LMZ14203H_15 [TI]
SIMPLE SWITCHER 6V to 42V, 3A High Output Voltage Power Module;
| 型号： | LMZ14203H_15 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | SIMPLE SWITCHER 6V to 42V, 3A High Output Voltage Power Module |
| 文件： | 总31页 (文件大小：1214K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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LMZ14203H
SNVS692G –JANUARY 2011–REVISED OCTOBER 2015
®
LMZ14203H SIMPLE SWITCHER 6V to 42V, 3A High Output Voltage Power Module
1 Features
2 Applications
1
•
Integrated Shielded Inductor
Simple PCB Layout
•
Intermediate Bus Conversions to 12-V and 24-V
Rail
•
•
•
•
Time-Critical Projects
Flexible Start-Up Sequencing Using External Soft-
Start and Precision Enable
Space Constrained and High Thermal
Requirement Applications
•
•
•
•
Protection Against Inrush Currents
•
Negative Output Voltage Applications
Input UVLO and Output Short-Circuit Protection
–40°C to 125°C Junction Temperature Range
3 Description
Single Exposed Pad and Standard Pinout for Easy
Mounting and Manufacturing
The LMZ14203H SIMPLE SWITCHER® power
module is an easy-to-use step-down DC-DC solution
that can drive up to 3-A load with exceptional power
conversion efficiency, line and load regulation, and
output accuracy. The LMZ14203H is available in an
•
•
Low Output Voltage Ripple
Pin-to-Pin Compatible Family:
–
LMZ14203H/2H/1H (42 V Maximum, 3-A, 2-A,
1-A)
innovative
package
that
enhances
thermal
performance and allows for hand or machine
soldering.
–
–
LMZ14203/2/1 (4 2V Maximum, 3-A, 2-A, 1-A)
LMZ12003/2/1 (20 V Maximum, 3-A, 2-A, 1-A)
Fully Enabled for WEBENCH® Power Designer
The LMZ14203H can accept an input voltage rail
between 6 V and 42 V and deliver an adjustable and
highly accurate output voltage as low as 5 V. The
LMZ14203H only requires three external resistors
and four external capacitors to complete the power
solution. The LMZ14203H is a reliable and robust
design with the following protection features: thermal
shutdown, input undervoltage lockout, output
overvoltage protection, short-circuit protection, output
current limit, and allows start-up into a prebiased
•
•
Electrical Specifications
–
–
–
–
Up to 3-A Output Current
Input Voltage Range 6 V to 42 V
Output Voltage as Low as 5 V
Efficiency up to 97%
•
Performance Benefits
–
High Efficiency Reduces System Heat
Generation
output.
frequency up to 1 MHz.
A single resistor adjusts the switching
–
–
–
Low Radiated EMI (EN 55022 Class B Tested)
No Compensation Required
Device Information(1)(2)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
Low Package Thermal Resistance
LMZ14203H
TO-PMOD (7)
10.16 mm × 9.85 mm
NOTE: EN 55022:2006, +A1:2007, FCC Part 15 Subpart B: 2007
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
(2) Peak reflow temperature equals 245°C. See SNAA214 for
more details.
Simplified Application Schematic
Efficiency VOUT = 12 V, TA = 25°C
100
LMZ14203H
95
90
85
80
V
IN
V
OUT
C
R
ON
FF
R
FBT
Enable
VIN = 15V
VIN = 24V
75
VIN = 30V
R
FBB
COUT
C
C
SS
IN
VIN = 36V
VIN = 42V
70
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
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.
LMZ14203H
SNVS692G –JANUARY 2011–REVISED OCTOBER 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
Features.................................................................. 1
Applications ........................................................... 1
Description ............................................................. 1
Revision History..................................................... 2
Pin Configuration and Functions......................... 3
Specifications......................................................... 3
6.1 Absolute Maximum Ratings ...................................... 3
6.2 ESD Ratings.............................................................. 3
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information.................................................. 4
6.5 Electrical Characteristics........................................... 4
6.6 Typical Characteristics.............................................. 6
Detailed Description ............................................ 14
7.1 Overview ................................................................. 14
7.2 Functional Block Diagram ....................................... 14
7.3 Feature Description................................................. 14
7.4 Device Functional Modes........................................ 15
8
Application and Implementation ........................ 16
8.1 Application Information............................................ 16
8.2 Typical Application ................................................. 16
Power Supply Recommendations...................... 21
9
10 Layout................................................................... 21
10.1 Layout Guidelines ................................................. 21
10.2 Layout Example .................................................... 22
10.3 Power Dissipation and Board Thermal
Requirements........................................................... 23
11 Device and Documentation Support ................. 25
11.1 Documentation Support ........................................ 25
11.2 Community Resources.......................................... 25
11.3 Trademarks........................................................... 25
11.4 Electrostatic Discharge Caution............................ 25
11.5 Glossary................................................................ 25
7
12 Mechanical, Packaging, and Orderable
Information ........................................................... 25
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision F (August 2015) to Revision G
Page
•
Added this new bullet to the Power Module SMT Guidelines section.................................................................................. 22
Changes from Revision E (June 2015) to Revision F
Page
•
Changed the title of the document ......................................................................................................................................... 1
Changes from Revision D (October 2013) to Revision E
Page
•
Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional
Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1
Changes from Revision C (June 2011) to Revision D
Page
•
•
•
Added Peak Reflow Case Temp = 245°C.............................................................................................................................. 1
Changed 10 mils................................................................................................................................................................... 21
Added Power Module SMT Guidelines................................................................................................................................. 21
2
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SNVS692G –JANUARY 2011–REVISED OCTOBER 2015
5 Pin Configuration and Functions
NDW Package
7-Pin TO-PMOD
Top View
VOUT
FB
SS
GND
EN
RON
VIN
7
6
5
4
3
2
1
Exposed Pad
Connect to GND
Pin Functions
PIN
TYPE
DESCRIPTION
NO.
NAME
1
VIN
Power
Analog
Supply input — Additional external input capacitance is required between this pin and the exposed pad (EP).
ON-time resistor — An external resistor from VIN to this pin sets the ON-time and frequency of the
application. Typical values range from 100k to 700k ohms.
