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LP2986
SNVS137I – MARCH 1999 – REVISED SEPTEMBER 2015
LP2986 Micropower, 200-mA Ultra-Low-Dropout Fixed or Adjustable Voltage Regulator
1 Features
3 Description
•
•
•
•
•
•
•
•
•
The LP2986 is a 200-mA high-precision LDO
regulator with a wide input voltage supply. The device
has two output voltage modes: a fixed-precision
output mode and an adjustable output voltage via an
external resistive divider.
1
Wide Supply Voltage Range (16 V Maximum)
Ultra-Low-Dropout Voltage
0.5% Output Voltage Accuracy (A Grade)
Ensured 200-mA Output Current
< 1-μA Quiescent Current when Shutdown
Low GROUND Pin Current at All Loads
High Peak Current Capability (400 mA Typical)
Overtemperature/Overcurrent Protection
−40°C to +125°C Junction Temperature Range
2 Applications
•
•
•
Cellular Phones
Palmtop/Laptop Computers
Camcorders, Personal Stereos, Cameras
Using an optimized Vertically Integrated PNP (VIP)
process, the LP2986 delivers superior performance:
• Dropout Voltage: Typically 180 mV at 200-mA
load, and 1 mV at 1-mA load.
• GROUND Pin Current: Typically 1 mA at 200-mA
load, and 200 μA at 10-mA load.
• Sleep Mode: The LP2986 draws less than 1 μA
quiescent current when SHUTDOWN pin is pulled
low.
• ERROR Flag: The built-in ERROR flag goes low
when the output drops approximately 5% below
nominal.
• Precision Output: The standard product versions
available can be pin-strapped (using the internal
resistive divider) to provide output voltages of 5 V,
3.3 V, or 3 V with ensured accuracy of 0.5% (A
grade) and 1% (standard grade) at room
temperature.
Device Information(1)
PART NUMBER
LP2986
PACKAGE
BODY SIZE (NOM)
SOIC (8)
4.90 mm × 3.91 mm
VSSOP (8)
3.00 mm × 3.00 mm
WSON (8)
4.00 mm × 4.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
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.
LP2986
SNVS137I – MARCH 1999 – REVISED SEPTEMBER 2015
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Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Function ...........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
5
5
8
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 13
7.1 Overview ................................................................. 13
7.2 Functional Block Diagram ....................................... 13
7.3 Feature Description................................................. 13
7.4 Device Functional Modes........................................ 14
8
Application and Implementation ........................ 15
8.1 Application Information............................................ 15
8.2 Typical Applications ................................................ 15
9 Power Supply Recommendations...................... 19
10 Layout................................................................... 20
10.1 Layout Guidelines ................................................. 20
10.2 Layout Examples................................................... 20
10.3 WSON Mounting ................................................... 21
11 Device and Documentation Support ................. 22
11.1
11.2
11.3
11.4
11.5
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision H (April 2013) to Revision I
Page
•
Added Device Information and Pin Configuration and Functions sections, ESD Ratings table, update Thermal
Values, Feature Description, Device Functional Modes, Application and Implementation, Power Supply
Recommendations, Layout, Device and Documentation Support, and Mechanical, Packaging, and Orderable
Information sections................................................................................................................................................................ 1
•
Deleted Lead Temp from Abs Max table (in POA); delete Heatsinking sections re: specific packages (outdated info) ....... 4
Changes from Revision G (April 2013) to Revision H
•
2
Page
Changed layout of National Data Sheet to TI format ........................................................................................................... 18
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5 Pin Configuration and Function
D Package
8-Pin SOIC
Top View
DGK Package
8-Pin VSSOP
Top View
GROUND
1
8
SHUTDOWN
FEEDBACK
2
7
ERROR
TAP
3
6
SENSE
IN
4
5
OUT
GROUND
1
8
SHUTDOWN
FEEDBACK
2
7
ERROR
TAP
3
6
SENSE
IN
4
5
OUT
NGN Package
8-Pin WSON
Top View
GROUND
1
FEEDBACK
2
TAP
3
IN
4
Exposed Pad
on Bottom
(DAP)
8
SHUTDOWN
7
ERROR
6
SENSE
5
OUT
See WSON Mounting.
Pin Functions: All Packages
PIN
NAME
NO.
