LP2985
SLVS522P – JULY 2004 – REVISED FEBRUARY 2022
LP2985 150-mA, Low-Noise, Low-Dropout Regulator With Shutdown
1 Features
3 Description
•
The LP2985 family of fixed-output, low-dropout
regulators
offers
exceptional,
cost-effective
performance for both portable and nonportable
applications. Available in voltages of 1.8 V, 2.5 V,
2.8 V, 2.9 V, 3 V, 3.1 V, 3.3 V, 5 V, and 10 V, the family
has an output tolerance of 1% for the A version (1.5%
for the non-A version) and is capable of delivering
150-mA continuous load current. Standard regulator
features, such as overcurrent and overtemperature
protection, are included.
•
•
•
•
•
•
•
•
•
Output tolerance of:
– 1% (A grade)
– 1.5% (standard grade)
Ultra-low dropout, typically:
– 280 mV at full load of 150 mA
– 7 mV at 1 mA
Wide VIN range: 16 V max
Low IQ: 850 μA at full load at 150 mA
Shutdown current: 0.01 μA typ
Low noise: 30 μVRMS with 10-nF bypass capacitor
Stable with low-ESR capacitors, including ceramic
Overcurrent and thermal protection
High peak-current capability
ESD protection exceeds JESD 22 :
– 2000-V human-body model (A114-A)
– 200-V machine model (A115-A)
Device Information(1)
PART NUMBER
LP2985
(1)
PACKAGE
SOT-23 (5)
BODY SIZE (NOM)
2.90 mm × 1.60 mm
For all available packages, see the orderable addendum at
the end of the data sheet.
2 Applications
•
•
•
•
Washer and dryer
Land mobile radio
Active antenna system mMIMO
Cordless power tool
Dropout Voltage vs Temperature
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.
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Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Pin Configuration and Functions...................................3
6 Specifications.................................................................. 4
6.1 Absolute Maximum Ratings........................................ 4
6.2 ESD Ratings............................................................... 4
6.3 Recommended Operating Conditions.........................4
6.4 Thermal Information....................................................4
6.5 Electrical Characteristics.............................................5
6.6 Typical Characteristics................................................ 7
7 Detailed Description...................................................... 11
7.1 Overview................................................................... 11
7.2 Functional Block Diagram......................................... 11
7.3 Feature Description...................................................11
7.4 Device Functional Modes..........................................11
8 Application and Implementation.................................. 13
8.1 Application Information............................................. 13
8.2 Typical Application.................................................... 15
9 Power Supply Recommendations................................18
10 Layout...........................................................................18
10.1 Layout Guidelines................................................... 18
10.2 Layout Example...................................................... 18
11 Device and Documentation Support..........................19
11.1 Receiving Notification of Documentation Updates.. 19
11.2 Support Resources................................................. 19
11.3 Trademarks............................................................. 19
11.4 Electrostatic Discharge Caution.............................. 19
11.5 Glossary.................................................................. 19
12 Mechanical, Packaging, and Orderable
Information.................................................................... 19
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision O (January 2015) to Revision P (February 2022)
Page
• Changed Applications section............................................................................................................................ 1
• Changed Thermal Information table: changed RθJA value from 206°C/W to 205.4°C/W and added RθJC(top),
RθJB, ΨJT, and ΨJB rows.....................................................................................................................................4
• Changed Application Information section......................................................................................................... 13
• Changed Typical Application section to follow current standards.....................................................................15
Changes from Revision N (June 2011) to Revision O (January 2015)
Page
• Added Applications, Device Information table, Pin Functions table, ESD Ratings table, Thermal Information
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
• Deleted Ordering Information table.....................................................................................................................1
2
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5 Pin Configuration and Functions
DBV (SOT-23) PACKAGE
(TOP VIEW)
VIN
GND
ON/OFF
1
5
VOUT
4
BYPASS
2
3
Table 5-1. Pin Functions
PIN
NAME
NO.
TYPE
DESCRIPTION
BYPASS
4
I/O
Attach a 10-nF capacitor to improve low-noise performance.
