LT3050 Series
APPLICATIONS INFORMATION
The LT3050 IN pin withstands reverse voltages of 50V. The
device limits current flow to less than 300μA (typically less
than 10μA) and no negative voltage appears at OUT. The
device protects both itself and the load against batteries
that are plugged in backwards.
The SHDN pin cannot be driven below GND unless tied
to the IN pin. If the SHDN pin is driven below GND while
IN is powered, the output may turn on. SHDN pin logic
cannot be referenced to a negative rail.
The LT3050 incurs no damage if its output is pulled be-
low ground. If the input is left open-circuit or grounded,
the output can be pulled below ground by 50V. No cur-
rent flows through the pass transistor from the output.
However, current flows in (but is limited by) the resistor
divider that sets the output voltage. Current flows from
the bottom resistor in the divider and from the ADJ pin’s
internal clamp through the top resistor in the divider to
the external circuitry pulling OUT below ground. If the
input is powered by a voltage source, the output sources
current equal to its current limit capability and the LT3050
protects itself by thermal limiting. In this case, grounding
the SHDN pin turns off the device and stops the output
from sourcing current.
1.0
ALL PINS GROUNDED EXCEPT FOR OUT
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
VOUT (V)
3050 F07
Figure 7. Reverse Output Current
3050fa
22