ST LD3980 User Manual
Feature summary
■ Input voltage from 1.7 to 3.6V
■ Ultra low dropout voltage (130mV typ. at
300mA load)
■ Very low quiescent current (110µA typ. at no
load, 130µA max. at 300mA load; max 0.5µA in
OFF MODE)
■ Output voltage tolerance: +/- 1.0% @ 25°C, +/-
2.0% full temperature range
■ Guaranteed output current up to 300mA
■ Wide range of output voltage: 0.8V to 3.0V
■ Logic-controlled electronic shutdown
■ Compatible with ceramic capacitor C
■ Internal current and thermal limit
■ Temperature range: -40°C to 85°C
= 1µF
O
Description
The LD3980 provides up to 300mA, from 1.7V to
3.6V input voltage. It can deliver a guaranteed
300mA continuous load current with a low 100mV
dropout. It is stable with ceramic capacitor. The
LD3980
Low drop - Low supply voltage
Low ESR capacitor compatible
DFN6 (3x3)
ultra low drop-voltage, low quiescent current and
low noise makes it suitable for low power
applications and in battery powered systems.
High power supply rejection is maintained down
to low input voltage levels common to battery
operated circuits. Shutdown Logic Control
function is available 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 device also
includes a constant current limiting and thermal
overload protection. Typical applications are in
mobile phone, personal digital assistant (PDAs),
cordless phone and similar battery powered
wireless systems, portable information
appliances..
Block diagram
December 2006 Rev. 1 1/16
www.st.com
16
LD3980
Contents
1 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.1 Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.2 Current limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.3 Thermal overload protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.4 Power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6.5 Output capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
8 Order code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
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LD3980 Pin configuration
1 Pin configuration
Figure 1. Pin connections
Table 1. Pin description
Pin N° Symbol Name and function
1 OUT Output Voltage of the LDO
2, 3 NC Not connected
4 GND Common ground.
SHUTDOWN Input Voltage:
5 SHDN
6 IN Input Voltage of the LDO
Active-Low Shutdown input. A logic Low reduces supply current to below 1µA.
Connect to IN or logic high for normal operation
Table 2. Thermal data
Symbol Parameter Value Unit
R
thJA
Thermal resistance junction-ambient 55 °C/W
3/16
Maximum ratings LD3980
2 Maximum ratings
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
DC Input voltage -0.3 to 4.6 V
DC Output voltage -0.3 to VI +0.3 V
Shutdown input voltage -0.3 to VI +0.3 V
Reset output voltage -0.3 to VI +0.3 V
Output current Internally limited mA
Power dissipation Internally limited mW
Storage temperature range -65 to 150 °C
Operating junction temperature range -40 to 85 °C
V
V
SHDN
V
RESET
P
T
T
V
I
O
I
O
D
STG
OP
Note: Absolute Maximum Ratings are those values beyond which damage to the device may
occur. Functional operation under these condition is not implied.
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LD3980 Typical application
3 Typical application
Figure 2. Application circuit
5/16
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