PTEA420025 Datasheet, PDF (9/16 Pages) Texas Instruments – 20-A, 48-V INPUT, ISOLATED, 1/8th BRICK DC-DC CONVERTER

PTEA420025, PTEA420033
www.ti.com
SLTS288C – JUNE 2007 – REVISED OCTOBER 2010
Differential Remote Sense
The remote sense pins allows the converter to precisely regulate the DC output voltage at a remote location.
This might be a power plane on an inner layer of the host PCB. Connecting Sense(+) directly to +V_O , and
Sense(–) to –V_O will improve output voltage accuracy. In the event that the sense pins are left open-circuit, an
internal 100-Ω (S+) or 10-Ω (S–) resistor between each sense pin and its corresponding output prevents an
excessive rise in the output voltage. For practical reasons, the amount of IR voltage compensation should be
limited to 0.5 V maximum.
The remote sense feature is designed to compensate for limited amounts of IR voltage drop. It is not intended to
compensate for the forward drop of a non-linear or frequency dependent components that may be placed in
series with the converter output. Examples of such components include OR-ing diodes, filter inductors, ferrite
beads, and fuses. Enclosing these components with the remote sense connections effectively places them inside
the regulation control loop, which can affect the stability of the regulator.
Using the Remote On/Off Function on the PTEA Series of DC/DC Converters
For applications requiring output voltage On/Off control, the PTEA series of DC/DC converters incorporate a
Remote On/Off control (pin 2). This feature can be used to switch the module off without removing the applied
input source voltage. When placed in the Off state, the standby current drawn from the input source is typically
reduced to 3 mA.
Negative Output Enable (NEN)
Models using the negative enable option, the Remote On/Off (pin 2) control must be driven to a logic low voltage
for the converter to produce an output. This is accomplished by either permanently connecting pin 2 to –V_I (pin
3), or driving it low with an external control signal. Table 2 shows the input requirements of pin 2 for those
modules with the NEN option.
Table 2. On/Off Control Requirements
for Negative Enable
PARAMETER
V_IH
Disable
V_IL
Enable
V_o/c
Open-Circuit
I_I
Pin 2 at –V_I
MIN
2.4 V
–0.2 V
TYP
3.3 V
MAX
20 V
0.8 V
4V
–0.2 mA
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 3 gives the input requirements of pin 2 for modules with the PEN
option.
Table 3. On/Off Control Requirements
for Positive Enable
PARAMETER
V_IH
Enable
V_IL
Disable
V_o/c
Open-Circuit
I_I
Pin 2 at –V_I
MIN
4.5 V
–0.2 V
TYP
3.3 V
MAX
20 V
0.8 V
4V
–0.2 mA
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