PTEA420025 Datasheet, PDF (10/16 Pages) Texas Instruments – 20-A, 48-V INPUT, ISOLATED, 1/8th BRICK DC-DC CONVERTER

PTEA420025, PTEA420033
SLTS288C – JUNE 2007 – REVISED OCTOBER 2010
www.ti.com
Notes:
1. The Remote On/Off control uses –V_I (pin 3) as its ground reference. All voltages are with respect to –V_I.
2. An open-collector device (preferably a discrete transistor) is recommended. A pull-up resistor is not required.
If one is added the pull-up voltage should not exceed 20 V.
Caution: Do not use a pull-resistor to +V_I (pin 1). The remote On/Off control has a maximum input voltage of
20 V. Exceeding this voltage will overstress, and possibly damage, the converter.
3. The Remote On/Off pin may be controlled with devices that have a totem-pole output. This is provided the
output high level voltage (V_OH) meets the module's minimum V_IH specified in Table 2. If a TTL gate is used, a
pull-up resistor may be required to the logic supply voltage.
4. The converter incorporates an undervoltage lockout (UVLO). The UVLO keeps the converter off until the
input voltage is close to the minimum specified operating voltage. This is regardless of the state of the
Remote On/Off control. Consult the product specification for the UVLO input voltage thresholds.
Q1
BSS138
1 = Disable
PTEA4200xx
2 _Remote
On/Off
−V_I
3 _−VI
Figure 9. Recommended Control or Remote On/Off Input
Turn-On: With a valid input source voltage applied, the converter produces a regulated output voltage within 75
ms of the output being enabled. Figure 10 shows the output response of the PTEA420033P following the
removal of the logic-low signal from the Remote On/Off (pin 2); see Figure 9. This corresponds to the drop in Q1
V_GS in Figure 10. Although the rise-time of the output voltage is short (<10 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 10-A resistive load.
Turn-Off Time: When a valid input source is removed or if the Remote On/Off (pin 2) is used to disable the
output, with no external output capacitance, the module powers down within 200 ms. Figure 11 shows that, during
power down, there is no output voltage undershoot. If used to supply processor I/O voltages, the lack of
undershoot ensures the parasitic diodes do not conduct current and potentially cause damage to external
circuitry.
10
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