Order
Now
Product
Folder
Support &
Community
Tools &
Software
Technical
Documents
Reference
Design
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
LP38798 800-mA Ultra-Low-Noise, High-PSRR LDO
1 Features
3 Description
•
The LP38798-ADJ is a high-performance, low-noise
LDO that can supply up to 800 mA output current.
Designed to meet the requirements of sensitive
RF/Analog circuitry, the LP38798-ADJ implements a
novel linear topology on an advanced CMOS process
to deliver ultra-low output noise and high PSRR at
switching
power
supply
frequencies.
The
LP38798SD-ADJ is stable with both ceramic and
tantalum output capacitors and requires a minimum
output capacitance of only 1 µF for stability.
1
•
•
•
•
•
•
•
•
Wide Operating Input Voltage Range:
3 V to 20 V
Ultra-Low Output Noise: 5 µVRMS
(10 Hz to 100 kHz)
High PSRR: 90 dB at 10 kHz, 60 dB at 100 kHz
±1% Output Voltage Initial Accuracy (TJ = 25°C)
Very Low Dropout: 200 mV (Typical) at 800 mA
Stable with Ceramic or Tantalum Output
Capacitors
Excellent Line and Load Transient Response
Current Limit and Overtemperature Protection
Create a Custom Design Using the LP38798 With
the WEBENCH® Power Designer
The LP38798-ADJ can operate over a wide input
voltage range (3 V to 20 V) making it well suited for
many post-regulation applications.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
WSON (12)
4.00 mm × 4.00 mm
2 Applications
LP38798
•
•
•
•
•
•
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
RF Power Supplies: PLLs, VCOs, Mixers, LNAs
Telecom Infrastructure
Wireless Infrastructure
Very Low-Noise Instrumentation
Precision Power Supplies
High-Speed, High-Precision Data Converters
space
space
space
space
space
space
Simplified Schematic
1
VIN
2
3
+
VEN
IN
OUT
IN
OUT
OUT(FB)
IN(CP)
12
VOUT
11
10
COUT
LP38798
CIN
4
CP
SET
EN
FB
9
CCP
R1
5
8
ON
OFF
6
7
R2
GND
GND(CP)
DAP
GND
GND
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.
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
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
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
7
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 14
7.1
7.2
7.3
7.4
7.5
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
Programming...........................................................
14
14
14
15
16
8
Application and Implementation ........................ 17
8.1 Application Information............................................ 17
8.2 Typical Application: VOUT = 5 V ............................. 17
9 Power Supply Recommendations...................... 20
10 Layout................................................................... 20
10.1
10.2
10.3
10.4
Layout Guidelines .................................................
Layout Example ....................................................
Thermal Considerations ........................................
Estimating the Junction Temperature ...................
20
20
20
20
11 Device and Documentation Support ................. 21
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Device Support......................................................
Documentation Support ........................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
21
21
21
21
21
21
22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
Changes from Revision E (August 2016) to Revision F
•
Page
Created Rev F toonly add WEBENCH links to data sheet..................................................................................................... 1
Changes from Revision D (June 2016) to Revision E
Page
•
Changed title of data sheet and updated list of Applications ................................................................................................ 1
•
Changed first wording of first sentence of Description .......................................................................................................... 1
Changes from Revision C (June2016) to Revision D
Page
•
Added 1.2 V row to Table 1 ................................................................................................................................................. 16
•
Changed "Value for R2 = 12.9 kΩ and 100 kΩ" to "R2 = 12.9 kΩ minimum to 100 kΩ maximum"..................................... 19
•
Changed "value of 13.3 kΩ" to "value of 15 kΩ for R2" ....................................................................................................... 19
•
Changed "for R1 is" to "needed for R1 to provide an output voltage of 5 V is" ................................................................... 19
Changes from Revision B (December 2014) to Revision C
Page
•
Changed "linear regulator" to "LDO" on page 1; add top nav icon for reference design ....................................................... 1
•
Changed Handling Ratings table to ESD Ratings table; move storage temperature to Abs Max table ............................... 4
•
Added links for Community Resources ............................................................................................................................... 21
Changes from Revision A (May 2013) to Revision B
•
2
Page
Added Device Information and Handling Rating tables, Feature Description, Device Functional Modes, Application
and Implementation, Power Supply Recommendations, Layout, Device and Documentation Support, and
Mechanical, Packaging, and Orderable Information sections; updated Thermal Information; moved some curves to
Application Curves section ..................................................................................................................................................... 1
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
5 Pin Configuration and Functions
DNT Package
12-Pin WSON
Top View
1
12 OUT
IN
2
11 OUT
IN(CP)
3
CP
4
EN
5
GND(CP)
6
Exposed Pad
on Bottom
(DAP)
LP38798SD
IN
10 OUT(FB)
9
SET
8
FB
7
GND
Connect WSON DAP to GND at Pins 6 and 7.
Pin Functions
PIN
NUMBER
1, 2
NAME
I/O
DESCRIPTION
IN
I
Device unregulated input voltage pins. Connect pins together at the package.
3
IN(CP)
I
Charge pump input voltage pin. Connect directly to pins 1 and 2 at the package.
4
CP
O
Charge pump output. See Charge Pump section in Application and Implementation for more
information.
5
EN
I
Enable pin. This pin has an internal pullup to turn the LDO output on by default. A logic low
level turns the LDO output Off, and reduce the operating current of the device. See Enable
Input Operation section in Application and Implementation for more information.