I/O
DESCRIPTION
ERROR
7
O
Active-low open-collector error output. Goes low when VOUT drops by 5% of its
nominal value.
FEEDBACK
2
I
Determines the output voltage. Connect to TAP (with OUT tied to SENSE) to output
the fixed voltage corresponding to the part version, or connect to a resistor divider to
adjust the output voltage (see Typical Applications).
GROUND
1
—
IN
4
I
Input voltage supply.
OUT
5
O
Regulated output.
SENSE
6
I
Connect to OUT (with FEEDBACK tied to TAP) to output the voltage corresponding to
the part version (see Typical Applications).
SHUTDOWN
8
I
Active-high. pull low to showdown the output voltage.
TAP
3
O
Middle tap of the Internal voltage divider. Tie to FEEDBACK (with OUT tied to
SENSE) to output the fixed voltage corresponding to the part version (see Typical
Applications).
—
The exposed thermal pad on the bottom of the WSON package should be connected
to a copper thermal pad on the PCB under the package. The use of thermal vias to
remove heat from the package into the PCB is recommended. Connect the thermal
pad to ground potential or leave floating. Do not connect the thermal pad to any
potential other than the same ground potential seen at device pin 1. For additional
information on using TI's non-pullback WSON package, see Application Note AN1187 Leadless Leadframe Package (LLP) (SNOA401).
DAP (Thermal Pad WSON only)
√
Ground.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1) (2)
MIN
MAX
UNIT
–0.3
16
V
Input supply voltage (operating)
2.1
16
V
SHUTDOWN pin
–0.3
16
V
FEEDBACK pin
–0.3
5
V
–0.3
16
V
Input supply voltage (survival)
Output voltage (survival)
(3)
IOUT (survival)
Short-circuit protected
Input-output voltage (survival) (4)
Power dissipation
–0.3
(5)
(2)
(3)
(4)
(5)
V
Internally limited
−65
Storage temperature, Tstg
(1)
16
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.
If Military/Aerospace specified devices are required, contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
If used in a dual-supply system where the regulator load is returned to a negative supply, the LM2986 output must be diode-clamped to
ground.
The output PNP structure contains a diode between the IN and OUT pins that is normally reverse-biased. Forcing the output above the
input will turn on this diode and may induce a latch-up mode which can damage the part (see Reverse Input-Output Voltage).
The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal
resistance, RθJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated
using: P(MAX) = TJ(MAX) – TA / RθJA
For improved thermal resistance and power dissipation for the WSON package, refer to Texas Instruments Application Note Leadless
Leadframe Package (LLP) (SNOA401). Exceeding the maximum allowable power dissipation will cause excessive die temperature, and
the regulator will go into thermal shutdown.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per
ANSI/ESDA/JEDEC JS-001 (1)
All pins except
FEEDBACK, IN, and TAP
±2000
FEEDBACK pin
±500
IN pin
±1000
TAP pin
±1500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
UNIT
Supply input voltage
2.1
16
V
Enable input voltage
0
16
V
200
mA
125
°C
Output current
−40
Operating junction temperature
4
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6.4 Thermal Information
LP2986
THERMAL METRIC (1)
D (SOIC)
DGK (VSSOP)
NGN (WSON)
UNIT
8 PINS
RθJA (2)
Junction-to-ambient thermal resistance, High-K
114.4
156.5
37.8 (3)
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
61.4
51.0
28.58
°C/W
RθJB
Junction-to-board thermal resistance
55.5
76.5
15.0
°C/W
ψJT
Junction-to-top characterization parameter
9.8
4.9
0.2
°C/W
ψJB
Junction-to-board characterization parameter
54.9
75.2
15.2
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
n/a
n/a
4.4
°C/W
(1)
(2)
(3)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
Thermal resistance value RθJA is based on the EIA/JEDEC High-K printed circuit board defined by: JESD51-7 - High Effective Thermal
Conductivity Test Board for Leaded Surface Mount Packages.
The PCB for the NGN (WSON) package RθJA includes four (4) thermal vias under the exposed thermal pad per EIA/JEDEC JESD51-5.
6.5 Electrical Characteristics
Unless otherwise specified: TJ = 25°C, VIN = VOUT(NOM) + 1 V, IOUT = 1 mA, COUT = 4.7 µF, CIN = 2.2 µF, VSD = 2 V.
