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 65C 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
.
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
5
10
mS
Input Reflected Ripple Current
Full Load, 12uH source
inductance
50
mA p-p
Inrush Transient
Vin=Vin.max
0.1
A
2
s
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
S
Admissible Load Capacitance
I
rated
, Nom Vin
20,000
F
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
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
12
15
18
21
24
27
30
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
10
20
30
40
50
60
70
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
10
20
30
40
50
60
70
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
10
20
30
40
50
60
70
Input voltage, VDC
Input current, ADC
Fig. 6 QLS30ZY Input Characteristic
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
33F electrolytic capacitor with the ESR<0.7
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
10F tantalum and a 1F 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.
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
k
(1)
where A and B are constants from the table
below, and V is the absolute value of the desired
change in the output voltage in Volts.
Model
Trim up
Trim down
A
B
A
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
V change in the
output voltage.
+
-
+
=
%
%
2
100
%
225
.
1
%)
100
(
11
.
5
V
V
V
V
Vout
R
UP
,k
-
=
2
%
100
11
.
5
V
R
DOWN
, k
For QLS30ZY use the following equations.
+
=
%
225
.
1
%)
100
(
11
.
5
V
V
Vout
R
UP
,K
-
=
2
1
%
2
100
11
.
5
V
R
DOWN
,K
where
V% 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
V
B
A
R
TRIM
-
=
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
.
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
2
On/Off
3
+Vin
4
-Vout
5
-Sense
6
Trim
7
+Sense
8
+Vout
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