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LMZ12008
SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016
LMZ12008 8-A SIMPLE SWITCHER® Power Module With 20-V Maximum Input Voltage
1 Features
2 Applications
•
•
•
•
•
•
•
1
•
•
•
•
•
•
•
Integrated Shielded Inductor
Simple PCB Layout
Fixed Switching Frequency (350kHz)
Flexible Start-up Sequencing Using External Softstart, Tracking and Precision Enable
Protection Against Inrush Currents and Faults
such as Input UVLO and Output Short Circuit
Junction Temperature Range –40°C to 125°C
Single Exposed Pad and Standard Pinout for Easy
Mounting and Manufacturing
Fully Enabled for WEBENCH® Power Designer
Pin Compatible With LMZ22010/08/06,
LMZ12010/06, LMZ23610/08/06, and
LMZ13610/08/06
Electrical Specifications
– 40-W Maximum Total Output Power
– Up to 8-A Output Current
– Input Voltage Range 6 V to 20 V
– Output Voltage Range 0.8 V to 6 V
– Efficiency up to 92%
Performance Benefits
– High Efficiency Reduces System Heat
Generation
– Low Radiated Emissions (EMI) Tested to
EN55022
NOTE: EN 55022:2006, +A1:2007, FCC Part 15 Subpart B,
tested on Evaluation Board with EMI configuration
– Only 7 External Components
– Low Output Voltage Ripple
– No External Heat Sink Required
Simplified Application Schematic
•
Point-of-load Conversions from 12-V Input Rail
Time-Critical Projects
Space Constrained / High Thermal Requirement
Applications
Negative Output Voltage Applications
See AN-2027 SNVA425.
3 Description
The LMZ12008 SIMPLE SWITCHER® power module
is an easy-to-use step-down DC-DC solution capable
of driving up to 8-A load. The LMZ12008 is available
in an innovative package that enhances thermal
performance and allows for hand or machine
soldering.
The LMZ12008 can accept an input voltage rail
between 6 V and 20 V and can deliver an adjustable
and highly accurate output voltage as low as 0.8 V.
The LMZ12008 only requires two external resistors
and external capacitors to complete the power
solution. The LMZ12008 is a reliable and robust
design with the following protection features: thermal
shutdown, programmable input undervoltage lockout,
output overvoltage protection, short circuit protection,
output current limit, and the device allows start-up
into a prebiased output.
Device Information(1)(2)
PART NUMBER
LMZ12008
NDY (11)
100
EFFICIENCY (%)
VOUT
SS
FB
AGND
PGND
EN
VIN
90
VOUT
Enable
RFBT
3 x 10 PF
0.47 PF
(OPT)
RFBB
See Table
80
70
60
6Vin
8Vin
10Vin
12Vin
16Vin
20Vin
50
See Table
CIN
15.00 mm × 15.00 mm
Efficiency 3.3-V Output at 25°C
CFF 4.7 nF (OPT)
CSS
BODY SIZE (NOM)
(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.
LMZ12008
VIN
PACKAGE
COUT
2 x 330 PF
40
0
2
4
6
OUTPUT CURRENT (A)
8
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.
LMZ12008
SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specification...........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
6
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
Overview .................................................................
Functional Block Diagram .......................................
Feature Description.................................................
Device Functional Modes........................................
14
14
14
15
8
Application and Implementation ........................ 17
8.1 Application Information............................................ 17
8.2 Typical Application ................................................. 17
9 Power Supply Recommendations...................... 23
10 Layout................................................................... 23
10.1
10.2
10.3
10.4
Layout Guidelines .................................................
Layout Examples...................................................
Power Dissipation and Thermal Considerations ...
Power Module SMT Guidelines ............................
23
24
26
26
11 Device and Documentation Support ................. 28
11.1
11.2
11.3
11.4
11.5
11.6
Device Support......................................................