GND
2
—
Ground
ON/OFF
3
I
Active-low shutdown pin. Tie to VIN if unused.
VIN
1
I
Supply input
VOUT
5
O
Voltage output
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6 Specifications
6.1 Absolute Maximum Ratings
over virtual junction temperature range (unless otherwise noted)(1)
MIN
MAX
VIN
Continuous input voltage range(3)
–0.3
16
V
VON/OFF
ON/OFF input voltage range
–0.3
16
V
Output voltage range(2)
–0.3
9
V
Internally limited
(short-circuit protected)
IO
Output current(4)
RθJA
Package thermal impedance(4) (5)
TJ
Operating virtual junction temperature
Tstg
Storage temperature range
(1)
(2)
(3)
(4)
(5)
–65
UNIT
—
206
°C/W
150
°C
150
°C
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If load is returned to a negative power supply in a dual-supply system, the output must be diode clamped to GND.
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 the Application and
Implementation section for more details).
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.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins(1)
2000
Charged device model (CDM), per JEDEC specification JESD22-C101,
all pins(2)
1000
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.
6.3 Recommended Operating Conditions
VIN
Supply input voltage
VON/OFF
ON/OFF input voltage
IOUT
Output current
TJ
Virtual junction temperature
(1)
MIN
MAX
2.2(1)
16
0
–40
UNIT
V
VIN
V
150
mA
125
°C
Recommended minimum VIN is the greater of 2.5 V or VOUT(max) + rated dropout voltage (max) for operating IL.
6.4 Thermal Information
LP2985
THERMAL
METRIC(1)
DBV
UNIT
5 PINS
RθJA
Junction-to-ambient thermal resistance
205.4
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
78.8
°C/W
RθJB
Junction-to-board thermal resistance
46.7
°C/W
ΨJT
Junction-to-top characterization parameter
8.3
°C/W
ΨJB
Junction-to-board characterization parameter
46.3
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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6.5 Electrical Characteristics
at specified virtual junction temperature range, VIN = VOUT(NOM) + 1 V, VON/OFF = 2 V, CIN = 1 μF, and IL = 1 mA, COUT =
4.7 μF (unless otherwise noted)
PARAMETER
TEST CONDITIONS
IL = 1 mA
ΔVOUT
Output voltage
tolerance
1 mA ≤ IL ≤ 50 mA
1 mA ≤ IL ≤ 150 mA
Line regulation
VIN = [VOUT(NOM) + 1 V] to 16 V
LP2985A-xx
MIN
TYP
1
–1.5
1.5
1.5
–2.5
2.5
–40°C to 125°C
–2.5
2.5
–3.5
3.5
25°C
–2.5
2.5
–3
3
–40°C to 125°C
–3.5
3.5
–4
25°C
0.007
–40°C to 125°C
1
7
120
–40°C to 125°C
280
–40°C to 125°C
65
75
120
VON/OFF
VON/OFF = LOW → output OFF
VON/OFF = 0 V
ION/OFF
ON/OFF input current
VON/OFF = 5 V
225
350
280
350
575
95
65
95
110
75
110
140
140
170
170
220
120
220
25°C (LP2985-10)
250
250
–40°C to 125°C
400
400
350
600
350
650
1800
–40°C to 125°C
2500
600
1000
1500
25°C (LP2985-10)
850
1500
1800
2500
25°C
0.01
0.8
0.01
0.8
–40°C to 105°C
0.05
2
0.05
2
5
25°C
–40°C to 125°C
25°C
25°C
–40°C to 125°C
1.4
1.6
1.6
0.55
V
0.55
0.15
0.01
–40°C to 125°C
25°C
5
1.4
–40°C to 125°C
μA
650
1000
850
mV
150
160
–40°C to 125°C
VON/OFF = HIGH → output ON
120
160
25°C
ON/OFF input
voltage(2)
150
125
–40°C to 125°C
