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' 2030 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
Applications
Telecommunications
Data communications
Wireless
Servers
MCD10159 Rev. 1.2, 20-Apr-12
Page 1 of 70
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 in2)
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 industrystandard 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 60950-1/CSA 22.2 No. 60950-1-07 Second
Edition, IEC 60950-1: 2005, and EN 60950-1:2006
Meets conducted emissions requirements of FCC
Class B and EN 55022 Class B with external filter
All materials meet UL94, V-0 flammability rating
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: TA=25 ºC, Airflow=300 LFM (1.5 m/s), Vin=24 VDC, All output voltages, unless otherwise specified.
PARAMETER
NOTES
MIN
TYP
MAX
UNITS
40
85
125
VDC
°C
°C
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
0
-40
-55
INPUT CHARACTERISTICS
Operating Input Voltage Range
Input Under Voltage Lockout
Turn-on Threshold
Turn-off Threshold
18
24
36
VDC
16
15
17
16
17.5
16.5
VDC
VDC
Non-latching
ISOLATION CHARACTERISTICS
I/O Isolation
Isolation Capacitance:
2000
1.0 - 3.3 V
5.0 - 6.0 V
8.0 V, 12 V
VDC
pF
pF
pF
MΩ
160
260
230
Isolation Resistance
10
FEATURE CHARACTERISTICS
Switching Frequency
1
Output Voltage Trim Range
415
1
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
Industry-std. equations (1.5 - 12 V)
Industry-std. equations (1.0 - 1.2 V)
Percent of VOUT(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
kHz
%
%
%
%
%
ms
ms
-20
2.4
0.8
20
VDC
VDC
2.4
-20
20
0.8
VDC
VDC
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 VOUT(NOM), in order to insure specified operation of over-voltage protection circuitry. See “Output Voltage Adjust/Trim” for
detailed information.
MCD10159 Rev. 1.2, 20-Apr-12
Page 2 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
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.
Operation
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.
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 < 1
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.
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).
Converter
(Top View)
Vin
ON/OFF
Vout (+)
Rw
100
SENSE (+)
TRIM
Rload
SENSE (-)
ON/OFF (Pin 2)
10
Vin (-)
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.
SemiQ Family
TM
Vin (+)
Converter
(Top View)
ON/OFF
Vin
SemiQ Family
TM
Vin (+)
Vout (+)
SENSE (+)
TRIM
Rload
SENSE (-)
Vin (-)
Rw
Fig. B: Remote sense circuit configuration.
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.
Vout (-)
CONTROL
INPUT
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,
MCD10159 Rev. 1.2, 20-Apr-12
Vout (-)
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,
Page 3 of 70
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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.
Fig. C: Configuration for increasing output voltage.
To decrease the output voltage (Fig. D), a trim resistor,
RT-DECR, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
511
10.22
|Δ|
Output Voltage Adjust /TRIM (Pin 6)
RTDECR
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.
where,
RTDECR Required value of trim-down resistor [k]
and Δ is as defined above.
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, RT-INCR, should be connected between the TRIM
(Pin 6) and SENSE(+) (Pin 7), with a value of:
[k]
(1.0 – 12V)
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industrystandard 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.
SemiQ Family
TM
RTINCR
Vin (+)
5.11(100 Δ)VONOM 626
10.22 [k] (1.5 –12V)
1.225Δ
(Top View)
Vin
RTINCR
485
Δ
[k] (1.2V)
RTINCR
323
2
Δ
[k] (1.0V)
(Top View)
Vin
ON/OFF
Vout (-)
[VOUT() VOUT()] [VSENSE() VSENSE()] VO - NOM X 10% [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.
TM
Rload
R T-DECR
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
VOUT(NOM), or:
VOREQ Desired (trimmed) output voltage [V].
Converter
TRIM
Fig. D: Configuration for decreasing output voltage.
(VO-REQ VO -NOM)
X 100 [%]
VO -NOM
SemiQ Family
Vout (+)
SENSE (+)
SENSE (-)
RTINCR Required value of trim-up resistor k]
VONOM Nominal value of output voltage [V]
Vin (+)
ON/OFF
Vin (-)
where,
Δ
Converter
This equation is applicable for any condition of output
sensing and/or output trim.
Vout (+)
SENSE (+)
R T-INCR
TRIM
Rload
SENSE (-)
Vin (-)
MCD10159 Rev. 1.2, 20-Apr-12
Vout (-)
Page 4 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
provides the recommended fuse rating for use with this
family of products.
Protection Features
Input Undervoltage Lockout
Output Voltage
Input undervoltage lockout is standard with this converter.
The converter will shut down when the input voltage drops
below a pre-determined voltage.