PARAMETER
Output voltage (5-V
version)
VOUT
Output voltage (3.3-V
version)
Output voltage (3-V
version)
ΔVOUT/ΔVIN
Output voltage line
regulation
TEST CONDITIONS
LP2986AI-X.X (1)
MIN
TYP
MAX
MIN
TYP
MAX
4.975
5
5.025
4.95
5
5.05
0.1 mA < IOUT < 200 mA
4.96
5
5.04
4.92
5
5.08
0.1 mA < IOUT < 200 mA
–40°C ≤ TJ ≤ 125°C
4.91
5.09
4.86
3.283
3.3
3.317
3.267
3.3
3.333
3.274
3.3
3.326
3.247
3.3
3.353
0.1 mA < IOUT < 200 mA
–40°C ≤ TJ ≤ 125°C
3.241
3.359
3.208
2.985
3
3.015
2.97
3
3.03
2.976
3
3.024
2.952
3
3.048
0.1 mA < IOUT < 200 mA
–40°C ≤ TJ ≤ 125°C
2.946
3.054
2.916
0.007
IOUT = 75 mA
IOUT = 200 mA
–40°C ≤ TJ ≤ 125°C
(1)
(2)
V
3.084
0.007
0.032
1
0.014
2
0.032
1
3.5
90
IOUT = 75 mA
–40°C ≤ TJ ≤ 125°C
IOUT = 200 mA
V
%/V
VOUT(NOM) + 1 V ≤ VIN ≤ 16
V,
–40°C ≤ TJ ≤ 125°C
IOUT = 100 µA
–40°C ≤ TJ ≤ 125°C
Dropout voltage (2)
0.014
V
3.392
0.1 mA < IOUT < 200 mA
VOUT(NOM) + 1 V ≤ VIN ≤ 16
V
UNIT
5.14
0.1 mA < IOUT < 200 mA
IOUT = 100 µA
VIN – VOUT
LP2986I-X.X (1)
120
3.5
90
170
180
230
350
2
120
170
180
mV
230
350
Limits are 100% production tested at 25°C. Limits over the operating temperature range are specified through correlation using
Statistical Quality Control (SQC) methods. The limits are used to calculate TI’s Average Outgoing Quality Level (AOQL).
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.
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Electrical Characteristics (continued)
Unless otherwise specified: TJ = 25°C, VIN = VOUT(NOM) + 1 V, IOUT = 1 mA, COUT = 4.7 µF, CIN = 2.2 µF, VSD = 2 V.
PARAMETER
TEST CONDITIONS
LP2986AI-X.X (1)
MIN
IOUT = 100 µA
TYP
MAX
100
IOUT = 100 µA
–40°C ≤ TJ ≤ 125°C
IOUT = 75 mA
IGND
Ground pin current
500
IOUT = 75 mA
–40°C ≤ TJ ≤ 125°C
IOUT = 200 mA
1
TYP
MAX
120
100
120
150
110
150
800
500
800
2.1
1
250
(3)
mA
0.05
1.5
VOUT ≥ VOUT(NOM) − 5%
µA
2.1
3.7
0.05
VSD < 0.3 V
–40°C ≤ TJ ≤ 125°C
UNIT
1400
3.7
VSD < 0.3 V
Peak output current
MIN
1400
IOUT = 200 mA
–40°C ≤ TJ ≤ 125°C
IOUT(PK)
LP2986I-X.X (1)
400
1.5
250
µA
400
mA
IOUT(MAX)
Short-circuit current
RL = 0 (steady state)
400
400
mA
en
Output noise voltage
(RMS)
BW = 300 Hz to 50 kHz,
COUT = 10 µF
160
160
µVRMS
ƒ = 1 kHz, COUT = 10 µF
65
65
dB
See (4)
20
20
ppm/°C
ΔVOUT/ΔVIN Ripple rejection
ΔVOUT/ΔTD
Output voltage
temperature coefficient
FEEDBACK PIN
1.21
VFB
FEEDBACK pin voltage
–40°C ≤ TJ ≤ 125°C
See (5)
ΔVFB/ΔT
FEEDBACK pin voltage
temperature coefficient
IFB
FEEDBACK pin bias
current
ΔIFB/ΔT
FEEDBACK pin bias
current temperature
coefficient
1.25
1.2
1.2
1.26
1.19
1.27
1.19
1.28
1.18
1.29
See (6)
1.23
20
IOUT = 200 mA
150
IOUT = 200 mA
–40°C ≤ TJ ≤ 125°C
1.23
1.26
20
330
150
760
ppm/°C
330
760
See (6)
0.1
0.1
VH = Output ON
1.4
1.4
V
nA
nA/°C
SHUTDOWN INPUT
VSD
SD Input voltage
(7)
VH = Output ON
–40°C ≤ TJ ≤ 125°C
1.6
VL = Output OFF
0.55
VL = Output OFF
–40°C ≤ TJ ≤ 125°C
VSD = 0 V
ISD
SD Input current
0
6
0.18
µA
0
–1
5
VSD = 5 V, –40°C ≤ TJ ≤
125°C
(3)
(4)
(5)
(6)
(7)
0.55
0.18
VSD = 0 V, –40°C ≤ TJ ≤
125°C
VSD = 5 V
V
1.6
–1
V
5
15
15
µA
See the Typical Characteristics section.
Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range.
VFB ≤ VOUT ≤ (VIN − 1), 2.5 V ≤ VIN ≤ 16 V, 100 μA ≤ IL ≤ 200 mA, TJ ≤ 125°C.
Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range.
To prevent mis-operation, the SHUTDOWN pin must be driven by a signal that swings above VH and below VL with a slew rate not less
than 40 mV/μs (see Application and Implementation).
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Electrical Characteristics (continued)
Unless otherwise specified: TJ = 25°C, VIN = VOUT(NOM) + 1 V, IOUT = 1 mA, COUT = 4.7 µF, CIN = 2.2 µF, VSD = 2 V.
PARAMETER
TEST CONDITIONS
LP2986AI-X.X (1)
MIN
LP2986I-X.X (1)
TYP
MAX
0.01
MIN
UNIT
TYP
MAX
1
0.001
1
2
0.001
2
220
150
220
µA
350
mV
ERROR COMPARATOR
VOH = 16 V
IOH
Output HIGH leakage
VOH = 16 V, –40°C ≤ TJ ≤
125°C
VIN = VOUT(NOM) − 0.5 V
IOUT(COMP) = 300 µA
VOL
Output LOW voltage
VTHR(MAX)
Upper threshold voltage
VTHR(MIN)
Lower threshold voltage
HYST
Hysteresis
150
VIN = VOUT(NOM) − 0.5 V
IOUT(COMP) = 300 µA
–40°C ≤ TJ ≤ 125°C
350
−5.5
–40°C ≤ TJ ≤ 125°C
−7.7
−8.9
–40°C ≤ TJ ≤ 125°C
−4.6
−6.6
−13
2
−3.5
−5.5
−2.5
−7.7
−4.9
−8.9
−3.3
−13
−4.6
−3.5
−2.5
−6.6
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%VOUT
−4.9
−3.3 %VOUT
2
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6.6 Typical Characteristics
Unless otherwise specified: TA = 25°C, COUT = 4.7 µF, CIN = 2.2 µF, SD is tied to VIN, VIN = VO(NOM) + 1 V, IL = 1 mA.
8
Figure 1. VOUT vs Temperature
Figure 2. Dropout Voltage vs Temperature
Figure 3. Dropout Voltage vs Load Current
Figure 4. Dropout Characteristics
Figure 5. Ground Pin Current vs Temperature And Load
Figure 6. Ground Pin Current vs Load Current
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Typical Characteristics (continued)
Unless otherwise specified: TA = 25°C, COUT = 4.7 µF, CIN = 2.2 µF, SD is tied to VIN, VIN = VO(NOM) + 1 V, IL = 1 mA.
Figure 8. Input Current vs VIN
Figure 7. Input Current vs VIN
Figure 10. Turnoff Waveform
Figure 9. Turnon Waveform
Figure 11. Short-Circuit Current
Figure 12. Short-Circuit Current
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Typical Characteristics (continued)
Unless otherwise specified: TA = 25°C, COUT = 4.7 µF, CIN = 2.2 µF, SD is tied to VIN, VIN = VO(NOM) + 1 V, IL = 1 mA.