6
GND(CP)
—
Device charge pump ground pin.
7
GND
—
Device analog ground pin.
8
FB
i
9
SET
I/O
10
Feedback pin for programming the output voltage.
Reference voltage output, and noise filter input. A feedback resistor divider network from this
pin to FB and GND will set the output voltage of the device.
OUT(FB)
I
OUT buffer feedback input pin. Connect directly to pins 11 and 12 at the package.
11, 12
OUT
O
Device regulated output voltage pins. Connect pins together at the package.
Exposed Pad
DAP
—
The exposed die attach pad on the bottom of the package must be connected to a copper
thermal pad on the PCB at ground potential. Connect to ground potential or leave floating. Do
not connect to any potential other than the same ground potential seen at device pins 6
(GND(CP)) and 7 (GND). See Thermal Considerations section in Layout for more information.
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
3
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
VIN, VIN(CP)
–0.3
22
V
VOUT, VOUT(FB)
–0.3
VIN + 0.3
V
VSET
–0.3
VIN + 0.3
V
VFB
–0.3
VIN + 0.3
V
VEN
–0.3
6
V
Power dissipation (2)
Internally Limited
IOUT (Survival)
Internally Limited
Storage temperature, Tstg
(1)
(2)
–65
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 value of RθJA for the WSON package is dependent on PCB copper area, copper thickness, the number of copper layers in the PCB,
and the number of thermal vias under the exposed thermal pad (DAP). Exceeding the maximum allowable power dissipation will cause
excessive die temperature, and the regulator may go into thermal shutdown. See Thermal Considerations.
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 JESD22C101 (2)
±250
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
MIN
Input voltage, VIN
Output voltage, VOUT
Enable voltage, VEN
Junction temperature, TJ
MAX
UNIT
3
20
V
1.2
(VIN – VDO)
V
0
5
V
–40
125
°C
6.4 Thermal Information
LP38798
THERMAL METRIC
(1)
DNT (WSON)
UNIT
12 PINS
RθJA
Junction-to-ambient thermal resistance
35.4
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
29.4
°C/W
RθJB
Junction-to-board thermal resistance
12.6
°C/W
ψJT
Junction-to-top characterization parameter
0.2
°C/W
ψJB
Junction-to-board characterization parameter
12.8
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
2.6
°C/W
(1)
4
For more information about traditional and new thermal metrics, see Semiconductor and IC Package Thermal Metrics.
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
6.5 Electrical Characteristics
Unless otherwise stated the following conditions apply: VIN = 5.5 V, VSET = 5 V, CCP = 10 nF X7R, CIN = 10 μF, 50-mΩ
tantalum, COUT = 10 μF X7R MLCC, IOUT = 10 mA, and TJ = –40°C to +125°C.
MIN (1)
TYP (2)
MAX (1)
VIN = 5.5 V
TJ = 25°C
1.188
1.2
1.212
5.5 V ≤ VIN ≤ 20 V
1.176
1.2
1.224
0
3.5
16
mV
0
1
µA
67.8
μA
PARAMETER
VFB
Feedback voltage
VOS
VOUT – VSET
IFB
Feedback pin current
ISET
SET pin internal current
sink
TEST CONDITIONS
VFB = 1.2 V
VIN = 3 V, VSET = 2.5 V
VIN = 5.5 V, VSET = 5 V
52
71
ΔVOUT /
ΔVIN
Line regulation (3)
5.5 V ≤ VIN ≤ 20 V
IOUT = 10 mA
ΔVOUT /
ΔIOUT
Load regulation (4)
VIN = 5.5 V
10 mA ≤ IOUT ≤ 800 mA
VDO
Dropout voltage (5)
IOUT = 800 mA
UVLO
Undervoltage lock-out
VIN Rising until output is On
ΔUVLO
UVLO hysteresis
VIN Falling from > UVLO threshold until
output is Off
180
IGND
Ground pin current (6)
IOUT = 800 mA
1.4
2.25
VIN = 20 V, IOUT = 800 mA
1.6
2.51
IQ
Ground pin current,
quiescent (6)
IOUT = 0 mA
1.4
2.1
VIN = 20 V, IOUT = 0 mA
1.5
2.2
ISD
Ground pin current,
shutdown (6)
VEN = 0 V
ISC
Short-circuit current
RLOAD = 0 Ω
VCP – VIN
tSTART
Start-up time
PSRR
(1)
(2)
(3)
(4)
(5)
(6)
Power Supply Rejection
Ratio
V
46
25.2
VIN = 12.5 V, VSET = 12 V
ΔVCP
UNIT
2.47
VIN = 20 V, VEN = 0 V
850
0.005
%/V
–0.2
%/A
200
420
mV
2.65
2.83
V
mV
9
20
12
40
1200
1600
2.8
VIN = 20 V
2.3
From VEN > VEN(ON) to VOUT ≥ 98% of
VOUT(NOM)
155
VOUT = 1.2 V, f = 10 kHz
110
VOUT = 5 V, f = 10 kHz
90
VOUT = 1.2 V, f = 100 kHz
90
VOUT = 5 V, f = 100 kHz
60
VOUT = 1.2 V, f = 1 MHz
70
VOUT = 5 V, f = 1 MHz
60
mA
mA
µA
mA
V
300
µs
dB
Minimum and maximum limits are ensured through test, design, or statistical correlation over the operating junction temperature (TJ )
range of –40°C to 125°C, unless otherwise stated.
Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only.
Line Regulation: % change in VOUT(NOM) for every 1V change in VIN= (( ΔVOUT / VOUT(NOM)) / ΔVIN ) × 100%
Load Regulation: % change in VOUT(NOM) for every 1A change in IOUT = (( ΔVOUT / VOUT(NOM) ) / ΔIOUT ) × 100%
Dropout voltage (VDO) is defined as the differential voltage measured between VOUT and VIN when VIN, falling from VIN = VOUT + 1 V,
causes VOUT to drop 2% below the value measured with VIN = VOUT + 1 V. Dropout voltage specification does not apply when the
programmed output voltage is below the Minimum Operating Input Voltage.
Ground pin current is the sum of the current in both GND pins (pin 4 and pin 5) only, and does not include current from the SET pin.
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
5
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
Electrical Characteristics (continued)
Unless otherwise stated the following conditions apply: VIN = 5.5 V, VSET = 5 V, CCP = 10 nF X7R, CIN = 10 μF, 50-mΩ
tantalum, COUT = 10 μF X7R MLCC, IOUT = 10 mA, and TJ = –40°C to +125°C.
PARAMETER
eN
Output noise voltage (RMS)
TEST CONDITIONS
MIN (1)
TYP (2)
VIN = 3 V, VOUT = 1.2 V
COUT = 1 µF X7R
BW = 10 Hz to 100 kHz
4.96
VIN = 3 V, VOUT = 1.2 V
BW = 10 Hz to 100 kHz
5.21
VIN = 3 V, VOUT = 1.2 V
BW = 10 Hz to 10 MHz
11.53
VIN = 6 V, VOUT = 5 V
COUT = 1 µF X7R
BW = 10 Hz to 100 kHz
5.38
VIN = 6 V, VOUT = 5 V
BW = 10 Hz to 100 kHz
5.43
VIN = 6 V, VOUT = 5 V
BW = 10 Hz to 10 MHz
11.58
MAX (1)
UNIT
µV(RMS)
ENABLE INPUT
VEN(ON)
Enable ON threshold
voltage
VEN rising from 500 mV until Output is ON
ΔVEN
Enable threshold voltage
hysteresis
VEN falling from VEN(ON)
IEN(IL)
EN pin pullup current
VEN = 500 mV
2
3
IEN(IH)
EN pin pullup current
VEN = 2 V
2
3
VEN(CLAM
Enable pin clamp voltage
EN pin = Open
5
1.14
1.24
1.34
110
V
mV
µA
V
P)
THERMAL SHUTDOWN
TSD
Thermal shutdown
Junction temperature (TJ) rising
ΔTSD
Thermal shutdown
hysteresis
Junction temperature (TJ) falling from TSD
6
Submit Documentation Feedback
170
12
°C
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
6.6 Typical Characteristics
120
120
110
110
100
100
90
90
80
80
PSRR (dB)
PSRR (dB)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
70
60
10 mA
50
100 mA
40
30
200 mA
20
400 mA
10
70
60
10 mA
50
100 mA
40
VIN = 5.5 V
VOUT = 5.0 V
COUT = 10 µF MLCC
800 mA
30
200 mA
20
400 mA
10
0
VIN = 6.0 V
VOUT = 5.0 V
COUT = 10 µF MLCC
800 mA
0
10
100
1k
10k
100k
1M
10M
FREQUENCY (Hz)
10
100
1k
Figure 1. PSRR
1M
10M
C008
1
Cout = 1 µF
Cout = 1 µF
Cout = 10 µF
Cout = 10 µF
OUTPUT NOISE (µV¥Hz)
OUTPUT NOISE (µV¥Hz)
100k
Figure 2. PSRR
1
0.1
0.01
VIN = 3.0 V
VOUT = 1.2 V
IOUT = 500 mA
0.001
0.1
0.01
VIN = 6.0 V
VOUT = 5.0 V
IOUT = 500 mA
0.001
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
10M
10
100
110
100
100
90
90
80
80
PSRR (dB)
110
70
VOUT = 5.0 V
COUT = 10 µF MLCC
IOUT = 10 mA
40
100k
1M
10M
C010
Figure 4. Noise Density
120
50
10k
FREQUENCY (Hz)
120
60
1k
C009
Figure 3. Noise Density
PSRR (dB)
10k
FREQUENCY (Hz)
C007
70
VOUT = 5.0 V
COUT = 10 µF MLCC
IOUT = 100 mA
60
50
40
30
30
20
10
Vin = 5.5V
20
Vin = 6.0V
10
0
Vin = 5.5V
Vin = 6.0V
0
10
100
1k
10k
100k
FREQUENCY (Hz)
1M
10M
10
C001
Figure 5. PSRR
100
1k
10k
100k
1M
FREQUENCY (Hz)
10M
C002
Figure 6. PSRR
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
7
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
Typical Characteristics (continued)
120
120
110
110
100
100
90
90
80
80