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
28
28
28
28
28
28
12 Mechanical, Packaging, and Orderable
Information ........................................................... 29
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision G (August 2015) to Revision H
•
Changed pin number from 2 to 3............................................................................................................................................ 3
Changes from Revision F (October 2013) to Revision G
•
Page
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 E (March 2013) to Revision F
Page
•
Changed 12 mil .................................................................................................................................................................... 23
•
Changed 12 mil .................................................................................................................................................................... 26
•
Added Power Module SMT Guidelines................................................................................................................................. 26
2
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SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016
5 Pin Configuration and Functions
NDY Package
11-Pin
Top View
11
10
9
8
7
6
5
4
3
2
1
PGND/EP
Connect to AGND
VOUT
VOUT
NC
SS
FB
AGND
AGND
EN
AGND
VIN
VIN
Pin Functions
PIN
NAME
NO.
AGND
3
TYPE
DESCRIPTION
Ground
Analog Ground — Reference point for all stated voltages. Must be externally connected to
PGND(EP).
5
6
EN
4
Analog
Enable — Input to the precision enable comparator. Rising threshold is 1.274 V typical. Once
the module is enabled, a 13-µA source current is internally activated to facilitate programmable
hysteresis.
FB
7
Analog
Feedback — Internally connected to the regulation amplifier and overvoltage comparator. The
regulation reference point is 0.795 V at this input pin. Connect the feedback resistor divider
between VOUT and AGND to set the output voltage.
NC
9
—
PGND
—
Ground
Exposed Pad / Power Ground — Electrical path for the power circuits within the module. PGND
is not internally connected to AGND (pin 5,6). Must be electrically connected to pins 5 and 6
external to the package. The exposed pad is also used to dissipate heat from the package
during operation. Use one hundred 12 mil thermal vias from top to bottom copper for best
thermal performance.
SS
8
Analog
Soft-Start/Track Input — To extend the 1.6-ms internal soft-start connect an external soft-start
capacitor. For tracking connect to an external resistive divider connected to a higher priority
supply rail. See Detailed Design Procedure section.
VIN
1
Power
Input supply — Nominal operating range is 6 V to 20 V. A small amount of internal capacitance
is contained within the package assembly. Additional external input capacitance is required
between this pin and the exposed pad (PGND).
Power
Output Voltage — Output from the internal inductor. Connect the output capacitor between this
pin and exposed pad (PGND).
2
VOUT
10
11
No Connect — This pin must remain floating, do not ground.
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SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016
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6 Specification
6.1 Absolute Maximum Ratings
(1) (2) (3)
MIN
MAX
UNIT
VIN to PGND
–0.3
24
V
EN to AGND
–0.3
5.5
V
SS, FB to AGND
–0.3
2.5
V
AGND to PGND
–0.3
0.3
V
Junction Temperature
150
°C
Peak Reflow Case Temperature (30 sec)
245
°C
150
°C
Storage Temperature, Tstg
(1)
(2)
(3)
–65
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
For soldering specifications, refer to the following document: SNOA549
6.2 ESD Ratings
V(ESD)
(1)
Electrostatic discharge
VALUE
UNIT
±2000
V
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions (1)
MIN
MAX
VIN
6
20
EN
0
5
V
−40
125
°C
Operation Junction Temperature
(1)
UNIT
V
Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which
operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical Characteristics.
