LD2982BXX18

Very low drop and low noise voltage regulator with

inhibit function, low ESR capacitors compatible

Features
■ Very low dropout voltage (120 mV at 50 mA
and 7 mV at 1 mA load)

s )
t(
■ Very low quiescent current (375 mA typ. at
50 mA load and 75 mA at 1 mA)
■ Output current up to 50 mA
u c
■ Logic controlled electronic shutdown
o d
■ Output voltage of 1.8 V r
SOT23-5L

P )
■ Internal current and thermal limit
t e t( s
■ Available in ± 1 % tolerance
(at 25 °C, A version)
o e u c
Typical application are in cellular phone,
l
palmtop/laptop computer, personal digital
■ Supply voltage rejection: 45 dB (typ)
b s
camera.
r d
assistant (PDA), personal stereo, camcorder and
o
■ Only 1 µF for stability

- O e P
et
■ Low output noise voltage 30 µVrms

s ) l
t(
■ Smallest package SOT23-5L
o
c bs
■ Temperature range: -40 °C to 125 °C

d u O
ro
Description
) -
e P t( s
The LD2982 is a 50 mA fixed output voltage
regulator. The ultra low drop voltage and the low

o l et d uc
quiescent current make them particularly suitable
for low noise, low power applications, and in

s r o
battery powered systems. In sleep mode

Ob eP
quiescent current is less than 1 µA when INHIBIT
pin is pulled low. Shutdown logic control function
t
is available on pin 3 (TTL compatible). This
e
ol
means that when the device is used as local

b s
regulator, it is possible to put a part of the board in
standby, decreasing the total power consumption.

OAn external capacitor CBYP = 10 nF connected

between bypass pin and GND reduce the noise to
30 µVrms.

Table 1. Device summary

Order code Output voltage

LD2982BM18R 1.8 V

July 2009 Doc ID 8188 Rev 7 1/17

www.st.com 17
 Contents LD2982BXX18

Contents

1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
s )
c t(
5
u
Typical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
d
6 r o
Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

e P s )
t(
6.1 External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.2
l e t c
Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.3
s o du
Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
b r o
6.4

- O e P
Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

et
6.5 Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

s ) l
t(
6.6 Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
o
c data . . . . . . .b. .s. . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7
d u
Package mechanical
O
o
Revision rhistory . . . . . . )
-
8
e P t( s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

le t u c
s o r o d
O b P
e t e
ol
b s
O

2/17 Doc ID 8188 Rev 7

 LD2982BXX18 Diagram

1 Diagram

Figure 1. Schematic diagram

s )
ct(
d u
r o
e P s )
l e t c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o l et d uc
s r o
Ob t eP
ol e
b s
O

Doc ID 8188 Rev 7 3/17

 Pin configuration LD2982BXX18

2 Pin configuration

Figure 2. Pin connections (top view)

s )
c t(
d u
Table 2. Pin description
r o
Pin n° Symbol Name and function

e P s )
1 IN Input port
l e t c t(
2 GND Ground pin

s o du
3 INHIBIT
b r o
Control switch ON/OFF. Inhibit is not internally pulled-up; it cannot be left floating.

O P
Disable the device when connected to GND or to a positive voltage less than 0.18V

- e
et
Bypass Pin: Capacitor to be connected to GND in order to improve the thermal noise
4 Bypass
performances
s ) l
5 OUT Output port
t( o
d u c
O bs
Table 3. Thermal data
ro ) -
eP ( s
Symbol Parameter SOT23-5L Unit

t c t
RthJC

o l
RthJA e d u
Thermal resistance junction-case
Thermal resistance junction-ambient
81
255
°C/W
°C/W

b s r o
O e P
l e t
s o
O b

4/17 Doc ID 8188 Rev 7

 LD2982BXX18 Maximum ratings

3 Maximum ratings

Table 4. Absolute maximum ratings

Symbol Parameter Value Unit

VI DC input voltage 16 V
VINH INHIBIT input voltage 16 V
IO Output current Internally limited
PD Power dissipation Internally limited
TSTG Storage temperature range -65 to 150
s
°C
)
TOP Operating junction temperature range -40 to 125
c t( °C

d u
Note:
r o
Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.

e P s )
l e t c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o l et d uc
s r o
Ob t eP
ol e
b s
O

Doc ID 8188 Rev 7 5/17

 Electrical characteristics LD2982BXX18

4 Electrical characteristics

TJ = 25 °C, VI = VO + 1 V, IO = 1 mA, VSHDN = 2 V, CI = CO = 1 µF, unless otherwise

specified.