VON/OFF < 0.15 V (OFF)
90
125
25°C
VON/OFF < 0.3 V (OFF)
60
–40°C to 125°C
(LP2985-10)
25°C (LP2985-10)
IL = 150 mA
40
–40°C to 125°C
25°C
IL = 50 mA
15
60
125
–40°C to 125°C
GND pin current
10
125
25°C (LP2985-10)
%/V
3
25°C (LP2985-10)
25°C
IGND
7
575
25°C
IL = 10 mA
10
225
25°C
%VNOM
5
90
25°C
IL = 1 mA
1
15
40
0.014
0.032
3
UNIT
4
0.007
5
–40°C to 125°C
IL = 0 mA
0.014
0.032
25°C
IL = 150 mA
MAX
–1
25°C
IL = 50 mA
TYP
–1.5
–40°C to 125°C
IL = 10 mA
MIN
25°C
–40°C to 125°C
IL = 1 mA
LP2985-xx
MAX
25°C
25°C
IL = 0
VIN – VOUT Dropout voltage(1)
TJ
0.15
0.01
–2
5
–2
5
15
μA
15
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6.5 Electrical Characteristics (continued)
at specified virtual junction temperature range, VIN = VOUT(NOM) + 1 V, VON/OFF = 2 V, CIN = 1 μF, and IL = 1 mA, COUT =
4.7 μF (unless otherwise noted)
PARAMETER
TJ
LP2985A-xx
MIN
TYP
LP2985-xx
MAX
MIN
TYP
MAX
UNIT
Vn
Output noise (RMS)
BW = 300 Hz to 50 kHz,
COUT = 10 μF,
CBYPASS = 10 nF
25°C
30
30
μV
ΔVOUT/
ΔVIN
Ripple rejection
f = 1kHz, COUT = 10 μF,
CBYPASS = 10 nF
25°C
45
45
dB
IOUT(PK)
Peak output current
VOUT ≥ VO(NOM) – 5%
25°C
350
350
mA
25°C
400
400
mA
IOUT(SC)
(1)
(2)
(3)
6
TEST CONDITIONS
Short-circuit current
RL = 0 (steady
state)(3)
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.
The ON/OFF input must be driven properly for reliable operation (see the Application and Implementation section).
See Figure 6-6 in the Typical Characteristics section.
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6.6 Typical Characteristics
CIN = 1 μF, COUT = 4.7 μF, VIN = VOUT(NOM) + 1 V, TA = 25°C, and ON/OFF pin tied to VIN (unless otherwise specified)
3.345
10.20
VI = 4.3 V
VO = 3.3 V
Ci = 1 mF
Co = 4.7 mF
IO = 1 mA
VI = 11 V
10.15
VO = 10 V
10.10
3.335
CO = 4.7 µF
Output Voltage − (V)
Output Voltage – V
CI = 1 µF
IO = 1 mA
10.05
10.00
9.95
3.315
3.305
9.90
9.85
-50
3.325
-25
0
25
50
75
100
125
150
3.295
−50
−25
0
Temperature – °C
25
50
75
100
125
150
Temperature − (°C)
Figure 6-1. Output Voltage vs Temperature
Figure 6-2. Output Voltage vs Temperature
0.5
Short-Circuit Current − (A)
0.45
0.4
VI = 6 V
VO = 3.3 V
Ci = 1 mF
Cbyp = 0.01 mF
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
−500
0
500
1000
Time − (ms)
1500
2000
Figure 6-4. Short-Circuit Current vs Time
Figure 6-3. Dropout Voltage vs Temperature
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6.6 Typical Characteristics (continued)
CIN = 1 μF, COUT = 4.7 μF, VIN = VOUT(NOM) + 1 V, TA = 25°C, and ON/OFF pin tied to VIN (unless otherwise specified)
0.5
0.4
VO = 3.3 V
300
0.35
ISC − (mA)
Short-Circuit Current − (A)
320
VI = 16 V
VO = 3.3 V
Ci = 1 mF
Cbyp = 0.01 mF
0.45
0.3
0.25
280
260
0.2
240
0.15
0.1
220
0.05
0
−100
100
300
500
Time − (ms)
200
700
0
Figure 6-5. Short-Circuit Current vs Time
1.5
2
2.5
Output Voltage − (V)
3
3.5
100
VO = 3.3 V
Cbyp = 10 nF
1100
VI = 5 V
VO = 3.3 V
Co = 10 mF
Cbyp = 0 nF
90
1000
Ripple Rejection − (dB)
80
900
Ground Pin Current − mA
1
Figure 6-6. Short-Circuit Current vs Output Voltage
1200
800
700
600
500
400
70
50 mA
1 mA
60
50
40
150 mA
30
300