2
RON
3
4
5
EN
GND
SS
Analog
Ground
Analog
Enable — Input to the precision enable comparator. Rising threshold is 1.18 V.
Ground — Reference point for all stated voltages. Must be externally connected to EP.
Soft-Start — An internal 8-µA current source charges an external capacitor to produce the soft-start function.
Feedback — Internally connected to the regulation, overvoltage, and short-circuit comparators. The
regulation reference point is 0.8 V at this input pin. Connect the feedback resistor divider between the output
and ground to set the output voltage.
6
FB
Analog
Output Voltage — Output from the internal inductor. Connect the output capacitor between this pin and the
EP.
7
VOUT
EP
Power
Exposed Pad — Internally connected to pin 4. Used to dissipate heat from the package during operation.
Must be electrically connected to pin 4 external to the package.
—
Ground
6 Specifications
6.1 Absolute Maximum Ratings(1)(2)(3)
MIN
–0.3
–0.3
MAX
43.5
7
UNIT
V
VIN, RON to GND
EN, FB, SS to GND
V
Junction Temperature
Peak Reflow Case Temperature (30 s)
Storage Temperature
150
245
150
°C
°C
°C
–65
(1) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
(2) 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.
(3) For soldering specifications, see the application note Absolute Maximum Ratings for Soldering (SNOA549)
6.2 ESD Ratings
VALUE
UNIT
V(ESD)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)
±2000
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
Copyright © 2011–2015, Texas Instruments Incorporated
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6.3 Recommended Operating Conditions
MIN
6
MAX
42
UNIT
V
VIN
EN
0
6.5
V
Operation Junction Temperature
−40
125
°C
6.4 Thermal Information
LMZ14203H
THERMAL METRIC(1)
NDW (TO-PMOD)
7 PINS
UNIT
4 layer printed-circuit-board, 7.62 cm x 7.62 cm
(3 in x 3 in) area, 1-oz copper, no air flow
16
RθJA
Junction-to-ambient thermal resistance
Junction-to-case (top) thermal resistance
°C/W
°C/W
4 layer printed-circuit-board, 6.35 cm x 6.35 cm
(2.5 in x 2.5 in) area, 1-oz copper, no air flow
18.4
1.9
RθJC(top)
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
6.5 Electrical Characteristics
Minimum and Maximum limits are ensured through test, design or statistical correlation. Typical values represent the most
likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated the following
conditions apply: VIN = 24 V, VOUT = 12 V, RON = 249 kΩ
PARAMETER
SYSTEM PARAMETERS
ENABLE CONTROL
TEST CONDITIONS
VEN rising, TJ = –40°C to 125°C
VSS = 0 V, TJ = –40°C to 125°C
DC average, TJ = –40°C to 125°C
MIN(1)
1.10
8
TYP(2)
MAX(1) UNIT
VEN
EN threshold trip point
1.18
90
1.25
15
V
VEN-HYS
SOFT-START
ISS
EN threshold hysteresis
mV
SS source current
10
µA
µA
ISS-DIS
SS discharge current
–200
CURRENT LIMIT
ICL
Current limit threshold
3.2
4.7
5.5
A
VIN UVLO
EN pin floating
VIN rising
VINUVLO
Input UVLO
Hysteresis
3.75
130
V
EN pin floating
VIN falling
VINUVLO-HYST
mV
ON/OFF TIMER
tON-MIN
ON timer minimum pulse width
OFF timer pulse width
150
260
ns
ns
tOFF
(1) Minimum and Maximum limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through
correlation using Statistical Quality Control (SQC) methods. Limits are used to calculate National’s Average Outgoing Quality Level
(AOQL).
(2) Typical numbers are at 25°C and represent the most likely parametric norm.
4
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Electrical Characteristics (continued)
Minimum and Maximum limits are ensured through test, design or statistical correlation. Typical values represent the most
likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Unless otherwise stated the following
conditions apply: VIN = 24 V, VOUT = 12 V, RON = 249 kΩ
PARAMETER
TEST CONDITIONS
MIN(1)
0.782
0.786
0.780
0.787
TYP(2)
0.803
0.803
0.803
MAX(1) UNIT
REGULATION AND OVERVOLTAGE COMPARATOR
VIN = 24 V, VOUT = 12 V
VSS >+ 0.8 V
TJ = –40°C to 125°C
IOUT = 10 mA to 3 A
0.822
VFB
In-regulation feedback voltage
V
VIN = 24 V, VOUT = 12 V
VSS >+ 0.8 V
0.818
TJ = 25°C
IOUT = 10 mA to 3 A
VIN = 36 V, VOUT = 24 V
VSS >+ 0.8 V
TJ = –40°C to 125°C
IOUT = 10 mA to 3 A
0.826
VFB
In-regulation feedback voltage
V
VIN = 36 V, VOUT = 24 V
VSS >+ 0.8 V
0.803
0.92
0.819
TJ = 25°C
IOUT = 10 mA to 3 A
Feedback overvoltage protection
threshold
VFB-OVP
V
IFB
IQ
Feedback input bias current
Nonswitching Input Current
Shutdown quiescent current
5
1
nA
mA
μA
VFB= 0.86 V
VEN= 0 V
ISD
25
THERMAL CHARACTERISTICS
TSD
Thermal shutdown (rising)
Thermal shutdown hysteresis
165
15
°C
°C
TSD-HYST
PERFORMANCE PARAMETERS
ΔVOUT
Output Voltage Ripple
VOUT = 5 V, CO = 100-µF 6.3-V X7R
VIN = 16 V to 42 V, IOUT= 3 A
8
0.01%
1.5
mV
PP
ΔVOUT/ΔVIN
Line Regulation
Load Regulation
Efficiency
ΔVOUT/ΔIOUT
VIN = 24 V, IOUT = 0 A to 3 A
mV/A
η
η
VIN = 24 V, VOUT = 12 V, IOUT = 1 A
VIN = 24 V, VO = 12 V, IO = 3 A
94%
Efficiency
93%
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6.6 Typical Characteristics
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
100
95
90
85
80
75
70
5
4
3
2
1
0
VIN = 8V
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 42V
VIN = 8V
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 42V
