1
DESCRIPTION
The compact, dual output DFA20 series provides power densities
up to 11 watts per cubic inch (0.67 watts per cm
3
). Ideal for
battery operated industrial, medical control and remote data
collection systems, this converter has fully filtered inputs and
outputs. Complete overload protection with independent
pulse-by-pulse current limiting and an overtemperature shutdown
ensures reliable system operation. Converters with 48 volt inputs
are isolated to 1544 volts.
DFA20 SERIES
DUAL OUTPUT
FEATURES
Remote ON/OFF and TRIM
Water Washable Case
Overcurrent Protection and Thermal Shutdown
Efficiencies to 85%
Low Input to Output Capacitance
700Volt to 1544Volt Isolation
Five-Side Shielded Case
Extended Range Input (2:1)
1
BOTTOM VIEW
SIDE VIEW
0.000
0.000
0.25
0.000
2.02
(51.31)
(6.35)
0.040 (1.02) DIA
7 PLACES
0.45
2.02
(11.43)
(51.31)
2
3
7
6
5
4
1.800
0.11
1.100
0.700
0.300
0.100
0.600
0.400
0.51
(7.62)
(2.54)
(13.0)
(17.78)
(15.24)
(10.16)
(27.94)
(45.72)
(2.8)
NOTES
(1)
All parameters measured at Tc = 25C, nominal input voltage and full rated load unless otherwise noted.
Refer to the Technical Reference Section for the definition of terms, measurement circuits and other
information.
Mechanical tolerances unless otherwise noted:
X.XX dimensions: 0.020 inches
X.XXX dimensions: 0.005 inches
NOTES (cont)
(2)
Case is electrically connected to Pin 2, -Input.
(3)
The functional case operating range is intended to give an additional data point for evaluating this
converter. Sustained operation at the higher operating range will reduce expected operational life.
The data Sheet specifications are not guaranteed beyond the case operating range.
(4)
The case thermal impedance is specified as the case temperature rise over ambient per package watt
dissipated.
Rev. 04/2000
2
DFA20 SERIES DUAL OUTPUT
Specification notes for this page are located on the next page.
3
Remote ON/OFF Operation
The remote ON/OFF pin may be left floating if this function is
not used. It is recommended to drive this pin with an open
collector arrangement or a relay contact. When the ON/OFF pin
is pulled low with respect to the -INPUT, the converter is placed
in a low power drain state.
Output TRIM
The TRIM pin may be used to adjust the output 5% from the
nominal setting. This function allows adjustment for voltage
drops in the system wiring. Figure 1 shows the proper connections
to use this function. If the TRIM function is not required the pin
may be left floating.
DFA20 SERIES DUAL OUTPUT
NOTES
(1)
All parameters measured at Tc=25C, nominal input voltage and full rated load unless otherwise noted.
Refer to the Technical Reference Section for the definition of terms, measurement circuits and other
information.
(2)
Noise is measured per Technical Reference Section. Measurement bandwidth is 0-20 MHz for peak-peak
measurements, 10 kHz to 1 MHz for RMS measurements. Output noise is measured with a
1F tantalum located 1" away from the converter to simulate PCB standard decoupling. Input reflected
ripple is measured into a 1 H source impedance.
(3)
Load regulation for the outputs is specified as the voltage change when both outputs are changed from
maximum to minimum at the same time.
(4)
Cross regulation is defined as the change in one output when the other output is changed from full load
to 25% of full load. The converter can be run at no load on either or both outputs with no damage.
(5)
Short term stability is specified after a 30 minute warmup at full load, constant line and recording the
drift over a 24 hour period.
(6)
The input ripple rejection is specified for DC to 120 Hz ripple with a modulation amplitude of 1% of Vin.
DFA20 SERIES APPLICATION NOTES:
External Capacitance Requirements
No external capacitance is required for operation of the DFA20
Series. The use of input capacitors with less than 0.5 ESR may
cause peaking in the input filter and degrade filter performance.
External output capacitance is not required for operation, however it
is recommended that 1 F to 10 F of tantalum and 0.001 to 0.1 F
ceramic capacitance be selected for reduced system noise. Additional
output capacitance may be added for increased filtering, but should
not exceed 400 F.
