Q24S25033-NBA0 [BEL]
DC-DC Regulated Power Supply Module, 1 Output, Hybrid,;型号: | Q24S25033-NBA0 |
厂家: | BEL FUSE INC. |
描述: | DC-DC Regulated Power Supply Module, 1 Output, Hybrid, |
文件: | 总14页 (文件大小:392K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
Q24T25033
Data Sheet
18-36 Vdc Input, 25 A, 3.3 Vdc Output
The Q24T25033 through-hole mounted DC/DC converter
offers unprecedented performance in the industry-standard
quarter brick format. This is accomplished through the use of
patent pending circuit and packaging techniques to achieve
ultra-high efficiency, excellent thermal performance and a
very low body profile.
&&
In telecommunications applications theQFamily 25 A con-
verters provide thermal performance that far exceeds all
quarter bricks and is comparable even to existing half-bricks.
Low body profile and the preclusion of heatsinks minimize
airflow shadowing, thus enhancing cooling for downstream
devices. The use of 100% surface-mount technologies for
assembly, coupled with di/dt’s advanced electric and thermal
circuitry and packaging, results in a product with extremely
high quality and reliability.
Q24T25033 Converter
Features
30
25
20
15
•
•
Delivers up to 25 A
Higher current capability at 70ºC than existing
quarter brick and half brick converters
High efficiency: 88.5% @ 25 A, 88.5% @ 12.5 A
Starts-up into pre-biased output
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
No minimum load required
No heatsink required
500 LFM (2.5 m/s)
400 LFM (2.0 m/s)
Lowest profile in industry: 0.28” [7.2 mm]
Lowest weight in industry: 1 oz [28 g] typical
Industry-standard footprint: 1.45” x 2.30”
Industry-standard pinout
10
5
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
30 LFM (0.15 m/s)
Meets Basic Insulation Requirements of EN60950
On-board LC input filter
0
20
30
40
50
60
70
80
90
Fixed frequency operation
Ambient Temperature [°C]
Fully protected
Fig. 1: Available load current vs. ambient air temperature and air-
flow rates for Q24T25033 converter mounted vertically with air flow-
ing from pin 3 to pin 1, MOSFET temperature ≤ 120°C, Vin = 27 V.
Remote output sense
Output voltage trim range: +10%/-20%
Trim resistor via industry-standard equations
High reliability: MTBF 2.6 million hours, calculated per
Telcordia TR-332, Method I Case 1
Applications
•
•
Positive or negative logic ON/OFF option
UL 60950 recognized in U.S. & Canada, and DEMKO
certified per IEC/EN 60950
•
•
•
•
Telecommunications
Datacommunications
Wireless
•
•
Meets conducted emissions requirements of FCC
Class B and EN55022 Class B with external filter
All materials meet UL94, V-0 flammability rating
Servers
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Page 1 of 14
Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
Electrical Specifications
Conditions: TA=25ºC, Airflow=300 LFM (1.5 m/s), Vin=24 Vdc, unless otherwise specified.
PARAMETER
NOTES
MIN
TYP
MAX UNITS
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Continuous
0
-40
-55
40
85
125
Vdc
°C
°C
Operating Ambient Temperature
Storage Temperature
INPUT CHARACTERISTICS
Operating Input Voltage Range
Input Under Voltage Lockout
Turn-on Threshold
18
24
36
Vdc
Non-latching
16
15
17
16
17.5
16.5
Vdc
Vdc
Turn-off Threshold
OUTPUT CHARACTERISTICS
External Load Capacitance
Output Current Range
Plus full load (resistive)
30,000
25
µF
Adc
Adc
A
0
27.5
Current Limit Inception
Non-latching
Non-latching. Short=10mΩ.
Non-latching
30
35
33
Peak Short-Circuit Current
RMS Short-Circuit Current
46
6.7
Arms
ISOLATION CHARACTERISTICS
I/O Isolation
2000
10
Vdc
ρF
Isolation Capacitance
Isolation Resistance
230
435
Mꢀ
FEATURE CHARACTERISTICS
Switching Frequency
kHz
%
%
Output Voltage Trim Range1
Use trim equations on Page 6
Percent of VOUT(NOM)
Non-latching
Non-latching
Applies to all protection features
-20
+10
+10
127
Remote Sense Compensation1
Output Over-Voltage Protection
Over-Temperature Shutdown (PCB)
Auto-Restart Period
117
122
118
100
2.5
%
°C
ms
ms
Turn-On Time
ON/OFF Control (Positive Logic)
Converter Off
-20
2.4
0.8
20
Vdc
Vdc
Converter On
ON/OFF Control (Negative Logic)
Converter Off
2.4
-20
20
0.8
Vdc
Vdc
Converter On
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 further discussion at end of
Output Voltage Adjust /TRIM section.