10
Figure 13. Short-Circuit Current vs Output Voltage
Figure 14. Instantaneous Short-Circuit Current vs
Temperature
Figure 15. DC Load Regulation
Figure 16. Feedback Bias Current vs Load
Figure 17. Feedback Bias Current vs Temperature
Figure 18. SHUTDOWN Pin Current vs SHUTDOWN Pin
Voltage
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Typical Characteristics (continued)
Unless otherwise specified: TA = 25°C, COUT = 4.7 µF, CIN = 2.2 µF, SD is tied to VIN, VIN = VO(NOM) + 1 V, IL = 1 mA.
Figure 19. Shutdown Voltage vs Temperature
Figure 20. Input-to-Output Leakage vs Temperature
Figure 21. Output Noise Density
Figure 22. Output Impedance vs Frequency
Figure 23. Output Impedance vs Frequency
Figure 24. Ripple Rejection
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Typical Characteristics (continued)
Unless otherwise specified: TA = 25°C, COUT = 4.7 µF, CIN = 2.2 µF, SD is tied to VIN, VIN = VO(NOM) + 1 V, IL = 1 mA.
12
Figure 25. Load Transient Response
Figure 26. Load Transient Response
Figure 27. Line Transient Response
Figure 28. Line Transient Response
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7 Detailed Description
7.1 Overview
The LP2986 is a bipolar, low-dropout (LDO) voltage regulator that can accommodate a wide input supply-voltage
range of up to 16 V. The LP2986 LDO is able to output either a fixed or adjustable output from the same device.
By tying the OUT and SENSE pins together, and the FEEDBACK and TAP pins together, the LP2986 device
outputs a fixed 5 V, 3.3 V, or 3 V (depending on the version). Alternatively, by leaving the SENSE and TAP pins
open and connecting FEEDBACK to an external resistor divider, the output can be set to any value between 2.1
V to 16 V. The LP2986 device also offers additional functionality that makes it particularly suitable for batterypowered applications. For example, a logic-compatible shutdown feature allows the regulator to be put in standby
mode for power savings. In addition, there is a built-in supervisor reset function in which the ERROR output goes
low when VOUT drops by 5% of its nominal value for whatever reasons – due to a drop in VIN, current limiting, or
thermal shutdown.
The LP2986 devices are designed to minimize all error contributions to the output voltage. With a tight output
tolerance (0.5% at 25°C), a very low output voltage temperature coefficient (20 ppm typical), extremely good line
and load regulation and remote sensing capability, the part can be used as either low-power voltage reference or
200-mA regulator.
Multiple features of the device include:
• Very high-accuracy 1.23-V reference
• Sleep mode
• Error flag output
• Internal protection circuitry, such as overcurrent limit, and thermal shutdown.
7.2 Functional Block Diagram
7.3 Feature Description
7.3.1 High-Accuracy Output Voltage
With special careful design to minimize all contributions to the output voltage error, the LP2989 distinguishes
itself as a very high output-voltage-accuracy micro-power LDO. This includes a tight initial tolerance (0.5%
typical, A grade), extremely good line regulation (0.007%/V typical).
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Feature Description (continued)
7.3.2 Error Detection Comparator Output
The LP2989 will generate a logic low output whenever its output falls out of regulation by more than
approximately 5% below nominal. Because the ERROR comparator has an open-collector output, an external
pull-up resistor is required to pull the output up to VOUT or another supply voltage (up to 16 V). The output of the
comparator is rated to sink up to 300 µA. If ERROR pin is not used, it can be left open.
Because the ERROR comparator has an open-collector output, an external pull-up resistor is required to pull the
output up to VOUT or another supply voltage (up to 16 V). The output of the comparator is rated to sink up to
300 µA. If ERROR pin is not used, it can be left open.
7.3.3 Thermal Protection
The device contains a thermal shutdown protection circuit to turn off the output current when excessive heat is
dissipated in the LDO. The circuitry is not intended to replace proper heat sinking. Continuously running the
device into thermal shutdown degrades its reliability.
7.3.4 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. Note also that 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.
7.4 Device Functional Modes
7.4.1 Shutdown Mode
The LP2986 is shut off by driving the shutdown input low, and turned on by pulling it high. If this feature is not to
be used, the SHUTDOWN input should be tied to VIN to keep the regulator output on at all times.
To assure proper operation, the signal source used to drive the SHUTDOWN input must be able to swing above
and below the specified turnon/turnoff voltage thresholds listed as VH and VL, respectively (see Typical
Characteristics).