6.4 Thermal Information
LMZ12008
THERMAL METRIC (1)
NDY
UNIT
11 PINS
Junction-to-ambient thermal
resistance
RθJA
RθJC(top)
(1)
4
Natural Convection
9.9
225 LFPM
6.8
500 LFPM
5.2
Junction-to-case (top) thermal resistance
1.0
°C/W
°C/W
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016
6.5 Electrical Characteristics
Limits are for TJ = 25°C unless otherwise specified. 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 = 12V, VOUT = 3.3V (1)
PARAMETER
TEST CONDITIONS
MIN (2)
TYP (3)
MAX (2)
UNIT
SYSTEM PARAMETERS
ENABLE CONTROL
1.274
VEN
EN threshold
VEN rising
IEN-HYS
EN hysteresis source
current
VEN > 1.274 V
ISS
SS source current
VSS = 0 V
tSS
Internal soft-start interval
over the junction temperature
(TJ) range of –40°C to +125°C
1.096
1.452
13
V
µA
SOFT-START
50
over the junction temperature
(TJ) range of –40°C to +125°C
40
60
1.6
µA
msec
CURRENT LIMIT
ICL
Current limit threshold
DC average
10.5
A
INTERNAL SWITCHING OSCILLATOR
fosc
Free-running oscillator
frequency
314
359
404
kHz
REGULATION AND OVERVOLTAGE COMPARATOR
VFB
In-regulation feedback
voltage
VFB-OV
Feedback overvoltage
protection threshold
IFB
VSS >+ 0.8 V
IO = 8 A
0.795
over the junction temperature
(TJ) range of –40°C to +125°C
0.775
0.815
V
0.86
V
Feedback input bias
current
5
nA
IQ
Non-Switching Quiescent
Current
3
mA
ISD
Shutdown Quiescent
Current
32
μA
Dmax
Maximum Duty Factor
VEN = 0 V
85%
THERMAL CHARACTERISTICS
TSD
Thermal Shutdown
Rising
165
TSD-HYST
Thermal shutdown
hysteresis
Falling
15
°C
°C
PERFORMANCE PARAMETERS (4)
ΔVO
Output voltage ripple
BW at 20 MHz
ΔVO/ΔVIN
Line regulation
VIN = 12 V to 20 V, IOUT= 8 A
ΔVO/ΔIOUT
Load regulation
VIN = 12 V, IOUT= 0.001 A to 8 A
η
Peak efficiency
VIN = 12 V VOUT = 3.3 V, IOUT = 5 A
89.5%
η
Full load efficiency
VIN = 12 V VOUT = 3.3 V, IOUT = 8 A
88.5%
(1)
(2)
(3)
(4)
24
mVPP
±0.2%
1
mV/A
EN 55022:2006, +A1:2007, FCC Part 15 Subpart B, tested on Evaluation Board with EMI configuration
Min and Max 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 Average Outgoing Quality Level (AOQL).
Typical numbers are at 25°C and represent the most likely parametric norm.
Refer to BOM in Table 1.
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SNVS716H – MARCH 2011 – REVISED FEBRUARY 2016
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6.6 Typical Characteristics
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
100
8
DISSIPATION (W)
90
EFFICIENCY (%)
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
7
80
70
60
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
50
40
0
2
4
6
OUTPUT CURRENT (A)
6
5
4
3
2
1
0
8
0
Figure 1. Efficiency 5-V Output at 25°C
8
6Vin
8Vin
10Vin
12Vin
16Vin
20Vin
DISSIPATION (W)
EFFICIENCY (%)
90
70
60
6Vin
8Vin
10Vin
12Vin
16Vin
20Vin
50
40
0
2
4
6
OUTPUT CURRENT (A)
2
0
0
8
90
7
80
70
60
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
30
0
2
4
6
OUTPUT CURRENT (A)
2
4
6
OUTPUT CURRENT (A)
8
Figure 4. Dissipation 3.3-V Output at 25°C
DISSIPATION (W)
EFFICIENCY (%)
4
100
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
6
5
4
3
2
1
0
8
Figure 5. Efficiency 2.5-V Output at 25°C
6
6
8
Figure 3. Efficiency 3.3-V Output at 25°C
50
8
Figure 2. Dissipation 5-V Output at 25°C
100
80
2
4
6
OUTPUT CURRENT (A)
0
2
4
6
OUTPUT CURRENT (A)
8
Figure 6. Dissipation 2.5-V Output at 25°C
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Typical Characteristics (continued)
90
7
80
6
DISSIPATION (W)