Table 5. Electrical characteristics for LD2982BXX18

Symbol Parameter Test conditions Min. Typ. Max. Unit
VOP Operating input voltage 2.5 16 V
VI = 2.5V 1.477 1.5 1.523
VO Output voltage IO = 1 to 50mA 1.470 1.530

( s )
V
IO = 1 to 50mA, TJ= -40 to 125°C
VI = 2.8V
1.447
1.773 1.8
c t
1.553
1.827

u
od
VO Output voltage IO = 1 to 50mA 1.764 1.836 V

Pr
IO = 1 to 50mA, TJ= -40 to 125°C 1.737 1.863
VI = 3.5V

e
2.462 2.5 2.537

s )
VO Output voltage IO = 1 to 50mA

e t 2.45

c
2.55
t( V

ol
IO = 1 to 50mA, TJ= -40 to 125°C 2.412 2.587
VI = 3.8V 2.758 2.8
du 2.842
VO Output voltage IO = 1 to 50mA
bs 2.744
r o 2.856 V

-O eP
IO = 1 to 50mA, TJ= -40 to 125°C 2.702 2.898

) let
VI = 3.85V 2.807 2.85 2.893
VO Output voltage

t ( s
IO = 1 to 50mA
o
2.793 2.907 V

u c VI = 4.0V b s
IO = 1 to 50mA, TJ= -40 to 125°C 2.750
2.955 3.0
2.950
3.045
VO Output voltage
o d IO = 1 to 50mA
- O 2.94 3.06 V
r )
eP t(s
IO = 1 to 50mA, TJ= -40 to 125°C 2.895 3.105
VI = 4.1V 3.053 3.1 3.146
VO
l e t
Output voltage
uc IO = 1 to 50mA 3.038 3.162 V

s o r o d IO = 1 to 50mA, TJ= -40 to 125°C 2.991 3.208

O b VO P Output voltage
VI = 4.2V
IO = 1 to 50mA
3.152
3.136
3.2 3.248
3.264 V

e t e IO = 1 to 50mA, TJ= -40 to 125°C 3.088 3.312

ol VI = 4.3V 3.250 3.3 3.349

b s VO Output voltage IO = 1 to 50mA 3.234 3.366 V

O IO = 1 to 50mA, TJ= -40 to 125°C

VI = 4.5V
3.184
3.447 3.5
3.415
3.552
VO Output voltage IO = 1 to 50mA 3.430 3.370 V
IO = 1 to 50mA, TJ= -40 to 125°C 3.377 3.662
VI = 4.6V 3.546 3.6 3.654
VO Output voltage IO = 1 to 50mA 3.528 3.672 V
IO = 1 to 50mA, TJ= -40 to 125°C 3.474 3.726

6/17 Doc ID 8188 Rev 7

 LD2982BXX18 Electrical characteristics

Table 5. Electrical characteristics for LD2982BXX18 (continued)

Symbol Parameter Test conditions Min. Typ. Max. Unit
VI = 4.8V 3.743 3.8 3.857
VO Output voltage IO = 1 to 50mA 3.724 3.876 V
IO = 1 to 50mA, TJ= -40 to 125°C 3.667 3.933
VI = 5.0V 3.94 4 4.06
VO Output voltage IO = 1 to 50mA 3.92 4.08 V
IO = 1 to 50mA, TJ= -40 to 125°C 3.86 4.14
VI = 5.7V 4.629 4.7 4.77
VO Output voltage IO = 1 to 50mA
IO = 1 to 50mA, TJ= -40 to 125°C
4.606
4.535
4.794
4.864
( s )
V

VI = 6.0V 4.925 5
c t
5.075

u
od
VO Output voltage IO = 1 to 50mA 4.9 5.1 V

ISC Short circuit current

IO = 1 to 100 mA, TJ= -40 to 125°C
RL = 0
P r
4.825
400
5.175
mA
)
VI = VO + 1V to 16V, IO = 1 mA
te 0.003 0.014
t( s
ΔVO/ΔVI Line regulation VI = VO + 1V to 16V, IO = 1 mA,
TJ= -40 to 125°C
o l e u c 0.032
%/VI

IO = 0
bs r o1d 3

-O eP
IO = 0, TJ= -40 to 125°C 5

let
IO = 1mA 7 10

s )
IO = 1mA, TJ= -40 to 125°C 15

t( o
VDROP Dropout voltage mV
IO = 10mA

uc b s
IO = 10mA, TJ= -40 to 125°C
40 60
90

od -O
IO = 50mA 120 150

P r s )
IO = 50mA, TJ= -40 to 125°C 225

t(
IO = 0 80 100
e
let c
IO = 0, TJ= -40 to 125°C 150

d u
so
IO = 1mA 100 150

r o
Quiescent current IO = 1mA, TJ= -40 to 125°C 200

Ob eP
ON MODE IO = 10mA 200 300
IQ µA

e t IO = 10mA, TJ= -40 to 125°C 400

ol
IO = 50mA 600 900

b s IO = 50mA, TJ= -40 to 125°C

VINH<0.18V 0
1200

O SVR
OFF MODE

Supply voltage rejection

VINH<0.18V, TJ= -40 to 125°C
CBYP = 0.01µF, CO = 10µF, f = 1kHz 45
1
dB
VIL Inhibit input logic low TJ= -40 to 125°C 0.15 V
VIH Inhibit input logic high TJ= -40 to 125°C 2 V
VINH = 0V, TJ= -40 to 125°C 5 15
IINH Inhibit input current µA
VINH = 5V, TJ= -40 to 125°C 0 -1
B = 300 Hz to 50 kHz, CBYP = 0.01µF,
eN Output noise voltage 30 µV
CO = 10µF