Since the SHUTDOWN input comparator does not have hysteresis, It is also important that the turnon (and
turnoff) voltage signals applied to the SHUTDOWN input have a slew rate which is not less than 40 mV/µs when
moving between the VH and VL thresholds.
CAUTION
The regulator output state (either On or Off) cannot be specified if a slow-moving AC
(or DC) signal is applied that is in the range between VH and VL.
7.4.2 Fixed or Adjustable Regulated Output
A unique feature of the LP2986 device is its ability to output either a fixed voltage or an adjustable voltage,
depending on the external pin connections. To output the internally programmed fixed voltage, tie the SENSE pin
to the OUTPUT pin and the FEEDBACK pin to the TAP pin.
Alternatively, a user-programmable voltage ranging from the internal reference to a 16-V maximum can be set by
using an external resistor divider pair. The resistor divider is tied to VOUT, and the divided-down voltage is tied
directly to FEEDBACK for comparison against the internal voltage reference. To satisfy the steady-state condition
in which its two inputs are equal, the error amplifier drives the output to equal to Equation 1. For detailed
information see Application and Implementation.
14
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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 LP2986 can provide 200-mA output current with 2.1-V to 16-V input. It is stable with a minimum of 4.7-µF
ceramic output capacitor. An input capacitor of (≥ 2.2 μF) is required. An optional external bypass capacitor
reduces the output noise without slowing down the load transient response. Typical output noise is 160 µVRMS at
frequencies from 300 Hz to 50 kHz. Typical power supply rejection is 65 dB at 1 kHz.
8.2 Typical Applications
Figure 29. Application Using Internal Resistive Divider
Figure 30. Application Using External Divider
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Typical Applications (continued)
8.2.1 Design Requirements
For typical ultra-low-dropout linear regulator applications, use the parameters listed in Table 1.
Table 1. Design Parameters
DESIGN PARAMETER
EXAMPLE VALUE
Input voltage
4.3 V
Output voltage
3.3 V
Output current
200 mA (maximum)
RMS noise, 300 Hz to 50 kHz
150 µVRMS typical
PSRR at 1 kHz
65 dB typical
8.2.2 Detailed Design Procedure
8.2.2.1 Using an External Resistive Divider
The LP2986 output voltage can be programmed using an external resistive divider. Figure 30 shows a typical
circuit application using external resistive divider.
The resistor connected between the FEEDBACK pin and ground should be 51.1 kΩ. The value for the other
resistor (R1) connected between the FEEDBACK pin and the regulated output is found using the formula:
VOUT = VFB × (1 + ( R1 / 51.1k ))
(1)
It should be noted that the 25 µA of current flowing through the external divider is approximately equal to the
current saved by not connecting the internal divider, which means the quiescent current is not increased by using
external resistors.
A lead compensation capacitor (CF) must also be used to place a zero in the loop response at about 50 kHz. The
value for C F can be found using:
CF = 1/(2π × R1 × 50k)
(2)
A good quality capacitor must be used for CF to ensure that the value is accurate and does not change
significantly over temperature. Mica or ceramic capacitors can be used, assuming a tolerance of ±20% or better
is selected.
If a ceramic is used, select one with a temperature coefficient of NPO, COG, Y5P, or X7R. Capacitor types Z5U,
Y5V, and Z4V can not be used because their value varies more that 50% over the −25°C to +85°C temperature
range.
8.2.2.2 External Capacitors
Like any low-dropout regulator, external capacitors are required to assure stability. These capacitors must be
correctly selected for proper performance.
8.2.2.2.1 Input Capacitor
An input capacitor (≥ 2.2 µF) is required between the LP2986 input and ground (amount of capacitance may be
increased without limit).
This capacitor must be located a distance of not more than 0.5 inches from the input pin and returned to a clean
analog ground. Any good quality ceramic or tantalum may be used for this capacitor.
8.2.2.2.2 Output Capacitor
The output capacitor must meet the requirement for minimum amount of capacitance and also have an
appropriate equivalent series resistance (ESR) value.
Curves are provided which show the allowable ESR range as a function of load current for various output
voltages and capacitor values (see Figure 31 and Figure 32).
