PTEA415050 Datasheet, PDF (10/14 Pages) Texas Instruments – 15-A, 48-V INPUT, 5-V OUTPUT, ISOLATED, 1/8th BRICK DC/DC CONVERTER

PTEA415050
SLTS291B – JULY 2008 – REVISED NOVEMBER 2010
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Adjusting the Output Voltage of the PTEA415050 Isolated DC/DC Converter
The output voltage adjustment of the PTEA415050 isolated DC/DC converter follows the standard adopted by
popular 1/8-brick DC/DC converters. Adjustment is accomplished with a single external resistor that can adjust
the output voltage from –20% to +10% of the nominal set-point voltage. The placement of the resistor determines
the direction of adjustment, up or down, and the value of the magnitude of adjustment. To ensure good V_O
set-point accuracy, a 1% maximum tolerance resistor is recommended.
Adjust Up: To increase the output voltage add a resistor, R1, between V_O Adjust (pin 6) and Sense(+) (pin 7).
Adjust Down: Add a resistor, (R2), between V_O Adjust (pin 6) and Sense(–) (pin 5).
Refer to Figure 7 for the placement of the required resistor, R1 or (R2).
The values of R1 [adjust up], and (R2) [adjust down], can be calculated using the following formulas.
R1
+
5.11
V_O (100 )
1.225 D%
D%)
*
511
D%
*
10.22
(kW)
(1)
(R2)
+
5.11
100
D%
*
10.22
(kW)
(2)
Where:
Δ% = Amount of adjustment in %
V_O = Original set-point voltage
Notes:
1. Use a 1% resistor for either the R1 or (R2). Place the resistor as close to the converter as possible.
2. If V_O is increased, the maximum load current must be derated according to the following equation.
I_O(max) + ^VO
I_O(rated)
V_A
where
• V_O is the original set-point voltage
• V_A is the adjusted output voltage (measured between pin 8 and pin 4)
(3)
In any instance, the load current must not exceed the converter's maximum rated output current of 15 A.
3. The overvoltage threshold is fixed, and is set approximately 20% above the nominal output voltage. Adjusting
the output voltage higher reduces the voltage margin between the adjusted output voltage and the
overvoltage (OV) protection threshold. This could make the module sensitive to OV fault detection, as a
result of random noise and load transients.
Sense(+)
+V_O
7
Sense(+)
(R1)
+V_I
1 +V_I
+V_O 8
Adjust
Up
+
–V_I
PTEA415050N
Adjust 6
L
O
A
3 –V_I
(R2)
D
Remote
On/Off
Sense(–) ^{–VO 4}
Adjust
Down
–V_O
2
5
Sense(–)
UDG-10014
Figure 7.
10
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