DFA20 SERIES – DUAL OUTPUT
NOTES
(1)
All parameters measured at Tc=25°C, 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.
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
1µF tantalum located 1" away from the converter to simulate PCB standard decoupling. Input reflected
ripple is measured into a 1 µH source impedance.
Load regulation for the outputs is specified as the voltage change when both outputs are changed from
maximum to minimum at the same time.
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.
Short term stability is specified after a 30 minute warmup at full load, constant line and recording the
drift over a 24 hour period.
The input ripple rejection is specified for DC to 120 Hz ripple with a modulation amplitude of 1% of Vin.
(2)
(3)
(4)
(5)
(6)
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.
+OUT
4
TRIM
7
-OUT
6
USING TRIMPOT
10K
LOAD
+OUT
4
TRIM
DOWN
TRIM
7
-OUT
6
USING FIXED RESISTORS
LOAD
TRIM
UP
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.
Figure 1.
DFA20 SERIES BLOCK DIAGRAM
OUTPUT POWER DERATING
SHIELDED ISOLATION TRANSFORMER
20
THERMAL LIMIT
+
+
+ INPUT
4
5
6
+ OUTPUT
15
POWER OUTPUT
CMN
1
– INPUT
2
LOW
NOISE
FILTER
CURRENT
MODE
PWM
– OUTPUT
10
+
ON/OFF
7
TRIM
3
–
5
SHIELDED COPPER CASE
0
50
60
70
80
90
AMBIENT TEMPERATURE
100
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.
3
POWER-ONE [ POWER-ONE ]
