Product
Folder
Sample &
Buy
Support &
Community
Tools &
Software
Technical
Documents
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
LP2981 100-mA Ultra-Low Dropout Regulators With Shutdown
1 Features
3 Description
•
The LP2981 and LP2981A families of fixed-output,
low-dropout regulators offer exceptional, costeffective performance for both portable and nonportable applications. Available in fixed voltages of
2.8 V, 3 V, 3.3 V, and 5 V, the family has an output
tolerance of 0.75% for the A-grade devices (1.25%
for the standard grade) and is capable of delivering
100-mA continuous load current. Standard regulator
features, such as overcurrent and overtemperature
protection, are included.
1
•
•
•
•
•
•
•
•
Output Tolerance of
– 0.75% (A Grade)
– 1.25% (Standard Grade)
Ultra-Low Dropout Typically:
– 200 mV at Full Load of 100 mA
– 7 mV at 1 mA
Low IQ: 600 µA Typical at Full Load of 100 mA
Shutdown Current: 0.01 µA Typical
Fast Transient Response to Line and Load
Overcurrent and Thermal Protection
High Peak Current Capability
Low ZOUT Over Wide Frequency Range
−40°C to 125°C Temperature Range
The LP2981 and LP2981A have features that make
the regulators ideal candidates for a variety of
portable applications:
• Low dropout: A PNP pass element allows a typical
dropout of 200 mV at 100-mA load current and 7
mV at 1-mA load.
• Low quiescent current: The use of a vertical PNP
process allows for quiescent currents that are
considerably lower than those associated with
traditional lateral PNP regulators.
• Shutdown: A shutdown feature is available,
allowing the regulator to consume only 0.01 µA
when the ON/OFF pin is pulled low.
2 Applications
•
•
•
•
•
Smart Meters
Servo and Motor Control
Mobile Phones and Cameras
Audio and Portable Speakers
Telecommunication and Networking
Device Information(1)
PART NUMBER
LP2981-XXDBV
LP2981A-XXDBV
PACKAGE (PINS)
SOT-23 (5)
BODY SIZE (NOM)
2.90 mm × 1.60 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Block Diagram
V IN
ON/OFF
1.23 V
í
VREF
+
R1
VOUT
R2
Overcurrent/
Overtemperature
Protection
GND
Copyright © 2016, Texas Instruments Incorporated
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
6.1
6.2
6.3
6.4
6.5
6.6
6.7
3
3
4
4
4
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics: LP2981-xx ......................
Electrical Characteristics: LP2981A-xx .....................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1 Overview ................................................................... 7
7.2 Functional Block Diagram ......................................... 7
7.3 Feature Description................................................... 7
7.4 Device Functional Modes.......................................... 9
8
Application and Implementation ........................ 10
8.1 Application Information............................................ 10
8.2 Typical Application ................................................. 10
9 Power Supply Recommendations...................... 12
10 Layout................................................................... 12
10.1 Layout Guidelines ................................................. 12
10.2 Layout Example .................................................... 12
11 Device and Documentation Support ................. 13
11.1
11.2
11.3
11.4
11.5
11.6
Related Links ........................................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
13
13
13
13
13
13
12 Mechanical, Packaging, and Orderable
Information ........................................................... 14
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision F (August 2008) to Revision G
Page
•
Added Device Information table, ESD Ratings table, Feature Description section, Device Functional Modes,
Application and Implementation section, Power Supply Recommendations section, Layout section, Device and
Documentation Support section, and Mechanical, Packaging, and Orderable Information section....................................... 1
•
Changed thermal table to align with JEDEC standards ......................................................................................................... 4
2
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
www.ti.com
SLVS521G – JULY 2004 – REVISED AUGUST 2016
5 Pin Configuration and Functions
DBV Package
5-Pin SOT-23
Top View
VIN
1
GND
2
ON/OFF
3
5
VOUT
4
NC
Not to scale
Pin Functions
PIN
NO.
