SQ48 DC-DC Series Data Sheet
36-75 VDC Input; 1.0-12 VDC Output
Features
•
RoHS lead-free solder and lead-solder-exempted
products are available
•
Delivers up to 15A (50W)
•
Industry-standard quarter-brick pinout
•
Outputs available in 12.0, 8.0, 6.0, 5.0, 3.3, 2.5, 2.0,
1.8, 1.5, 1.2, and 1.0 V
•
Available in through-hole and SMT packages
•
Low profile: 0.258” (6.55 mm)
•
Low weight: 0.53 oz (15 g)
•
On-board input differential LC-filter
•
Startup into pre-biased output
•
No minimum load required
•
Meets Basic Insulation requirements
•
Withstands 100 V input transient for 100 ms
•
Fixed-frequency operation
•
Fully protected
•
Remote output sense
•
Positive or negative logic ON/OFF option
•
Output voltage trim range: +10%/−20% with
industry-standard trim equations (except 1.2 V and
1.0 V outputs with trim range ±10%)
•
High reliability: MTBF = 3.4 million hours, calculated
per Telcordia TR-332, Method
I
Case 1
nd
•
Safety according to IEC/EN 60950-1 2 Edition and
nd
UL/CSA 60950-1 2 Edition
•
Designed to meet Class B conducted emissions per
FCC and EN55022 when used with external filter
•
All materials meet UL94, V-0 flammability rating
Applications
•
•
•
•
Telecommunications
Data communications
Wireless communications
Servers
Benefits
•
High efficiency – no heat sink required
•
For output voltages ranging from 3.3 to 1.0 V, 40%
higher current capability at elevated temperatures
than most competitors' 20-25A quarter-bricks
2
•
Extremely small footprint: 0.896” x 2.30” (2.06 in ),
40% smaller than conventional quarter-bricks
Description
The SemiQ™ Series of dc-dc converters provides a high-efficiency single output in a size that is only 60% of
industry-standard quarter-bricks, while preserving the same pinout and functionality.
In high temperature environments, for output voltages ranging from 3.3 V to 1.0 V, the thermal performance of
SemiQ™ converters exceeds that of most competitors' 20-25 A quarter-bricks. This performance is accomplished
through the use of patent-pending circuit, packaging, and processing techniques to achieve ultra-high efficiency,
excellent thermal management, and a very low body profile.
Low body profile and the preclusion of heat sinks minimize airflow shadowing, thus enhancing cooling for
downstream devices. The use of 100% automation for assembly, coupled with advanced electronic circuits and
thermal design, results in a product with extremely high reliability.
Operating from a 36-75 V input, the SQ48 Series converters provide any standard output voltage from 12 V down
to 1.0 V. Outputs can be trimmed from –20% to +10% of the nominal output voltage (±10% for output voltages
1.2 V and 1.0 V), thus providing outstanding design flexibility.
With a standard pinout and trim equations, the SQ48 Series converters are perfect drop-in replacements for
existing quarter-brick designs. Inclusion of this converter in new designs can result in significant board space and
cost savings. In both cases the designer can expect reliability improvement over other available converters
because of the SQ48 Series’ optimized thermal efficiency.
Rev6 11-Apr-2011
Page 1 of 64
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SQ48 DC-DC Series Data Sheet
36-75 VDC Input; 1.0-12 VDC Output
Electrical Specifications (common for all versions)
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, All output voltages, unless otherwise specified.
