Additional output capacitance may be added for
increased filtering, but should not exceed 400μF.
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.
NOTES
(1) All parameters measured at Tc=25°C, nominal input voltage and
full rated load unless otherwise noted.
(2) Noise 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.
(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
0.5V 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 1μF to 10μF of tantalum and 0.001 to 0.1μF ceramic
capacitance be selected for reduced system noise.
