M
E
BU
Y
The ASQ24 eighth-brick dc-dc converters are ideally suited for aerospace
applications where high reliability, low profile, and low weight are critical. They
are designed for reliable operation in harsh thermal and mechanical
environments.
In high-ambient temperature applications, the ASQ24 Series converters
provide thermal performance that exceeds competing dc-dc converters that
have a higher nominal rating and much larger package size. This performance
is accomplished through the use of patented/patent-pending circuits,
packaging, and processing techniques to achieve ultra-high efficiency,
excellent thermal management, and a low-body profile. Coupled with the use
of 100% automation for assembly, this results in a product with extremely high
quality and reliability.
Available in through-hole and surface-mount packages, the ASQ24 Series
converters are also ideal for environments with little or no airflow.
Operating from an 18 to 36 VDC input, the ASQ24 Series converters provide
any standard output voltage from 12 VDC down to 1.0 VDC. Outputs can be
trimmed from –20% to +10% of the nominal output voltage (±10% for output
voltages 1.2 VDC and 1.0 VDC), thus providing outstanding design flexibility.
RoHS lead-solder-exemption compliant
Delivers up to 15A (50 W)
Operates from – 55°C to 85°C ambient
Survives 1000 g mechanical shock, MIL-STD-883E
Industry-standard quarter-brick pinout
Available in through-hole and surface-mount packages
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
Low profile: 0.274” (6.96 mm)
Low weight: 0.53 oz [15 g] typical
Extremely small footprint: 0.896" x 2.30" (2.06 in2)
On-board input differential LC-filter
Extremely low output and input ripple
Start-up into pre-biased load
No minimum load required
2000 VDC I/O isolation
Fixed-frequency operation
Fully protected
Remote output sense
Positive or negative logic ON/OFF option
Output voltage trim range: +10%/-20% (except 1.2 and 1.0V outputs with a trim
range of ±10%) with industry-standard trim equations
High reliability: MTBF 3.4 million hours, calculated per Telcordia TR-332,
Method I Case 1
Meets conducted emissions requirements per FCC Class B and EN55022 Class
B when used with an external filter
All materials meet UL94, V-0 flammability rating
Approved to the latest edition of the following standards: UL/CSA60950-1,
IEC60950-1 and EN60950-1.
LA
ST
TI
Telecommunications, Wireless, Servers, Workstations
ASQ24 Series
2
Conditions: TA = 25ºC, Airflow = 300 LFM (1.5 m/s), Vin = 24 VDC, All output voltages, unless otherwise specified.
PARAMETER
CONDITIONS / DESCRIPTION
MIN
TYP
MAX
UNITS
40
VDC
85
°C
125
°C
Input Voltage
Continuous
0
Operating Ambient Temperature
-55
Storage Temperature
-55
BU
Input Characteristics
Operating Input Voltage Range
Turn-on Threshold
Input Under Voltage Lockout (Non-latching)
Turn-off Threshold
Isolation Characteristics
I/O Isolation
Remote Sense Compensation1
Output Over-Voltage Protection
Auto-Restart Period
VDC
16
17
17.5
VDC
15
16
16.5
VDC
VDC
160
pF
5.0 - 6.0V
260
pF
230
pF
10
TI
M
Output Voltage Trim Range1
36
1.0 - 3.3V
Isolation Resistance
Switching Frequency
24
2000
8.0V, 12V
Feature Characteristics
18
E
Isolation Capacitance:
Y
Absolute Maximum Ratings
MΩ
415
kHz
Industry-std. equations (1.5 - 12V)
-20
+10
%
Industry-std. equations (1.0 - 1.2V)
-10
+10
%
+10
%
Percent of VOUT(NOM)
Non-latching (1.5 - 12V)
117
125
140
%
Non-latching (1.0 - 1.2V)
124
132
140
%
Applies to all protection features
ST
Turn-On Time
100
ms
4
ms
Converter Off
-20
0.8
VDC
Converter On
2.4
20
VDC
ON/OFF Control (Positive Logic)
Converter Off
2.4
20
VDC
Converter On
-20
0.8
VDC
LA
ON/OFF Control (Negative Logic)
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.
tech.support@psbel.com
ASQ24 Series
3
BU
Y
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.
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)
Vout (+)
SENSE (+)
Vin
TRIM
Rload
E
ON/OFF
SENSE (-)
Vin (-)
Vout (-)
TI
M
CONTROL
INPUT
Figure A. Circuit configuration for ON/OFF function.
ST
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 0.2 mA at a low level voltage 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 Start-up Information section for
system timing waveforms associated with use of the ON/OFF pin.
LA
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).