Parameter
Absolute Maximum Ratings
Input Voltage
Operating Ambient Temperature
Storage Temperature
Input Characteristics
Operating Input Voltage Range
Input Undervoltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Voltage Transient
Isolation Characteristics
I/O Isolation
Isolation Capacitance
1.0 - 3.3 V
5.0 - 6.0 V
8.0 - 12 V
Isolation Resistance
Feature Characteristics
Switching Frequency
Output Voltage Trim Range
1
1
Notes
Continuous
Min
0
-40
-55
36
Typ
Max
80
85
125
Units
VDC
°C
°C
VDC
VDC
VDC
VDC
VDC
48
34
32
75
35
33
100
Non-latching
33
31
100 ms
2000
160
260
230
10
415
Industry-std. equations (1.5 - 12V)
Use trim equation on Page 4 (1.0 -1.2 V)
Percent of V
OUT
(
NOM
)
Non-latching (1.5 - 12 V)
Non-latching (1.0 - 1.2 V)
Applies to all protection features
See Figs. F, G and H
-20
2.4
2.4
-20
117
124
122
132
100
4
0.8
20
20
0.8
-20
-10
+10
+10
+10
127
140
pF
pF
pF
MΩ
kHz
%
%
%
%
%
ms
ms
VDC
VDC
VDC
VDC
Remote Sense Compensation
Output Overvoltage Protection
Auto-Restart Period
Turn-On Time
ON/OFF Control (Positive Logic)
Converter Off (logic low)
Converter On (logic high)
ON/OFF Control (Negative Logic)
Converter Off (logic high)
Converter On (logic low)
1
Additional Notes:
Vout can be increased up to 10% via the sense leads or up to 10% via the trim function. However, the total output voltage trim from all
sources should not exceed 10% of V
OUT
(
NOM
), in order to ensure specified operation of overvoltage protection circuitry.
Rev6 11-Apr-2011
Page 2 of 64
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SQ48 DC-DC Series Data Sheet
36-75 VDC Input; 1.0-12 VDC Output
of
≤
0.8 V. An external voltage source (±20 V
maximum) may be connected directly to the ON/OFF
input, in which case it must be capable of sourcing or
sinking up to 1 mA depending on the signal polarity.
See the Startup Information section for system timing
waveforms associated with use of the ON/OFF pin.
Remote Sense (Pins 5 and 7)
The remote sense feature of the converter
compensates for voltage drops occurring between the
output pins of the converter and the load. The
SENSE(-) (Pin 5) and SENSE(+) (Pin 7) pins should
be connected at the load or at the point where
regulation is required (see Fig. B).
Vin (+)
Operations
Input and Output Impedance
These power converters have been designed to be
stable with no external capacitors when used in low
inductance input and output circuits.
In many applications, the inductance associated with
the distribution from the power source to the input of
the converter can affect the stability of the converter.
The addition of a 33 µF electrolytic capacitor with an
ESR < 1 Ω across the input helps to ensure stability
of the converter. In many applications, the user has
to use decoupling capacitance at the load. The
power converter will exhibit stable operation with
external load capacitance up to 1000 µF on 12 V,
2,200 µF on 8.0 V, 10,000 µF on 5.0 – 6.0 V, and
15,000 µF on 3.3 – 1.0 V outputs.
Additionally, see the EMC section of this data sheet
for discussion of other external components which
may be required for control of conducted emissions.
ON/OFF (Pin 2)
The ON/OFF pin is used to turn the power converter
on or off remotely via a system signal. There are two
remote control options available, positive logic and
negative logic, with both referenced to Vin(-). A
typical connection is shown in Fig. A.
Vin (+)
Semi
Q
Family
TM
Converter
Vout (+)
100
Rw
(Top View)
Vin
ON/OFF
SENSE (+)
TRI
M
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
Fig. B: Remote sense circuit configuration.
CAUTION
If remote sensing is not utilized, the SENSE(-) pin must be
connected to the Vout(-) pin (Pin 4), and the SENSE(+) pin
must be connected to the Vout(+) pin (Pin 8) to ensure the
converter will regulate at the specified output voltage. If these
connections are not made, the converter will deliver an output
voltage that is slightly higher than the specified data sheet
value.
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
(Top View)
Vin
ON/OFF
Vin (-)
CONTROL
INPUT
Vout (-)
Fig. A: Circuit configuration for ON/OFF function.
Because the sense leads carry minimal current, large
traces on the end-user board are not required.
However, sense traces should be run side by side and
located close to a ground plane to minimize system
noise and ensure optimum performance.
When using the remote sense function, the
converter’s output overvoltage protection (OVP)
senses the voltage across Vout(+) and Vout(-), and
not across the sense lines, so the resistance (and
resulting voltage drop) between the output pins of the
converter and the load should be minimized to
prevent unwanted triggering of the OVP.
