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Very low drop voltage regulators with inhibit
Features
■ Very low dropout voltage (0.2 V typ. at 50 mA
load)
■ Very low quiescent current (typ. 500 µA at 50
mA load)
■ Output current up to 50 mA
■ Logic-controlled electronic shutdown
■ Output voltages of 3.0; 3.3; 3.8; 5.0 V
■ Internal current and thermal limit
■ Supply voltage rejection: 63 dB (typ)
■ Only 1 µF for stability
■ Selection at 25 °C
■ Temperature range: -25 °C to 125 °C
■ Package available: SOT23-5L
LD2979xx
SOT23-5L
Description
The LD2979 series are very low drop regulators
available in SOT23-5L.
The very low drop-voltage and the very low
quiescent current make them particularly suitable
for low noise, low power applications and in
battery powered systems.
Shutdown logic control function is available on
five pin version (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 Order codes Output voltages
LD2979XX30 LD2979M30TR 3.0 V
LD2979XX33 LD2979M33TR 3.3 V
LD2979XX38 LD2979M38TR 3.8 V
LD2979XX50 LD2979M50TR 5.0 V
April 2008 Rev 14 1/15
www.st.com
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Contents LD2979xx
Contents
1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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LD2979xx Diagram
1 Diagram
Figure 1. Schematic diagram
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Pin configuration LD2979xx
2 Pin configuration
Figure 2. Pin connections (top view)
SOT23-5L
Table 2. Pin description
Symbol Name and function Pin number
V
I
Input voltage 1
GND Ground 2
INHIBIT Control switch ON/OFF
(1)
3
NC Not to be connected 4
V
O
1. Inhibit pin is not internally pulled-up then it must not be left floating. Connect to a positive voltage higher than 2 V to able the
device.
Output voltage 5
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LD2979xx Maximum ratings
3 Maximum ratings
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
DC input voltage 16 V
DC inhibit input voltage V
IN
Output current Internally limited
Power dissipation Internally limited
Storage temperature range -40 to 150 °C
Operating junction temperature range -25 to 125 °C
V
V
T
P
STG
T
V
INH
I
O
OP
I
D
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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Electrical characteristics LD2979xx
4 Electrical characteristics
Table 4. Electrical characteristics for LD2979xx (refer to the test circuits, Ta = 25 °C,
V
= V
IN
O(NOM)
Symbol Parameter Test conditions Min. Typ. Max. Unit
V
Output voltage
O
V
Output voltage
O
V
Output voltage
O
V
Output voltage
O
V
Output voltage
O
Output current limit 100 mA
I
O
ΔV
Line regulation
O
Quiescent current (On
Mode)
I
d
Quiescent current (Off
Mode)
SVR Supply voltage rejection I
V
Dropout voltage
d
Inhibit input logic low Device Off, Ta= -25 to 125°C 0.18 V
V
IL
V
Inhibit input logic high Device On, Ta= -25 to 125°C 2 V
IH
+ 1 V, IO = 1 mA, V
= 3.85 V 2.793 2.85 2.907
V
IN
= 1 to 50mA, Ta= -25 to 125°C 2.736 2.964
I
O
V
= 4 V 2.940 3 3.060
IN
= 1 to 50mA, Ta= -25 to 125°C 2.880 3.120
I
O
V
= 4.3 V 3.234 3.3 3.366
IN
= 1 to 50mA, Ta= -25 to 125°C 3.168 3.432
I
O
= 4.8 V 3.724 3.8 3.876
V
IN
= 1 to 50mA, Ta= -25 to 125°C 3.648 3.952
I
O
V
= 6 V 4.9 5 5.1
IN
= 1 to 50mA, Ta= -25 to 125°C 4.8 5.2
I
O
V
= V
IN
O(NOM)
Ta= -25 to 125°C 0.064
IO = 0 80 110
I
= 0, Ta= -25 to 125°C 170
O
I
= 50mA 500 700
O
= 50mA, Ta= -25 to 125°C 1300
I
O
< 0.18 V 0
V
INH
< 0.18 V, Ta= -25 to 125°C 1
V
INH
= 50mA, C
O
= 0 6 12
I
O
I
= 0, Ta= -25 to 125°C 18
O
= 1mA 30 60
I
O
= 1mA, Ta= -25 to 125°C 90
I
O
I
= 10mA 100 200
O
= 10mA, Ta= -25 to 125°C 300
I
O
= 50mA 200 400
I
O
I
= 50mA, Ta= -25 to 125°C 600
O
= 2 V, CO = 1 µF, unless otherwise specified).
