Datasheet

= - ´
VOUT VIN ON VOUT
V V R I
RSET
SET
200 k
R
I
W
=
TPS2421-1
TPS2421-2
www.ti.com SLUS907H –JANUARY 2009–REVISED JANUARY 2014
ISET: A resistor from this pin to GND sets both the fault current (I
SET
) and current limit (I
LIM
) levels. The current
limit is internally set at 150% of the fault current. The fault timer described in the CT section starts when I
VOUT
exceeds I
SET
.
The internal MOSFET actively limits current if I
VIN
reaches the current limit set point. The fault timer operation is
the same in this mode as described previously.
The fault current value is programmed as shown in Equation 3:
(3)
EN: When this pin is pulled low, the device is enabled. The input threshold is hysteretic, allowing the user to
program a startup delay with an external RC circuit. EN is pulled to VIN with a 10-MΩ resistor and to GND with a
16.8-MΩ resistor. Because high impedance pullup and pulldown resistors are used to reduce current draw, any
external FET controlling this pin should be low leakage.
VIN: Input voltage to the TPS2421 device. The recommended operating voltage range is 3 V to 20 V. Connect
VIN to the power source.
NOTE
(For TPS2421-1 only) Brownout-type conditions (VIN < 2.85 V) prior to start up can trigger
the fault logic and prevent start up. For more information go to E2E.TI.com.
VOUT: Output connection for the TPS2421 device. V
VOUT
in the ON condition considering the ON resistance of
the internal MOSFET, R
ON
is shown in Equation 4:
(4)
Connect VOUT to the load.
PG: Active low, Open Drain output, Power Good indicates that there is no fault condition and the output voltage
is within 0.5 V of the input voltage. PG becomes operational before UV, whenever V
VIN
is greater than 1 V.
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Product Folder Links: TPS2421-1 TPS2421-2