When utilizing the remote sense feature, care must be
taken not to exceed the maximum allowable output
power capability of the converter, which is equal to the
product of the nominal output voltage and the
allowable output current for the given conditions.
When using remote sense, the output voltage at the
converter can be increased by as much as 10%
above the nominal rating in order to maintain the
required voltage across the load. Therefore, the
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The positive logic version turns on when the ON/OFF
pin is at a logic high and turns off when at a logic low.
The converter is on when the ON/OFF pin is left
open. See Electrical Specifications for logic high/low
definitions.
The negative logic version turns on when the pin is at
a logic low and turns off when the pin is at a logic
high. The ON/OFF pin can be hardwired directly to
Vin(-) to enable automatic power up of the converter
without the need of an external control signal.
The ON/OFF pin is internally pulled up to 5V through
a resistor. A properly debounced mechanical switch,
open collector transistor, or FET can be used to drive
the input of the ON/OFF pin. The device must be
capable of sinking up to 0.2 mA at a low level voltage
Rev6 11-Apr-2011
Page 3 of 64
SQ48 DC-DC Series Data Sheet
36-75 VDC Input; 1.0-12 VDC Output
designer must, if necessary, decrease the maximum
current (originally obtained from the derating curves)
by the same percentage to ensure the converter’s
actual output power remains at or below the
maximum allowable output power.
Output Voltage Adjust /TRIM (Pin 6)
The output voltage can be adjusted up 10% or down
20% for Vout≥ 1. 5 V, and
±10%
for Vout = 1.2 V
relative to the rated output voltage by the addition of
an externally connected resistor. For output voltage
3.3 V, trim up to 10% is guaranteed only at
Vin ≥ 40 V, and it is marginal (8% to 10%) at
Vin = 36 V.
The TRIM pin should be left open if trimming is not
being used. To minimize noise pickup, a 0.1 µF
capacitor is connected internally between the TRIM
and SENSE(-) pins.
To increase the output voltage, refer to Fig. C. A trim
resistor, R
T-INCR
, should be connected between the
TRIM (Pin 6) and SENSE(+) (Pin 7), with a value of:
When trimming up, care must be taken not to exceed
the converter‘s maximum allowable output power. See
the previous section for a complete discussion of this
requirement.
To decrease the output voltage (Fig. D), a trim
resistor, R
T-DECR
, should be connected between the
TRIM (Pin 6) and SENSE(-) (Pin 5), with a value of:
R
T
−
DECR
=
R
T
−
DECR
=
R
T
−
DECR
=
511
−
10.22
Δ
700
−
15
Δ
700
−
17
|Δ|
[kΩ] (1.5 – 12 V)
[kΩ] (1.2 V)
[kΩ] (1.0 V)
where,
R
T
−DECR
=
Required value of trim-down resistor [kΩ]
and
Δ
is defined above.
Note:
The above equations for calculation of trim resistor values match
those typically used in conventional industry-standard quarter-
bricks and one-eighth bricks (except for 1.2 V and 1.0 V outputs).
5.11(100
+
Δ)V
O
−
NOM
−
626
−
10.22
1.225Δ
for 1.5 – 12 V.
R
T
−
INCR
=
R
T
−
INCR
=
R
T
−
INCR
=
84.6
−
7.2
Δ
120
−
9
Δ
[kΩ] (1.2 V)
[kΩ] (1.0 V)
[kΩ],
Converters with output voltages 1.2 V and 1.0 V are
available with alternative trim feature to provide the
customers with the flexibility of second sourcing.
These converters have a “T” character in the part
number. The trim equations of “T” version of
converters and more information can be found in
Application Note 103.
Vin (+)
where,
R
T
−INCR
=
Required value of trim-up resistor [kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-DECR
Rload
(Top View)
Vin
ON/OFF
(V
O -REQ
−
V
O -NOM
)
Δ
=
X 100
[%]
V
O -NOM
V
O
−REQ
=
Desired (trimmed) output voltage [V].
Vin (-)
Vout (-)
Fig. D: Configuration for decreasing output voltage.