20
200
10
100
0
0
20
0
40
60
80
100
Load Current − mA
120
160
140
10
100k
1M
VI = 5 V
VO = 3.3 V
Co = 4.7 mF
Cbyp = 10 nF
90
80
Ripple Rejection − (dB)
80
Ripple Rejection − (dB)
10k
100
VI = 3.7 V
VO = 3.3 V
Co = 10 mF
Cbyp = 0 nF
90
70
1 mA
60
50 mA
40
30
1k
Figure 6-8. Ripple Rejection vs Frequency
100
50
100
Frequency − (Hz)
Figure 6-7. Ground Pin Current vs Load Current
150 mA
70
60
1 mA
50
40
50 mA
30
20
20
10
10
0
150 mA
0
10
100
1k
10k
100k
1M
10
Frequency − (Hz)
100
1k
10k
100k
1M
Frequency − (Hz)
Figure 6-9. Ripple Rejection vs Frequency
8
0.5
Figure 6-10. Ripple Rejection vs Frequency
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6.6 Typical Characteristics (continued)
CIN = 1 μF, COUT = 4.7 μF, VIN = VOUT(NOM) + 1 V, TA = 25°C, and ON/OFF pin tied to VIN (unless otherwise specified)
100
10
Ripple Rejection − (dB)
80
70
Output Impedance − (W)
VI = 5 V
VO = 3.3 V
Co = 4.7 mF
Cbyp = 10 nF
90
1 mA
60
10 mA
50
40
100 mA
30
Ci = 1 mF
Co = 10 mF
VO = 3.3 V
1
1 mA
10 mA
100 mA
0.1
0.01
20
10
0
10
100
1k
10k
Frequency − (Hz)
100k
Noise Density − (mV/ Hz)
Output Impedance − (W)
100k
1M
ILOAD = 150 mA
10 mA
100 mA
0.1
0.01
1
Cbyp = 100 pF
Cbyp = 1 nF
0.1
Cbyp = 10 nF
0.01
100
1k
10k
100k
100
1M
1k
10k
100k
Frequency − (Hz)
Frequency − (Hz)
Figure 6-13. Output Impedance vs Frequency
Figure 6-14. Output Noise Density vs Frequency
1.8
10
ILOAD = 1 mA
VO = 3.3 V
Cbyp = 10 nF
1.6
RL = 3.3 kW
1.4
1
Input Current − (mA)
Noise Density − (mV/ Hz)
10k
10
1 mA
0.001
10
1k
Figure 6-12. Output Impedance vs Frequency
Ci = 1 mF
Co = 4.7 mF
VO = 3.3 V
1
100
Frequency − (Hz)
Figure 6-11. Ripple Rejection vs Frequency
10
0.001
10
1M
Cbyp = 100 pF
Cbyp = 1 nF
0.1
1.2
1
0.8
RL = Open
0.6
Cbyp = 10 nF
0.4
0.2
0.01
0
100
1k
10k
Frequency − (Hz)
100k
0
1
2
3
4
5
6
Input Voltage − (V)
Figure 6-15. Output Noise Density vs Frequency
Figure 6-16. Input Current vs Input Voltage
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6.6 Typical Characteristics (continued)
CIN = 1 μF, COUT = 4.7 μF, VIN = VOUT(NOM) + 1 V, TA = 25°C, and ON/OFF pin tied to VIN (unless otherwise specified)
1400
Ground Current − (C)
1200
VO = 3.3 V
Cbyp = 10 nF
150 mA
1000
800
600
1 mA
400
50 mA
0 mA
200
10 mA
0
−50
−25
0
25
50
75
100
125
150
Temperature − (°C)
Figure 6-17. Ground-Pin Current vs Temperature
Figure 6-18. 2.2-μF Stable ESR Range for Output Voltage ≤ 2.3 V
Figure 6-19. 4.7-μF Stable ESR Range for Output Voltage ≤ 2.3 V Figure 6-20. 2.2-μF, 3.3-μF Stable ESR Range for Output Voltage
≥ 2.5 V
10
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7 Detailed Description
7.1 Overview
The LP2985 family of fixed-output, low-dropout regulators offers exceptional, cost-effective performance for both
portable and nonportable applications. Available in voltages of 1.8 V, 2.5 V, 2.8 V, 2.9 V, 3 V, 3.1 V, 3.3 V,
5 V, and 10 V, the family has an output tolerance of 1% for the A version (1.5% for the non-A version) and
is capable of delivering 150-mA continuous load current. Standard regulator features, such as overcurrent and
overtemperature protection, are included.
