PTEA404120 Datasheet, PDF (8/14 Pages) Texas Instruments – 50-W, 48-V INPUT, 12-V OUTPUT, ISOLATED DC/DC CONVERTER

PTEA404120
SLTS274A – DECEMBER 2006 – REVISED JANUARY 2007
www.ti.com
Positive Output Enable (PEN)
For those models with the positive enable (PEN) option, leaving pin 2 open circuit, (or driving it to an equivalent
logic high voltage), will enable the converter output. This allows the module to produce an output voltage
whenever a valid input source voltage is applied to +V_I with respect to –V_I. If a logic-low signal is then applied to
pin 2 the converter output is disabled. Table 2 gives the input requirements of pin 2 for modules with the PEN
option.
Table 2. On/Off Control Requirements
for Positive Enable
V_IH
Enable
V_IL
Disable
V_o/c
Open-Circuit
I_I
Pin 2 at –V_I
PARAMETER
MIN
TYP
MAX UNITS
4.5
20
V
–0.2
0.8
5
7
–0.5
mA
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 1. 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.
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