SQ24T/S03150
19-36 Vdc Input, 3.3 A, 15 Vdc Output
The new
SemiQ™ Family
of DC/DC converters from di/dt
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, the thermal performance
of
SemiQ™
converters exceeds that of most competitors'
quarter bricks. This is accomplished through the use of pat-
ent 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 heatsinks minimize
airflow shadowing, thus enhancing cooling for downstream
devices. The use of 100% automation for assembly, coupled
with di/dt’s advanced electrical and thermal design, results in
a product with extremely high reliability.
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 de-
signs 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 improve-
ment over other available converters because of the
SQ24
Series’
optimized thermal efficiency.
Data Sheet
SQ24T03150 and SQ24S03150 Converters
Features
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Delivers up to 3.3 A @ 15 V
Industry-standard quarter brick pinout
Extremely small footprint: 0.896” x 2.30” (2.06 in
2
),
40% smaller than conventional quarter bricks
Higher current capability at elevated temperatures
than most competitors' quarter bricks
On-board input differential LC-filter
High efficiency – no heatsink required
Start up into pre-biased output
No minimum load required
Available in through-hole and SM packages
Lowest profile in industry: 0.274” (6.96 mm)
Lowest weight in industry: 0.53 oz (15 g)
Meets Basic Insulation requirements of EN60950
Fixed frequency operation
Fully protected
Remote output sense
Output voltage trim range: +10%/−20% 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 recognized in US and Canada and DEMKO
certified 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
Datacommunications
Wireless
Servers
SQ24x03150 FDS Ver 4 01-21-04
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Page 1 of 15
SQ24T/S03150
19-36 Vdc Input, 3.3 A, 15 Vdc Output
Electrical Specifications
Conditions: T
A
=25ºC, Airflow=300 LFM (1.5 m/s), Vin=24 Vdc, All output voltages, unless otherwise specified.
Data Sheet
PARAMETER
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Operating Ambient Temperature
Storage Temperature
Continuous
NOTES
MIN
0
-40
-55
19
TYP
MAX
40
85
125
UNITS
Vdc
°C
°C
Vdc
Vdc
Vdc
Vdc
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
230
10
415
Industry-std. equations
Percent of V
OUT
(
NOM
)
Non-latching
Applies to all protection features
-20
117
125
100
4
+10
+10
140
ISOLATION CHARACTERISTICS
I/O Isolation
Isolation Capacitance:
Isolation Resistance
FEATURE CHARACTERISTICS
Switching Frequency
1
Output Voltage Trim Range
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
-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 for Vin > 21 V, 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. Vout can be increased
up to 5% for Vin > 20V.
SQ24x03150 FDS Ver 4 01-21-04
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Page 2 of 15
SQ24T/S03150
19-36 Vdc Input, 3.3 A, 15 Vdc Output
Electrical Specifications (continued
)
Conditions: T
A
=25ºC, Airflow=300 LFM (1.5 m/s), Vin=24 Vdc, Vout=15 Vdc unless otherwise specified.
Data Sheet
PARAMETER
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
NOTES
3.3 Adc, 15 Vdc Out @ 19 Vdc In
Vin = 24 V, converter disabled
Vin = 24 V, converter enabled
25MHz bandwidth
120Hz
MIN
TYP
MAX
3.2
UNITS
Adc
mAdc
mAdc
mA
PK-PK
dB
Vdc
mV
mV
Vdc
mV
PK-PK
µF
Adc
Adc
A
Arms
mV
mV
µs
%
%
3
105
7
TBD
14.850
15.000
±4
±4
15.150
±10
±10
15.225
140
1000
3.3
4.5
15
OUTPUT CHARACTERISTICS
Output Voltage Set Point (no load)
Output Regulation
Over Line
Over Load
Output Voltage Range
Output Ripple and Noise - 25MHz bandwidth
External Load Capacitance
Output Current Range
Current Limit Inception
Peak Short-Circuit Current
RMS Short-Circuit Current
Over line, load and temperature
Full load + 10 µF tantalum + 1 µF ceramic
Plus full load (resistive)
Non-latching
Non-latching. Short=10mΩ
Non-latching
Co = 1 µF ceramic
Co = 47 µF tant. + 1 µF ceramic
Co = 47 µF tant. + 1 µF ceramic
2
14.775
110
0
4
12
0.75
200
150
150
89
88
DYNAMIC RESPONSE
Load Change 25% of Iout Max, di/dt = 0.1 A/µS
di/dt = 5 A/µS
Setting Time to 1%
Load Change (25%-75%-25%), di/dt = 5 A/µS
EFFICIENCY
100% Load
50% Load
Additional Notes: 2.