3.3V
12V - 5.0V, 2.5V
2.0V - 1.0V
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)
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)
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 per UL 60950-1/CSA 22.2
No. 60950-1-07 Second Edition, IEC 60950-1: 2005, and
EN 60950-1:2006.
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
MCD10159 Rev. 1.2, 20-Apr-12
Fuse Rating
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)
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 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.
Page 5 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
Test Conditions
All data presented were taken with the converter soldered to
a test board, specifically a 0.060” thick printed wiring board
(PWB) with four layers. The top and bottom layers were not
metalized. The two inner layers, comprising two-ounce
copper, were used to provide traces for connectivity to the
converter.
The lack of metalization on the outer layers as well as the
limited thermal connection ensured that heat transfer from
the converter to the PWB was minimized. This provides a
worst-case but consistent scenario for thermal derating
purposes.
All measurements requiring airflow were made in vertical
and horizontal wind tunnel facilities using Infrared (IR)
thermography and thermocouples for thermometry.
Ensuring components on the converter do not exceed their
ratings is important to maintaining high reliability. If one
anticipates operating the converter at or close to the
maximum loads specified in the derating curves, it is prudent
to check actual operating temperatures in the application.
Thermographic imaging is preferable; if this capability is not
available, then thermocouples may be used. Power-One
recommends the use of AWG #40 gauge thermocouples to
ensure measurement accuracy. Careful routing of the
thermocouple leads will further minimize measurement error.
Refer to Figure H for optimum measuring thermocouple
location.
Thermal Derating
Load current vs. ambient temperature and airflow rates are
given in Fig. x.1 for through-hole version. Ambient
temperature was varied between 25 °C and 85 °C, with
airflow rates from 30 to 500 LFM (0.15 to 2.5 m/s), and
vertical and horizontal converter mounting.
For each set of conditions, the maximum load current was
defined as the lowest of:
(i) The output current at which any FET junction temperature
did not exceed a maximum specified temperature (120 °C)
as indicated by the thermographic image, or
(ii) The nominal rating of the converter (4 A on 12 V, 5.3 A
on 8.0 V, 8 A on 6.0 V, 10 A on 5.0 V, and 15 A on
3.3 – 1.0 V).
During normal operation, derating curves with maximum FET
temperature less than or equal to 120 °C should not be
exceeded. Temperature on the PCB at the thermocouple
location shown in Fig. H should not exceed 118 °C in order
to operate inside the derating curves.
MCD10159 Rev. 1.2, 20-Apr-12
Fig. H: Location of the thermocouple for thermal testing.
Efficiency
Fig. x.5 shows the efficiency vs. load current plot for ambient
temperature of 25 ºC, airflow rate of 300 LFM (1.5 m/s) with
vertical mounting and input voltages of 18 V, 24 V and 36 V.
Also, a plot of efficiency vs. load current, as a function of
ambient temperature with Vin = 24 V, airflow rate of 200 LFM
(1 m/s) with vertical mounting is shown in Fig. x.6.
Power Dissipation
Fig. x.7 shows the power dissipation vs. load current plot for
Ta = 25 ºC, airflow rate of 300 LFM (1.5 m/s) with vertical
mounting and input voltages of 18 V, 24 V and 36 V. Also, a
plot of power dissipation vs. load current, as a function of
ambient temperature with Vin = 24 V, airflow rate of 200 LFM
(1 m/s) with vertical mounting is shown in Fig. x.8.
Start-up
Output voltage waveforms, during the turn-on transient using
the ON/OFF pin for full rated load currents (resistive load)
are shown without and with external load capacitance in
Fig. x.9 and Fig. x.10, respectively.
Ripple and Noise
Fig. x.13 shows the output voltage ripple waveform,
measured at full rated load current with a 10 µF tantalum
and 1 µF ceramic capacitor across the output. Note that all
output voltage waveforms are measured across a 1 F
ceramic capacitor.
The input reflected ripple current waveforms are obtained
using the test setup shown in Fig x.14. The corresponding
waveforms are shown in Fig. x.15 and Fig. x.16.
Page 6 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
V IN
Start-up Information (using negative ON/OFF)
Scenario #1: Initial Start-up From Bulk Supply
ON/OFF function enabled, converter started via application of VIN.
See Figure E.
Time
Comments
t0
ON/OFF pin is ON; system front end power is toggled
on, VIN to converter begins to rise.
t1
VIN crosses Under-Voltage Lockout protection circuit
threshold; converter enabled.
t2
Converter begins to respond to turn-on command
(converter turn-on delay).
t3
Converter VOUT reaches 100% of nominal value.
For this example, the total converter start-up time (t3- t1) is typically
4 ms.