PSRR (dB)
PSRR (dB)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
70
VOUT = 5.0 V
COUT = 10 µF MLCC
IOUT = 200 mA
60
50
40
70
VOUT = 5.0 V
COUT = 10 µF MLCC
IOUT = 400 mA
60
50
40
30
30
20
10
Vin = 5.5V
20
Vin = 5.5V
Vin = 6.0V
10
Vin = 6.0V
0
0
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
10M
10
100
1k
110
110
100
100
90
90
80
80
70
VOUT = 5.0 V
COUT = 10 µF MLCC
IOUT = 800 mA
50
40
10M
C004
VIN = 5.5 V
VOUT = 5.0 V
IOUT = 800 mA
60
50
30
20
20
Vin = 5.5V
10
Cout = 10 µF
10
Vin = 6.0V
0
Cout = 50 µF
0
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
10M
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
C005
Figure 9. PSRR
10M
C006
Figure 10. PSRR
3.0
1.40
2.9
Rising VIN (ON)
2.8
ENABLE THRESHOLDS (V)
UVLO THRESHOLDS (V)
1M
70
40
30
2.7
2.6
2.5
2.4
2.3
Falling VIN (OFF)
2.2
1.35
Rising VEN (ON)
1.30
1.25
1.20
1.15
1.10
Falling VEN (OFF)
1.05
2.1
2.0
1.00
-50
-25
0
25
50
75
100
TEMPERATURE, TJ (ƒC)
125
-50
C023
Figure 11. UVLO Thresholds vs TJ
8
100k
Figure 8. PSRR
120
PSRR (dB)
PSRR (dB)
Figure 7. PSRR
120
60
10k
FREQUENCY (Hz)
C003
Submit Documentation Feedback
-25
0
25
50
75
100
TEMPERATURE, TJ (ƒC)
125
C024
Figure 12. Enable Thresholds vs TJ
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
Typical Characteristics (continued)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
2.5
1.35
2.0
Rising VEN (ON)
1.30
VIN = 5.5 V
VOUT = 1.2 V
1.5
1.25
VOLTS (V)
ENABLE THRESHOLDS (V)
1.40
1.20
1.15
1.0
Ven
0.5
Vout 125ƒC
1.10
0.0
1.05
Vout 25ƒC
Falling VEN (OFF)
Vout -40ƒC
1.00
-0.5
0
2
4
6
8
10
12
14
16
18
TIME (50µs/DIV)
20
INPUT VOLTAGE, VIN (V)
C025
C026
Figure 13. Enable Thresholds vs VIN
Figure 14. Start-Up Time
2.5
5.5
5.0
2.0
4.0
VIN = 5.5 V
VOUT = 1.5 V
3.5
VOLTS (V)
1.5
VOLTS (V)
VIN = 5.5 V
VOUT = 5.0 V
4.5
1.0
Ven
0.5
0.0
2.5
2.0
Ven
1.5
Vout 125ƒC
1.0
Vout -40ƒC
Vout 25ƒC
0.5
Vout 25ƒC
0.0
Vout -40ƒC
-0.5
3.0
Vout 125ƒC
-0.5
TIME (50µs/DIV)
TIME (50µs/DIV)
C027
C028
Figure 15. Start-Up Time
Figure 16. Start-Up Time
6.0
0.5
Vout = 5.0V
0.4
Vout = 3.3V
Vout = 1.2V
4.0
VOUT (V)
VIN = 5.5 V
Normalized to TJ = 25ƒC
0.3
VFB VARIATION (%)
5.0
3.0
2.0
UVLO
0.2
0.1
0.0
-0.1
-0.2
-0.3
1.0
-0.4
0.0
-0.5
0.0
1.0
2.0
3.0
4.0
VIN (V)
5.0
6.0
-50
C038
Figure 17. VOUT vs Rising VIN
-25
0
25
50
75
100
TEMPERATURE, TJ (ƒC )
125
C029
Figure 18. VFB Variation vs TJ
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
9
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
20
5.5
5.0
VEN = 0.0V
16
4.5
14
4.0
VEN(CLAMP) (V)
INPUT CURRENT, IIN (µA)
18
12
10
8
6
4
2
3.5
3.0
2.5
2.0
125ƒC
1.5
125ƒC
25ƒC
1.0
25ƒC
0.5
-40ƒC
0
-40ƒC
0.0
0
2
4
6
8
10
12
14
16
18
INPUT VOLTAGE, VIN (V)
20
0
2
4
6
8
10
12
14
16
18
INPUT VOLTAGE, VIN (V)
C030
Figure 19. IN Pin Current vs VIN
20
C031
Figure 20. VEN(CLAMP) vs VIN
3.0
350
DROPOUT VOLTAGE, VDO (mV)
IEN(IL) PULL-UP CURRENT (µA)
125ƒC
2.5
2.0
1.5
1.0
125ƒC
0.5
25ƒC
300
25ƒC
250
-40ƒC
200
VOUT = 3.0V
150
100
50
-40ƒC
0.0
0
2
4
6
8
10
12
14
16
18
INPUT VOLTAGE, VIN (V)
0
0.01
20
Figure 21. Enable Pin Pull-Up Current vs VIN
2.0
125ƒC
300
25ƒC
250
-40ƒC
200
VOUT = 5.0V
VIN = 5.5 V
VOUT = 5.0 V
IOUT = 800 mA
Normalized to 25ƒC
1.5
VOUT VARIATION (%)
DROPOUT VOLTAGE, VDO (mV)
1
C033
Figure 22. Dropout Voltage vs Output Current
350
150
100
50
1.0
0.5
0.0
-0.5
-1.0
-1.5
0
0.01
-2.0
0.1
1
OUTPUT CURRENT (A)
-50
C034
Figure 23. Dropout Voltage vs Output Current
10
0.1
OUTPUT CURRENT (A)
C032
Submit Documentation Feedback
-25
0
25
50
75
