LT1521-3.3 LINER [Linear Technology], LT1521-3.3 Datasheet

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LT1521-3.3

Manufacturer Part Number
LT1521-3.3
Description
300mA Low Dropout Regulators with Micropower Quiescent Current and Shutdown
Manufacturer
LINER [Linear Technology]
Datasheet
APPLICATIONS
FEATURES
TYPICAL
Low Current Regulator
Regulator for Battery-Powered Systems
Post Regulator for Switching Supplies
Dropout Voltage: 0.5V
Output Current: 300mA
Quiescent Current: 12 A
No Protection Diodes Needed
Adjustable Output from 3.8V to 20V
Fixed Output Voltages: 3V, 3.3V, 5V
Controlled Quiescent Current in Dropout
Shutdown I
Reverse Battery Protection
No Reverse Current
Thermal Limiting
6V
5V Battery-Powered Supply with Shutdown
APPLICATION
Q
1 F
= 6 A
8
5
U
V
IN
SHDN
SHDN
<0.25
>2.80
NC
LT1521-5
(PIN 5) OUTPUT
GND
3
SENSE
OFF
ON
ON
OUT
U
1
2
Quiescent Current and Shutdown
+
LT1521 • TA01
1.5 F
5V
300mA
Regulators with Micropower
DESCRIPTION
The LT
dropout regulators with micropower quiescent current
and shutdown. These devices are capable of supplying
300mA of output current with a dropout voltage of 0.5V.
Designed for use in battery-powered systems, the low
quiescent current, 12 A operating and 6 A in
shutdown, makes them an ideal choice. The quiescent
current is well controlled; it does not rise in dropout as it
does with many other low dropout PNP regulators.
Other features of the LT1521/LT1521-3/LT1521-3.3/
LT1521-5 include the ability to operate with very small
output capacitors. They are stable with only 1.5 F on the
output while most older devices require between 10 F and
100 F for stability. Small ceramic capacitors can be used,
enhancing manufacturability. Also, the input may be con-
nected to voltages lower than the output voltage, including
negative voltages, without reverse current flow from out-
put to input. This makes the LT1521 series ideal for backup
power situations where the output is held high and the
input is low or reversed. Under these conditions only 5 A
will flow from the output pin to ground.
, LTC and LT are registered trademarks of Linear Technology Corporation.
®
1521/LT1521-3/LT1521-3.3/LT1521-5 are low
0.6
0.5
0.1
0.4
0.3
0.2
300mA Low Dropout
0
0
50
U
Dropout Voltage
OUTPUT CURRENT (mA)
LT1521-3.3/LT1521-5
100
150
LT1521/LT1521-3
200
250
LT1521 • TA02
300
1

Related parts for LT1521-3.3

LT1521-3.3 Summary of contents

Page 1

... The quiescent current is well controlled; it does not rise in dropout as it does with many other low dropout PNP regulators. Other features of the LT1521/LT1521-3/LT1521-3.3/ LT1521-5 include the ability to operate with very small output capacitors. They are stable with only 1 the output while most older devices require between 10 F and 100 F for stability ...

Page 2

... IN SENSE/ADJ GND GND 3 6 GND SHDN S8 PACKAGE 8-LEAD PLASTIC SO *PIN 2 = SENSE FOR LT1521-3/LT1521-3.3/LT1521-5 = ADJ FOR LT1521 T = 125 JMAX JA SEE THE APPLICATIONS INFORMATION SECTION ORDER PART NUMBER LT1521CS8 LT1521CS8-3 LT1521CS8-3.3 LT1521CS8-5 LT1521IS8 LT1521IS8-3 LT1521IS8-3.3 LT1521IS8-5 ...

Page 3

... V = 1V(Avg 0.5V , OUT RIPPLE P–P = 120Hz 150mA LOAD – 7V OUT (NOMINAL) + 1.5V – 0.1V OUT OUT LT1521/LT1521-3 LT1521-3.3/LT1521-5 MIN TYP MAX 2.950 3.000 3.050 2.900 3.000 3.100 3.250 3.300 3.350 < 300mA 3.200 3.300 3.400 4.925 5.000 5.075 4.850 5.000 5 ...

Page 4

... ELECTRICAL CHARACTERISTICS PARAMETER CONDITIONS Input Reverse Leakage Current V Reverse Output Current (Note 11) LT1521-3 LT1521-3.3 LT1521-5 LT1521 (Note 5) The denotes specifications which apply over the full operating temperature range. Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. ...