EFFICIENCY (%)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
70
60
50
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
40
30
20
0
2
4
6
OUTPUT CURRENT (A)
3
2
0
8
0
7
80
6
70
60
50
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
10
0
2
4
6
OUTPUT CURRENT (A)
4
3
2
0
8
0
7
DISSIPATION (W)
80
70
60
50
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
0
2
4
6
OUTPUT CURRENT (A)
2
4
6
OUTPUT CURRENT (A)
8
Figure 10. Dissipation 1.5-V Output at 25°C
8
20
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
5
90
30
8
1
Figure 9. Efficiency 1.5-V Output at 25°C
40
2
4
6
OUTPUT CURRENT (A)
Figure 8. Dissipation 1.8-V Output at 25°C
DISSIPATION (W)
EFFICIENCY (%)
4
90
20
EFFICIENCY (%)
5
1
Figure 7. Efficiency 1.8-V Output at 25°C
30
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
6
5
4
3
2
1
0
8
Figure 11. Efficiency 1.2-V Output at 25°C
0
2
4
6
OUTPUT CURRENT (A)
8
Figure 12. Dissipation 1.2-V Output at 25°C
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Typical Characteristics (continued)
90
7
80
6
70
DISSIPATION (W)
EFFICIENCY (%)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
60
50
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
30
20
10
0
2
4
6
OUTPUT CURRENT (A)
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
5
4
3
2
1
0
8
Figure 13. Efficiency 1-V Output at 25°C
0
9
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
8
90
DISSIPATION (W)
EFFICIENCY (%)
7
70
60
50
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
40
30
0
2
4
6
OUTPUT CURRENT (A)
4
3
1
0
8
0
8
90
7
80
6
70
60
50
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
20
0
2
4
6
OUTPUT CURRENT (A)
2
4
6
OUTPUT CURRENT (A)
8
Figure 16. Dissipation 5-V Output at 85°C
DISSIPATION (W)
EFFICIENCY (%)
5
100
30
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
5
4
3
2
1
0
8
Figure 17. Efficiency 3.3-V Output at 85°C
8
6
2
Figure 15. Efficiency 5-V Output at 85°C
40
8
Figure 14. Dissipation 1-V Output at 25°C
100
80
2
4
6
OUTPUT CURRENT (A)
0
2
4
6
OUTPUT CURRENT (A)
8
Figure 18. Dissipation 3.3-V Output at 85°C
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Typical Characteristics (continued)
100
8
90
7
80
6
DISSIPATION (W)
EFFICIECNY (%)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
70
60
50
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
40
30
20
0
2
4
6
OUTPUT CURRENT (A)
3
2
0
8
0
8
80
7
70
6
60
50
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
10
0
2
4
6
OUTPUT CURRENT (A)
4
3
1
0
8
0
7
70
6
DISSPATION (W)
80
60
50
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
0
2
4
6
OUTPUT CURRENT (A)
2
4
6
OUTPUT CURRENT (A)
8
Figure 22. Dissipation 1.8-V Output at 85°C
8
10
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
5
90
20
8
2
Figure 21. Efficiency 1.8-V Output at 85°C
30
2
4
6
OUTPUT CURRENT (A)
Figure 20. Dissipation 2.5-V Output at 85°C
DISSPATION (W)
EFFICIENCY (%)
4
90
20
EFFICIENCY (%)
5
1
Figure 19. Efficiency 2.5-V Output at 85°C
30
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
5
4
3
2
1
0
8
Figure 23. Efficiency 1.5-V Output at 85°C
0
2
4
6
OUTPUT CURRENT (A)
8
Figure 24. Dissipation 1.5-V Output at 85°C
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Typical Characteristics (continued)
90
8
80
7
70
6
DISSIPATION (W)
EFFICIENCY (%)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
60
50
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
30
20
10
0
2
0
0
8
80
7
70
6
60
50
40