TEMPERATURE, TJ (ƒC)
100
125
C035
Figure 24. VOUT Variation vs TJ
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
Typical Characteristics (continued)
2.0
0.05
1.8
0.04
LINE REGULATION (%/V)
LOAD REGULATION (%/A)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
1.6
1.4
1.2
1.0
0.8
0.6
VIN = 5.5 V
VOUT = 5.0 V
ûIOUT = 10 mA to 800 mA
0.4
0.2
ûVIN = 5.5 V to 15 V
VOUT = 5.0 V
IOUT = 10 mA
0.03
0.02
0.01
0.00
-0.01
-0.02
-0.03
-0.04
0.0
-0.05
-50
-25
0
25
50
75
100
TEMPERATURE, TJ (ƒC)
125
-50
-25
0
25
50
75
100
TEMPERATURE, TJ (ƒC)
C036
Figure 25. Load Regulation vs TJ
125
C037
Figure 26. Line Regulation vs TJ
1.5
CURRENT LIMIT, ISC (A)
1.4
VIN
1V
/DIV
1.3
VIN = 7.0 V
VIN = 6.0 V
VOUT = 5.0 V
COUT = 10 µF
IOUT = 800 mA
1.2
1.1
ûVOUT
1.0
ûVOUT
20 mV
/DIV
0.9
0.8
-50
-25
0
25
50
75
100
TEMPERATURE (ƒC)
TIME (500µs/DIV)
125
C039
C022
Figure 27. Current Limit, ISC vs TJ
VIN
1V
/DIV
Figure 28. Line Transient
VIN
1V
/DIV
VIN = 7.0V
VIN = 6.0V
VOUT = 5.0 V
COUT = 10 µF
IOUT = 400 mA
VIN = 7.0 V
VOUT = 5.0 V
COUT = 10 µF
IOUT = 10 mA
ûVOUT
ûVOUT
20 mV
/DIV
VIN = 6.0 V
ûVOUT
ûVOUT
20 mV
/DIV
TIME (500µs/DIV)
TIME (500µs/DIV)
C021
Figure 29. Line Transient
C020
Figure 30. Line Transient
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
11
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
Typical Characteristics (continued)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
VIN
1V
/DIV
VOUT = 1.2 V
COUT = 10 µF
IOUT = 800 mA
VOUT = 1.2 V
COUT = 10 µF
IOUT = 400 mA
VIN = 4.3 V
VIN = 3.3 V
VIN = 4.3 V
VIN = 3.3 V
VIN
1V
/DIV
ûVOUT
ûVOUT
ûVOUT
20 mV
/DIV
ûVOUT
20 mV
/DIV
TIME (500µs/DIV)
TIME (500µs/DIV)
C019
C018
Figure 31. Line Transient
VIN
1V
/DIV
VOUT = 1.2 V
COUT = 10 µF
IOUT = 10 mA
Figure 32. Line Transient
IOUT
200 mA
/DIV
VIN = 4.3 V
VIN = 3.3 V
IOUT = 800 mA
IOUT = 400 mA
VIN = 5.5 V
VOUT = 5.0 V
COUT = 10 µF
ûVOUT
ûVOUT
20 mV
/DIV
ûVOUT
20 mV
/DIV
ûVOUT
TIME (500µs/DIV)
TIME (500µs/DIV)
C017
C016
Figure 33. Line Transient
IOUT
200 mA
/DIV
VIN = 5.5 V
VOUT = 5.0 V
COUT = 10 µF
Figure 34. Load Transient
IOUT
200 mA
/DIV
IOUT = 800 mA
VIN = 5.5 V
VOUT = 5.0 V
COUT = 10 µF
IOUT = 400 mA
IOUT = 10 mA
IOUT = 10 mA
ûVOUT
20 mV
/DIV
ûVOUT
20 mV
/DIV
ûVOUT
TIME (500µs/DIV)
ûVOUT
TIME (500µs/DIV)
C015
Figure 35. Load Transient
12
C014
Figure 36. Load Transient
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
Typical Characteristics (continued)
Unless otherwise specified: VIN = 5.5 V, VOUT = 5 V, IOUT = 10 mA, COUT = 10 µF MLCC 16 V X7R, and TJ = 25°C.
IOUT
200 mA
/DIV
IOUT
200 mA
/DIV
IOUT = 800 mA
VIN = 3.3 V
VOUT = 1.2 V
COUT = 10 µF
VIN = 3.3 V
VOUT = 1.2 V
COUT = 10 µF
IOUT = 800 mA
IOUT = 400 mA
IOUT = 10 mA
ûVOUT
20 mV
/DIV
ûVOUT
20 mV
/DIV
ûVOUT
ûVOUT
TIME (500µs/DIV)
TIME (500µs/DIV)
C013
C012
Figure 37. Load Transient
IOUT
200 mA
/DIV
Figure 38. Load Transient
VIN = 3.3 V
VOUT = 1.2 V
COUT = 10 µF
IOUT = 400 mA
IOUT = 10 mA
ûVOUT
20 mV
/DIV
ûVOUT
TIME (500µs/DIV)
C011
Figure 39. Load Transient
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
13
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
7 Detailed Description
7.1 Overview
The LP38798 is a positive voltage (20 V), ultra-low-noise (5 µVRMS), low-dropout (LDO) regulator capable of
supplying a well-regulated, low-noise voltage to an 800-mA load. The LP38798 uses an advanced design with a
CMOS process to deliver ultra low output noise and high PSRR at switching power supply (SMPS) frequencies.