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
Figure 1. Efficiency VOUT = 5 V, TA = 25°C
Figure 2. Power Dissipation VOUT = 5 V, TA = 25°C
5
100
VIN = 15V
VIN = 24V
VIN = 30V
95
90
85
80
75
70
VIN = 36V
VIN = 42V
4
3
2
1
0
VIN = 15V
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Figure 4. Power Dissipation VOUT = 12 V, TA = 25°C
Figure 3. Efficiency VOUT = 12 V, TA = 25°C
100
5
VIN = 24V
VIN = 30V
VIN = 36V
95
90
85
VIN = 42V
4
3
2
1
0
80
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
75
70
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
Figure 5. Efficiency VOUT = 15 V, TA = 25°C
Figure 6. Power Dissipation VOUT = 15 V, TA = 25°C
6
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
100
95
90
85
80
75
70
5
4
3
2
1
0
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
Figure 7. Efficiency VOUT = 18 V, TA = 25°C
100
OUTPUT CURRENT (A)
Figure 8. Power Dissipation VOUT = 18 V, TA = 25°C
5
VIN = 28V
VIN = 30V
VIN = 36V
95
90
85
VIN = 42V
4
3
2
1
0
80
VIN = 28V
VIN = 30V
VIN = 36V
VIN = 42V
75
70
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
Figure 9. Efficiency VOUT = 24 V, TA = 25°C
100
OUTPUT CURRENT (A)
Figure 10. Power Dissipation VOUT = 24 V, TA = 25°C
5
95
90
85
80
4
3
2
1
VIN = 34V
VIN = 36V
VIN = 42V
VIN = 34V
VIN = 36V
VIN = 42V
75
70
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Figure 11. Efficiency VOUT = 30 V, TA = 25°C
Figure 12. Power Dissipation VOUT = 30 V, TA = 25°C
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
100
95
90
85
80
75
70
5
4
3
2
1
0
VIN = 8V
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 42V
VIN = 8V
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 42V
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
Figure 13. Efficiency VOUT = 5 V, TA = 85°C
100
OUTPUT CURRENT (A)
Figure 14. Power Dissipation VOUT = 5 V, TA = 85°C
5
VIN = 15V
VIN = 24V
VIN = 30V
95
90
85
VIN = 36V
VIN = 42V
4
3
2
1
0
80
VIN = 15V
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
75
70
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
Figure 15. Efficiency VOUT = 12 V, TA = 85°C
100
OUTPUT CURRENT (A)
Figure 16. Power Dissipation VOUT = 12 V, TA = 85°C
5
VIN = 24V
VIN = 30V
VIN = 36V
95
90
85
VIN = 42V
4
3
2
1
0
80
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
75
70
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Figure 17. Efficiency VOUT = 15 V, TA = 85°C
Figure 18. Power Dissipation VOUT = 15 V, TA = 85°C
8
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
100
95
90
85
80
75
70
5
4
3
2
1
0
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Figure 19. Efficiency VOUT = 18 V, TA = 85°C
100
Figure 20. Power Dissipation VOUT = 18 V, TA = 85°C
5
VIN = 28V
VIN = 30V
VIN = 36V
95
90
85
VIN = 42V
4
3
2
1
0
80
VIN = 28V
VIN = 30V
VIN = 36V
VIN = 42V
75
70
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
Figure 21. Efficiency VOUT = 24 V, TA = 85°C
100
OUTPUT CURRENT (A)
Figure 22. Power Dissipation VOUT = 24 V, TA = 85°C
5
95
90
85
80
4
3
2
1
VIN = 34V
VIN = 36V
VIN = 42V
VIN = 34V
VIN = 36V
VIN = 42V
75
70
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Figure 23. Efficiency VOUT = 30 V, TA = 85°C
Figure 24. Power Dissipation VOUT = 30 V, TA = 85°C
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
VIN = 15V
VIN = 24V
VIN = 42V
VIN = 15V
VIN = 24V
VIN = 42V
-20
0
20 40 60 80 100 120 140
-20
0
20 40 60 80 100 120 140
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
Figure 25. Thermal Derating VOUT = 12 V, RθJA = 16°C/W
Figure 26. Thermal Derating VOUT = 12 V, RθJA = 20°C/W
3.5
3.5
VIN = 30V
VIN = 36V
VIN = 42V
3.0
2.5
2.0
1.5
1.0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
VIN = 30V
0.5
VIN = 42V
0.0
VIN = 36V
-20
0
20 40 60 80 100 120 140
-20
0
20 40 60 80 100 120 140
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
Figure 27. Thermal Derating VOUT = 24 V, RθJA = 16°C/W
Figure 28. Thermal Derating VOUT = 24 V, RθJA = 20°C/W
3.5
3.5
VIN = 34V
VIN = 36V
VIN = 42V
3.0
2.5
2.0
1.5
1.0
3.0
2.5
2.0
1.5
1.0
0.5
0.0
VIN = 34V
0.5
VIN = 42V
0.0
VIN = 36V
-20
0
20 40 60 80 100 120 140
-20
0
20 40 60 80 100 120 140
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
Figure 29. Thermal Derating VOUT = 30 V, RθJA = 16°C/W
Figure 30. Thermal Derating VOUT = 30 V, RθJA = 20°C/W
10
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
40
35
30
25
20
15
10
5
12.6
12.4
12.2
12.0
11.8
11.6
0LFM (0m/s) air
VIN = 15V
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
±1%
225LFM (1.14m/s) air
500LFM (2.54m/s) air
Evaluation Board Area
0
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0
10
20
30
40
50
60
2
BOARD AREA (cm )
OUTPUT CURRENT (A)
Figure 31. Package Thermal Resistance RθJA
4-Layer Printed-Circuit-Board With 1-oz Copper
Figure 32. Line and Load Regulation TA = 25°C
VOUT=5V
VOUT=12V
1 µs/div
1 µs/div
20 mV/div
100 mV/div
Figure 33. Output Ripple
Figure 34. Output Ripple
VIN = 12 V, IOUT = 3 A, Ceramic COUT, BW = 200 MHz
VIN = 24 V, IOUT = 3 A, Polymer Electrolytic COUT, BW = 200
MHz
200 mV/div
VOUT=12V
200 mV/div
VOUT=12V
IOUT
1.0 A/div
IOUT
1.0 A/div
1 ms/div
1 ms/div
Figure 35. Load Transient Response VIN = 24 V, VOUT = 12 V