7.2 Functional Block Diagram
7.3 Feature Description
The LP2985 has a host of features that makes the regulator an ideal candidate for a variety of portable
applications:
•
•
•
•
•
•
Low dropout: A PNP pass element allows a typical dropout of 280 mV at 150-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.
Low-ESR-capacitor friendly: The regulator is stable with low-ESR capacitors, allowing the use of small,
inexpensive, ceramic capacitors in cost-sensitive applications.
Low noise: A BYPASS pin allows for low-noise operation, with a typical output noise of 30 μVRMS, with the
use of a 10-nF bypass capacitor.
Small packaging: For the most space-constrained needs, the regulator is available in the SOT-23 package.
7.4 Device Functional Modes
7.4.1 Normal Operation
In normal operation, the device will output a fixed voltage corresponding with the orderable part number. The
device can deliver 150 mA of continuous load current.
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7.4.2 Shutdown Mode
Set the ON/OFF pin low to shut down the device when VIN is still present. If a shutdown mode is not needed, tie
the pin to VIN. For proper operation, do not leave ON/OFF unconnected, and apply a signal with a slew rate of ≥
40 mV/μs.
12
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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, as well as validating and testing their design
implementation to confirm system functionality.
8.1 Application Information
8.1.1 Capacitors
8.1.1.1 Input Capacitor (CIN)
A minimum value of 1 μF (over the entire operating temperature range) is required at the input of the LP2985.
In addition, this input capacitor must be located within 1 cm of the input pin and connected to a clean analog
ground. There are no equivalent series resistance (ESR) requirements for this capacitor, and the capacitance
can be increased without limit.
8.1.1.2 Output Capacitor (COUT)
As an advantage over other regulators, the LP2985 permits the use of low-ESR capacitors at the output,
including ceramic capacitors that can have an ESR as low as 5 mΩ. Tantalum and film capacitors also can be
used if size and cost are not issues. The output capacitor must be located within 1 cm of the output pin and be
returned to a clean analog ground.
As with other PNP LDOs, stability conditions require the output capacitor to have a minimum capacitance and an
ESR that falls within a certain range.
•
•
Minimum COUT: 2.2 μF (can be increased without limit to improve transient response stability margin)
ESR range: see Figure 6-18 through Figure 6-20
Both the minimum capacitance and ESR requirement are critical to be met over the entire operating temperature
range. Depending on the type of capacitors used, both these parameters can vary significantly with temperature
(see the Capacitor Characteristics section).
8.1.1.3 Noise Bypass Capacitor (CBYPASS)
The LP2985 allows for low-noise performance with the use of a bypass capacitor that is connected to the internal
band-gap reference via the BYPASS pin. This high-impedance band-gap circuitry is biased in the microampere
range and, thus, cannot be loaded significantly, otherwise, its output (and, correspondingly, the output of the
regulator) changes. Thus, for best output accuracy, dc leakage current through CBYPASS must be minimized as
much as possible and must never exceed 100 nA.