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
Electrical Specifications (continued)
Conditions: TA=25ºC, Airflow=300 LFM (1.5 m/s), Vin=24 Vdc, unless otherwise specified.
PARAMETER
NOTES
MIN
TYP
MAX UNITS
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
25 Adc, 3.3 Vdc Out @ 18 Vdc In
Vin = 24 V, converter disabled
Vin = 24 V, converter enabled
See Figure 25 - 25MHz bandwidth
120Hz
5.2
Adc
mAdc
mAdc
mAPK-PK
dB
3.5
140
6
TBD
OUTPUT CHARACTERISTICS
Output Voltage Set Point (no load)
Output Regulation
-40ºC to 85ºC
3.267
3.250
3.300
3.333
Vdc
Over Line
±2
±2
±5
±5
3.350
50
mV
mV
Vdc
Over Load
Output Voltage Range
Output Ripple and Noise - 25MHz bandwidth
Over line, load and temperature
Full load + 10 µF tantalum + 1 µF ceramic
30
mVPK-PK
DYNAMIC RESPONSE
Load Change 25% of Iout Max, di/dt = 0.1 A/µS
di/dt = 5 A/µS
Co = 1 µF ceramic (Fig.20)
Co = 450 µF tant. + 1 µF ceramic (Fig.21)
50
140
100
mV
mV
µs
Setting Time to 1%
EFFICIENCY
100% Load
88.5
88.5
%
%
50% Load
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
Physical Information
Pin Connections
Function
Pin #
1
2
3
4
5
6
7
8
Vin (+)
ON/OFF
Vin (-)
Vout (-)
SENSE(-)
TRIM
1
2
3
8
7
6
5
4
TOP VIEW
SIDE VIEW
SENSE(+)
Vout (+)
•
•
All dimensions are in inches [mm]
Pins 1-3 and 5-7 are Ø 0.040” [1.02]
with Ø 0.078” [1.98] shoulder
Pins 4 and 8 are Ø 0.062” [1.57]
without shoulder
•
•
•
•
Pin Material: Brass
Pin Finish: Tin/Lead over Nickel
Converter Weight: 1 oz [28 g] typical
HT
CL
PL
Height
Option
(Maximum Height)
(Minimum Clearance)
Pin
(Pin Length)
Option
+0.000 [+0.00]
-0.038 [-0.97]
0.303 [7.69]
0.336 [8.53]
0.500 [12.70]
0.400 [10.16]
+0.016 [+0.41]
-0.000 [-0.00]
0.030 [0.77]
0.063 [1.60]
0.227 [5.77]
0.127 [3.23]
±0.005 [±0.13]
A
B
C
D
A
B
C
0.188 [4.77]
0.145 [3.68]
0.110 [2.79]
Converter Part Numbering Scheme
Rated
Product
Input
Mounting
Output
ON/OFF
Logic
Maximum
Pin
Special
Load
Series
Voltage
Scheme
Voltage
Height (HT)
Length (PL)
Features
Current
24
T
25
033
-
N
A
0
Q
B
A ⇒ 0.303”
B ⇒ 0.336”
C ⇒ 0.500”
D ⇒ 0.400”
A ⇒ 0.188”
B ⇒ 0.145”
C ⇒ 0.110”
Quarter-Brick
Format
Through-
hole
N ⇒ Negative
P ⇒ Positive
0 ⇒ STD
18-36 V
25 Adc
033 ⇒ 3.3 V
The example above describes P/N Q24T25033-NBA0: 18-36 V input, through-hole mounting, 25 A @ 3.3 V output, negative ON/OFF logic, a
maximum height of 0.336”, and a through the board pin length of 0.188”. Please consult factory regarding availability of a specific version.
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
age of ≤ 0.8 V. An external voltage source of ±20 V max.
may be connected directly to the ON/OFF input, in which
case it should be capable of sourcing or sinking up to 1 mA
depending on the signal polarity. See the Start-up Informa-
tion 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 in-
put and output circuits.