-40ºC to 85ºC
SQ24x03150 FDS Ver 4 01-21-04
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Page 3 of 15
SQ24T/S03150
19-36 Vdc Input, 3.3 A, 15 Vdc Output
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.
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 100
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 1000
µF.
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.
Remote Sense (Pins 5 and 7)
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. B).
ON/OFF (Pin 2)
The ON/OFF pin is used to turn the power converter on or
off remotely via a system signal. There are two remote con-
trol options available, positive logic and negative logic and
both are referenced to Vin(-). Typical connections are shown
in Fig. A.
Vin (+)
Vin (+)
Semi
Q
Family
TM
Converter
Vout (+)
100
Rw
(Top View)
Vin
ON/OFF
SENSE (+)
TRIM
SENSE (-)
10
Rload
Vin (-)
Vout (-)
Rw
Semi
Q
Family
TM
Fig. B:
Remote sense circuit configuration.
Vout (+)
SENSE (+)
TRIM
SENSE (-)
Rload
Converter
(Top View)
Vin
ON/OFF
Vin (-)
CONTROL
INPUT
Vout (-)
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 capabil-
ity of the converter, equal to the product of the nominal out-
put voltage and the allowable output current for the given
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 0.2 mA at a low level volt-
SQ24x03150 FDS Ver 4 01-21-04
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Page 4 of 15
SQ24T/S03150
19-36 Vdc Input, 3.3 A, 15 Vdc Output
conditions.
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.
Vin (+)
Data Sheet
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
R
T-INCR
(Top View)
Vin
ON/OFF
TRIM
SENSE (-)
Rload
Vin (-)
Vout (-)
Fig. C:
Configuration for increasing output voltage.
Output Voltage Adjust /TRIM (Pin 6)
The converter’s output voltage can be adjusted up 10% or
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
≥
21 V, and to 5% is guaranteed only at
Vin
≥
20 V.
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.
To increase the output voltage, refer to Fig. C. A trim resis-
tor, 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
+
∆)V
O
−
NOM
−
626
−
10.22
[kΩ]
1.225∆
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
[kΩ]
|
∆
|
where,
R
T
−DECR
=
Required value of trim-down resistor [kΩ]
and
∆
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 brick. For more in-
formation, see Application Note 103.
where,
R
T
−INCR
=
Required value of trim-up resistor kΩ]
V
O
−NOM
=
Nominal value of output voltage [V]
Vin
Vin (+)
Semi
Q
Family
TM
Converter
Vout (+)
SENSE (+)
TRIM
SENSE (-)
R
T-DECR
Rload
(Top View)
ON/OFF
(V
O-REQ
−
V
O -NOM
)
∆
=
X 100
[%]
V
O -NOM
Vin (-)
Vout (-)
V
O
−REQ
=
Desired (trimmed) output voltage [V].
Fig. D:
Configuration for decreasing output voltage.
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.
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 10%
of V
OUT
(
NOM
)
,
or:
[V
OUT
(
+
)
−
V
OUT
(
−
)]
−
[V
SENSE
(
+
)
−
V
SENSE
(
−
)]
≤
V
O - NOM X
10%
[V]
This equation is applicable for any condition of output sens-
ing and/or output trim.
SQ24x03150 FDS Ver 4 01-21-04
USA Toll Free 866 WOW-didt
Page 5 of 15
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