Load Step From 10% to 100%
Figure 36. Load Transient Response VIN = 24 V, VOUT = 12 V
Load Step From 30% to 100%
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
6.0
5.5
5.0
4.5
4.0
3.5
3.0
6
5
4
3
2
1
0
VIN = 12V
VIN = 24V
VIN = 36V
VIN = 42V
Fsw = 250kHz
Fsw = 400kHz
Fsw = 600kHz
5
10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
200 300 400 500 600 700 800
SWITCHING FREQUENCY (kHz)
Figure 37. Current Limit vs Input Voltage
VOUT = 5 V
Figure 38. Switching Frequency vs Power Dissipation
VOUT = 5 V
6.0
5.5
5.0
4.5
6
VIN = 15V
VIN = 24V
VIN = 36V
VIN = 42V
5
4
3
2
1
0
4.0
Fsw = 250kHz
3.5
Fsw = 400kHz
Fsw = 600kHz
3.0
5
10 15 20 25 30 35 40 45
INPUT VOLTAGE (V)
200 300 400 500 600 700 800
SWITCHING FREQUENCY (kHz)
Figure 39. Current Limit vs Input Voltage
VOUT = 12 V
Figure 40. Switching Frequency vs Power Dissipation
VOUT = 12 V
6.0
5.5
5.0
4.5
6
5
4
3
4.0
2
VIN = 30V
VIN = 36V
Fsw = 250kHz
VIN = 42V
3.5
1
Fsw = 400kHz
Fsw = 600kHz
3.0
0
30
33
36
39
42
45
200 300 400 500 600 700 800
SWITCHING FREQUENCY (kHz)
INPUT VOLTAGE (V)
Figure 41. Current Limit vs Input Voltage
VOUT = 24 V
Figure 42. Switching Frequency vs Power Dissipation
VOUT = 24 V
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 24 V; Cin = 10-uF X7R Ceramic; CO = 47 uF; TA = 25°C.
80
Emissions (Evaluation Board)
EN 55022 Limit (Class B)
70
60
50
VOUT
40
30
20
ENABLE
5V/Div
10
0
1 ms/Div
0
200
FREQUENCY (MHz)
Figure 44. Radiated EMI of Evaluation Board, VOUT = 12 V
400
600
800 1,000
Figure 43. Startup
VIN = 24 V, IOUT = 3 A
80
70
60
50
40
30
20
10
0
Emissions
CISPR 22 Quasi Peak
CISPR 22 Average
0.1
1
10
100
FREQUENCY (MHz)
Figure 45. Conducted EMI, VOUT = 12 V
Evaluation Board BOM and 3.3 µH 2x10 µF LC Line Filter
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7 Detailed Description
7.1 Overview
7.1.1 COT Control Circuit Overview
Constant ON-time control is based on a comparator and an ON-time one-shot, with the output voltage feedback
compared to an internal 0.8-V reference. If the feedback voltage is below the reference, the high-side MOSFET
is turned on for a fixed ON-time determined by a programming resistor RON. RON is connected to VIN such that
ON-time is reduced with increasing input supply voltage. Following this ON-time, the high-side MOSFET remains
off for a minimum of 260 ns. If the voltage on the feedback pin falls below the reference level again the ON-time
cycle is repeated. Regulation is achieved in this manner.
7.2 Functional Block Diagram
Vin
R
R
ENT
1
VIN
3
5
EN
SS
Linear reg
ENB
C
IN
Cvcc
Css
0.47 éF
VOUT
R
ON
7
2
6
RON
FB
V
O
Timer
C
10 éH
FF
Co
R
FBT
Internal
Passives
Regulator IC
R
FBB
GND
4
7.3 Feature Description
7.3.1 Output Overvoltage Comparator
The voltage at FB is compared to a 0.92-V internal reference. If FB rises above 0.92 V the ON-time is
immediately terminated. This condition is known as overvoltage protection (OVP). It can occur if the input voltage
is increased very suddenly or if the output load is decreased very suddenly. Once OVP is activated, the top
MOSFET ON-times will be inhibited until the condition clears. Additionally, the synchronous MOSFET will remain
on until inductor current falls to zero.
7.3.2 Current Limit
Current limit detection is carried out during the OFF-time by monitoring the current in the synchronous MOSFET.
Referring to the Functional Block Diagram, when the top MOSFET is turned off, the inductor current flows
through the load, the PGND pin and the internal synchronous MOSFET. If this current exceeds 4.2 A (typical) the
current limit comparator disables the start of the next ON-time period. The next switching cycle will occur only if
the FB input is less than 0.8 V and the inductor current has decreased below 4.2 A. Inductor current is monitored
during the period of time the synchronous MOSFET is conducting. So long as inductor current exceeds 4.2 A,
further ON-time intervals for the top MOSFET will not occur. Switching frequency is lower during current limit due
to the longer OFF-time.
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Feature Description (continued)
NOTE
The DC current limit varies with duty cycle, switching frequency, and temperature.
7.3.3 Thermal Protection
The junction temperature of the LMZ14203H should not be allowed to exceed its maximum ratings. Thermal
protection is implemented by an internal Thermal Shutdown circuit which activates at 165 °C (typical) causing the
device to enter a low power standby state. In this state the main MOSFET remains off causing VO to fall, and
additionally the CSS capacitor is discharged to ground. Thermal protection helps prevent catastrophic failures for
accidental device overheating. When the junction temperature falls back below 145 °C (typical Hyst = 20 °C) the
SS pin is released, VO rises smoothly, and normal operation resumes.
7.3.4 Zero Coil Current Detection
The current of the lower (synchronous) MOSFET is monitored by a zero coil current detection circuit which
inhibits the synchronous MOSFET when its current reaches zero until the next ON-time. This circuit enables the
DCM operating mode, which improves efficiency at light loads.