Remote Sense (Pins 5 and 7)
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 addi-
tion of a 33 µF electrolytic capacitor with an ESR < 1 Ω
across the input helps ensure stability of the converter. In
many applications, the user has to use decoupling capaci-
tance at the load. The power converter will exhibit stable op-
eration with external load capacitance up to 30,000 µF.
The remote sense feature of the converter compensates for
voltage drops occurring between the output pins of the con-
verter 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. 3).
TM
Rw
Family
Q
Vout (+)
Vin (+)
Converter
100
ON/OFF (Pin 2)
SENSE (+)
(Top View)
Rload
ON/OFF
Vin (-)
TRIM
Vin
The ON/OFF pin is used to turn the power converter on or
off remotely via a system signal. There are two remote con-
trol options available, positive logic and negative logic and
both are referenced to Vin(-). Typical connections are shown
in Fig. 2.
SENSE (-)
10
Vout (-)
Rw
Fig. 3: Remote sense circuit configuration.
TM
Family
Q
Vin (+)
ON/OFF
Vin (-)
Vout (+)
SENSE (+)
TRIM
Converter
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.
(Top View)
Rload
Vin
SENSE (-)
Vout (-)
CONTROL
INPUT
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.
Fig. 2: 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.
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 capabil-
ity of the converter, equal to the product of the nominal out-
put voltage and the allowable output current for the given
conditions.
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 volt-
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
When using remote sense, the output voltage at the con-
verter 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 con-
verter’s actual output power remains at or below the maxi-
mum allowable output power.
TM
Family
Q
Vin (+)
ON/OFF
Vin (-)
Vout (+)
Converter
SENSE (+)
TRIM
(Top View)
R T-INCR
Rload
Vin
SENSE (-)
Vout (-)
Output Voltage Adjust /TRIM (Pin 6)
Fig. 4: Configuration for increasing output voltage.
The converter’s output voltage can be adjusted up 10% or
where,
down 20% relative to the rated output voltage by the addition
of an externally connected resistor. Trim up to 10% is guar-
anteed only at Vin ≥ 20 V, and it is marginal (8% to 10%) at
Vin = 18 V.
RT−DECR = Required value of trim-down resistor [kΩ]
and ∆ 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 con-
nected internally between the TRIM and SENSE(-) pins.
Note: The above equations for calculation of trim resistor
values match those typically used in conventional industry-
standard quarter bricks.
To increase the output voltage, refer to Fig. 4. A trim resistor,
R
T-INCR, should be connected between the TRIM (Pin 6) and
TM
SENSE(+) (Pin 7), with a value of:
Family
Q
Vin (+)
ON/OFF
Vin (-)
Vout (+)
SENSE (+)
TRIM
Converter
(Top View)
Rload
5.11(100 + ∆)VO−NOM − 626
Vin
RT-DECR
R
T−INCR
=
− 10.22 [kΩ]
SENSE (-)
Vout (-)
1.225∆
where,
RT−INCR = Required value of trim-up resistor kΩ]
VO−NOM = Nominal value of output voltage [V]
Fig. 5: Configuration for decreasing output voltage.
(VO-REQ − VO-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 protec-
tion (OVP) circuit. The designer should ensure that the dif-
ference between the voltages across the converter’s output
pins and its sense pins does not exceed 0.33 V, or:
∆ =
X 100 [%]
VO -NOM
VO−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.
[VOUT(+) − VOUT(−)]−[VSENSE(+) − VSENSE(−)] ≤ 0.33 [V]
This equation is applicable for any condition of output sens-
ing and/or output trim.
To decrease the output voltage (Fig. 5), a trim resistor,
RT-DECR, should be connected between the TRIM (Pin 6) and
SENSE(-) (Pin 5), with a value of:
511
RT−DECR
=
− 10.22 [kΩ]
∆
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
Protection Features
Input Under-Voltage Lockout
Safety Requirements
Input under-voltage lockout is standard with this converter.
The converter will shut down when the input voltage drops
below a pre-determined voltage.
The converters meet North American and International
safety regulatory requirements per UL60950 and EN60950.
Basic Insulation is provided between input and output.
The input voltage must be at least 17.5 V for the converter to
turn on. Once the converter has been turned on, it will shut
off when the input voltage drops below 15 V. This feature is
beneficial in preventing deep discharging of batteries used in
telecom applications.
