the source to the converter and any
hazardous voltages. The entire system,
including the QLS30 converter, must pass a
dielectric withstand test for reinforced
insulation. Design of this type of systems
requires expert engineering and
understanding of the overall safety
requirements and should be performed by
qualified personnel.
Thermal Considerations
The QLS30 series converters are designed for
both natural and forced convection cooling. The
maximum allowable output current of the
converters is determined by meeting the derating
criteria of all electronic components used in the
power supplies. An example of the derating
criteria for the semiconductor junction
temperature is not to exceed 120°C to provide
reliable long-term operation of the converters.
Please contact Power-One for more derating
criteria for other components. The graphs in
Figures 10-12 show the maximum output current
of the QLS30 series converters at different
ambient temperatures under both natural and
forced (longitudinal airflow direction, from pin 1 to
pin 3) convection. As an example, from Figure
11, the QLS30ZA operating at 55°C can deliver
up to 25A reliably with 100LFM forced air, while
up to 29A reliably with 200LFM forced air.
0
5
10
15
20
25
30
35
25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature (C)
Output Current (A)
0
100LFM
200LFM
300LFM
400LFM
Fig.10 QLS30ZB (1.8V) derating curves
0
5
10
15
20
25
30
35
25 30 35 40 45 50 55 60 65 70 75 80
Ambient Temperature ( C )
Output Current (A)
0
100LFM
200LFM
300LFM
400LFM
Fig.11 QLS30ZA (1.5V) derating curves
0
5
10
15
20
25
30
35
25 30 35 40 45 50 55 60 65 70 75 80 85
Ambient Temperature ( C )
Output Current (A)
0
100LF
M
200LF
Fig.12 QLS30ZY (1.2V) derating curves
.
Page 8
QLS30 Series – 30A Quarter-Brick DC/DC Converter
48V Input Data Sheet
1.8V, 1.5V, 1.2V Output
REV. 10/01 Page 8 of 8
Mechanical Drawing
Ordering Information
Options Suffixes to add to part number
Remote ON/OFF Positive- Standard, no suffix required
Negative- Add “N” suffix
Trim Negative- Standard, no suffix required
Positive - Add “T” suffix
Pin Length 0.18”- Standard, no suffix required
0.11”- Add “8” suffix
0.15”- Add “9” suffix
Notes
1. Consult factory for the complete list of available options.
2. Power-One products are not authorized for use as critical components in life support systems, equipment used in hazardous
environments, or nuclear control systems without the express written consent of the President of Power-One, Inc.
3. Specifications are subject to change without notice.
Tolerances: .xx + .020 (.5)
.xxx + .010 (.25)
Pin Diameter + 0.002 (.05)
PIN FUNCTION
1-Vin
2On/Off
3+Vin
4 -Vout
5 -Sense
6Trim
7 +Sense
8 +Vout
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