7.2 Functional Block Diagram
IN
OUT
Active Ripple
Rejection
IN
UVLO
+
-
200 mV
IN(CP)
OUT
PMOS
Current
Limit
OUT(FB)
Thermal
Shutdown
98%
Charge Pump
3.5 MHz
tau= 2s
CP
SET
IEN
2 PA
99.5%
+
-
ISET
52 PA
EN
FB
5V
1.24V
VREF
1.200V
GND(CP)
GND
7.3 Feature Description
7.3.1 Noise Filter
Any noise at LP38798 SET pin is reduced by an internal passive, first order low-pass RC filter before it is passed
to the output buffer stage. The low-pass filter has a –3-dB cut-off frequency of approximately 0.08 Hz.
To keep the low-pass filter from interfering with the output voltage rise time at start-up, a voltage comparator
keeps the filter in a fast-charge mode while the output voltage (VOUT) is less than 99.5% of the SET pin voltage
(VSET) . When the rising VOUT is within 0.5% of VSET the fast-charge mode ends, and VOUT will rise the final 0.5%
based on the RC time constant (τ = 2s) of the filter.
Should VOUT be more than 2% above the VSET voltage, a voltage comparator will put the filter into the fast-charge
mode to allow the filter to discharge and VOUT to fall a value closer to VSET. When the falling VOUT is within 2% of
VSET the fast-charge mode ends, and VOUT will fall the final 2% based on the RC time constant (τ = 2s) of the
filter.
If the input voltage has an extended rise time, the output voltage may exhibit a stair-case waveform as the fastcharge mode is activated and de-activated as VSET rises with VIN, and VOUT follows. Once the VIN has risen
above the programmed VSET voltage, and VOUT is within 0.5% of VSET, the stair-case behavior will end.
14
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
Feature Description (continued)
7.3.2 Enable Input Operation
The Enable pin (EN) is pulled high internally by a 2 μA (typical) current source from the IN pin, and internally
clamped at 5 V (typical) by a zener. Pulling the EN pin low, by sinking the IEN current to ground, will turn the
output off.
If the EN function is not needed the EN pin should be left open (floating). Do not connect the EN pin directly to
VIN if there is any possibility that VIN might exceed 5.5 V (that is, EN pin AbsMax). If external pullup is required,
the external current into the EN pin should be limited to no more than 10 μA.
RPULL-UP > (VPULL-UP – 5 V) / 10 μA )
(1)
7.3.3 Undervoltage Lockout (UVLO)
The LP38798 incorporates UVLO. The UVLO circuit monitors the input voltage and keeps the LP38798 disabled
while a rising VIN is less than 2.65 V (typical). The rising UVLO threshold is approximately 350 mV below the
recommended minimum operating VIN of 3 V.
7.3.4 Output Current Limiting
The LP38798 incorporates active output current limiting. The threshold for the output current limiting is set well
above the ensured output operating current such that it does not interfere with normal operation.
Note that output current limiting is provided as a safety feature and is outside the recommended operating
conditions. Operation at the current limit is not recommended as the device junction temperature (TJ) will rise
rapidly and operation will likely cross into thermal shutdown behavior .
7.3.5 Thermal Shutdown
The LP38798 includes thermal protection that will shut-off the output current when activated by excessive device
dissipation. Thermal shutdown (TSD) will occur when the junction temperature has risen to 170°C. The junction
temperature must fall typically 12°C from the shutdown temperature for the output current to be restored.
Junction temperature is calculated from the formula in Equation 2:
TJ = (TA + (PD × RθJA))
(2)
Where the power being dissipated, PD, is defined as:
PD = ((VIN – VOUT) × IOUT)
(3)
NOTE
Thermal shutdown is provided as a safety feature and is outside the specified Operating
Ratings temperature range. Operation with a junction temperature (TJ) above 125°C is not
recommended as the device behavior is not specified.
7.4 Device Functional Modes
The LP38798 has two functional modes:
1. Enabled: When the EN pin voltage is above the VEN(ON) threshold, and VIN is above the UVLO threshold, the
device is enabled.
2. Disabled: When the EN pin voltage is below the (VEN(ON) + ΔVEN) threshold, or VIN is below the UVLO
threshold, the device is disabled.
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
15
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
7.5 Programming
7.5.1 Programming the Output Voltage
Current sourced from the SET pin, through R1 and R2, must be kept to less than 100 µA. The minimum allowed
value for R2 is 12.9 kΩ.
ISET = VFB / R2
R2MIN = VFB(MAX) / 100 μA
R2MIN = 12.9 kΩ;
(4)
(5)
(6)
The values for R1 and R2 may be adjusted as needed to achieve the desired output voltage as long as the value
for R2 is no less than 12.9 kΩ. The maximum recommended value for R2 is 100 kΩ.
Equation 7 is used to determine the output voltage:
VOUT = (VFB × (1 + (R1 / R2 ))) + VOS
(7)
Alternately, Equation 8 can be used to determine the appropriate R1 value for a given R2 value:
R1 = R2 × (((VOUT) / VFB) – 1)
(8)
Table 1 suggests some ±1% values for R1 and R2 for a range of output voltages using the typical VFB value of
1.200V. This is not a definitive list, as other combinations exist that will provide similar, possibly better,
performance.