To comply with safety agencies requirements, an input line
fuse must be used external to the converter. A 10-A fuse is
recommended for use with this product.
Electromagnetic Compatibility (EMC)
Output Over-Current Protection (OCP)
EMC requirements must be met at the end-product system
level, as no specific standards dedicated to EMC character-
istics of board mounted component dc-dc converters exist.
However, di/dt tests its converters to several system level
standards, primary of which is the more stringent EN55022,
Information technology equipment - Radio disturbance char-
acteristics - Limits and methods of measurement.
The converter is protected against over-current or short cir-
cuit conditions. Upon sensing an over-current condition, the
converter will switch to constant current operation and
thereby begin to reduce output voltage. When the output
voltage drops below 1.2 Vdc, the converter will shut down
(Fig. 26).
With the addition of a simple external filter (see application
notes), all versions of the Q24T25 converters pass the re-
quirements of Class B conducted emissions per EN55022
and FCC, and meet at a minimum, Class A radiated emis-
sions per EN 55022 and Class B per FCC Title 47CFR, Part
15-J. Please contact di/dt Applications Engineering for de-
tails of this testing.
Once the converter has shut down, it will attempt to restart
nominally every 100 ms with a 3% duty cycle (Fig 27). The
attempted restart will continue indefinitely until the overload
or short circuit conditions are removed or the output voltage
rises above 1.2 Vdc.
Output Over-Voltage 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 refer-
ence, 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.
Over-Temperature Protection (OTP)
The converter will shut down under an over-temperature
condition to protect itself from overheating caused by opera-
tion outside the thermal derating curves, or operation in ab-
normal conditions such as system fan failure. After the con-
verter has cooled to a safe operating temperature, it will
automatically restart.
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
tween 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.
Characterization
General Information
For each set of conditions, the maximum load current was
defined as the lowest of:
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.
(i) The output current at which either any FET junction tem-
perature did not exceed a maximum specified temperature
(either 105°C or 120°C) as indicated by the thermographic
image, or
(ii) The nominal rating of the converter (25 A)
The following pages contain specific plots or waveforms as-
sociated with the converter. Additional comments for specific
data are provided below.
During normal operation, derating curves with maximum FET
temperature less than or equal to 120°C should not be ex-
ceeded. Temperature on the PCB at the thermocouple loca-
tion shown in Fig. 28 should not exceed 118°C in order to
operate inside the derating curves.
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 cop-
per, were used to provide traces for connectivity to the con-
verter.
Efficiency
Efficiency vs. load current plots are shown in Figs. 14 and 16
for ambient temperature of 25ºC, airflow rate of 300 LFM
(1.5 m/s), both vertical and horizontal orientations, and input
voltages of 18 V, 27 V and 36 V. Also, plots of efficiency vs.
load current, as a function of ambient temperature with Vin =
27 V, airflow rate of 200 LFM (1 m/s) are shown for both a
vertically and horizontally mounted converter in Figs. 15 and
17, respectively.
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 pur-
poses.
All measurements requiring airflow were made in di/dt’s ver-
tical and horizontal wind tunnel facilities using Infrared (IR)
thermography and thermocouples for thermometry.
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 10,000 µF load capacitance in
Figs. 18 and 19, respectively.
Ensuring components on the converter do not exceed their
ratings is important to maintaining high reliability. If one an-
ticipates 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. Thermo-
graphic imaging is preferable; if this capability is not avail-
able, then thermocouples may be used. di/dt recommends
the use of AWG #40 gauge thermocouples to ensure meas-
urement accuracy. Careful routing of the thermocouple leads
will further minimize measurement error. Refer to Figure 28
for optimum measuring thermocouple location.
Ripple and Noise
Figure 22 shows the output voltage ripple waveform, meas-
ured 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 µF ceramic ca-
pacitor.
Thermal Derating
The input reflected ripple current waveforms are obtained
using the test setup shown in Fig 23. The corresponding
waveforms are shown in Figs. 24 and 25.
Load current vs. ambient temperature and airflow rates are
given in Figs. 10-13. Ambient temperature was varied be-
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Start-up Information (using negative ON/OFF)
Data Sheet
VIN
Scenario #1: Initial Start-up From Bulk Supply
ON/OFF function enabled, converter started via application of VIN.
See Figure 7.