I/O
NAME
DESCRIPTION
1
VIN
I
2
GND
—
Supply input
3
ON/OFF
I
4
NC
—
No connect
5
VOUT
O
Voltage output
Ground
Active-low shutdown pin. Tie to VIN if unused.
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
(2)
MIN
MAX
UNIT
VIN
Continuous input voltage
–0.3
16
V
VON/OFF
ON/OFF input voltage
–0.3
16
V
VOUT
Output voltage (3)
–0.3
9
V
IOUT
Output current
TJ
Operating virtual junction temperature
Tstg
Storage temperature
(1)
(2)
(3)
Internally limited
(short-circuit protected)
–65
150
°C
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
The PNP pass transistor has a parasitic diode connected between the input and output. This diode normally is reverse-biased
(VIN > VOUT), but is forward-biased if the output voltage exceeds the input voltage by a diode drop (see Application and Implementation
for more details).
If load is returned to a negative power supply, the output must be diode clamped to GND.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic
discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
±1000
Machine model (MM)
±200
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
Copyright © 2004–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
3
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
6.3 Recommended Operating Conditions
VIN
Supply input voltage
VON/OFF
ON/OFF input voltage
VIN – VOUT
Input-output differential
IOUT
Output current
TJ
Virtual junction temperature
(1)
MIN
MAX
2.2 (1)
16
V
0
VIN
V
0.7
11
V
100
mA
125
°C
–40
UNIT
Minimum VIN of 2.2 V is needed for proper biasing of LDO control circuitry.
6.4 Thermal Information
LP2981-XX
THERMAL METRIC
(1)
DBV (SOT-23)
UNIT
5 PINS
RθJA
Junction-to-ambient thermal resistance (2) (3)
205.2
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
11.83
°C/W
RθJB
Junction-to-board thermal resistance
37.7
°C/W
ψJT
Junction-to-top characterization parameter
12.2
°C/W
ψJB
Junction-to-board characterization parameter
33.8
°C/W
(1)
(2)
(3)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
Maximum power dissipation is a function of TJ(max), RθJA , and TA . The maximum allowable power dissipation at any allowable ambient
temperature is PD = (TJ(max) – TA )/ RθJA . Operating at the absolute maximum TJ of 150°C can affect reliability.
The package thermal impedance is calculated in accordance with JESD 51-7.
6.5 Electrical Characteristics: LP2981-xx
at specified free-air temperature range, VIN = VOUT(NOM) + 1 V, VON/OFF = 2 V, CIN = 1 µF, IL = 1 mA, COUT = 4.7 µF
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
IL = 1 mA
Output voltage
tolerance
ΔVOUT
ΔVOUT/ΔVIN
Output voltage line
regulation
IL = 1 mA to 100 mA
VIN = (VOUT(NOM) + 1 V) to 16 V
IL = 0
IL = 1 mA
VIN – VOUT
Dropout voltage (1)
IL = 25 mA
IL = 100 mA
(1)
4
TA
MIN
25°C
TYP
–1.25
25°C
–40°C to 125°C
25°C
–2
2
–3.5
3.5
0.007
1
3
7
10
70
100
15
–40°C to 125°C
25°C
%/V
mV
150
200
–40°C to 125°C
%VNOM
5
–40°C to 125°C
25°C
0.014
0.032
–40°C to 125°C
25°C
UNIT
1.25
–40°C to 125°C
25°C
MAX
250
375
Dropout voltage is defined as the input-to-output differential at which the output voltage drops 100 mV below the value measured with a
1-V differential. This dropout specification does not apply to the 1.8-V option, as the minimum VIN = 2.2 V must be observed for proper
biasing of LDO control circuitry.