Vin (+)
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-INCR
Rload
(Top View)
Vin
ON/OFF
Trimming/sensing beyond 110% of the rated output
voltage is not an acceptable design practice, as this
condition could cause unwanted triggering of the
output overvoltage protection (OVP) circuit. The
designer should ensure that the difference between
the voltages across the converter’s output pins and its
sense pins does not exceed 10% of V
OUT
(
NOM
), or:
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
(
+
)
−
V
SENSE
(
−
)]
≤
V
O - NOM X
10%
[V]
Vin (-)
Vout (-)
Fig. C: Configuration for increasing output voltage.
This equation is applicable for any condition of output
sensing and/or output trim.
Rev6 11-Apr-2011
Page 4 of 64
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SQ48 DC-DC Series Data Sheet
36-75 VDC Input; 1.0-12 VDC Output
Protection Features
Input Undervoltage Lockout
Input undervoltage lockout is standard with this
converter. The converter will shut down when the
input voltage drops below a pre-determined voltage.
The input voltage must be typically 34 V for the
converter to turn on. Once the converter has been
turned on, it will shut off when the input voltage drops
typically below 32 V. This feature is beneficial in
preventing deep discharging of batteries used in
telecom applications.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or
short circuit conditions. Upon sensing an overcurrent
condition, the converter will switch to constant
current operation and thereby begin to reduce output
voltage. When the output voltage drops below 50%
of the nominal value of output voltage, the converter
will shut down (Fig. x.17).
Once the converter has shut down, it will attempt to
restart nominally every 100 ms with a typical 1-2%
duty cycle (Fig. x.18). The attempted restart will
continue indefinitely until the overload or short circuit
conditions are removed or the output voltage rises
above 50% of its nominal value.
Once the output current is brought back into its
specified range, the converter automatically exits the
hiccup mode and continues normal operation.
Output Overvoltage Protection (OVP)
The converter will shut down if the output voltage
across Vout(+) (Pin 8) and Vout(-) (Pin 4) exceeds
the threshold of the OVP circuitry. The OVP circuitry
contains its own reference, independent of the output
voltage regulation loop. Once the converter has shut
down, it will attempt to restart every 100 ms until the
OVP condition is removed.
Overtemperature Protection (OTP)
The converter will shut down under an
overtemperature condition to protect itself from
overheating caused by operation outside the thermal
derating curves, or operation in abnormal conditions
such as system fan failure. After the converter has
cooled to a safe operating temperature, it will
automatically restart.
Safety Requirements
The converters meet North American and
International safety regulatory requirements. Basic
Insulation is provided between input and output.
Rev6 11-Apr-2011
To comply with safety agencies’ requirements, an
input line fuse must be used external to the converter.
The Table below provides the recommended fuse
rating for use with this family of products.
Output Voltage
3.3 V
12 - 5.0 V, 2.5 V
2.0 - 1.2 V
Fuse Rating
4A
3A
2A
All SQ converters are UL approved for a maximum
fuse rating of 15 Amps. To protect a group of
converters with a single fuse, the rating can be
increased from the recommended values above.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product
system level, as no specific standards dedicated to
EMC characteristics of board mounted component dc-
dc converters exist. However, Power-One tests its
converters to several system level standards, primary
of which is the more stringent EN55022,
Information
technology
equipment
-
Radio
disturbance
characteristics - Limits and methods of measurement.
An effective internal LC differential filter significantly
reduces input reflected ripple current, and improves
EMC.
With the addition of a simple external filter (see
Application Note 100), all versions of the SQ48 Series
converters pass the requirements of Class B
conducted emissions per EN55022 and FCC
requirements. Please contact Power-One Applications
Engineering for details of this testing.
Characterization
General Information
The converter has been characterized for many
operational aspects, to include thermal derating
(maximum load current as a function of ambient
temperature and airflow) for vertical and horizontal
mounting,
efficiency,
startup
and
shutdown
parameters, output ripple and noise, transient
response to load step-change, overload, and short
circuit.
The figures are numbered as Fig. x.y, where x
indicates the different output voltages, and y
associates with specific plots (y = 1 for the vertical
thermal derating, …). For example, Fig. x.1 will refer
to the vertical thermal derating for all the output
voltages in general.
The following pages contain specific plots or
waveforms associated with the converter. Additional
comments for specific data are provided below.
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