7.3.5 Prebiased Startup
The LMZ14203H will properly start up into a prebiased output. This startup situation is common in multiple rail
logic applications where current paths may exist between different power rails during the startup sequence. The
prebias level of the output voltage must be less than the input UVLO set point. This will prevent the output pre-
bias from enabling the regulator through the high-side MOSFET body diode.
7.4 Device Functional Modes
7.4.1 Discontinuous Conduction and Continuous Conduction Modes
At light-load, the regulator will operate in discontinuous conduction mode (DCM). With load currents above the
critical conduction point, it will operate in continuous conduction mode (CCM). When operating in DCM the
switching cycle begins at zero amps inductor current; increases up to a peak value, and then recedes back to
zero before the end of the OFF-time. During the period of time that inductor current is zero, all load current is
supplied by the output capacitor. The next ON-time period starts when the voltage on the FB pin falls below the
internal reference. The switching frequency is lower in DCM and varies more with load current as compared to
CCM. Conversion efficiency in DCM is maintained since conduction and switching losses are reduced with the
smaller load and lower switching frequency.
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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 LMZ14203H is a step down DC-to-DC power module. It is typically used to convert a higher DC voltage to a
lower DC voltage with a maximum output current of 3 A. The following design procedure can be used to select
components for the LMZ14203H. Alternately, the WEBENCH software may be used to generate complete
designs.
When generating a design, the WEBENCH software uses iterative design procedure and accesses
comprehensive databases of components. For more details, go to www.ti.com.
8.2 Typical Application
V
R
34 k:
R
R
C
C
V
IN
OUT
FBT
FBB
ON
OUT
OUT-ESR
LMZ14203H
30V
24V
18V
15V
12V
5V
931: 619 k: 33 PF
1-45 m:
1-40 m:
1-40 m:
1-42 m:
1-45 m:
34 - 42V
28 - 42V
22 - 42V
18 - 42V
15 - 42V
8 - 42V
34 k: 1.18 k: 499 k: 33 PF
34 k: 1.58 k: 374 k: 33 PF
34 k: 1.91 k: 287 k: 47 PF
34 k: 2.43 k: 249 k: 47 PF
V
IN
34 k: 6.49 k: 100 k: 100 PF 1-95 m:
V
OUT
C
FF
R
ON
0.022 PF
* R
ENT
VIN
R
FBT
C
IN
10ꢀPF
* R
ENB
C
SS
4700 pF
R
FBB
C
OUT
* See equation 1
to calculate values
Figure 46. Simplified Application Schematic
8.2.1 Design Requirements
For this example the following application parameters exist.
•
•
•
VIN Range = Up to 42 V
VOUT = 5 V to 30 V
IOUT = 3 A
Refer to the table in Figure 46 for more information.
8.2.2 Detailed Design Procedure
8.2.2.1 Design Steps for the LMZ14203H Application
The LMZ14203H is fully supported by WEBENCH which offers the following: component selection, electrical
simulation, thermal simulation, as well as a build-it prototype board for a reduction in design time. The following
list of steps can be used to manually design the LMZ14203H application.
1. Select minimum operating VIN with enable divider resistors.
2. Program VO with divider resistor selection.
3. Program turnon time with soft-start capacitor selection.
4. Select CO.
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Typical Application (continued)
5. Select CIN.
6. Set operating frequency with RON
.
7. Determine module dissipation.
8. Lay out PCB for required thermal performance.
8.2.2.1.1 Enable Divider, RENT and RENB Selection
The enable input provides a precise 1.18-V reference threshold to allow direct logic drive or connection to a
voltage divider from a higher enable voltage such as VIN. The enable input also incorporates 90 mV (typical) of
hysteresis resulting in a falling threshold of 1.09 V. The maximum recommended voltage into the EN pin is 6.5 V.
For applications where the midpoint of the enable divider exceeds 6.5 V, a small Zener diode can be added to
limit this voltage.
The function of the RENT and RENB divider is to allow the designer to choose an input voltage below which the
circuit will be disabled. This implements the feature of programmable under voltage lockout. This is often used in
battery-powered systems to prevent deep discharge of the system battery. It is also useful in system designs for
sequencing of output rails or to prevent early turnon of the supply as the main input voltage rail rises at power
up. Applying the enable divider to the main input rail is often done in the case of higher input voltage systems
such as 24-V AC/DC systems where a lower boundary of operation should be established. In the case of
sequencing supplies, the divider is connected to a rail that becomes active earlier in the power-up cycle than the
LMZ14203H output rail. The two resistors should be chosen based on the following ratio:
RENT / RENB = (VIN-ENABLE/ 1.18 V) – 1
(1)
The EN pin is internally pulled up to VIN and can be left floating for always-on operation. However, it is good
practice to use the enable divider and turn on the regulator when VIN is close to reaching its nominal value. This
will ensure smooth start-up and will prevent overloading the input supply.
8.2.2.1.2 Output Voltage Selection
Output voltage is determined by a divider of two resistors connected between VO and ground. The midpoint of
the divider is connected to the FB input. The voltage at FB is compared to a 0.8-V internal reference. In normal
operation an ON-time cycle is initiated when the voltage on the FB pin falls below 0.8 V. The high-side MOSFET
ON-time cycle causes the output voltage to rise and the voltage at the FB to exceed 0.8 V. As long as the
voltage at FB is above 0.8 V, ON-time cycles will not occur.
The regulated output voltage determined by the external divider resistors RFBT and RFBB is:
VO = 0.8 V × (1 + RFBT / RFBB
)
(2)
(3)
Rearranging terms; the ratio of the feedback resistors for a desired output voltage is:
RFBT / RFBB = (VO / 0.8 V) - 1
These resistors should be chosen from values in the range of 1 kΩ to 50 kΩ.
A feed-forward capacitor is placed in parallel with RFBT to improve load step transient response. Its value is
usually determined experimentally by load stepping between DCM and CCM conduction modes and adjusting for
best transient response and minimum output ripple.
A table of values for RFBT , RFBB , and RON is included in the simplified applications schematic (see Figure 46).
