SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
The
SemiQ™ Family
of dc-dc converters from 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-
30 A quarter-bricks. This 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 electric and thermal design, results
in a product with extremely high reliability.
Operating from an 18-36 V input, the
SQ24 Series
converters of the
SemiQ™ Family
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
SQ24
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. The device is also available in a surface mount
package.
In both cases the designer can expect reliability
improvement over other available converters because of
the
SQ24 Series’
optimized thermal efficiency.
SQ24T and SQ24S Converters
Features
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RoHS lead-free solder and lead-solder-exempted
products are available
Delivers up to 15 A (50 W)
Available in through-hole and SM packages
Low weight: 0.53 oz (15 g)
Low profile: 0.274” (6.96 mm)
Extremely small footprint: 0.896” x 2.30” (2.06 in
2
)
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
High efficiency – no heat sink required
On-board input differential LC-filter
Extremely low output and input ripple
Start-up into pre-biased output
No minimum load required
Meets Basic Insulation requirements of EN60950
Fixed-frequency operation
Fully protected
Remote output sense
Output voltage trim range: +10%/−20% (except 1.2 V
and 1.0 V outputs with trim range
±10%)
with industry-
standard trim equations
High reliability: MTBF of 3.4 million hours, calculated
per Telcordia TR-332, Method
I
Case 1
Positive or negative logic ON/OFF option
UL 60950 recognition in US and Canada and DEMKO
certification per IEC/EN 60950
Meets conducted emissions requirements of FCC
Class B and EN 55022 Class B with external filter
All materials meet UL94, V-0 flammability rating
Applications
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Telecommunications
Data communications
Wireless
Servers
AUG 25, 2006 revised to MAR 19, 2007
Page 1 of 70
www.power-one.com
SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
Electrical Specifications (common to all versions)
Conditions: T
A
=25 ºC, Airflow=300 LFM (1.5 m/s), Vin=24 VDC, All output voltages, unless otherwise specified.
PARAMETER
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
NOTES
MIN
0
-40
-55
18
TYP
MAX
40
85
125
UNITS
VDC
°C
°C
VDC
VDC
VDC
VDC
pF
pF
pF
MΩ
kHz
%
%
%
%
%
ms
ms
VDC
VDC
VDC
VDC
INPUT CHARACTERISTICS
Operating Input Voltage Range
Input Under Voltage Lockout
Turn-on Threshold
Turn-off Threshold
24
17
16
36
17.5
16.5
Non-latching
16
15
2000
1.0 - 3.3 V
5.0 - 6.0 V
8.0 V, 12 V
10
415
Industry-std. equations (1.5 - 12 V)
Industry-std. equations (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
-20
-10
117
124
125
132
100
4
+10
+10
+10
140
140
160
260
230
ISOLATION CHARACTERISTICS
I/O Isolation
Isolation Capacitance:
Isolation Resistance
FEATURE CHARACTERISTICS
Switching Frequency
1
Output Voltage Trim Range
Remote Sense Compensation
Output Over-Voltage Protection
Auto-Restart Period
Turn-On Time
ON/OFF Control (Positive Logic)
Converter Off
Converter On
ON/OFF Control (Negative Logic)
Converter Off
Converter On
1
-20
2.4
2.4
-20
0.8
20
20
0.8
Additional Notes:
1. Vout can be increased up to 10% via the sense leads or up to 10% via the trim function, however total output voltage trim from all sources
should not exceed 10% of V
OUT
(
NOM
), in order to insure specified operation of over-voltage protection circuitry. See “Output Voltage Adjust/Trim” for
detailed information.
AUG 25, 2006 revised to MAR 19, 2007
Page 2 of 70
www.power-one.com
SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
Operation
Input and Output Impedance
in which case it must be capable of sourcing or sinking up to
1mA depending on the signal polarity. See the Start-up
Information section for system timing waveforms associated
with use of the ON/OFF pin.
Remote Sense (Pins 5 and 7)
These power converters have been designed to be stable
with no external capacitors when used in low inductance
input and output circuits.
However, 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 100 µF electrolytic capacitor with an ESR < 1Ω
across the input helps 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 V –
6.0 V, and 15,000 µF on 3.3 V – 1.0 V outputs.
ON/OFF (Pin 2)
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 (+)
Semi
Q
Family
TM
Converter
Vout (+)
100
Rw
(Top View)
Vin
ON/OFF
SENSE (+)
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
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
and both are referenced to Vin(-). Typical connections are
shown in Fig. A.
Vin (+)
Fig. B:
Remote sense circuit configuration.
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
(Top View)
Vin
ON/OFF
If remote sensing is not required, 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 value.