ON/OFF
STATE
Time
Comments
OFF
ON
t0
ON/OFF pin is ON; system front end power is toggled
on, VIN to converter begins to rise.
t1
t2
t3
VIN crosses Under-Voltage Lockout protection circuit
threshold; converter enabled.
VOUT
Converter begins to respond to turn-on command (con-
verter turn-on delay).
Converter VOUT reaches 100% of nominal value.
For this example, the total converter start-up time (t3- t1) is typically
2.5 ms.
t
t0
t1 t2
t3
Fig. 7: Start-up scenario #1.
VIN
Scenario #2: Initial Start-up Using ON/OFF Pin
With VIN previously powered, converter started via ON/OFF pin.
See Figure 8.
Time
Comments
t0
t1
VINPUT at nominal value.
Arbitrary time when ON/OFF pin is enabled (converter
enabled).
ON/OFF
STATE
OFF
ON
t2
t3
End of converter turn-on delay.
Converter VOUT reaches 100% of nominal value.
For this example, the total converter start-up time (t3- t1) is typically
2.5 ms.
VOUT
Scenario #3: Turn-off and Restart Using ON/OFF Pin
With VIN previously powered, converter is disabled and then en-
abled via ON/OFF pin. See Figure 9.
t
t0
t1 t2
t3
Time
Comments
t0
t1
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.
ON/OFF pin is externally re-enabled.
Fig. 8: Start-up scenario #2.
VIN
t2
If (t2- t1) ≤ 100 ms, external action of ON/OFF pin
is locked out by start-up inhibit timer.
100 ms
If (t2- t1) > 100 ms, ON/OFF pin action is internally
enabled.
ON/OFF
STATE
OFF
ON
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 8.
t4
t5
End of converter turn-on delay.
VOUT
Converter VOUT reaches 100% of nominal value.
For the condition, (t2- t1) ≤ 100 ms, the total converter start-up
time (t5- t2) is typically 102.5 ms. For (t2- t1) > 100 ms, start-up will
be typically 2.5 ms after release of ON/OFF pin.
t
t0
t1
t2
t3 t4
t5
Fig. 9: Start-up scenario #3.
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
30
25
20
15
30
25
20
15
10
5
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)
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)
10
5
0
0
20
30
40
50
60
70
80
90
20
30
40
50
60
70
80
90
Ambient Temperature [°C]
Ambient Temperature [°C]
Fig. 10: Available load current vs. ambient air temperature and
airflow rates for converter mounted vertically with Vin = 27 V,
air flowing from pin 3 to pin 1 and maximum FET temperature ≤
120°C.
Fig. 11: Available load current vs. ambient air temperature and
airflow rates for converter mounted vertically with Vin = 27 V,
air flowing from pin 3 to pin 1 and maximum FET temperature ≤
105°C.
30
25
20
15
30
25
20
15
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)
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)
10
5
10
5
0
0
20
30
40
50
60
70
80
90
20
30
40
50
60
70
80
90
Ambient Temperature [°C]
Ambient Temperature [°C]
Fig. 12: Available load current vs. ambient temperature and
airflow rates for converter mounted horizontally with Vin = 27
V, air flowing from pin 3 to pin 4 and maximum FET tempera-
ture ≤ 120°C.
Fig. 13: Available load current vs. ambient temperature and
airflow rates for converter mounted horizontally with Vin = 27
V, air flowing from pin 3 to pin 4 and maximum FET tempera-
ture ≤ 105°C.
Q24T25033 FDS Ver 2 05-01-03
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Page 10 of 14
Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
0.95
0.90
0.85
0.80
0.95
0.90
0.85
0.80
0.75
0.70
0.65
36 V
27 V
18 V
0.75
70 C
55 C
40 C
0.70
0.65
0
5
10
15
20
25
30
0
5
10
15
20
25
30
Load Current [Adc]
Load Current [Adc]
Fig. 14: Efficiency vs. load current and input voltage for con-
verter mounted vertically with air flowing from pin 3 to pin 1 at a
rate of 300 LFM (1.5 m/s) and Ta = 25°C.
Fig. 15: Efficiency vs. load current and ambient temperature
for converter mounted vertically with Vin = 27 V and air flowing
from pin 3 to pin 1 at a rate of 200 LFM (1.0 m/s).