8.2.2.1.3 Soft-Start Capacitor, CSS, Selection
Programmable soft-start permits the regulator to slowly ramp to its steady-state operating point after being
enabled, thereby reducing current inrush from the input supply and slowing the output voltage rise-time to
prevent overshoot.
Upon turnon, after all UVLO conditions have been passed, an internal 8-uA current source begins charging the
external soft-start capacitor. The soft-start time duration to reach steady-state operation is given by the formula:
tSS = VREF × CSS / Iss = 0.8 V × CSS / 8 µA
(4)
(5)
17
Equation 4 can be rearranged as follows:
CSS = tSS × 8 μA / 0.8 V
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Typical Application (continued)
Use of a 4700-pF capacitor results in 0.5-ms soft-start duration. This is a recommended value. Note high values
of CSS capacitance will cause more output voltage droop when a load transient goes across the DCM-CCM
boundary. Use Equation 22 to find the DCM-CCM boundary load current for the specific operating condition. If a
fast load transient response is desired for steps between DCM and CCM mode the soft-start capacitor value
should be less than 0.018 µF.
Note the following conditions will reset the soft-start capacitor by discharging the SS input to ground with an
internal 200-μA current sink:
•
•
•
•
The enable input being pulled low
Thermal shutdown condition
Overcurrent fault
Internal VINUVLO
8.2.2.1.4 Output Capacitor, CO, Selection
None of the required output capacitance is contained within the module. At a minimum, the output capacitor must
meet the worst-case RMS current rating of 0.5 × ILR P-P, as calculated in Equation 23. Beyond that, additional
capacitance will reduce output ripple so long as the ESR is low enough to permit it. A minimum value of 10 μF is
generally required. Experimentation will be required if attempting to operate with a minimum value. Low-ESR
capacitors, such as ceramic and polymer electrolytic capacitors are recommended.
8.2.2.1.4.1 Capacitance
Equation 6 provides a good first pass approximation of CO for load transient requirements:
CO≥ ISTEP × VFB × L × VIN/ (4 × VO × (VIN — VO) × VOUT-TRAN
)
(6)
As an example, for 3-A load step, VIN = 24 V, VOUT = 12 V, VOUT-TRAN = 50 mV:
CO≥ 3 A × 0.8 V × 10 μH × 24 V / (4 x 12V ( 24 V – 12 V) × 50 mV)
CO≥ 20μF
(7)
(8)
8.2.2.1.4.2 ESR
The ESR of the output capacitor affects the output voltage ripple. High ESR will result in larger VOUT peak-to-
peak ripple voltage. Furthermore, high output voltage ripple caused by excessive ESR can trigger the
overvoltage protection monitored at the FB pin. The ESR should be chosen to satisfy the maximum desired VOUT
peak-to-peak ripple voltage and to avoid overvoltage protection during normal operation. The following equations
can be used:
ESRMAX-RIPPLE ≤ VOUT-RIPPLE / ILR P-P
where
•
ILR P-P is calculated using Equation 23.
(9)
ESRMAX-OVP < (VFB-OVP - VFB) / (ILR P-P × AFB
)
where
•
AFB is the gain of the feedback network from VOUT to VFB at the switching frequency.
(10)
As worst-case, assume the gain of AFB with the CFF capacitor at the switching frequency is 1.
The selected capacitor should have sufficient voltage and RMS current rating. The RMS current through the
output capacitor is:
I(COUT(RMS)) = ILR P-P / √12
(11)
8.2.2.1.5 Input Capacitor, CIN, Selection
The LMZ14203H module contains an internal 0.47-µF input ceramic capacitor. Additional input capacitance is
required external to the module to handle the input ripple current of the application. This input capacitance should
be as close as possible to the module. Input capacitor selection is generally directed to satisfy the input ripple
current requirements rather than by capacitance value.
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Typical Application (continued)
Worst-case input ripple current rating is dictated by Equation 12.
I(CIN(RMS)) ≊ 1 / 2 × IO × √ (D / 1-D)
where
•
D ≊ VO / VIN
(12)
(As a point of reference, the worst-case ripple current will occur when the module is presented with full load
current and when VIN = 2 × VO).
Recommended minimum input capacitance is 10-uF X7R ceramic with a voltage rating at least 25% higher than
the maximum applied input voltage for the application. TI also recommends to pay attention to the voltage and
temperature deratings of the capacitor selected. It should be noted that ripple current rating of ceramic capacitors
may be missing from the capacitor data sheet and you may have to contact the capacitor manufacturer for this
rating.
If the system design requires a certain maximum value of input ripple voltage ΔVIN to be maintained then
Equation 13 may be used.
CIN ≥ IO × D × (1–D) / fSW-CCM × ΔVIN
(13)
If ΔVIN is 1% of VIN for a 24-V input to 12V output application this equals 240 mV and fSW = 400 kHz.
CIN≥ 3 A × 12 V/24 V × (1– 12 V/24 V) / (400000 × 0.240 V)
CIN≥ 7.8 μF
(14)
(15)
Additional bulk capacitance with higher ESR may be required to damp any resonant effects of the input
capacitance and parasitic inductance of the incoming supply lines.
8.2.2.1.6 ON-Time, RON, Resistor Selection
Many designs will begin with a desired switching frequency in mind. As seen in the Typical Characteristics
section, the best efficiency is achieved in the 300kHz-400kHz switching frequency range. Equation 16 can be
used to calculate the RON value.
f
SW(CCM) ≊ VO / (1.3 × 10-10 × RON
)
(16)
This can be rearranged as
R
ON ≊ VO / (1.3 × 10 -10 × fSW(CCM)
(17)
The selection of RON and fSW(CCM) must be confined by limitations in the ON-time and OFF-time for the COT
Control Circuit Overview section.