ON/OFF
STATE
OFF
ON
V OUT
t1 t2
t0
t
t3
Fig. E: Start-up scenario #1
Scenario #2: Initial Start-up Using ON/OFF Pin
With VIN previously powered, converter started via ON/OFF pin.
See Figure F.
Time
Comments
t0
VINPUT at nominal value.
t1
Arbitrary time when ON/OFF pin is enabled (converter
enabled).
t2
End of converter turn-on delay.
t3
Converter VOUT reaches 100% of nominal value.
For this example, the total converter start-up time (t3- t1) is typically
4 ms.
VIN
ON/OFF
STATE OFF
ON
VOUT
Scenario #3: Turn-off and Restart Using ON/OFF Pin
With VIN previously powered, converter is disabled and then
enabled via ON/OFF pin. See Figure G.
Time
Comments
t0
VIN and VOUT are at nominal values; ON/OFF pin ON.
t1
ON/OFF pin arbitrarily disabled; converter output falls
to zero; turn-on inhibit delay period (100 ms typical) is
initiated, and ON/OFF pin action is internally inhibited.
t2
ON/OFF pin is externally re-enabled.
If (t2- t1) ≤ 100 ms, external action of ON/OFF pin
is locked out by start-up inhibit timer.
If (t2- t1) > 100 ms, ON/OFF pin action is internally
enabled.
t3
Turn-on inhibit delay period ends. If ON/OFF pin is ON,
converter begins turn-on; if off, converter awaits
ON/OFF pin ON signal; see Figure F.
t4
End of converter turn-on delay.
t5
Converter VOUT reaches 100% of nominal value.
For the condition, (t2- t1) ≤ 100 ms, the total converter start-up
time (t5- t2) is typically 104 ms. For (t2- t1) > 100 ms, start-up will
be typically 4 ms after release of ON/OFF pin.
t0
t1 t2
t
t3
Fig. F: Start-up scenario #2.
V IN
100 ms
ON/OFF
STATE OFF
ON
V OUT
t0
t1
t2
t3 t4
t
t5
Fig. G: Start-up scenario #3.
MCD10159 Rev. 1.2, 20-Apr-12
Page 7 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
Electrical Specifications: SQ24T/S04120 (12 Volts Out)
Conditions: TA=25 ºC, Airflow=300 LFM (1.5 m/s), Vin=24 VDC, Vout=12 VDC unless otherwise specified.
PARAMETER
NOTES
MIN
TYP
MAX
UNITS
3.1
ADC
mADC
mADC
mAPK-PK
dB
12.000
12.120
VDC
±4
±4
±10
±10
12.180
120
1000
4
5.5
10
1
mV
mV
VDC
mVPK-PK
μF
ADC
ADC
A
Arms
INPUT CHARACTERISTICS
Maximum Input Current
Input Stand-by Current
Input No Load Current (0 load on the output)
Input Reflected-Ripple Current
Input Voltage Ripple Rejection
4 ADC, 12 VDC Out @ 18 VDC In
Vin = 24 V, converter disabled
Vin = 24 V, converter enabled
25MHz bandwidth
120Hz
3
100
6
TBD
OUTPUT CHARACTERISTICS
Output Voltage Set Point (no load)
Output Regulation
Over Line
Over Load
Output Voltage Range
Output Ripple and Noise - 25 MHz bandwidth
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
11.880
1
Over line, load and temperature
Full load + 10 μF tantalum + 1 μF ceramic
Plus full load (resistive)
11.820
90
0
Non-latching
Non-latching. Short=10mΩ.
Non-latching
5
7.5
Co = 1 μF ceramic
1 μF ceramic
150
200
20
mV
mV
µs
87
87
%
%
DYNAMIC RESPONSE
Load Change 25% of Iout Max, di/dt = 0.1 A/μs
di/dt = 5 A/μs
Setting Time to 1%
EFFICIENCY
100% Load
50% Load
Additional Notes: 1.
-40 ºC to 85 ºC
MCD10159 Rev. 1.2, 20-Apr-12
Page 8 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
5
5
4
4
Load Current [Adc]
Load Current [Adc]
SQ24T/S04120 (12 Volts Out)
3
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
2
1
3
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
2
1
0
0
20
30
40
50
60
70
80
20
90
30
60
70
80
90
Fig. 12V.2: Available load current vs. ambient air temperature
and airflow rates for SQ24T04120 converter with B height pins
mounted horizontally with Vin = 24V, air flowing from pin 3 to pin
1 and maximum FET temperature 120C.
5
5
4
4
Load Current [Adc]
Load Current [Adc]
Fig. 12V.1: Available load current vs. ambient air temperature
and airflow rates for SQ24T04120 converter with B height pins
mounted vertically with Vin = 24V, air flowing from pin 3 to pin 1
and maximum FET temperature 120C.