A 10-nF capacitor is recommended for CBYPASS. Ceramic and film capacitors are well suited for this purpose.
8.1.1.4 Capacitor Characteristics
8.1.1.4.1 Ceramics
Ceramic capacitors are ideal choices for use on the output of the LP2985 for several reasons. For capacitances
in the range of 2.2 μF to 4.7 μF, ceramic capacitors have the lowest cost and the lowest ESR, making them
choice candidates for filtering high-frequency noise. For instance, a typical 2.2-μF ceramic capacitor has an ESR
in the range of 10 mΩ to 20 mΩ and, thus, satisfies minimum ESR requirements of the regulator.
Ceramic capacitors have one major disadvantage that must be taken into account—a poor temperature
coefficient, where the capacitance can vary significantly with temperature. For instance, a large-value ceramic
capacitor (≥ 2.2 μF) can lose more than half of its capacitance as the temperature rises from 25°C to 85°C.
Thus, a 2.2-μF capacitor at 25°C drops well below the minimum COUT required for stability, as ambient
temperature rises. For this reason, select an output capacitor that maintains the minimum 2.2 μF required for
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stability over the entire operating temperature range. There are some ceramic capacitors that can maintain a
±15% capacitance tolerance over temperature.
8.1.1.4.2 Tantalum
Tantalum capacitors can be used at the output of the LP2985, but there are significant disadvantages that can
prohibit their use:
•
•
•
In the 1-μF to 4.7-μF range, tantalum capacitors are more expensive than ceramics of the equivalent
capacitance and voltage ratings.
Tantalum capacitors have higher ESRs than their equivalent-sized ceramic counterparts. Thus, to meet the
ESR requirements, a higher-capacitance tantalum may be required, at the expense of larger size and higher
cost.
The ESR of a tantalum capacitor increases as temperature drops, as much as double from +25°C to –40°C.
Thus, ESR margins must be maintained over the temperature range to prevent regulator instability.
8.1.2 Reverse Input-Output Voltage
As shown in Figure 8-1, there is an inherent diode present across the PNP pass element of the LP2985.
VIN
VOUT
Figure 8-1. Inherent PNP Body Diode
With the anode connected to the output, this diode is reverse biased during normal operation, since the input
voltage is higher than the output. However, if the output is pulled higher than the input for any reason, this diode
is forward biased and can cause a parasitic silicon-controlled rectifier (SCR) to latch, resulting in high current
flowing from the output to the input. Thus, to prevent possible damage to the regulator in any application where
the output may be pulled above the input, or the input may be shorted to ground, connect an external Schottky
diode between the output and input. With the anode on the output, this Schottky diode limits the reverse voltage
across the output and input pins to approximately 0.3 V (as shown in Figure 8-2), preventing the regulator
internal diode from forward biasing.
Schottky
VIN
VOUT
LP2985
Figure 8-2. External Schottky Diode to Prevent Reverse Current Through the Device
14
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8.2 Typical Application
Figure 8-3 shows the standard usage of the LP2985 as a low-dropout regulator.
LP2985
VIN
1
VOUT
5
2.2 µF
1 µF
GND
ON/OFF
2
3
4
BYPASS
10 nF
Figure 8-3. LP2985 Typical Application
8.2.1 Design Requirements
Minimum COUT value for stability (can be increased without limit for improved stability and transient response)
ON/OFF must be actively terminated. Connect to VIN if shutdown feature is not used.
Optional BYPASS capacitor for low-noise operation.
8.2.2 Detailed Design Procedure
8.2.2.1 ON/OFF Operation
The LP2985 allows for a shutdown mode via the ON/OFF pin. Driving the pin LOW (≤ 0.3 V) turns the device
OFF; conversely, a HIGH (≥ 1.6 V) turns the device ON. If the shutdown feature is not used, connect ON/OFF to
the input to ensure that the regulator is on at all times. For proper operation, do not leave ON/OFF unconnected,
and apply a signal with a slew rate of ≥ 40 mV/μs.