The ON-time of the LMZ14203H timer is determined by the resistor RON and the input voltage VIN. It is calculated
as follows:
tON = (1.3 × 10-10 x RON) / VIN
(18)
The inverse relationship of tON and VIN gives a nearly constant switching frequency as VIN is varied. RON should
be selected such that the ON-time at maximum VIN is greater than 150 ns. The ON-timer has a limiter to ensure
a minimum of 150 ns for tON. This limits the maximum operating frequency, which is governed by Equation 19.
fSW(MAX) = VO / (VIN(MAX) × 150 ns)
(19)
This equation can be used to select RON if a certain operating frequency is desired so long as the minimum ON-
time of 150 ns is observed. The limit for RON can be calculated as follows:
R
ON ≥ VIN(MAX) × 150 nsec / (1.3 × 10 -10
)
(20)
If RON calculated in Equation 17 is less than the minimum value determined in Equation 20, a lower frequency
should be selected. Alternatively, VIN(MAX) can also be limited in order to keep the frequency unchanged.
Additionally, the minimum OFF-time of 260 ns (typical) limits the maximum duty ratio. Larger RON (lower FSW
)
should be selected in any application requiring large duty ratio.
8.2.2.1.6.1 Discontinuous Conduction and Continuous Conduction Mode Selection
Operating frequency in DCM can be calculated as follows:
2
f
SW(DCM) ≊ VO × (VIN-1) × 10 μH × 1.18 × 1020 × IO / (VIN–VO) × RON
(21)
19
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Typical Application (continued)
In CCM, current flows through the inductor through the entire switching cycle and never falls to zero during the
OFF-time. The switching frequency remains relatively constant with load current and line voltage variations. The
CCM operating frequency can be calculated using Equation 16.
The approximate formula for determining the DCM/CCM boundary is as follows:
IDCB ≊ VO × (VIN–VO) / ( 2 × 10 μH × fSW(CCM) × VIN)
(22)
The inductor internal to the module is 10 μH. This value was chosen as a good balance between low and high
input voltage applications. The main parameter affected by the inductor is the amplitude of the inductor ripple
current (ILR). ILR can be calculated with:
ILR P-P = VO × (VIN- VO) / (10 µH × fSW × VIN)
where
•
VIN is the maximum input voltage and fSW is determined from Equation 16.
(23)
If the output current IO is determined by assuming that IO = IL, the higher and lower peak of ILR can be
determined. Be aware that the lower peak of ILR must be positive if CCM operation is required.
8.2.3 Application Curve
100
95
90
85
80
VIN = 28V
VIN = 30V
VIN = 36V
VIN = 42V
75
70
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT CURRENT (A)
Figure 47. Efficiency VOUT = 24 V, TA = 25°C
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9 Power Supply Recommendations
The LMZ14203H device is designed to operate from an input voltage supply range between 4.5 V and 42 V. This
input supply should be well regulated and able to withstand maximum input current and maintain a stable
voltage. The resistance of the input supply rail should be low enough that an input current transient does not
cause a high enough drop at the LMZ14203H supply voltage that can cause a false UVLO fault triggering and
system reset. If the input supply is more than a few inches from the LMZ14203H, additional bulk capacitance
may be required in addition to the ceramic bypass capacitors. The amount of bulk capacitance is not critical, but
a 47-μF or 100-μF electrolytic capacitor is a typical choice.
10 Layout
10.1 Layout Guidelines
PCB layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a
DC-DC converter and surrounding circuitry by contributing to EMI, ground bounce and resistive voltage drop in
the traces. These can send erroneous signals to the DC-DC converter resulting in poor regulation or instability.
Good layout can be implemented by following a few simple design rules.
1. Minimize area of switched current loops.
From an EMI reduction standpoint, it is imperative to minimize the high di/dt paths during PCB layout. The
high current loops that do not overlap have high di/dt content that will cause observable high frequency noise
on the output pin if the input capacitor (Cin1) is placed at a distance away from the LMZ14203. Therefore
place CIN1 as close as possible to the LMZ14203 VIN and GND exposed pad. This will minimize the high
di/dt area and reduce radiated EMI. Additionally, grounding for both the input and output capacitor should
consist of a localized top side plane that connects to the GND exposed pad (EP).
2. Have a single point ground.
The ground connections for the feedback, soft-start, and enable components should be routed to the GND
pin of the device. This prevents any switched or load currents from flowing in the analog ground traces. If not
properly handled, poor grounding can result in degraded load regulation or erratic output voltage ripple
behavior. Provide the single point ground connection from pin 4 to EP.
3. Minimize trace length to the FB pin.
Both feedback resistors, RFBT and RFBB, and the feed forward capacitor CFF, should be close to the FB pin.
Since the FB node is high impedance, maintain the copper area as small as possible. The trace are from
RFBT, RFBB, and CFF should be routed away from the body of the LMZ14203 to minimize noise.
4. Make input and output bus connections as wide as possible.
This reduces any voltage drops on the input or output of the converter and maximizes efficiency. To optimize
voltage accuracy at the load, ensure that a separate feedback voltage sense trace is made to the load. Doing
so will correct for voltage drops and provide optimum output accuracy.
5. Provide adequate device heat-sinking.
Use an array of heat-sinking vias to connect the exposed pad to the ground plane on the bottom PCB layer.
If the PCB has a plurality of copper layers, these thermal vias can also be employed to make connection to
inner layer heat-spreading ground planes. For best results use a 6 × 6 via array with minimum via diameter
of 8 mils thermal vias spaced 59 mils (1.5 mm). Ensure enough copper area is used for heat-sinking to keep
the junction temperature below 125°C.
10.1.1 Power Module SMT Guidelines
The recommendations below are for a standard module surface mount assembly
•
•
Land Pattern – Follow the PCB land pattern with either soldermask defined or non-soldermask defined pads
Stencil Aperture
–
For the exposed die attach pad (DAP), adjust the stencil for approximately 80% coverage of the PCB land
pattern
–
For all other I/O pads use a 1:1 ratio between the aperture and the land pattern recommendation
•
Solder Paste – Use a standard SAC Alloy such as SAC 305, type 3 or higher
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Layout Guidelines (continued)
•
•
•
Stencil Thickness – 0.125 mm to 0.15 mm
Reflow - Refer to solder paste supplier recommendation and optimized per board size and density
Refer to AN Design Summary LMZ1xxx and LMZ2xxx Power Modules Family (SNAA214) for Reflow
information.
