PTEA404120 Datasheet, PDF (9/14 Pages) Texas Instruments – 50-W, 48-V INPUT, 12-V OUTPUT, ISOLATED DC/DC CONVERTER

www.ti.com
PTEA404120
SLTS274A – DECEMBER 2006 – REVISED JANUARY 2007
PTEA404120P
1=Disable
−V_I
2 Remote On/Off
Q1
BSS138
3 −V_I
Figure 5. Recommended Control or Remote On/Off Input
Turn-On: With a valid input source voltage applied, the converter produces a regulated output voltage within 10
ms of the output being enabled. Figure 6 shows the output response of the PTEA following the removal of the
logic-low signal from the Remote On/Off (pin 2); see Figure 5. This corresponds to the drop in Q1 V_GS in
Figure 6. Although the rise-time of the output voltage is short (<5 ms), the indicated delay time will vary
depending upon the input voltage and the module’s internal timing. The waveforms were measured with 48 VDC
input voltage, and a 4-A resistive load.
V_O (5 V/div)
Q1 V_gs (5 V/div)
T − Time − 4 ms/div
Figure 6. Power Up
Adjusting the Output Voltage of the 50-W Rated PTEA404120 Isolated DC/DC Converter
The output voltage adjustment of the PTEA404120 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 –40% 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)
Submit Documentation Feedback
9