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Figure 31. ESR Curves For 5-V Output
Figure 32. ESR Curves for 2.5-V Output
NOTE
The output capacitor must maintain its ESR in the stable region over the full operating
temperature range of the application to assure stability.
The minimum required amount of output capacitance is 4.7 µF. Output capacitor size can be increased without
limit.
It is important to remember that capacitor tolerance and variation with temperature must be taken into
consideration when selecting an output capacitor so that the minimum required amount of output capacitance is
provided over the full operating temperature range. A good tantalum capacitor will show very little variation with
temperature, but a ceramic may not be as good (see Capacitor Characteristics).
8.2.2.3 Capacitor Characteristics
8.2.2.3.1 Tantalum
The best choice for size, cost, and performance are solid tantalum capacitors. Available from many sources, their
typical ESR is very close to the ideal value required on the output of many LDO regulators.
Tantalums also have good temperature stability: a 4.7 µF was tested and showed only a 10% decline in
capacitance as the temperature was decreased from +125°C to −40°C. The ESR increased only about 2:1 over
the same range of temperature.
However, it should be noted that the increasing ESR at lower temperatures present in all tantalums can cause
oscillations when marginal quality capacitors are used (where the ESR of the capacitor is near the upper limit of
the stability range at room temperature).
8.2.2.3.2 Ceramic
For a given amount of a capacitance, ceramics are usually larger and more costly than tantalums.
Be warned that the ESR of a ceramic capacitor can be low enough to cause instability: a 2.2-µF ceramic
capacitor was measured and found to have an ESR of about 15 mΩ.
If a ceramic capacitor is to be used on the LP2986 output, a 1-Ω resistor should be placed in series with the
capacitor to provide a minimum ESR for the regulator.
Another disadvantage of ceramic capacitors is that their capacitance varies a lot with temperature:
Large ceramic capacitors are typically manufactured with the Z5U temperature characteristic, which results in the
capacitance dropping by a 50% as the temperature goes from +25°C to 80°C.
This means you have to buy a capacitor with twice the minimum COUT to assure stable operation up to 80°C.
8.2.2.3.3 Aluminum
The large physical size of aluminum electrolytics makes them unattractive for use with the LP2986. Their ESR
characteristics are also not well suited to the requirements of LDO regulators.
The ESR of an aluminum electrolytic is higher than a tantalum, and it also varies greatly with temperature.
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A typical aluminum electrolytic can exhibit an ESR increase of 50× when going from +20°C to −40°C. Also, some
aluminum electrolytics can not be used below −25°C because the electrolyte will freeze.
8.2.2.4 Reverse Input-Output Voltage
The PNP power transistor used as the pass element in the LP2986 has an inherent diode connected between
the regulator output and input.
During normal operation (where the input voltage is higher than the output) this diode is reverse-biased.
However, if the output voltage is pulled above the input, or the input voltage is pulled below the output, this diode
will turn ON and current will flow into the regulator OUT pin.
LP2986
VIN
VOUT
PNP
GND
Figure 33. Inherent Diode
In such cases, a parasitic SCR can latch which will allow a high current to flow into VIN (and out the GROUND
pin), which can damage the part.
In any application where the output voltage may be higher than the input, an external Schottky diode must be
connected from VIN to VOUT (cathode on VIN, anode on VOUT), to limit the reverse voltage across the LP2986 to
0.3 V (see Absolute Maximum Ratings).
SCHOTTKY DIODE
LP2986
VIN
VOUT
PNP
GND
Figure 34. Inherent and External Schottky Diodes
8.2.2.5 WSON Package Devices
The LP2986 is offered in the 8-pin WSON surface mount package to allow for increased power dissipation
compared to the 8-pin SOIC-8 and 8-pin VSSOP. For details on WSON thermal performance as well as
mounting and soldering specifications, refer to WSON Mounting.
18
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8.2.3 Application Curves
Figure 35. Load Transient Response
Figure 36. Load Transient Response
Figure 37. Line Transient Response
Figure 38. Line Transient Response
9 Power Supply Recommendations
The LP2986 is designed to operate from an input voltage supply range from 2.1 V to 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.