Doc ID 8188 Rev 7 7/17

 Typical characteristics LD2982BXX18

5 Typical characteristics

(TJ = 25 °C, VI = VO(NOM) +1 V, CI = 1 µF (X7R), CO = 2.2 µF (X7R), VINH = 2 V, unless

otherwise specified).
Figure 3. Output voltage vs. temperature Figure 4. Dropout voltage vs. temperature

s )
c t(
d u
r o
e P s )
l e t c t(
Figure 5. Dropout voltage vs. output current Figure 6.
s o du
Quiescent current vs. load current

b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o let d uc
s r o
Ob
Figure 7.

t eP
Quiescent current vs. temperature Figure 8. Supply voltage rejection vs. temp.

ol e
b s
O

8/17 Doc ID 8188 Rev 7

 LD2982BXX18 Typical characteristics

Figure 9. Supply voltage rejection vs. output Figure 10. Supply voltage rejection vs. output
current current

s )
c t(
d u
r o
Figure 11. Supply voltage rejection vs. P
Figure 12. Supply voltage rejection vs.
e s )
frequency
t
frequency

l e c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o l et
Figure 13. Line transient
d uc Figure 14. Line transient
s r o
Ob t eP
ol e
b s
O

VO = 2.5V, IO = 50mA, no CI, CO = 4.7µF, tr=tf=2ns VO = 2.5V, IO = 50mA, no CI, CO = 4.7µF, tr=tf=1µs

Doc ID 8188 Rev 7 9/17

 Typical characteristics LD2982BXX18

Figure 15. Load transient Figure 16. Load transient

s )
c t(
d u
VO = 2.5V, IO = 0 to 50mA, no CI, CO = 10µF, tr=tf=2ns
r o
VO = 2.5V, IO = 0 to 50mA, no CI, CO = 4.7µF, tr=tf=2ns

e P s )
l e t c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o l et d uc
s r o
Ob t eP
ol e
b s
O

10/17 Doc ID 8188 Rev 7

 LD2982BXX18 Application notes

6 Application notes

6.1 External capacitors

Like any low-dropout regulator, the LD2982 requires external capacitors for regulator
stability. This capacitor must be selected to meet the requirements of minimum capacitance
and equivalent series resistance. We suggest to solder input and output capacitors as close
as possible to the relative pins.

6.2 Input capacitor

s )
c t(
An input capacitor whose value is 1 µF is required with the LD2982 (amount of capacitance
can be increased without limit). This capacitor must be located a distance of not more than

d u
0.5" from the input pin of the device and returned to a clean analog ground. Any good quality
ceramic, tantalum or film capacitors can be used for this capacitor.
r o
e P s )
6.3 Output capacitor
l e t c t(
o u
The LD2982 is designed specifically to work with ceramic output capacitors. It may also be

s d
b r o
possible to use tantalum capacitors, but these are not as attractive for reasons of size and
cost. By the way, the output capacitor must meet both the requirement for minimum amount
O P
of capacitance and ESR (equivalent series resistance) value. Due to the different loop gain,
- e
et
the stability improves for higher output versions and so the suggested minimum output

s ) l
capacitor value, if low ESR ceramic type is used, is 1 µF for output voltages equal or major

t( o
than 3.8 V, 2.2 µF for VO going from 1.8 to 3.3 V, and 3.3 µF for the other versions. However,

c bs
if an output capacitor lower than the suggested one is used, it's possible to make stable the

d u
regulator adding a resistor in series to the capacitor.
O
r o ) -
6.4 P
Important
e t( s
le t uc
The output capacitor must maintain its ESR in the stable region over the full operating

s o r o d
temperature to assure stability. Also, capacitor tolerance and variation with temperature
must be considered to assure the minimum amount of capacitance is provided at all times.

O b P
This capacitor should be located not more than 0.5" from the output pin of the device and

e t e
returned to a clean analog ground.

l
6.5 o Inhibit input operation
b s
O The inhibit pin can be used to turn OFF the regulator when pulled low, so drastically
reducing the current consumption down to less than 1 µA. When the inhibit feature is not
used, this pin must be tied to VI to keep the regulator output ON at all times. To assure
proper operation, the signal source used to drive the inhibit pin must be able to swing above
and below the specified thresholds listed in the electrical characteristics section under VIH
VIL. Any slew rate can be used to drive the inhibit.