Table 1. Typical R1 and R2 Values for Assorted Output Voltages
TARGET VOUT
16
R1
R2
TYPICAL VOUT
1.2 V
0Ω
15 kΩ
1.2 V
1.5 V
4.22 kΩ
16.9 kΩ
1.5 V
1.8 V
10.5 kΩ
21 kΩ
1.8 V
2V
10 kΩ
15 kΩ
2V
2.5 V
16.2 kΩ
15.0 kΩ
2.496 V
3V
21 kΩ
14 kΩ
3V
3.3 V
23.2 kΩ
13.3 kΩ
3.293 V
5V
47.5 kΩ
15 kΩ
5V
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
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 LP38798 is a high-performance linear regulator capable of supplying a well-regulated, low-noise voltage into
an 800-mA load. The LP38798 can operate over a wide input voltage range (3 V to 20 V) making it well suited for
many post-regulation applications.
8.2 Typical Application: VOUT = 5 V
1
5.50V
VIN
2
3
CIN
1 PF
MLCC
OUT
IN
OUT
IN(CP)
OUT(FB)
12
VOUT
11
5
6
CP
SET
EN
FB
+ COUT
10 PF
9 (5.00V)
8 (1.20V)
R1
47.5k
R2
15.0k
7
GND(CP)
5.00V
10
LP38798
4
CCP
10 nF
VEN
IN
GND
DAP
GND
GND
Figure 40. Typical Application, VOUT = 5 V
8.2.1 Design Requirements
DESIGN PARAMETER
EXAMPLE VALUE
Input voltage
5.5 V, ±10%
Output voltage
5. V, ±3.5%
Output current
500 mA
8.2.2 Detailed Design Procedure
8.2.2.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LP39798 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
17
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
•
•
www.ti.com
Export customized schematic and layout into popular CAD formats
Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
8.2.2.2 Input Capacitor Recommendations
The LP38798 is designed and characterized for operation with a ceramic capacitor of 1 µF, or greater, at the
input. Note especially that the input capacitances must be located as near as practical to the IN pins
The minimum recommended input capacitance is 1 µF, ceramic or tantalum. However, if the LP38798 is
operating in conditions where input ripple, fast changes in the input voltage, or large changes in the load current
demand are expected, a minimum input capacitance of 10 µF is strongly recommended
Ceramic capacitor tolerance and variations due temperature and applied voltage must be considered when
selecting a capacitor to assure the minimum input capacitance requirement is met over the intended operating
range.
The input capacitor must be located as close as physically possible to the input pin and returned to a clean
analog ground. Any good quality tantalum capacitor may be used, while a ceramic capacitor should be X5R or
X7R rated with appropriate adjustments due to the loss of capacitance value from the applied DC voltage.
Attention must be given to the input capacitance value to minimize transient input voltage droop during load
current steps at the OUT pin. Larger input capacitor values are necessary for good transient load response, and
have no detrimental influence on the stability of the device. Note, however, that using large value ceramic input
capacitances can also cause unwanted ringing at the output if the input capacitor, in combination with the trace
inductance, creates a high-Q peaking effect during transients. Short, well-designed interconnect leads to the upstream supply minimize this effect without adding damping. Damping of unwanted ringing can be accomplished
by using a tantalum capacitor, with a few hundred milli-ohms of ESR, in parallel with the ceramic input capacitor.
8.2.2.3 Output Capacitor Recommendations
The LP38798 requires an output capacitance of at least 1 µF, ceramic or tantalum; however, a minimum output
capacitance of 10 µF is strongly recommended if fast load transient conditions are expected. While the LP38798
is designed to work with Ceramic output capacitors, the output capacitor can be Ceramic, Tantalum, or a
combination. The total output capacitance must be sized appropriately to handle any fast load current steps.
Capacitance type, tolerance, ESR, as well as temperature and voltage characteristics, must be considered when
selecting an output capacitor for the application.
Note especially that the output capacitances must be located as near as practical to the OUT pins.
Even though the LP38798 is stable with an output capacitance of 1 µF to 10 µF, a single output capacitor will
generally not be able to provide the best PSRR performance across a wide frequency range. Multiple parallel
capacitors, each with a different self-resonance frequency will provide better performance over a wider frequency
range.
The LP38798 is characterized with a ceramic capacitor of 10 µF, or greater, at the output. Noise performance is
characterized using a single output capacitor of 10 µF ±10%, 16V, X7R, 1206.
8.2.2.4 Charge Pump
The charge pump is running when both the input voltage is above the UVLO threshold (2.65 V typical) and the
EN pin voltage is above the VEN(ON) threshold (1.24 V typical). The typical charge pump operating frequency is
3.5 MHz.
A low leakage 10 nF X7R storage capacitor is required between the CP pin and ground to store the energy
required for gate drive of the internal NMOS pass device. Larger values of capacitance may slow start-up times,
while smaller capacitance values may result in degraded dynamic performance.
Do not make any other connection to the CP pin. Loading this pin in any manner degrades regulator
performance. No external biasing may be applied to, or derived from, this pin, as permanent damage to the
internal charge pump circuitry may occur.