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10 Layout
10.1 Layout Guidelines
For best overall performance, place all circuit components on the same side of the circuit board and as near as
practical to the respective LDO pin connections. Place ground return connections to the input and output
capacitor, 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 Examples
GND
1
8
FEEDBACK
2
7
ERROR
3
6
SENSE
4
5
SHUTDOWN
DAP
TAP
IN
Error Resistor
OUT
COUT
CIN
Figure 39. WSON Layout with Internal Resistor Divider
GND
GND
R2
FEEDBACK
1
8
2
7
ERROR
DAP
R1
CF
SHUTDOWN
TAP
IN
3
6
4
5
SENSE
Error Pullup
Resistor
OUT
COUT
CIN
Figure 40. WSON Layout with External Resistor Divider
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10.3 WSON Mounting
The LDC08A (pullback) 8-pin WSON package requires specific mounting techniques which are detailed in Texas
Instruments Application Note Leadless Leadframe Package (LLP) (SNOA401). Referring to the section PCB
Design Recommendations in SNOA401, the pad style which should be used with this WSON package is the
NSMD (non-solder mask defined) type. Additionally, for optimal reliability, there is a recommended 1:1 ratio
between the package pad and the PCB pad for the pullback WSON.
The thermal dissipation of the WSON package is directly related to the printed circuit board construction and the
amount of additional copper area connected to the DAP.
The DAP (exposed pad) on the bottom of the WSON package is connected to the die substrate with a conductive
die attach adhesive. The DAP has no direct electrical (wire) connection to any of the eight pins. There is a
parasitic PN junction between the die substrate and the device ground. As such, it is strongly recommend that
the DAP be connected directly to the ground at device pin 1 (GROUND). Alternately, but not recommended, the
DAP may be left floating (that is, no electrical connection). The DAP must not be connected to any potential other
than ground.
For the LP2986 in the NGN 8-pin WSON package, the junction-to-case thermal rating (RθJC) is 4.4°C/W, where
the case is on the bottom of the package at the center of the DAP.
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11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
For additional information, see the following:
Texas Instruments Application Note Leadless Leadframe Package (LLP) (SNOA401).
11.2 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.
11.3 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
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.
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PACKAGE OPTION ADDENDUM
www.ti.com
30-Sep-2021
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)
(4/5)
(6)
LP2986AILD-3.3/NOPB
ACTIVE
WSON
NGN
8
1000
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L005A
LP2986AILDX-3.3/NOPB
ACTIVE
WSON
NGN
8
4500
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L005A
LP2986AIM-3.0/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986A
IM3.0
LP2986AIM-3.3
NRND
SOIC
D
8
95
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-40 to 125
2986A
IM3.3
LP2986AIM-3.3/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986A
IM3.3
LP2986AIM-5.0
NRND
SOIC
D
8
95
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-40 to 125
2986A
IM5.0
LP2986AIM-5.0/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986A
IM5.0
LP2986AIMM-3.0/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L39A
LP2986AIMM-3.3/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L40A
LP2986AIMM-5.0/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L41A
LP2986AIMMX-3.0/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L39A
LP2986AIMMX-5.0/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L41A
LP2986AIMX-3.3/NOPB
ACTIVE
SOIC
D
8
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986A
IM3.3
LP2986AIMX-5.0/NOPB
ACTIVE
SOIC
D
8
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986A
IM5.0
LP2986ILD-3.3/NOPB
ACTIVE
WSON
NGN
8
1000
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
L005A
B
LP2986IM-3.0/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986I
M3.0
LP2986IM-3.3/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986I
M3.3
LP2986IM-5.0
NRND
SOIC
D
8
95
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-40 to 125
2986I
M5.0
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
30-Sep-2021
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)
(4/5)
(6)
LP2986IM-5.0/NOPB
ACTIVE
SOIC
D
8
95
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986I
M5.0
LP2986IMM-3.0/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L39B
LP2986IMM-3.3/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L40B
LP2986IMM-5.0/NOPB
ACTIVE
VSSOP
DGK
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L41B
LP2986IMMX-5.0/NOPB
ACTIVE
VSSOP
DGK
8
3500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L41B
LP2986IMX-3.3/NOPB
ACTIVE
SOIC
D
8
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986I
M3.3
LP2986IMX-5.0
NRND
SOIC
D
8
2500
Non-RoHS
& Green
Call TI
Level-1-235C-UNLIM
-40 to 125
2986I
M5.0
LP2986IMX-5.0/NOPB
ACTIVE
SOIC
D
8
2500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
2986I
M5.0
(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
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