INH
+1V to 16V, IO = 1mA 0.028
= 10μF, f = 120Hz 63 dB
OUT
%/V
µA
µA
mV
V
V
V
V
V
IN
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LD2979xx Electrical characteristics
Table 4. Electrical characteristics for LD2979xx (continued) (refer to the test circuits, Ta = 25 °C,
V
= V
IN
O(NOM)
Symbol Parameter Test conditions Min. Typ. Max. Unit
Inhibit input current
I
I
Output noise voltage
eN
(RMS)
+ 1 V, IO = 1 mA, V
V
= 0 V 0 -1
INH
= 5V, Ta= -25 to 125°C 5 15
V
INH
BW= 300Hz to 50kHz, C
= 2 V, CO = 1 µF, unless otherwise specified).
INH
= 10µF 160 µV
O
µA
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Typical characteristics LD2979xx
5 Typical characteristics
(unless otherwise specified TA = 25 °C)
Figure 3. Output voltage vs temperature Figure 4. Output voltage vs input voltage
Figure 5. Output voltage vs input voltage Figure 6. Dropout voltage vs output current
Figure 7. Dropout voltage vs temperature Figure 8. Quiescent current vs temperature
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LD2979xx Typical characteristics
Figure 9. Short circuit current vs dropout
voltage
Figure 11. Supply voltage rejection vs
frequency
Figure 10. Inhibit voltage vs temperature
Figure 12. Load transient response
CO = 10µF (ESR = 1 at 1kHz)
Figure 13. Inhibit current vs temperature Figure 14. Load transient response
CO = 10µF (ESR = 1 at 1kHz)
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Typical characteristics LD2979xx
Figure 15. Line transient response
CO = 10µF (ESR = 1 at 1kHz)
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LD2979xx Package mechanical data
6 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second Level Interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com.
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Package mechanical data LD2979xx
SOT23-5L mechanical data
mm. mils.
Dim.
Min. Typ. Max. Min. Typ. Max.
A0.90 1.45 35.4 57.1
A1 0.00 0.10 0.0 3.9
A2 0.901.30 35.4 51.2
b 0.35 0.50 13.7 19.7
C0.09 0.20 3.5 7.8
D2.80 3.00 110.2 118.1
E 1.50 1.75 59.0 68.8
e0.95 37.4
H 2.60 3.00 102.3 118.1
L 0.10 0.60 3.9 23.6
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7049676D
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LD2979xx Package mechanical data
Tape & reel SOT23-xL mechanical data
Dim.
Min. Typ. Max. Min. Typ. Max.
A180 7.086
C 12.8 13.0 13.2 0.504 0.512 0.519
D 20.2 0.79 5
N60 2.362
T 14.4 0.567
Ao 3.133.233.33 0.123 0.127 0.131
Bo 3.07 3.17 3.27 0.120 0.124 0.128
Ko 1.27 1.37 1.47 0.050 0.054 0.0.58
Po 3.9 4.0 4.1 0.153 0.157 0.161
P 3.9 4.0 4.1 0.153 0.157 0.161
mm. inch.
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Revision history LD2979xx
7 Revision history
Table 5. Document revision history
Date Revision Changes
15-Mar-2005 10 Add tape & reel for TO-92.
03-Jul-2006 11 Order codes updated.
16-May-2007 12 Order codes updated.
08-Jun-2007 13 Order codes updated.
09-Apr-2008 14 Modified: Table 1 on page 1.
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LD2979xx
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