SemiQ Family
Rw
TM
Vin (+)
Converter
Vout (+)
100
(Top View)
Vin
ON/OFF
SENSE (+)
TRIM
Rload
SENSE (-)
10
Vin (-)
Vout (-)
Rw
Figure B. Remote sense circuit configuration.
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ASQ24 Series
4
BU
Y
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 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, 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, 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.
The converter’s output voltage can be adjusted up 10% or down 20% for Vout ≥ 1.5 V, and ±10% for Vout = 1.2 V and 1.0
V, relative to the rated output voltage by the addition of an externally connected resistor. For output voltages 3.3 V, trim up
to 10% is guaranteed only at Vin ≥ 20 V, and it is marginal (8% to 10%) at Vin = 18 V depending on load current.
5.11(100 Δ)VONOM 626
10.22
1.225Δ
[k] (1.5 –12 V)
TI
M
RTINCR
E
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:
485
Δ
323
RTINCR
2
Δ
RTINCR
where,
[k] (1.2V)
[k] (1.0V)
RTINCR Required value of trim-up resistor k]
ST
VONOM Nominal value of output voltage [V]
VOREQ
Δ
(VO-REQ VO-NOM )
X 100
VO -NOM
[%]
Desired (trimmed) output voltage [V].
LA
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.
SemiQ Family
TM
Vin (+)
Converter
(Top View)
Vin
ON/OFF
Vout (+)
SENSE (+)
R T-INCR
TRIM
Rload
SENSE (-)
Vin (-)
Vout (-)
Figure C. Configuration for increasing output voltage.
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ASQ24 Series
5
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:
RTDECR
511
10.22
|Δ|
[k]
(1.0 – 12V)
where,
RTDECR Required value of trim-down resistor [k]
Δ
is as defined above.
Y
and
SemiQ Family
TM
Vin (+)
Converter
(Top View)
ON/OFF
Vin
BU
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 1.2 V and 1.0 V 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.
Vout (+)
SENSE (+)
TRIM
Rload
R T-DECR
SENSE (-)
Vout (-)
E
Vin (-)
TI
M
Figure D. Configuration for decreasing output voltage.
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 VOUT(nom), or:
[VOUT() VOUT()] [VSENSE() VSENSE()] VO - NOM X 10%
[V]
LA
ST
This equation is applicable for any condition of output sensing and/or output trim.
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ASQ24 Series
6
Y
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.
BU
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.
TI
M
E
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.
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.
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
provides the recommended fuse rating for use with this family of products.
FUSE RATING
8A
12 V - 5.0 V, 2.5 V
6A
2.0 V - 1.0 V
4A
ST
OUTPUT VOLTAGE
3.3 V
LA
If one input fuse is used for a group of modules, the maximum fuse rating should not exceed 15-A (ASQ modules are UL
approved with up to a 15-A fuse).
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, Bel Power Solutions 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 ASQ24 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.
tech.support@psbel.com
ASQ24 Series
7
BU
Y
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.
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.
TI
M
E
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.
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 2.5m/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 does not exceed a maximum specified temperature (120 °C) as
indicated by the thermographic image, or
LA
ST
(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 – 1.0V).
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.
Fig. H: Location of the thermocouple for thermal testing.
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.
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ASQ24 Series
8
Y
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.
BU
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.
LA
ST
TI
M
E
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.
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ASQ24 Series
9
Scenario #1: Initial Start-up From Bulk Supply
ON/OFF function enabled, converter started via application of
VIN. See Figure E.
VIN
Time
t0
ON/OFF
STATE
Y
OFF
ON
VOUT
BU
Comments
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.
t0
t1 t2
t
t3
Figure E. Startup scenario #1.
Comments
VINPUT at nominal value.
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.
ON/OFF
STATE OFF
TI
M
Time
t0
t1
VIN
E
Scenario #2: Initial Start-up Using ON/OFF Pin
With VIN previously powered, converter started via ON/OFF pin.
See Figure F.
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.
LA
t0
t1 t2
t
t3
Figure F. Startup scenario #2.
VIN
Comments
VIN and VOUT are at nominal values; ON/OFF pin ON.
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.
ST
Time
t0
t1
ON
100 ms
ON/OFF
STATE OFF
ON
VOUT
t0
t1
t2
t3 t4
t5
t
Figure G. Startup scenario #3.
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ASQ24 Series
10
Conditions: TA = 25ºC, Airflow = 300 LFM (1.5 m/s), Vin = 24 VDC, Vout = 12 VDC unless otherwise specified.