•
Maximum number of reflows allowed is one
Figure 48. Sample Reflow Profile
Table 1. Sample Reflow Profile Table
MAX TEMP
(°C)
REACHED TIME ABOVE REACHED TIME ABOVE REACHED TIME ABOVE REACHED
PROBE
MAX TEMP
235°C
235°C
245°C
245°C
260°C
260°C
1
2
3
242.5
242.5
241
6.58
0.49
6.39
0
0
0
–
7.1
–
0
0
0
–
–
–
7.1
0.55
6.31
7.09
0.42
6.44
10.2 Layout Example
V
IN
V
O
LMZ14203H
VOUT
VIN
High
di/dt
C
in1
C
O1
GND
Loop 2
Loop 1
Figure 49. Minimize Area of Current Loops in Buck Module
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Layout Example (continued)
Top View
Thermal Vias
GND
GND
EPAD
CIN
COUT
1
2
3
4
5
6
7
VOUT
VIN
RON
RFBT
RENT
RENB
CFF
CSS
RFBB
GND Plane
Figure 50. PCB Layout Guide
10.3 Power Dissipation and Board Thermal Requirements
For a design case of VIN = 24 V, VOUT = 12 V, IOUT = 3 A, TA (MAX) = 65°C , and TJUNCTION = 125°C, the device
must see a maximum junction-to-ambient thermal resistance of:
RθJA-MAX < (TJ-MAX - TA(MAX)) / PD
(24)
This RθJA-MAX will ensure that the junction temperature of the regulator does not exceed TJ-MAX in the particular
application ambient temperature.
To calculate the required RθJA-MAX we need to get an estimate for the power losses in the IC. The following graph
is taken form the Typical Characteristics section (Figure 16) and shows the power dissipation of the LMZ14203H
for VOUT = 12 V at 85°C TA.
5
VIN = 15V
VIN = 24V
VIN = 30V
VIN = 36V
VIN = 42V
4
3
2
1
0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
OUTPUT CURRENT (A)
Figure 51. Power Dissipation VOUT = 12V TA = 85°C
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Power Dissipation and Board Thermal Requirements (continued)
Using the 85°C TA power dissipation data as a conservative starting point, the power dissipation PD for VIN = 24
V and VOUT = 12V is estimated to be 3.5W. The necessary RθJA-MAX can now be calculated.
RθJA-MAX < (125°C - 65°C) / 3.5W
RθJA-MAX < 17.1°C/W
(25)
(26)
To achieve this thermal resistance the PCB is required to dissipate the heat effectively. The area of the PCB will
have a direct effect on the overall junction-to-ambient thermal resistance. In order to estimate the necessary
copper area we can refer to Figure 52. This graph is taken from the Typical Characteristics section (Figure 31)
and shows how the RθJA varies with the PCB area.
40
0LFM (0m/s) air
225LFM (1.14m/s) air
35
500LFM (2.54m/s) air
Evaluation Board Area
30
25
20
15
10
5
0
0
10
20
30
40
50
60
2
BOARD AREA (cm )
Figure 52. Package Thermal Resistance RθJA 4-Layer PCB With 1-oz Copper
For RθJA-MAX< 17.1°C/W and only natural convection (that is., no air flow), the PCB area will have to be at least
52 cm2. This corresponds to a square board with 7.25 cm x 7.25 cm (2.85 in x 2.85 in) copper area, 4 layers, and
1oz copper thickness. Higher copper thickness will further improve the overall thermal performance. As a
reference, the evaluation board has 2-oz copper on the top and bottom layers, achieving RθJA of 14.9°C/W for
the same board area. Note thermal vias should be placed under the IC package to easily transfer heat from the
top layer of the PCB to the inner layers and the bottom layer.
For more guidelines and insight on PCB copper area, thermal vias placement, and general thermal design
practices see the application note, AN-2020 Thermal Design By Insight, Not Hindsight (SNVA419).
24
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SNVS692G –JANUARY 2011–REVISED OCTOBER 2015
11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
11.1.1.1 Related Documentation
•
•
•
•
•
AN-2027 Inverting Application for the LMZ14203 SIMPLE SWITCHER Power Module, SNVA425
Evaluation Board Application Note AN-2024, SNVA422
AN-2026 Effect of PCB Design on Thermal Performance of SIMPLE SWITCHER Power Modules, SNVA424
AN-2020 Thermal Design By Insight, Not Hindsight, SNVA419
AN Design Summary LMZ1xxx and LMZ2xxx Power Modules Family, SNAA214
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.
WEBENCH, SIMPLE SWITCHER are registered trademarks 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
3-Sep-2015
PACKAGING INFORMATION
Orderable Device
LMZ14203HTZ/NOPB
LMZ14203HTZE/NOPB
LMZ14203HTZX/NOPB
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
ACTIVE
TO-PMOD
TO-PMOD
TO-PMOD
NDW
7
7
7
250
Green (RoHS
& no Sb/Br)
CU SN
CU SN
CU SN
Level-3-245C-168 HR
Level-3-245C-168 HR
Level-3-245C-168 HR
LMZ14203
HTZ
ACTIVE
ACTIVE
NDW
NDW
45
Green (RoHS
& no Sb/Br)
-40 to 125
LMZ14203
HTZ
500
Green (RoHS
& no Sb/Br)
-40 to 125
LMZ14203
HTZ
(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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
3-Sep-2015
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
3-Sep-2015
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LMZ14203HTZ/NOPB
LMZ14203HTZX/NOPB
TO-
PMOD
NDW
NDW
7
7
250
500
330.0
24.4
10.6 14.22
5.0
16.0
24.0
Q2
TO-
330.0
24.4
10.6 14.22
5.0
16.0
24.0
Q2
PMOD
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
3-Sep-2015
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LMZ14203HTZ/NOPB
LMZ14203HTZX/NOPB
TO-PMOD
TO-PMOD
NDW
NDW
7
7
250
500
367.0
367.0
367.0
367.0
45.0
45.0
Pack Materials-Page 2
MECHANICAL DATA
NDW0007A
BOTTOM SIDE OF PACKAGE
TOP SIDE OF PACKAGE
TZA07A (Rev D)
www.ti.com
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