0.95
0.90
0.85
0.80
0.95
0.90
0.85
0.80
70 C
55 C
40 C
0.75
36 V
27 V
18 V
0.75
0.70
0.65
0.70
0.65
0
5
10
15
20
25
30
0
5
10
15
20
25
30
Load Current [Adc]
Load Current [Adc]
Fig. 17: Efficiency vs. load current and ambient temperature
for converter mounted horizontally with Vin = 27 V and air flow-
ing from pin 3 to pin 4 at a rate of 200 LFM (1.0 m/s).
Fig. 16: Efficiency vs. load current and input voltage for con-
verter mounted horizontally with air flowing from pin 3 to pin 4
at a rate of 300 LFM (1.5 m/s) and Ta = 25°C.
Q24T25033 FDS Ver 2 05-01-03
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
Fig. 18: Turn-on transient at full rated load current (resistive)
with no output capacitor at Vin = 24 V, triggered via ON/OFF
pin. Top trace: ON/OFF signal (5 V/div.). Bottom trace: output
voltage (1 V/div.) Time scale: 1 ms/div.
Fig. 19: Turn-on transient at full rated load current (resistive)
plus 10,000 µF at Vin = 24 V, triggered via ON/OFF pin. Top
trace: ON/OFF signal (5 V/div.). Bottom trace: output voltage
(1 V/div.). Time scale: 1 ms/div.
Fig. 20: Output voltage response to load current step-change
(7.5 A – 15 A – 7.5 A) at Vin = 24 V. Top trace: output voltage
(100 mV/div). Bottom trace: load current (5 A/div.). Current
slew rate: 0.1 A/µs. Co = 1 µF ceramic. Time scale: 0.2 ms/div.
Fig. 21: Output voltage response to load current step-change
(7.5 A – 15 A – 7.5 A) at Vin = 24 V. Top trace: output voltage
(100 mV/div.). Bottom trace: load current (5 A/div). Current
slew rate: 5 A/µs. Co = 450 µF tantalum + 1 µF ceramic. Time
scale: 0.2 ms/div.
Q24T25033 FDS Ver 2 05-01-03
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Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
iS
iC
10 µH
source
TM
33 µF
1 µF
Family
inductance
Q
Ω
ESR <1
ceramic
DC/DC
Vout
electrolytic
capacitor
capacitor
Converter
Vsource
Fig. 23: Test Set-up for measuring input reflected ripple cur-
rents, ic and is.
Fig. 22: Output voltage ripple (20 mV/div.) at full rated load
current into a resistive load with Co = 10 µF tantalum + 1uF ce-
ramic and Vin = 24 V. Time scale: 1 µs/div.
Fig. 24: Input reflected ripple current, ic (100 mA/div), meas-
ured at input terminals at full rated load current and Vin = 24 V.
Refer to Fig. 23 for test setup. Time scale: 1 µs/div.
Fig. 25: Input reflected ripple current, is (10 mA/div), measured
through 10 µH at the source at full rated load current and Vin =
24 V. Refer to Fig. 23 for test setup. Time scale: 1µs/div.
Q24T25033 FDS Ver 2 05-01-03
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Page 13 of 14
Q24T25033 18-36 Vdc Input, 25 A, 3.3 Vdc Output
Data Sheet
4.0
3.0
2.0
1.0
0
0
10
20
30
Iout [Adc]
Fig. 26: Output voltage vs. load current showing current limit
point and converter shutdown point. Input voltage has almost
no effect on current limit characteristic.
Fig. 27: Load current (top trace, 20 A/div, 20 ms/div) into a 10
mΩ short circuit during restart, at Vin = 24 V. Bottom trace (20
A/div, 1 ms/div) is an expansion of the on-time portion of the
top trace.
Fig. 28: Location of the thermocouple for thermal testing.
For more infdorim/datt,ioInnpcl.ease contact
1822 Aston Avenue •• Carlsbad, CA •• 92008 •• USA
USA Toll Free 866-WOW-didt (969-3438)
www.didt.com •• support@didt.com
The information and specifications contained in this data sheet are believed to be accurate and reliable at the time of publication. However, di/dt, Inc. assumes no responsibility for its use or for
any infringements of patents or other rights of third parties, which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of di/dt, Inc. Specifi-
cations are subject to change without notice.
©Copyright di/dt, Inc. 2003
Q24T25033 FDS Ver 2 05-01-03
USA Toll Free 866 WOW-didt
Page 14 of 14
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