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
www.ti.com
SLVS521G – JULY 2004 – REVISED AUGUST 2016
Electrical Characteristics: LP2981-xx (continued)
at specified free-air temperature range, VIN = VOUT(NOM) + 1 V, VON/OFF = 2 V, CIN = 1 µF, IL = 1 mA, COUT = 4.7 µF
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
IL = 0
Ground pin current
IL = 25 mA
IL = 100 mA
VON/OFF < 0.3 V (OFF)
VON/OFF < 0.15 V (OFF)
High = O/P ON
ON/OFF input
voltage (2)
VON/OFF
Low = O/P OFF
VON/OFF = 0
ON/OFF input
current
ION/OFF
MIN
TYP
MAX
65
95
–40°C to 125°C
IL = 1 mA
IGND
TA
25°C
VON/OFF = 5 V
125
25°C
80
–40°C to 125°C
110
170
25°C
200
300
600
1000
–40°C to 125°C
550
25°C
–40°C to 125°C
µA
1700
25°C
0.01
0.8
–40°C to 105°C
0.05
2
–40°C to 125°C
5
25°C
–40°C to 125°C
UNIT
1.4
1.6
25°C
V
0.5
–40°C to 125°C
0.15
25°C
0.01
–40°C to 125°C
–1
25°C
µA
5
–40°C to 125°C
15
IOUT(PK)
Peak output current
VOUT ≥ VOUT(NOM) – 5%
25°C
400
mA
Vn
Output noise voltage BW = 300 Hz to 50 kHz,
(RMS)
COUT = 10 µF
25°C
160
µV
ΔVOUT/ΔVIN
Ripple rejection
f = 1 kHz, COUT = 10 µF
25°C
63
dB
IOUT(MAX)
Short-circuit current
RL = 0 (steady state)
25°C
150
mA
(2)
The ON/OFF input must be actively terminated. Connect to VIN if this function is not used (see Application and Implementation).
6.6 Electrical Characteristics: LP2981A-xx
at specified free-air temperature range, VIN = VOUT(NOM) + 1 V, VON/OFF = 2 V, CIN = 1 µF, IL = 1 mA, COUT = 4.7 µF
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
IL = 1 mA
Output voltage
tolerance
ΔVOUT
ΔVOUT/ΔVIN
Output voltage line
regulation
IL = 1 mA to 100 mA
VIN = (VOUT(NOM) + 1 V) to 16 V
IL = 0
IL = 1 mA
VIN – VOUT
Dropout voltage (1)
IL = 25 mA
IL = 100 mA
(1)
TA
MIN
TYP
MAX
25°C
–0.75
0.75
25°C
–1
1
–40°C to 125°C
25°C
–2.5
1
3
7
10
15
70
–40°C to 125°C
25°C
–40°C to 125°C
%/V
5
–40°C to 125°C
25°C
0.014
0.032
–40°C to 125°C
25°C
%VNOM
2.5
0.007
–40°C to 125°C
25°C
UNIT
100
mV
150
200
250
375
Dropout voltage is defined as the input-to-output differential at which the output voltage drops 100 mV below the value measured with a
1-V differential. This dropout specification does not apply to the 1.8-V option, as the minimum VIN = 2.2 V must be observed for proper
biasing of LDO control circuitry.
Copyright © 2004–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
5
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
Electrical Characteristics: LP2981A-xx (continued)
at specified free-air temperature range, VIN = VOUT(NOM) + 1 V, VON/OFF = 2 V, CIN = 1 µF, IL = 1 mA, COUT = 4.7 µF
(unless otherwise noted)
PARAMETER
TEST CONDITIONS
IL = 0
95
80
25°C
200
300
600
1000
–40°C to 125°C
25°C
0.01
0.8
–40°C to 105°C
0.05
2
–40°C to 125°C
5
1.4
–40°C to 125°C
1.6
25°C
Low = O/P OFF
0.15
25°C
VON/OFF = 0
0.01
–40°C to 125°C
–1
25°C
VON/OFF = 5 V
V
0.5
–40°C to 125°C
ON/OFF input
current
µA
1700
25°C
High = O/P ON
ON/OFF input
voltage (2)
110
550
25°C
VON/OFF < 0.15 V (OFF)
UNIT
170
–40°C to 125°C
VON/OFF < 0.3 V (OFF)
ION/OFF
MAX
65
–40°C to 125°C
IL = 100 mA
VON/OFF
TYP
125
25°C
IL = 25 mA
Ground pin current
MIN
–40°C to 125°C
IL = 1 mA
IGND
TA
25°C
5
–40°C to 125°C
µA
15
IOUT(PK)
Peak output current
VOUT ≥ VOUT(NOM) – 5%
25°C
Vn
Output noise voltage BW = 300 Hz to 50 kHz,
(RMS)
COUT = 10 µF
25°C
ΔVOUT/ΔVIN
Ripple rejection
f = 1 kHz, COUT = 10 µF
25°C
63
dB
IOUT(MAX)
Short-circuit current
RL = 0 (steady state)
25°C
150
mA
(2)
150
400
mA
160
µV
The ON/OFF input must be actively terminated. Connect to VIN if this function is not used (see Application and Implementation).