18
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
8.2.2.5 Setting the Output Voltage
The output voltage is buffered from the SET pin. The output voltage is defined as:
VOUT = VSET = (VFB × (1 + (R1 / R2))
where
•
•
VFB = 1.2 V (typical)
R2 = 12.9 kΩ minimum to 100 kΩ maximum
(9)
Selecting a standard 1% resistor value of 15 kΩ for R2, the resistor value needed for R1 to provide an output
voltage of 5V is calculated from:
R1 = R2 × (( VOUT / VFB) – 1 )
R1 = 15 kΩ × ((5 V / 1.2 V) – 1)
R1 = 47.5 kΩ
(10)
(11)
(12)
8.2.2.6 Device Dissipation
Device power dissipation is defined as:
PD = ((VIN – VOUT) × IOUT)
PD = ((5.5 V - 5 V) × 0.5 A)
PD = 250 mW
(13)
(14)
(15)
Given 250 mW of device power dissipation, a maximum operating junction temperature (TJ) of 125°C, and
presuming a RθJA of 35.4°C/W, the maximum ambient temperature (TA) is defined as:
TA(MAX) = TJ(MAX) – (PD × RθJA)
TA(MAX) = (125°C – (0.25 W × 35.4°C/W))
TA(MAX) = 116°C
(16)
(17)
(18)
8.2.3 Application Curve
5.5
5.0
4.5
VIN = 5.5 V
VOUT = 5.0 V
4.0
VOLTS (V)
3.5
3.0
2.5
2.0
Ven
1.5
1.0
Vout -40ƒC
0.5
Vout 25ƒC
0.0
-0.5
Vout 125ƒC
TIME (50µs/DIV)
C028
Figure 41. Start-Up Time
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
19
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
9 Power Supply Recommendations
The LP38798 device is designed to operate from an input voltage supply range of 3 V to 20 V. The input supply
must be able to supply enough current to keep the input voltage from drooping during load transients and high
load current. 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
The dynamic performance of the LP38798 is dependant on the layout of the PCB. PCB layout practices that are
adequate for typical LDOs may degrade the PSRR, noise, or transient performance of the LP38798.
Best performance is achieved by placing all of the components on the same side of the PCB as the LP38798,
and as close as is practical to the LP38798 package. All component ground connections must be back to the
LP38798 analog ground connection using as wide and short of a copper trace as is practical. The connection
from the FB pin to the VSET resistors must be as short as possible as the FB pin is a high impedance input. Any
trace length on the FB pin acts as an antenna.
Connections using long trace lengths, narrow trace widths; avoid connections through vias, which add parasitic
inductances and resistance that results in inferior performance especially during transient conditions.
A ground plane, either on the opposite side of a two-layer PCB, or embedded in a multi-layer PCB, is strongly
recommended. This Ground Plane serves two purposes :
1. Provides a circuit reference plane to assure accuracy, and
2. Provides a thermal plane to remove heat from the LP38798 through thermal vias under the package DAP.
10.2 Layout Example
Thermal
Vias
CIN
COUT
GND
GND
VIN
VOUT
CCP
VEN
R1
R2
GND
GND
10.3 Thermal Considerations
The value of RθJA for the 12-lead WSON package is specifically dependent on PCB copper area, copper
thickness, the number of layers, and thermal vias under the exposed thermal pad (DAP). Refer to A Guide to
Board Layout for Best Thermal Resistance for Exposed Packages for general guidelines for mounting packages
with exposed thermal pads.
Exceeding the maximum allowable power dissipation defined by the final RθJA will cause excessive die
temperature, and the regulator may go into thermal shutdown.
10.4 Estimating the Junction Temperature
The EIA/JEDEC standard (JESD51-2) provides methodologies to estimate the junction temperature from external
measurements (ΨJB references the temperature at the PCB, and ΨJT references the temperature at the top
surface of the package) when operating under steady-state power dissipation conditions. These methodologies
have been determined to be relatively independent of the copper thermal spreading area that may be attached to
the package DAP when compared to the more typical RθJA. Refer to Semiconductor and IC Package Thermal
Metrics, for specifics.
20
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
LP38798
www.ti.com
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
11 Device and Documentation Support
11.1 Device Support
11.1.1 Development Suppport
11.1.1.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the LP39798 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
• Export customized schematic and layout into popular CAD formats
• Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
• AN-1187 Leadless Leadframe Package (LLP) (SNOA401)
• A Guide to Board Layout for Best Thermal Resistance for Exposed Packages (SNVA183)
11.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates — go to the product folder for your device on ti.com. In the
upper right-hand corner, click the Alert me button to register and receive a weekly digest of product information
that has changed (if any). For change details, check the revision history of any revised document.
11.4 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.
11.5 Trademarks
E2E is a trademark of Texas Instruments.
WEBENCH is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.6 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.
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
21
LP38798
SNOSCT6F – MARCH 2013 – REVISED JANUARY 2017
www.ti.com
11.7 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.
22
Submit Documentation Feedback
Copyright © 2013–2017, Texas Instruments Incorporated
Product Folder Links: LP38798
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
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)
LP38798SD-ADJ/NOPB
ACTIVE
WSON
DNT
12
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L00075B
LP38798SDE-ADJ/NOPB
ACTIVE
WSON
DNT
12
250
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L00075B
LP38798SDX-ADJ/NOPB
ACTIVE
WSON
DNT
12
4500
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 125
L00075B
(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
工商网监
湘ICP备2023018690号