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3.4
200
3.38
150
3.38
150
3.36
100
3.36
100
3.3
0
−50
VO
3.28
−100
3.26
−150
3.24
−200
−250
3.22
IL
3.34
3.32
3.3
VO = 3.3 V
Cbyp = 10 nF
DIL = 150 mA
3.4
200
3.38
150
3.36
100
3.28
−100
3.26
−150
3.24
−200
3.22
−250
Figure 8-5. Load Transient Response
3.41
5.5
3.39
5
VI
VO = 3.3 V
Cbyp = 0 nF
DIL = 150 mA
0
−50
VO
3.28
−100
3.26
−150
3.24
−200
Output Voltage − (V)
50
IL
Load Current − (mA)
Output Voltage − (V)
3.37
3.3
−50
20 ms/div→
Figure 8-4. Load Transient Response
3.32
0
VO
20 ms/div→
3.34
50
3.35
4.5
VO = 3.3 V
Cbyp = 0 nF
IO = 150 mA
4
3.5
3.33
3.31
VO
3
2.5
3.29
3.27
−250
3.22
2
20 ms/div→
20 ms/div→
Figure 8-7. Line Transient Response
5.5
3.41
5.5
3.39
5
3.39
5
4.5
3.37
VI
3.35
VO = 3.3 V
Cbyp = 10 nF
IO = 150 mA
4
3.33
3.5
3.31
3.29
VO
3.27
Output Voltage − (V)
3.41
Input Voltage − (V)
Output Voltage − (V)
Figure 8-6. Load Transient Response
3.37
3.35
VI
VO = 3.3 V
Cbyp = 0 nF
IO = 1 mA
4.5
4
3.33
3.5
3
3.31
3
2.5
3.29
2.5
VO
2
3.27
2
20 ms/div→
20 ms/div→
Figure 8-8. Line Transient Response
16
Input Voltage − (V)
3.32
50
IL
VO = 3.3 V
Cbyp = 10 nF
DIL = 100 mA
Input Voltage − (V)
3.34
Load Current − (mA)
200
Output Voltage − (V)
3.4
Load Current − (mA)
Output Voltage − (V)
8.2.3 Application Curves
Figure 8-9. Line Transient Response
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5.5
3.41
4
10
VO
3
5
3.39
8
3.5
3.31
3
VO
1
6
0
VO = 3.3 V
Cbyp = 0
IO = 150 mA
−1
4
−2
VON/OFF
3.29
3.27
2.5
−3
2
−4
0
100 ms/div→
100 ms/div→
Figure 8-10. Line Transient Response
Figure 8-11. Turn-On Time
10
4
2
10
4
VO
VO
3
3
8
8
2
6
0
−1
VO = 3.3 V
Cbyp = 100 pF
ILOAD = 150 mA
4
−2
VON/OFF
Output Voltage − (V)
1
VON/OFF − (V)
Output Voltage − (V)
2
1
6
0
VO = 3.3 V
Cbyp = 1 nF
ILOAD = 150 mA
−1
4
VON/OFF − (V)
3.33
VO = 3.3 V
Cbyp = 10 nF
IO = 1 mA
VON/OFF − (V)
4
3.35
2
Output Voltage − (V)
Output Voltage − (V)
4.5
Input Voltage − (V)
VIN
3.37
VON/OFF
−2
2
2
−3
−3
0
−4
0
−4
2 ms/div→
200 ms/div→
Figure 8-13. Turn-On Time
Figure 8-12. Turn-On Time
4
Input
10
3
8
1
6
0
−1
4
VO = 3.3 V
Cbyp = 10 nF
ILOAD = 150 mA
VON/OFF − (V)
Output Voltage − (V)
2
Output
−2
2
−3
0
−4
20 ms/div→
Figure 8-14. Turn-On Time
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9 Power Supply Recommendations
A power supply can be used at the input voltage within the ranges given in the Recommended Operating
Conditions table. Use bypass capacitors as described in the Layout Guidelines section.
