PTEA420025 Datasheet, PDF (11/16 Pages) Texas Instruments – 20-A, 48-V INPUT, ISOLATED, 1/8th BRICK DC-DC CONVERTER

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V_O (1 V/div)
PTEA420025, PTEA420033
SLTS288C – JUNE 2007 – REVISED OCTOBER 2010
V_O (1 V/div)
I_I (500 mA/div)
I_I (500 mA/div)
Q1 V_DS (5V/div)
t − Time − 4 ms/div
Figure 10. Power Up
Q1 V_DS (5V/div)
t − Time − 1 ms/div
Figure 11. Power Down
Adjusting the Output Voltage of the 20–A Rated PTEA Series of Isolated DC/DC Converters
The output voltage adjustment of the PTEA series of isolated DC/DC converters 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.
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 12 for the placement of the required resistor, R1 or (R2).
7
+V_I
1 _+VI
Sense(+)
+V_O ⁸
PTEA4200xx
6
Adjust
−V_I
3 ^−VI
−V_O ⁴
Remote
On/Off
Sense(–)
2
5
Sense (+)
+V_O
R1
Adjust
Up
(R2)
Adjust
Down
L
C_O
330 µF
O
A
D
−V_O
Sense (–)
Figure 12.
The values of R1 [adjust up], and (R2) [adjust down], can be calculated using the following formulas.
R1 = ^{5.11 VO (100 + D%)} - ⁵¹¹ - 10.22 (kW)
1.224 D%
D%
(1)
(R 2 )
=
5.11
æ
çè
100
D%
ö
÷ø
-
10.22
(kW
)
(2)
Where:
Δ% = Amount of adjustment in %
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