LD2981
Ultra low-drop voltage regulators with inhibit
Datasheet
-
production data
Description
The LD2981 is a 100 mA fixed-output voltage
regulator. The low-drop voltage and the ultra low
quiescent current make them suitable for low
noise, low power applications and in battery
powered systems.
SOT23-5L
SOT-89
Features
•
Ultra low dropout voltage (0.17 V typ. at 100
mA load, 7 mV typ. at 1 mA load)
•
Very low quiescent current (80 µA typ. at no
load in on mode; max 1 µA in off mode)
•
Guaranteed output current up to 100mA
•
Logic-controlled electronic shutdown
•
Output voltage of 2.5; 3.0; 3.3; 5.0 V
•
Internal current and thermal limit
•
± 0.75% tolerance output voltage available
(A version)
•
Output low noise voltage 160 µV
RMS
•
Temperature range: -40 to 125 °C
•
Small package SOT23-5L and SOT-89
•
Fast dynamic response to line and load
changes
The quiescent current in sleep mode is less than
1 µA when INHIBIT pin is pulled low. Shutdown
logic control function is available on pin n° 3
(TTL compatible). This means that when the
device is used as local regulator, it is possible to
put a part of the board in standby, decreasing the
total power consumption. The LD2981 is
designed to work with low ESR ceramic capacitor.
Typical applications are in cellular phone,
palmtop/laptop computer, personal digital
assistant (PDA), personal stereo, camcorder and
camera.
March 2015
This is information on a product in full production.
DocID6279 Rev 16
1/25
www.st.com
Contents
LD2981
Contents
1
2
3
4
5
6
7
Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1
7.2
7.3
7.4
7.5
7.6
External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8
Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1
8.2
8.3
8.4
SOT23-5L package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
SOT23-5L packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
SOT-89 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
SOT-89 packing information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
9
10
Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2/25
DocID6279 Rev 16
LD2981
Diagram
1
Diagram
Figure 1. Schematic diagram
DocID6279 Rev 16
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Pin configuration
LD2981
2
Pin configuration
Figure 2. Pin connections (top view)
SOT23-5L
SOT-89
Table 1. Pin description
Pin n°
SOT23-5L
1
2
3
4
5
1
Pin n°
SOT-89
3
2
Symbol
V
IN
GND
INHIBIT
NC
V
OUT
Input port
Ground pin
Control switch ON/OFF. Inhibit is not internally pulled-up; it cannot be
left floating. Disable the device when connected to GND or to a
positive voltage less than 0.18 V
Not connected
Output port
Name and function
Table 2. Thermal data
Symbol
R
thJC
R
thJA
Parameter
Thermal resistance junction-case
Thermal resistance junction-ambient
SOT23-5L
81
255
SOT-89
15
110
Unit
°C/W
°C/W
4/25
DocID6279 Rev 16
LD2981
Maximum ratings
3
Maximum ratings
Table 3. Absolute maximum ratings
Symbol
V
I
V
INH
I
O
P
D
T
STG
T
OP
DC input voltage
INHIBIT input voltage
Output current
Power dissipation
Storage temperature range
Operating junction temperature range
Parameter
Value
-0.3 to 16
-0.3 to 16
Internally limited
Internally limited
-55 to 150
-40 to 125
°C
°C
Unit
V
V
Note:
Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.
DocID6279 Rev 16
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