LT1962 Linear Technology, LT1962 Datasheet - Page 8

• Manufacturer Part Number: LT1962
• Description: 300mA/ Low Noise/ Micropower LDO Regulators
• Manufacturer: Linear Technology

RELATED PARTS
APPLICATIO S I FOR ATIO
LT1962 Series
flow to less than 40 A. For adjustable versions, the output
will act like an open circuit; no current will flow out of the
pin. If the input is powered by a voltage source, the output
will source the short-circuit current of the device and will
protect itself by thermal limiting. In this case, grounding
the SHDN pin will turn off the device and stop the output
from sourcing the short-circuit current.
The ADJ pin of the adjustable device can be pulled above
or below ground by as much as 7V without damaging the
device. If the input is left open circuit or grounded, the ADJ
pin will act like an open circuit when pulled below ground
and like a large resistor (typically 100k) in series with a
diode when pulled above ground.
In situations where the ADJ pin is connected to a resistor
divider that would pull the ADJ pin above its 7V clamp
voltage if the output is pulled high, the ADJ pin input
current must be limited to less than 5mA. For example, a
resistor divider is used to provide a regulated 1.5V output
from the 1.22V reference when the output is forced to 20V.
The top resistor of the resistor divider must be chosen to
limit the current into the ADJ pin to less than 5mA when the
ADJ pin is at 7V. The 13V difference between OUT and ADJ
pin divided by the 5mA maximum current into the ADJ pin
yields a minimum top resistor value of 2.6k.
In circuits where a backup battery is required, several
different input/output conditions can occur. The output
PART NUMBER
LT1120
LT1121
LT1129
LT1175
LT1521
LT1529
LTC1627
LT1761
LT1762
LT1763
LT1764
LT1772
LT1963
Burst Mode is a trademark of Linear Technology Corporation.
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Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] FAX: [phone] www.linear-tech.com
DESCRIPTION
125mA Low Dropout Regulator with 20 A I
150mA Micropower Low Dropout Regulator
700mA Micropower Low Dropout Regulator
500mA Negative Low Dropout Micropower Regulator
300mA Low Dropout Micropower Regulator with Shutdown
3A Low Dropout Regulator with 50 A I
High Efficiency Synchronous Step-Down Switching Regulator
100mA, Low Noise, Low Dropout Micropower Regulator in SOT-23
150mA, Low Noise, LDO Micropower Regulator
500mA, Low Noise, LDO Micropower Regulator
3A, Fast Transient Response Low Dropout Regulator
Constant Frequency Current Mode Step-Down DC/DC Controller
1.5A, Fast Transient Response Low Dropout Regulator
U
U
W
Q
U
Q
voltage may be held up while the input is either pulled to
ground, pulled to some intermediate voltage or is left open
circuit. Current flow back into the output will follow the
curve shown in Figure 6.
When the IN pin of the LT1962 is forced below the OUT pin
or the OUT pin is pulled above the IN pin, input current will
typically drop to less than 2 A. This can happen if the input
of the device is connected to a discharged (low voltage)
battery and the output is held up by either a backup battery
or a second regulator circuit. The state of the SHDN pin will
have no effect on the reverse output current when the
output is pulled above the input.
COMMENTS
Includes 2.5V Reference and Comparator
30 A I
50 A Quiescent Current
45 A I
15 A I
500mV Dropout Voltage
Burst Mode
20 A Quiescent Current, 20 V
25 A Quiescent Current, 20 V
30 A Quiescent Current, 20 V
340mV Dropout Voltage
Up to 94% Efficiency, SOT-23 Package, 100% Duty Cycle
SO-8, SOT-223 Packages
100
90
80
70
60
50
40
30
20
10
0
0
Figure 6. Reverse Output Current
T
V
CURRENT FLOWS
INTO OUTPUT PIN
V
Q
Q
Q
J
IN
OUT
, SOT-223 Package
, 0.26V Dropout Voltage, SOT-223 Package
, Reverse Battery Protection
= 25 C
1
= 0V
= V
LT1962-3.3
TM
2
ADJ
Operation, Monolithic, 100% Duty Cycle
OUTPUT VOLTAGE (V)
LT1962-3
3
(LT1962)
4
LT1962
5
LINEAR TECHNOLOGY CORPORATION 2000
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1962i LT/TP 0400 4K • PRINTED IN USA
RMS
RMS
RMS
LT1962-5
LT1962-2.5
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Noise
Noise
Noise
8
9
1962 F06
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