6.7 Typical Characteristics
Output Voltage (V)
Unless otherwise specified: TA = 25°C, VIN = VO(NOM) + 1 V, COUT = 10 µF, CIN = 1 µF all voltage options, ON/OFF pin tied to
VIN.
3.315
3.3125
3.31
3.3075
3.305
3.3025
3.3
3.2975
3.295
3.2925
3.29
3.2875
3.285
3.2825
3.28
3.2775
0
10
20
30
40
50
60
70
Load Current (mA)
80
90
100
D001
Figure 1. Load Regulation - LP2981-33
6
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
www.ti.com
SLVS521G – JULY 2004 – REVISED AUGUST 2016
7 Detailed Description
7.1 Overview
The LP2981 and LP2981A are 100-mA fixed-output, low-dropout regulator. Available in assorted output voltages
from 2.5 V to 5 V, the device has an output tolerance of 0.75% for the A grade (1.25% for the non-A version).
The low-drop voltage and the ultra-low quiescent current make them suitable for low noise, low-power
applications and in battery-powered systems:
• Low dropout: A PNP pass element allows a typical dropout of 200 mV at 100-mA load current and 7 mV at
1-mA load.
• Low quiescent current: The use of a vertical PNP process allows for quiescent currents that are considerably
lower than those associated with traditional lateral PNP regulators.
• Shutdown: A shutdown feature is available, allowing the regulator to consume only 0.01 µA when the
ON/OFF pin is pulled low.
• Small packaging: For the most space-constrained needs, the regulator is available in the SOT-23 package.
7.2 Functional Block Diagram
V IN
ON/OFF
1.23 V
í
VREF
+
R1
VOUT
R2
Overcurrent/
Overtemperature
Protection
GND
Copyright © 2016, Texas Instruments Incorporated
7.3 Feature Description
7.3.1 Ultra-Low Dropout Voltage
The dropout voltage often refers to the voltage difference between the input and output voltage (VDO = VIN –
VOUT), where the main current pass-FET is fully on in the ohmic region of operation and is characterized by the
classic RDS(ON) of the FET. VDO indirectly specifies a minimum input voltage above the nominal programmed
output voltage at which the output voltage is expected to remain within its accuracy boundary. The LP2981's
pass-PNP allows a dropout of 200 mV at full load and 7 mV at 1 mA or lower loads. This allows for small voltage
drop regulation and reduces the total power dissipation.
7.3.2 Low Ground Current
LP2981 uses a vertical PNP process which allows for quiescent currents that are considerably lower than those
associated with traditional lateral PNP regulators, typically 600 µA at 100-mA load and 65 µA at 1-mA load.