Page 5

... INPUT VOLTAGE (V) LT1521/LT1521-3 LT1521-3.3/LT1521-5 LT1521-5 Output Voltage 5.08 5.06 5.04 5.02 5.00 4.98 4.96 4.94 4.92 100 125 –50 – TEMPERATURE ( C) LT1521 • TPC05 LT1521-3.3 Quiescent Current INPUT VOLTAGE (V) LT1521 • TPC08 ...

Page 6

... LOAD I = 100mA* LOAD INPUT VOLTAGE (V) LT1521 • TPC17 Ground Pin Current (LT1521- 3.3V (LT1521-3. 125 (LT1521- 3.75V (LT1521 DEVICE IS OPERATING IN DROPOUT ...

Page 7

... OUTPUT VOLTAGE (V) LT1521 • TPC26 Reverse Output Current (LT1521-3) OUT V = 3.3V (LT1521-3.3) OUT (LT1521-5) OUT V = 3.75V (LT1521) OUT –50 – 100 125 TEMPERATURE ( C) LT1521 • TPC29 LT1521/LT1521-3 LT1521-3 ...

Page 8

... Applications Information section for more on output capacitance and reverse output characteristics. SENSE (Pin 2): For fixed voltage versions of the LT1521 (LT1521-3, LT1521-3.3, LT1521-5), the sense pin is the input to the error amplifier. Optimum regulation will be obtained at the point where the sense pin is connected to ...

Page 9

... C, flows through R2 into the adjust pin. The output voltage can be calculated using the formula in Figure 2. The value of R1 should be less than 400k to minimize errors in the output voltage caused by the adjust pin bias current. Note that in shutdown the LT1521/LT1521-3 LT1521-3.3/LT1521-5 9 ...

Page 10

... LT1521/LT1521-3 LT1521-3.3/LT1521 APPLICATIONS INFORMATION IN OUT V LT1521 IN SHDN ADJ GND 3.75V R2) OUT ADJ 3.75V ADJ I = 50nA ADJ OUTPUT RANGE = 3.75V TO 20V Figure 2. Adjustable Operation output is turned off and the divider current will be zero. Curves of Adjust Pin Voltage vs Temperature and Adjust Pin Bias Current vs Temperature appear in the Typical Performance Characteristics ...

Page 11

... For the adjustable version of the device, the output pin is internally clamped at one diode drop below ground. Reverse current for the adjustable device must be limited to 5mA. LT1521/LT1521-3 LT1521-3.3/LT1521-5 11 ...

Page 12

... A (see Figure 4). The state of the shutdown pin will have no effect on the reverse output current when the output is pulled above the input. LT1521 LT1521 LT1521 • F03 (LT1521-3) OUT V = 3.3V (LT1521-3.3) OUT (LT1521-5) 4 OUT LT1521-3 LT1521-3 LT1521 ...

Page 13

... REF (0.65) TYP LT1521/LT1521-3 LT1521-3.3/LT1521-5 RESULTING CONDITIONS Reverse Output Current 5 A (See Figure 3) Input Current 1 A (See Figure 4) Reverse Output Current 5 A (See Figure 3) Input Current 1 A (See Figure 4) Reverse Output Current 5 A (See Figure 3) Reverse Output Current 5 A (See Figure 3) ...

Page 14

... LT1521/LT1521-3 LT1521-3.3/LT1521-5 PACKAGE DESCRIPTION 0.010 – 0.020 (0.254 – 0.508) 0.008 – 0.010 (0.203 – 0.254) 0.016 – 0.050 0.406 – 1.270 * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" ...

Page 15

... Dimensions in inches (millimeters) unless otherwise noted. ST Package 3-Lead Plastic SOT-223 (LTC DWG # 05-08-1630) 0.033 – 0.041 (0.84 – 1.04) 10 – MAX 0.025 – 0.033 0.012 (0.64 – 0.84) (0.31) MIN 0.181 (4.60) NOM LT1521/LT1521-3 LT1521-3.3/LT1521-5 0.010 – 0.014 (0.25 – 0.36) 10 – 16 0.0008 – 0.0040 (0.0203 – 0.1016) ST3 (SOT-233) 0792 15 ...

Page 16

... LT1521/LT1521-3 LT1521-3.3/LT1521-5 RELATED PARTS PART NUMBER DESCRIPTION ® LTC 1174 425mA High Efficiency Step-Down Switching Regulator LT1175 500mA Micropower Low Dropout Negative Linear Regulator LT1120A 125mA Micropower Low Dropout Linear Regulator LT1304 Micropower Step-Up DC/DC Converter LT1529 3A Micropower Low Dropout Regulator ...

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