lt3050 Linear Technology Corporation, lt3050 Datasheet - Page 18

• Manufacturer Part Number: lt3050
• Description: 100ma, Low Noise Linear Regulator With Precision Current Limit And Diagnostic Functions
• Manufacturer: Linear Technology Corporation

LT3050
APPLICATIONS INFORMATION
Protection Features
The LT3050 incorporates several protection features
that make it ideal for use in battery-powered circuits. In
addition to the normal protection features associated with
monolithic regulators, such as current limiting and thermal
limiting, the device also protects against reverse-input
voltages, reverse-output voltages and reverse output-to-
input voltages.
Current limit protection and thermal overload protection
protect the device against current overload conditions at
the output of the device. For normal operation, do not
exceed a junction temperature of 125°C.
The LT3050 IN pin withstands reverse voltages of 50V. The
device limits current fl ow 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.
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The LT3050 incurs no damage if its output is pulled below
ground. If the input is left open-circuit or grounded, the
output can be pulled below ground by 50V. No current
fl ows through the pass transistor from the output.
However, current fl ows in (but is limited by) the resistor
divider that sets the output voltage. Current fl ows 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
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
Figure 5. Reverse Output Current
ALL PINS GROUNDED EXCEPT FOR OUT
10
20
V
OUT
(V)
30
40
3050 F05
50
3050f