Copyright © 2004–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
7
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
Feature Description (continued)
7.3.3 Short-Circuit Protection (Current Limit)
The internal current-limit circuit is used to protect the LDO against high-load current faults or shorting events. The
LDO is not designed to operate in a steady-state current limit. During a current-limit event, the LDO sources
constant current. Therefore, the output voltage falls when load impedance decreases. If a current limit occurs
and the resulting output voltage is low, excessive power may be dissipated across the LDO resulting in a thermal
shutdown of the output. A foldback feature limits the short-circuit current to protect the regulator from damage
under all load conditions. If VOUT is forced below 0 V before ON/OFF goes high and the load current required
exceeds the foldback current limit, the device may not start up correctly.
7.3.4 Capacitor Characteristics
7.3.4.1 Ceramic
Due to their very low ESR values, ceramic capacitors are not suitable for use as the output capacitor. For
instance, a typical 2.2-µF ceramic capacitor has an ESR in the range of 10 mΩ to 20 mΩ and, thus, easily can
fall out of minimum ESR requirements under certain operating conditions.
If a ceramic capacitor is used at the output, a 1-Ω resistor must be placed in series with the capacitor to raise the
ESR seen by the regulator.
7.3.4.2 Tantalum
Solid tantalum capacitors are optimal choices for the LP2981, but they still must meet the minimum ESR
requirement. Note that the ESR of a tantalum capacitor increases as temperature drops, as much as doubling
from 25°C to –40°C. Thus, ESR margins must be maintained over the temperature range to prevent regulator
instability. For operation at very low temperatures, paralleling a tantalum capacitor with a ceramic one keeps the
combined ESR from increasing near the upper limit of the ESR curve.
7.3.4.3 Aluminum
Aluminum capacitors can be used, but use with the LP2981 is impractical due to their large physical dimensions.
They also must meet the ESR requirements over the full temperature range. In this regard, aluminium capacitors
are at a big disadvantage due to their sharp ESR increase as temperature drops. For example, over a
temperature drop from 20°C to –40°C, the ESR of an aluminum electrolytic capacitor can increase by a factor of
50. In addition, some of the electrolytes used in these capacitors can freeze at –25°C, making the capacitor
nonoperational.
8
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
www.ti.com
SLVS521G – JULY 2004 – REVISED AUGUST 2016
7.4 Device Functional Modes
7.4.1 ON/OFF Operation
The LP2981 allows for a shutdown mode through the ON/OFF pin. If the shutdown feature is not used, ON/OFF
must be connected to the input to ensure that the regulator is on at all times. To drive ON/OFF:
• A LOW (≤0.3 V) turns the regulator OFF; a HIGH (≥1.6 V) turns it ON.
– Use either a totem-pole output or an open-collector output with a pullup resistor tied to VIN (or another
logic supply)
• The HIGH signal can exceed VIN, but must not exceed the absolute maximum ratings of 20 V for the
ON/OFF pin
• Apply a signal with a slew rate of ≥40 mV/µs. A slow slew rate can cause the shutdown function to operate
incorrectly
7.4.2 Reverse Input-Output Voltage
An inherent diode is present across the PNP pass element of the LP2981.
VIN
VOUT
Figure 2. Internal PNP Diode Structure
With the anode connected to the output, this diode is reverse-biased during normal operation, because the input
voltage is higher than the output. However, if the output is pulled one VBE higher than the input, or if the input is
abruptly stepped below the output, this diode is forward-biased and can cause a parasitic silicon-controlled
rectifier (SCR) to latch, resulting in current flowing from the output to the input (values in excess of 100 mA can
cause damage). Thus, to prevent possible damage to the regulator in any application where the output may be
pulled above the input, an external Schottky diode must be connected between the output and input. With the
anode on output, this Schottky limits the reverse voltage across the output and input pins to approximately 0.3 V,
preventing the regulator's internal diode from forward biasing.
Schottky
VOUT
VIN
LP2981
Copyright © 2016, Texas Instruments Incorporated
Figure 3. Internal PNP Diode Bypass
Copyright © 2004–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
9
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LP2981 is a linear voltage regulator operating from 2.1 V to 16 V on the input and regulates voltages
between 2.5 V to 5 V with 0.75% accuracy and 100-mA maximum output current. Efficiency is defined by the
ratio of output voltage to input voltage because the LP2981 is a linear voltage regulator. To achieve high
efficiency, the dropout voltage (VIN – VOUT) must be as small as possible, thus requiring a very-low-dropout LDO.
