
PRELIMINARY Data Sheet
PLD08 Series – 8A Non-Isolated DC/DC Converter
5V Input, Dual 1.2 to 3.3V Output
3.3V Input, Dual 1.2 to 2.5V Output
REV. 3/36/02
Page 5 of 9
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Fig.9 PLD08 series trim down schematic
Fig.2 PLD08 series trim up schematic
1
99
.
4
*
)
8
.
0
(
=
Vadj
Vout
Vadj
R
TrimDOWN
kOhm
When the output voltage is trimmed up,
the output power from the converter must not
exceed its maximum rating. This is determined by
measuring the output voltage on the output pins,
and multiplying it by the output current.
In order to avoid creating apparent load
regulation degradation, it is important that the trim
resistors are connected directly to the Vout and
output GND pins, and not to the load or to traces
going to the load.
The PLD08 series converters will trim
down more than the 10% limit. In general, this is
permissible.
The user must confirm that the
results are acceptable in his application.
Safety Considerations
The PLD08 series converters do not provide
isolation from input to output.
Relevant isolation requirements according to all
IEC60950 based standards must be provided by
the input devices to the PLD08 series module.
Nevertheless, if the system using the converter
needs to receive safety agency approval, certain
rules must be followed in the design of the
system.
In particular, all of the creepage and
clearance requirements of the end-use safety
requirements
must
be
observed.
These
documents include UL60950 - CSA60950-00 and
EN60950, although specific applications may
have other or additional requirements.
The PLD08 series converters have no internal
fuse.
An external fuse must be provided to
protect the system from catastrophic failure.
A
fuse with a rating not greater than 7A, 125V is
recommended. The user can select a lower rating
fuse based upon the inrush transient and the
maximum input current of the converter, which
occurs at the minimum input voltage. Both input
traces and the chassis ground trace (if applicable)
must be capable of conducting a current of 1.5
times the value of the fuse without opening. The
fuse must not be placed in the grounded input
line, if any.
In order for the output of the PLD08 series
converter to be considered as SELV (Safety Extra
Low Voltage), according to all IEC60950 based
standards, the input to the module needs to be
supplied
by
an
isolated
secondary
source
providing a SELV also.
GND
TRIM 2
V
out2
R
down2
TRIM 1
V
out1
R
down1