DFA20 SERIES BLOCK DIAGRAM
4
+ OUTPUT
SHIELDED ISOLATION TRANSFORMER
+
6
OUTPUT
5
CMN
7
TRIM
SHIELDED COPPER CASE
+
+
2
INPUT
ON/OFF
1
3
+ INPUT
CURRENT
MODE
PWM
THERMAL LIMIT
LOW
NOISE
FILTER
50
0
5
10
15
20
60
70
80
90
100
OUTPUT POWER DERATING
AMBIENT TEMPERATURE
POWER OUTPUT
4
+OUT
7
TRIM
10K
LOAD
USING TRIMPOT
6
-OUT
4
+OUT
7
TRIM
TRIM
DOWN
TRIM
UP
LOAD
USING FIXED RESISTORS
6
-OUT
Figure 1.
NUCLEAR AND MEDICAL APPLICATIONS Power-One products are not authorized for use as critical components in life support systems, equipment used in hazardous environments,
or nuclear control systems without the express written consent of the President of Power-One, Inc.
TECHNICAL REVISIONS The appearance of products, including safety agency certifications pictured on labels, may change depending on the date manufactured. Specifications are
subject to change without notice.
4
DFA20 SERIES DUAL OUTPUT
Typical Performance: (Tc=25C, Vin=Nom VDC, Rated Load)
85
80
75
70
0
40
30
20
LINE = 18VDC
LINE = 12VDC
LINE = 9VDC
10
50
60
70
80
90 100
12 VOLT EFFICIENCY Vs. LOAD
LOAD (%)
EFFICIENCY (%)
85
80
75
70
9
15
13
14
17
16
12
11
100% FULL LOAD
50% FULL LOAD
10
18
12 VOLT EFFICIENCY Vs. LINE INPUT VOLTAGE
LINE INPUT (VOLTS)
EFFICIENCY (%)
90
80
85
75
70
0
40
30
20
LINE = 36VDC
LINE = 24VDC
LINE = 18VDC
10
50
60
70
80
90 100
24 VOLT EFFICIENCY Vs. LOAD
LOAD (%)
EFFICIENCY (%)
90
85
80
75
18
30
26
28
34
32
24
22
100% FULL LOAD
50% FULL LOAD
20
36
24 VOLT EFFICIENCY Vs. LINE INPUT VOLTAGE
LINE INPUT (VOLTS)
EFFICIENCY (%)
90
80
75
60
0
40
30
20
LINE = 72VDC
LINE = 48VDC
LINE = 36VDC
10
50
60
70
80
90 100
48 VOLT EFFICIENCY Vs. LOAD
LOAD (%)
EFFICIENCY (%)
90
85
80
75
70
36
60
52
56
68
64
48
44
100% FULL LOAD
50% FULL LOAD
40
72
48 VOLT EFFICIENCY Vs. LINE INPUT VOLTAGE
LINE INPUT (VOLTS)
EFFICIENCY (%)
1.00
0.50
0.75
0.25
0.00
0
40
30
20
100% LOAD
50% LOAD
10
50
60
70
80
48 VOLT INPUT CURRENT Vs. LINE INPUT VOLTAGE
LINE INPUT (VOLTS)
INPUT CURRENT (AMPS)
2)
The efficiency curves are for 12 volt output models. To use for other models
adjust as follows:
5 volt models subtract approximately 3%.
15volt models add approximately 1%.
NOTES ON USING THE CURVES
1)
The input currents are for 20 watts of output power. For 5 volt output models
the current is approximately 15% less.
2.0
1.0
1.5
0.5
0.0
0
16
12
8
100% LOAD
50% LOAD
4
20
24
28
32
36
24 VOLT INPUT CURRENT Vs. LINE INPUT VOLTAGE
LINE INPUT (VOLTS)
INPUT CURRENT (AMPS)
3.5
3.0
2.0
2.5
1.0
1.5
0.5
0.0
0
8
6
4
100% LOAD
50% LOAD
2
10
12
14
16
18
12 VOLT INPUT CURRENT Vs. LINE INPUT VOLTAGE
LINE INPUT (VOLTS)
INPUT CURRENT (AMPS)
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