Successfully implementing an LDO in an application depends on the application requirements. If the
requirements are simply input voltage and output voltage, compliance specifications (such as internal power
dissipation or stability) must be verified to ensure a solid design. If timing, start-up, noise, power supply rejection
ratio (PSRR), or any other transient specification is required, then the design becomes more challenging.
8.2 Typical Application
LP2981
VIN
1
VOUT
5
3.3 …F
(see Note A)
1 …F
(see Note A)
GND
ON/OFF
(see Note B)
2
3
4
NC
(see Note C)
Copyright © 2016, Texas Instruments Incorporated
A.
Minimum COUT value for stability (can be increased without limit for improved stability and transient response)
B.
ON/OFF must be actively terminated. Connect to VIN if shutdown feature is not used.
C.
Pin 4 (NC) must be left open. Do not connect anything to this pin.
Figure 4. LP2981 Typical Application
8.2.1 Design Requirements
Table 1 lists the parameters for this application.
Table 1. Design Parameters
10
PARAMETER
DESIGN REQUIREMENT
Input voltage
5 V ±10%, provided by an external regulator
Output voltage
3.3 V ±5%
Output current
100 mA (maximum), 1 mA (minimum)
RMS noise, 300 Hz to 50kHz
< 1 mVRMS
PSRR at 1kHz
> 40 dB
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
www.ti.com
SLVS521G – JULY 2004 – REVISED AUGUST 2016
8.2.2 Detailed Design Procedure
8.2.2.1 External Capacitors
Like any low-dropout regulator, the external capacitors used with the LP2981 must be carefully selected to
assure regulator loop stability.
8.2.2.1.1 Input Capacitor (Cin)
A minimum value of 1 µF (over the entire operating temperature range) is required at the input of the LP2981. In
addition, this input capacitor must be placed within 1 cm of the input pin and connected to a clean analog
ground. There is no Equivalent Series Resistance (ESR) requirement for this capacitor, and the capacitance can
be increased without limit. A good-quality ceramic or tantalum capacitor can be used.
8.2.2.1.2 Output Capacitor (Cout)
As a PNP regulator, the LP2981 requires the output capacitor to meet both a minimum capacitance and ESR
value. Required ESR values as a function of load current are provided for various output voltages, load currents,
and capacitances (see Figure 5 through Figure 8).
• Minimum Cout: 3.3 µF (can be increased without limit to improve transient response stability margin)
• ESR range: see Figure 5 through Figure 8
It is critical that both the minimum capacitance and ESR requirement be met over the entire operating
temperature range. Depending on the type of capacitor used, both of these parameters can vary significantly with
temperature (see Capacitor Characteristics).
8.2.3 Application Curves
Figure 5. 5-V/3.3-µF ESR Curves
Figure 7. 3-V/3.3-µF ESR Curves
Copyright © 2004–2016, Texas Instruments Incorporated
Figure 6. 5-V/10-µF ESR Curves
Figure 8. 3-V/10-µF ESR Curves
Submit Documentation Feedback
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
11
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
9 Power Supply Recommendations
The LP2981 is designed to operate from an input voltage supply range between 2.2 V and 16 V. The input
voltage range provides adequate headroom for the device to have a regulated output. This input supply must be
well regulated. If the input supply is noisy, additional input capacitors with low ESR can help improve the output
noise performance.