3
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
1
50
Ambient Temperature [°C]
Ambient Temperature [°C]
2
40
3
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
2
1
0
0
20
30
40
50
60
70
80
20
90
40
50
60
70
80
90
Ambient Temperature [°C]
Ambient Temperature [°C]
Fig. 12V.3: Available load current vs. ambient temperature and
airflow rates for SQ24S04120 converter mounted vertically with
Vin = 24V, air flowing from pin 3 to pin 1 and maximum FET
temperature 120C.
MCD10159 Rev. 1.2, 20-Apr-12
30
Fig. 12V.4: Available load current vs. ambient temperature and
airflow rates for SQ24S04120 converter mounted horizontally
with Vin = 24V, air flowing from pin 3 to pin 1 and maximum FET
temperature 120C.
Page 9 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
SQ24T/S04120 (12 Volts Out)
0.95
0.95
0.90
0.90
0.85
Efficiency
Efficiency
0.85
0.80
0.75
36 V
24 V
18 V
0.80
0.75
0.70
70 C
55 C
40 C
0.70
0.65
0
1
2
3
4
0.65
5
0
1
Load Current [Adc]
Fig. 12V.5: Efficiency vs. load current and input voltage for
SQ24T/S04120 converter mounted vertically with air flowing
from pin 3 to pin 1 at a rate of 300 LFM (1.5 m/s) and Ta =
25C.
3
4
5
Fig. 12V.6: Efficiency vs. load current and ambient
temperature for SQ24T/S04120 converter mounted vertically
with Vin = 24V and air flowing from pin 3 to pin 1 at a rate of
200 LFM (1.0 m/s).
10.00
10.00
8.00
8.00
Power Dissipation [W]
Power Dissipation [W]
2
Load Current [Adc]
6.00
4.00
36 V
24 V
18 V
2.00
6.00
4.00
70 C
55 C
40 C
2.00
0.00
0
1
2
3
4
0.00
5
0
Load Current [Adc]
2
3
4
5
Load Current [Adc]
Fig. 12V.7: Power dissipation vs. load current and input
voltage for SQ24T/S04120 converter mounted vertically with
air flowing from pin 3 to pin 1 at a rate of 300 LFM (1.5 m/s)
and Ta = 25C.
MCD10159 Rev. 1.2, 20-Apr-12
1
Fig. 12V.8: Power dissipation vs. load current and ambient
temperature for SQ24T/S04120 converter mounted vertically
with Vin = 24V and air flowing from pin 3 to pin 1 at a rate of
200 LFM (1.0 m/s).
Page 10 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
SQ24T/S04120 (12 Volts Out)
Fig. 12V.9: Turn-on transient at full rated load current
(resistive) with no output capacitor at Vin = 24V, triggered via
ON/OFF pin. Top trace: ON/OFF signal (5 V/div.). Bottom
trace: output voltage (5 V/div.). Time scale: 1 ms/div.
Fig. 12V.11: Output voltage response to load current stepchange (1A – 2A – 1A) at Vin = 24V. Top trace: output voltage
(200 mV/div.). Bottom trace: load current (1 A/div.). Current
slew rate: 0.1 A/s. Co = 1 F ceramic. Time scale: 0.5 ms/div.
MCD10159 Rev. 1.2, 20-Apr-12
Fig. 12V.10: Turn-on transient at full rated load current
(resistive) plus 1,000F at Vin = 24V, triggered via ON/OFF
pin. Top trace: ON/OFF signal (5 V/div.). Bottom trace: output
voltage (5 V/div.). Time scale: 2 ms/div.
Fig. 12V.12: Output voltage response to load current stepchange (1A – 2A – 1A) at Vin = 24V. Top trace: output voltage
(200 mV/div.). Bottom trace: load current (1 A/div.). Current
slew rate: 5 A/s. Co = 1 F ceramic. Time scale: 0.5 ms/div.
Page 11 of 70
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SQ24 Series DC-DC Converter Data Sheet
18-36 VDC Input; Standard Outputs from 1-12 VDC
SQ24T/S04120 (12 Volts Out)
iS
10 H
source
inductance
Vsource
Fig. 12V.13: Output voltage ripple (50 mV/div.) at full rated
load current into a resistive load with Co = 10 F tantalum +
1uF ceramic and Vin = 24 V. Time scale: 1 s/div.
Fig. 12V.15: Input reflected ripple current, ic (100 mA/div.),
measured at input terminals at full rated load current and Vin =
24V. Refer to Fig. 12V.14 for test setup. Time scale: 1 s/div.
MCD10159 Rev. 1.2, 20-Apr-12
iC
33 F
ESR
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