PARAMETER
CONDITIONS / DESCRIPTION
MIN
TYP
MAX
UNITS
3.1
ADC
Input Characteristics
Input Stand-by Current
Vin = 24V, converter disabled
Input No Load Current (0 load on the output)
Vin = 24V, converter enabled
Input Reflected-Ripple Current
25MHz bandwidth
Input Voltage Ripple Rejection
120Hz
Output Characteristics
Output Voltage Set Point (no load)
11.880
Over Line
Output Regulation
Over Load
Over line, load and temperature (-40ºC to 85ºC)
Output Ripple and Noise - 25MHz bandwidth
Full load + 10 μF tantalum + 1 μF ceramic
External Load Capacitance
Plus full load (resistive)
E
Output Voltage Range
Output Current Range
Non-latching
Peak Short-Circuit Current
Non-latching. Short=10mΩ.
Dynamic Response
TI
M
Current Limit Inception
RMS Short-Circuit Current
di/dt = 5 A/μS
Efficiency
100% Load
mADC
mADC
6
mAPK-PK
TBD
dB
12.000
12.120
VDC
±4
±10
mV
±4
±10
mV
11.820
12.180
VDC
120
mVPK-PK
1000
μF
4
ADC
5
5.5
ADC
7.5
10
A
1
Arms
90
0
Non-latching
Load Change 25% of Iout Max, di/dt = 0.1 A/μS
Setting Time to 1%
3
100
Y
4 ADC, 12 VDC Out @ 18 VDC In
BU
Maximum Input Current
Co = 1 μF ceramic
150
mV
1 μF ceramic
200
mV
20
µs
87
%
87
%
LA
ST
50% Load
tech.support@psbel.com
11
5
5
4
4
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
30
40
50
60
70
80
90
20
Ambient Temperature [°C]
4
60
70
80
90
E
Load Current [Adc]
4
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)
3
2
TI
M
Load Current [Adc]
5
1
0
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)
0
20
30
40
50
60
70
80
90
20
30
40
Ambient Temperature [°C]
Fig. 12V.3: Available load current vs. ambient temperature and
airflow rates for ASQ24S04120 converter mounted vertically with
Vin = 24V, air flowing from pin 3 to pin 1 and maximum FET
temperature 120C.
ST
0.85
0.85
Efficiency
0.90
0.80
LA
0.75
70
80
90
0.80
0.75
36 V
24 V
18 V
70 C
55 C
40 C
0.70
0.70
0.65
0.65
1
60
0.95
0.90
0
50
Ambient Temperature [°C]
Fig. 12V.4: Available load current vs. ambient temperature and
airflow rates for ASQ24S04120 converter mounted horizontally
with Vin = 24V, air flowing from pin 3 to pin 1 and maximum FET
temperature 120C.
0.95
Efficiency
50
Fig. 12V.2: Available load current vs. ambient air temperature and
airflow rates for ASQ24T04120 converter with B height pins
mounted horizontally with Vin = 24V, air flowing from pin 3 to pin 1
and maximum FET temperature 120C.
5
1
40
Ambient Temperature [°C]
Fig. 12V.1: Available load current vs. ambient air temperature and
airflow rates for ASQ24T04120 converter with B height pins
mounted vertically with Vin = 24V, air flowing from pin 3 to pin 1
and maximum FET temperature 120C.
2
30
BU
20
Y
Load Current [Adc]
Load Current [Adc]
ASQ24 Series
2
3
4
5
0
2
3
4
5
Load Current [Adc]
Load Current [Adc]
Fig. 12V.5: Efficiency vs. load current and input voltage for
ASQ24T/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.
1
Fig. 12V.6: Efficiency vs. load current and ambient temperature for
ASQ24T/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).
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North America
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© 2016 Bel Power Solutions & Protection
BCD.00784_AA
Asia-Pacific
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ASQ24 Series
10.00
10.00
8.00
8.00
6.00
4.00
36 V
24 V
18 V
4.00
70 C
55 C
40 C
2.00
0.00
0.00
0
1
2
3
4
0
5
BU
2.00
6.00
Y
Power Dissipation [W]
Power Dissipation [W]
12
1
2
3
4
5
Load Current [Adc]
Load Current [Adc]
Fig. 12V.8: Power dissipation vs. load current and ambient
temperature for ASQ24T/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).
TI
M
E
Fig. 12V.7: Power dissipation vs. load current and input voltage
for ASQ24T/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.
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.
LA
ST
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 step-change
(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.
Fig. 12V.12: Output voltage response to load current step-change
(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.
tech.support@psbel.com
ASQ24 Series
13
iS
iC
10 H
source
inductance
TM
DC/DC
Converter
1 F
ceramic
Vout
capacitor
BU
Fig. 12V.14: Test setup for measuring input reflected ripple
currents, ic and is.
TI
M
E
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 = 24V. Time scale: 1 s/div.
SemiQ Family
Y
Vsource
33 F
ESR
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