Because the sense leads carry minimal current, large traces
on the end-user board are not required. However, sense
traces should be located close to a ground plane to minimize
system noise and insure optimum performance. When wiring
discretely, twisted pair wires should be used to connect the
sense lines to the load to reduce susceptibility to noise.
The converter’s output over-voltage 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, 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 designer must, if necessary,
Vin (-)
CONTROL
INPUT
Vout (-)
Fig. A:
Circuit configuration for ON/OFF function.
The positive logic version turns on when the ON/OFF pin is
at logic high and turns off when at logic low. The converter is
on when the ON/OFF pin is left open
.
The negative logic version turns on when the pin is at logic
low and turns off when the pin is at logic high. The ON/OFF
pin can be hard wired directly to Vin(-) to enable automatic
power up of the converter without the need of an external
control signal.
ON/OFF pin is internally pulled-up to 5 V through a resistor.
A 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 0.2mA at a low level
voltage of
≤
0.8V. An external voltage source (±20V
maximum) may be connected directly to the ON/OFF input,
AUG 25, 2006 revised to MAR 19, 2007
Page 3 of 70
www.power-one.com
SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
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)
Fig. C:
Configuration for increasing output voltage.
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
=
511
−
10.22
|
Δ
|
[kΩ]
(1.0 – 12V)
The converter’s output voltage can be adjusted up 10% or
down 20% for Vout
≥
1.5V, and
±10%
for Vout = 1.2V and
1.0 V, relative to the rated output voltage by the addition of
an externally connected resistor. For output voltages 3.3V,
trim up to 10% is guaranteed only at Vin
≥
20V, and it is
marginal (8% to 10%) at Vin = 18V depending on load
current.
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:
R
T
−
INCR
5.11(100
+
Δ)V
O
−
NOM
−
626
=
−
10.22
[kΩ] (1.5 –12V)
1.225Δ
where,
R
T
−DECR
=
Required value of trim-down resistor [kΩ]
and
Δ
is as 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.
Converters with output voltage 1.2V and 1.0V have specific
trim schematic and equations, to provide the customers with
the flexibility of second sourcing. For these converters, the
last character of part number is “T”. More information about
trim feature, including corresponding schematic portions, can
be found in Application Note 103.
Vin (+)
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-DECR
Rload
(Top View)
Vin
ON/OFF
R
T
−
INCR
=
R
T
−
INCR
=
485
Δ
323
−
2
Δ
[kΩ] (1.2V)
[kΩ] (1.0V)
Vin (-)
Vout (-)
Fig. D:
Configuration for decreasing output voltage.
where,
R
T
−INCR
=
Required value of trim-up resistor kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
Δ
=
(V
O-REQ
−
V
O -NOM
)
X 100
[%]
V
O -NOM
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 over-voltage
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]
V
O
−REQ
=
Desired (trimmed) output voltage [V].
When trimming up, care must be taken not to exceed the
converter‘s maximum allowable output power. See previous
section for a complete discussion of this requirement.
This equation is applicable for any condition of output
sensing and/or output trim.
Vin (+)
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
R
T-INCR
(Top View)
Vin
ON/OFF
TRIM
SENSE (-)
Rload
Vin (-)
Vout (-)
AUG 25, 2006 revised to MAR 19, 2007
Page 4 of 70
www.power-one.com
SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
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 at least 17.5V for the converter to
turn on. Once the converter has been turned on, it will shut
off when the input voltage drops below 15V. This feature is
beneficial in preventing deep discharging of batteries used in
telecom applications.
Output Overcurrent Protection (OCP)
Output Voltage
Fuse Rating
3.3V
12V - 5.0V, 2.5V
2.0V - 1.0V
8A
6A
4A
If one input fuse is used for a group of modules, the
maximum fuse rating should not exceed 15-A (SQ modules
are UL approved with up to a 15-A fuse).
Electromagnetic Compatibility (EMC)
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.
Once the converter has shut down, it will attempt to restart
nominally every 100 ms with a typical 1-2% duty cycle. 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.
Output Overvoltage Protection (OVP)
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.
With the addition of a simple external filter (see application
notes), all versions of the
SQ24 Series
of converters pass
the requirements of Class B conducted emissions per
EN55022 and FCC, and meet at a minimum, Class A
radiated emissions per EN 55022 and Class B per FCC Title
47CFR, Part 15-J. Please contact di/dt Applications
Engineering for details of this testing.
Characterization
General Information
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 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, start-up 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 is associated with a specific
plot (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.
The converters meet North American and International
safety regulatory requirements per UL60950 and EN60950.
Basic Insulation is provided between input and output.
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.
AUG 25, 2006 revised to MAR 19, 2007
Page 5 of 70
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