
Input:
Output:
Current:
PPackage:
ackage:
35-75 V
12 V
25 A
25 A (300W)
(300W)
Quarter-brick
T
Technical S
echnical Specification
pecification
Product # PQ60120QEA25
Phone 1-888-567-9596
Doc.# 005-2QE612J Rev. A
05/05/06
Page 10
To increase the output voltage, the user should connect a resistor
between Pin 6 (TRIM) and Pin 7 (SENSE(+) input). For a desired
increase of the nominal output voltage, the value of the resistor
should be
Figure B graphs the relationship between the trim resistor value,
Rtrim-up and Rtrim-down, showing the total range the output volt-
age can be trimmed up or down.
Figure B: Trim Graph for 12Vout module
Note: The TRIM feature does not affect the voltage at which the
output over-voltage protection circuit is triggered. Trimming the
output voltage too high may cause the over-voltage protection cir-
cuit to engage, particularly during transients.
It is not necessary for the user to add capacitance at the Trim pin.
The node is internally filtered to eliminate noise.
Limited 10% up-trim: This converter is capable of operating
for an indefinite period of time with the output trimmed up to 5%
above the nominal 12V output level*. It may also be trimmed
down by as much as 50% (to 6.0V) indefinitely.
This converter is also capable of being trimmed up by as much as
10% (up to 13.2V) for shorter periods of time that are not a sig-
nificant fraction of the product lifetime. For example, in a test sit-
uation, or for output voltage margining where it would remain
trimmed up between 5% and 10% of the nominal voltage for a
few hundred hours, but not for an indefinite period or the product
lifetime. The OVP trip point is set above this level, so it will not
shut down from output overvoltage protection when trimmed up
between 5% and 10%. Continuous operation of this converter
while trimmed up more than 5% could affect long term reliability.
Total DC Variation of Vout: For the converter to meet its full
specifications, the maximum variation of the DC value of Vout,
due to both trimming and remote load voltage drops, should not
be greater than that specified for the output voltage trim range.
PROTECTION FEATURES
Input Under-Voltage Lockout: The converter is designed to
turn off when the input voltage is too low, helping to avoid an
input system instability problem, which is described in more detail
in the application note titled "Input System Instability" on the
hysteresis. When the input voltage is rising, it must exceed the typ-
ical "Turn-On Voltage Threshold" value* before the converter will
turn on. Once the converter is on, the input voltage must fall
below the typical Turn-Off Voltage Threshold value before the con-
verter will turn off.
Output Current Limit: If the output current exceeds the "Output
DC Current Limit Inception" point*, then a fast linear current limit
controller will reduce the output voltage to maintain a constant
output current. If as a result, the output voltage falls below the
"Output DC Current Limit Shutdown Voltage"* for more than
50ms, then the unit will enter into hiccup mode, with a 500ms
off-time. The unit will then automatically attempt to restart.
Back-Drive Current Limit: If there is negative output current of
a magnitude larger than the "Back-Drive Current Limit while
Enabled" specification*, then a fast back-drive limit controller will
increase the output voltage to maintain a constant output current.
If this results in the output voltage exceeding the "Output Over-
Voltage Protection" threshold*, then the unit will shut down. The
full I-V output characteristics can be seen in Figure
17.Output Over-Voltage Limit: If the voltage directly across the
output pins exceeds the "Output Over-Voltage Protection" thresh-
old*, the converter will immediately stop switching. This shutdown
is latching; unlike other shutdown types, the converter will not
restart unless the input power is cycled or the ON/OFF input is
toggled.
Over-Temperature Shutdown: A temperature sensor on the
converter senses the average temperature of the module. The ther-
0.1
1.0
10.0
100.0
1,000.0
10,000.0
100,000.0
1,000,000.0
0
5
10
15
20
25
30
35
40
45
50
T
ri
m
R
e
s
is
ta
n
c
e
(k
O
h
m
s
)
% Increase in Vout
% Decrease in Vout
Rtrim-up
(k
)
where
VOUT = Nominal Output Voltage
=
(
_ 511 _ 10.22
5.11VOUT(100+
%
)
1.225
%
%