10 Layout
10.1 Layout Guidelines
•
•
•
Bypass the input pin to ground with a bypass-capacitor.
The optimum placement of the bypass capacitor is closest to the VIN of the device and GND of the system.
Care must be taken to minimize the loop area formed by the bypass-capacitor connection, the VIN pin, and
the GND pin of the system.
For operation at full-rated load, use wide trace lengths to eliminate IR drop and heat dissipation.
10.2 Layout Example
VIN
VOUT
1
5
1 F
2.2 F
2
LP2985
3
4
ON/OFF
tied to VIN
if not used
10 nF
Figure 10-1. Layout Diagram
18
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11 Device and Documentation Support
11.1 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. Click on
Subscribe to updates 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.
11.2 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is 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.
11.3 Trademarks
TI E2E™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
11.4 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.
11.5 Glossary
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
14-Oct-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)
LP2985-10DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LRCG
Samples
LP2985-10DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LRCG
Samples
LP2985-18DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPHG, LPHL)
Samples
LP2985-18DBVRE4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPHG
Samples
LP2985-18DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPHG
Samples
LP2985-18DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPHG, LPHL)
Samples
LP2985-18DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPHG
Samples
LP2985-25DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPLG, LPLL)
Samples
LP2985-25DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPLG, LPLL)
Samples
LP2985-28DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPGG, LPGL)
Samples
LP2985-28DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPGG, LPGL)
Samples
LP2985-28DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPGG
Samples
LP2985-29DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPMG, LPML)
Samples
LP2985-30DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPNG, LPNL)
Samples
LP2985-30DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPNG, LPNL)
Samples
LP2985-30DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPNG, LPNL)
Samples
LP2985-30DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPNG, LPNL)
Samples
LP2985-33DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPFG, LPFL)
Samples
LP2985-33DBVRE4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPFG
Samples
LP2985-33DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPFG
Samples
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
14-Oct-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)
LP2985-33DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPFG, LPFL)
Samples
LP2985-33DBVTE4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPFG
Samples
LP2985-33DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPFG
Samples
LP2985-50DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPSG, LPSL)
Samples
LP2985-50DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPSG, LPSL)
Samples
LP2985-50DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPSG, LPSL)
Samples
LP2985-50DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPSG, LPSL)
Samples
LP2985A-10DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LRDG
Samples
LP2985A-10DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LRDG
Samples
LP2985A-18DBVJ
ACTIVE
SOT-23
DBV
5
10000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPTL
Samples
LP2985A-18DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPTG, LPTL)
Samples
LP2985A-18DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPTG
Samples
LP2985A-18DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPTG, LPTL)
Samples
LP2985A-25DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPUG, LPUL)
Samples
LP2985A-25DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPUG, LPUL)
Samples
LP2985A-25DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPUG, LPUL)
Samples
LP2985A-28DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPJG, LPJL)
Samples
LP2985A-28DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPJG, LPJL)
Samples
LP2985A-29DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LPZG, LPZL)
Samples
LP2985A-30DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LRAG, LRAL)
Samples
LP2985A-30DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LRAG, LRAL)
Samples
Addendum-Page 2
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
14-Oct-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)
LP2985A-33DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPKG, LPKL)
Samples
LP2985A-33DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPKG
Samples
LP2985A-33DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU | SN
Level-1-260C-UNLIM
-40 to 125
(LPKG, LPKL)
Samples
LP2985A-33DBVTE4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPKG
Samples
LP2985A-33DBVTG4
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
LPKG
Samples
LP2985A-50DBVR
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LR1G, LR1L)
Samples
LP2985A-50DBVRG4
ACTIVE
SOT-23
DBV
5
3000
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LR1G, LR1L)
Samples
LP2985A-50DBVT
ACTIVE
SOT-23
DBV
5
250
RoHS & Green
NIPDAU
Level-1-260C-UNLIM
-40 to 125
(LR1G, LR1L)
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