10 Layout
10.1 Layout Guidelines
For best overall performance, place all circuit components on the same side of the printed-circuit board and as
near as practical to the respective LDO pin connections. Place ground return connections to the input and output
capacitors, and to the LDO ground pin as close to each other as possible, connected by a wide, component-side,
copper surface. The use of vias and long traces to create LDO circuit connections is strongly discouraged and
negatively affects system performance. This grounding and layout scheme minimizes inductive parasitics, and
thereby reduces load-current transients, minimizes noise, and increases circuit stability. A ground reference
plane is also recommended and is either embedded in the PCB itself or located on the bottom side of the PCB
opposite the components. This reference plane serves to assure accuracy of the output voltage, shield noise,
and behaves similar to a thermal plane to spread (or sink) heat from the LDO device. In most applications, this
ground plane is necessary to meet thermal requirements.
10.2 Layout Example
VIN
IN
VOUT
OUT
Input
Capacitor
GND
ON/OFF
ON/OFF
Output
Capacitor
LP2981
NC
Figure 9. Recommended Layout
12
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
www.ti.com
SLVS521G – JULY 2004 – REVISED AUGUST 2016
11 Device and Documentation Support
11.1 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 2. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
LP2981-28
Click here
Click here
Click here
Click here
Click here
LP2981-29
Click here
Click here
Click here
Click here
Click here
LP2981-30
Click here
Click here
Click here
Click here
Click here
LP2981-33
Click here
Click here
Click here
Click here
Click here
LP2981-33
Click here
Click here
Click here
Click here
Click here
LP2981-50
Click here
Click here
Click here
Click here
Click here
LP2981A-28
Click here
Click here
Click here
Click here
Click here
LP2981A-29
Click here
Click here
Click here
Click here
Click here
LP2981A-30
Click here
Click here
Click here
Click here
Click here
LP2981A-33
Click here
Click here
Click here
Click here
Click here
LP2981A-50
Click here
Click here
Click here
Click here
Click here
11.2 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.5 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
Copyright © 2004–2016, Texas Instruments Incorporated
Submit Documentation Feedback
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
13
LP2981-28, LP2981-29, LP2981-30
LP2981-33, LP2981-50, LP2981A-28
LP2981A-29, LP2981A-30, LP2981A-33, LP2981A-50
SLVS521G – JULY 2004 – REVISED AUGUST 2016
www.ti.com
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
14
Submit Documentation Feedback
Copyright © 2004–2016, Texas Instruments Incorporated
Product Folder Links: LP2981-28 LP2981-29 LP2981-30 LP2981-33 LP2981-50 LP2981A-28 LP2981A-29 LP2981A30 LP2981A-33 LP2981A-50
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
LP2981-28DBVR
LIFEBUY
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP5G, LP5L)
LP2981-28DBVT
LIFEBUY
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP5G, LP5L)
LP2981-28DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LP5G
LP2981-29DBVR
LIFEBUY
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LP3G, LP3L)
LP2981-30DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP7G, LP7L)
Samples
LP2981-30DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP7G, LP7L)
Samples
LP2981-33DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPBG, LPBL)
Samples
LP2981-33DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPBG, LPBL)
Samples
LP2981-33DBVTE4
LIFEBUY
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPBG
LP2981-33DBVTG4
LIFEBUY
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPBG
LP2981-50DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPDG, LPDL)
Samples
LP2981-50DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPDG, LPDL)
Samples
LP2981-50DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPDG, LPDL)
Samples
LP2981A-28DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP6G, LP6L)
Samples
LP2981A-28DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP6G, LP6L)
Samples
LP2981A-29DBVR
LIFEBUY
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LRBG, LRBL)
LP2981A-30DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP8G, LP8L)
Samples
LP2981A-30DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LP8G
Samples
Samples
LP2981A-30DBVT
LIFEBUY
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LP8G, LP8L)
LP2981A-30DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LP8G
Samples
LP2981A-33DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPCG, LPCL)
Samples
LP2981A-33DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPCG
Samples
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
10-Dec-2022
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
Samples
(4/5)
(6)
LP2981A-33DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPCG, LPCL)
Samples
LP2981A-33DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPCG
Samples
LP2981A-50DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPEG, LPEL)
Samples
LP2981A-50DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPEG, LPEL)
Samples
LP2981A-50DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPEG, LPEL)
Samples
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