Doc ID 8188 Rev 7 11/17

 Application notes LD2982BXX18

6.6 Reverse current

The power transistor used in the LD2982 has not an inherent diode connected between the
regulator input and output. If the output is forced above the input, no current will flow from
the output to the input across the series pass transistor. When a VREV voltage is applied on
the output, the reverse current measured flows to the GND across the two feedback
resistors. This current typical value is 160 µA. R1 and R2 resistors are implanted type;
typical values are, respectively, 42.6 kΩ and 51.150 kΩ.

Figure 17. Reverse current test circuit

s )
c t(
d u
r o
e P s )
l e t c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o l et d uc
s r o
Ob t eP
ol e
b s
O

12/17 Doc ID 8188 Rev 7

 LD2982BXX18 Package mechanical data

7 Package mechanical data

In order to meet environmental requirements, ST offers these devices in different grades of

ECOPACK® packages, depending on their level of environmental compliance. ECOPACK®
specifications, grade definitions and product status are available at: www.st.com.
ECOPACK® is an ST trademark.

s )
c t(
d u
r o
e P s )
l e t c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o let d uc
s r o
Ob t eP
ol e
b s
O

Doc ID 8188 Rev 7 13/17

 Package mechanical data LD2982BXX18

SOT23-5L mechanical data

mm. mils.
Dim.
Min. Typ. Max. Min. Typ. Max.

A 0.90 1.45 35.4 57.1

A1 0.00 0.10 0.0 3.9

s )
t(
A2 0.90 1.30 35.4 51.2

b 0.35 0.50 13.7

d uc 19.7

C 0.09 0.20 3.5

r o 7.8

eP s )
D 2.80 3.00 110.2 118.1

l e t c t(
u
E 1.50 1.75 59.0 68.8

o d
e 0.95
bs r o
37.4

-O eP
H 2.60 3.00 102.3 118.1

s ) l e t
L 0.10

c t ( 0.60

so
3.9 23.6

du O b
r o ) -
e P t( s
o l et d uc
s r o
Ob t eP
ol e
b s
O

7049676D

14/17 Doc ID 8188 Rev 7

 LD2982BXX18 Package mechanical data

Tape & reel SOT23-xL mechanical data

mm. inch.
Dim.
Min. Typ. Max. Min. Typ. Max.

A 180 7.086

C 12.8 13.0 13.2 0.504 0.512 0.519

D 20.2 0.795

s )
t(
N 60 2.362

uc
T 14.4 0.567

od
Ao 3.13 3.23 3.33 0.123 0.127 0.131

Pr
Bo 3.07 3.17 3.27 0.120 0.124 0.128

e s )
t(
Ko 1.27 1.37 1.47 0.050 0.054 0.0.58

e t c
ol u
Po 3.9 4.0 4.1 0.153 0.157 0.161

P 3.9 4.0 4.1

bs
0.153
o
0.157

r d 0.161

- O e P
t ( s)
o l et
d u c
O bs
r o ) -
e P t( s
l e t uc
s o r o d
O b P
e t e
ol
b s
O

Doc ID 8188 Rev 7 15/17

 Revision history LD2982BXX18

8 Revision history

Table 6. Document revision history

Date Revision Changes

25-Jul-2006 4 Order codes updated.

14-Feb-2008 5 Added: Table 1 on page 1.
10-Jul-2008 6 Modified: Table 1 on page 1 and Table 5 on page 6.
29-Jul-2009 7 Modified: Table 1 on page 1.

s )
ct(
d u
r o
e P s )
le t c t(
s o du
b r o
- O e P
t( s )
o l et
d u c
O bs
P ro s ) -
e t(
o l et d uc
s r o
Ob t eP
ol e
b s
O

16/17 Doc ID 8188 Rev 7

 LD2982BXX18

s )
Please Read Carefully:

c t(
d u
Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the

time, without notice.

r o
right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any

All ST products are sold pursuant to ST’s terms and conditions of sale.

e P s )
l e t
liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
c t(
Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no

o du
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this

s
b r o
document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products
or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such

O
third party products or services or any intellectual property contained therein.

- e P
s ) l et
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED

t( o
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED

c bs
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS

d u
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.

O
UNLESS EXPRESSLY APPROVED IN WRITING BY AN AUTHORIZED ST REPRESENTATIVE, ST PRODUCTS ARE NOT

P ro s ) -
RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING
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e t(
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GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK.

o l et d uc
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void

s r o
any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any

Ob eP
liability of ST.

e t
ol
ST and the ST logo are trademarks or registered trademarks of ST in various countries.

b s Information in this document supersedes and replaces all information previously supplied.

The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.

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Doc ID 8188 Rev 7 17/17