LD2982Axx
LD2982Bxx
Very low drop and low noise voltage regulator with
inhibit function, low ESR capacitors compatible
Features
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Very low dropout voltage (120 mV at 50 mA
and 7 mV at 1 mA load)
Very low quiescent current (375 mA typ. at
50 mA load and 75 mA at 1 mA)
Output current up to 50 mA
Logic controlled electronic shutdown
Output voltage of 1.8, 2.7, 3.2, 3.3 V
Internal current and thermal limit
Available in ± 1 % tolerance
(at 25 °C, A version)
Supply voltage rejection: 45 dB (typ)
Only 1 µF for stability
Low output noise voltage 30 µVrms
Smallest package SOT23-5L
Temperature range: -40 °C to 125 °C
An external capacitor C
BYP
= 10 nF connected
between bypass pin and GND reduce the noise
to 30 µVrms.
Typical application are in cellular phone,
palmtop/laptop computer, personal digital
assistant (PDA), personal stereo, camcorder and
camera.
SOT23-5L
Description
The LD2982A/Bxx is a 50 mA fixed output voltage
regulator. The ultra low drop voltage and the low
quiescent current make them particularly suitable
for low noise, low power applications, and in
battery powered systems. In sleep mode
quiescent current is less than 1 µA when INHIBIT
pin is pulled low. Shutdown logic control function
is available on pin 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.
Table 1.
Device summary
Part numbers
A Version
LD2982AXX18
LD2982AXX27
LD2982AXX32
B Version
LD2982BXX18
LD2982BXX27
LD2982BXX32
Output voltage
1.8 V
2.7 V
3.2 V
July 2008
Rev 6
1/20
www.st.com
20
LD2982Axx - LD2982Bxx
Contents
1
2
3
4
5
6
Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1
6.2
6.3
6.4
6.5
6.6
External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7
8
9
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2/20
Pin configuration
LD2982Axx - LD2982Bxx
2
Figure 2.
Pin configuration
Pin connections (top view)
Table 2.
Pin n°
1
2
3
4
5
Pin description
Symbol
IN
GND
INHIBIT
Bypass
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 0.18V
Bypass Pin: Capacitor to be connected to GND in order to improve the thermal noise
performances
Output port
Name and function
Table 3.
Symbol
R
thJC
R
thJA
Thermal data
Parameter
Thermal resistance junction-case
Thermal resistance junction-ambient
SOT23-5L
81
255
Unit
°C/W
°C/W
4/20
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