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.
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.
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 100 mA
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 μVRMS
Temperature range: -40 to 125 °C
Small package SOT23-5L and SOT-89
Fast dynamic response to line and load
changes
April 2016
DocID6279 Rev 17
1/27
www.st.com
This is information on a product in full production.
Contents
LD2981
Contents
1
2
3
4
5
6
7
Diagram ............................................................................................ 5
Pin configuration ............................................................................. 6
Maximum ratings ............................................................................. 7
Typical application .......................................................................... 8
Electrical characteristics ................................................................ 9
Typical performance characteristics ........................................... 12
Application notes .......................................................................... 16
7.1
7.2
7.3
7.4
7.5
7.6
External capacitors.......................................................................... 16
Input capacitor................................................................................. 16
Output capacitor .............................................................................. 16
Important ......................................................................................... 16
Inhibit input operation ...................................................................... 16
Reverse current............................................................................... 17
SOT-89 package information .......................................................... 18
SOT-89 packing information............................................................ 21
SOT23-5L package information ...................................................... 22
SOT23-5L packing information........................................................ 24
8
Package information ..................................................................... 18
8.1
8.2
8.3
8.4
9
10
Ordering information..................................................................... 25
Revision history ............................................................................ 26
2/27
DocID6279 Rev 17
LD2981
List of tables
List of tables
Table 1: Pin description .............................................................................................................................. 6
Table 2: Thermal data ................................................................................................................................. 6
Table 3: Absolute maximum ratings ........................................................................................................... 7
Table 4: Electrical characteristics for LD2981AB ....................................................................................... 9
Table 5: Electrical characteristics for LD2981C ........................................................................................ 10
Table 6: SOT-89 mechanical data ............................................................................................................ 19
Table 7: SOT-89 carrier tape mechanical data ......................................................................................... 21
Table 8: SOT23-5L package mechanical data ......................................................................................... 22
Table 9: SOT23-5L tape and reel mechanical data .................................................................................. 24
Table 10: Order codes .............................................................................................................................. 25
Table 11: Document revision history ........................................................................................................ 26
DocID6279 Rev 17
3/27
List of figures
LD2981
List of figures
Figure 1: Schematic diagram ...................................................................................................................... 5
Figure 2: Pin connections (top view) ........................................................................................................... 6
Figure 3: Application circuit ......................................................................................................................... 8
Figure 4: Output voltage vs temperature .................................................................................................. 12
Figure 5: Dropout voltage vs temperature ................................................................................................ 12
Figure 6: Line regulation vs temperature .................................................................................................. 12
Figure 7: Load regulation vs temperature ................................................................................................. 12
Figure 8: Dropout voltage vs temperature ................................................................................................ 13
Figure 9: Quiescent current vs temperature ............................................................................................. 13
Figure 10: Quiescent current vs output current ........................................................................................ 13
Figure 11: Off mode quiescent current vs temperature ............................................................................ 13
Figure 12: Quiescent current vs input voltage .......................................................................................... 13
Figure 13: Dropout voltage vs output current ........................................................................................... 13
Figure 14: Inhibit input current vs temperature ......................................................................................... 14
Figure 15: Inhibit voltage vs temperature ................................................................................................. 14
Figure 16: Supply voltage rejection vs frequency ..................................................................................... 14
Figure 17: Noise voltage vs frequency ..................................................................................................... 14
Figure 18: Best case: highest output version ........................................................................................... 14
Figure 19: Worst case: lowest output version ........................................................................................... 14
Figure 20: Load transient response .......................................................................................................... 15
Figure 21: Line transient response ........................................................................................................... 15
Figure 22: Reverse current test circuit ...................................................................................................... 17
Figure 23: SOT-89 package outline .......................................................................................................... 18
Figure 24: SOT-89 recommended footprint .............................................................................................. 20
Figure 25: SOT-89 carrier tape outline ..................................................................................................... 21
Figure 26: SOT23-5L package outline ...................................................................................................... 22
Figure 27: SOT23-5L recommended footprint .......................................................................................... 23
Figure 28: SOT23-5L tape and reel outline .............................................................................................. 24
4/27
DocID6279 Rev 17
LD2981
Diagram
1
Diagram
Figure 1: Schematic diagram
DocID6279 Rev 17
5/27
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