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
10
0
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
5
4
3
1
0
8
Figure 27. Efficiency 1-V Output at 85°C
0
0.999
0.998
8
6
4
2
JA = 9.9 °C/W
JA = 6.8 °C/W
JA = 5.2 °C/W
0
1
2
3
4
5
6
7
OUTPUT CURRENT (A)
8
Figure 28. Dissipation 1-V Output at 85°C
MAXIMUM OUTPUT CURRENT (A)
1.000
0
2
4
6
OUTPUT CURRENT (A)
10
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
1.001
8
2
2
4
6
OUTPUT CURRENT (A)
1.002
2
4
6
OUTPUT CURRENT (A)
Figure 26. Dissipation 1.2-V Output at 85°C
DISSPATION (W)
EFFICIENCY (%)
3
90
20
NORMALIZED VOUT (V/V)
4
8
Figure 25. Efficiency 1.2-V Output at 85°C
8
20
VOUT = 3.3 V
40
60
80
100
TEMPERATURE (C)
120
VIN = 12 V, VOUT = 5 V
Figure 29. Normalized Line and Load Regulation
10
5
1
2
4
6
OUTPUT CURRENT (A)
30
6 Vin
8 Vin
10 Vin
12 Vin
16 Vin
20 Vin
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Figure 30. Thermal Derating
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
30
2 Layer 0 LFPM
2 Layer 225 LFPM
4 Layer 0 LFPM
4 Layer 225 LFPM
27
8
24
THETA JA (°C/W)
MAXIMUM OUTPUT CURRENT (A)
10
6
4
21
18
15
12
9
2
JA = 9.9 °C/W
JA = 6.8 °C/W
JA = 5.2 °C/W
0
20
40
60
80
100
TEMPERATURE (C)
6
3
120
0
2
4
6
8
2
COPPER AREA (in )
10
12
VIN = 12 V, VOUT = 3.3 V
Figure 31. Thermal Derating
12 VIN, 5 VOUT at Full Load, BW = 20 MHz
Figure 32. θJA vs Copper Heat Sinking Area
12 VIN, 5 VOUT at Full Load, BW = 250 MHz
Figure 33. Output Ripple
12 VIN, 3.3 VOUT at Full Load, BW = 20 MHz
Figure 34. Output Ripple
12 VIN, 3.3 VOUT at Full Load, BW = 250 MHz
Figure 36. Output Ripple
Figure 35. Output Ripple
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
12 VIN, 1.2 VOUT at Full Load, BW = 250 MHz
12 VIN, 1.2 VOUT at Full Load, BW = 20 MHz
Figure 38. Output Ripple
Figure 37. Output Ripple
12 VIN, 5 VOUT 1- to 8-A Step
12 VIN, 3.3 VOUT 1- to 8-A Step
Figure 39. Transient Response
Figure 40. Transient Response
16
14
CURRENT (A)
12
10
8
6
4
Output Current
Input Current
2
0
5
10
15
INPUT VOLTAGE (V)
20
12 VIN, 1.2 VOUT 1- to 8-A Step
Figure 41. Transient Response
12
Figure 42. Short Circuit Current vs Input Voltage
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Typical Characteristics (continued)
Unless otherwise specified, the following conditions apply: VIN = 12 V; CIN = three × 10 μF + 47-nF X7R Ceramic; COUT = two
× 330-μF Specialty Polymer + 47-µF Ceramic + 47-nF Ceramic; CFF = 4.7 nF; TA = 25° C for waveforms. All indicated
temperatures are ambient.
No CSS
CSS = 0.47 µF
Figure 43. 3.3 VOUT Soft-Start
Figure 44. 3.3 VOUT Soft-Start
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7 Detailed Description
7.1 Overview
The architecture used is an internally compensated emulated peak current mode control, based on a monolithic
synchronous SIMPLE SWITCHER core capable of supporting high load currents. The output voltage is
maintained through feedback compared with an internal 0.8-V reference. For emulated peak current-mode, the
valley current is sampled on the down-slope of the inductor current. This is used as the DC value of current to
start the next cycle.
The primary application for emulated peak current-mode is high input voltage to low output voltage operating at a
narrow duty cycle. By sampling the inductor current at the end of the switching cycle and adding an external
ramp, the minimum ON-time can be significantly reduced, without the need for blanking or filtering which is
normally required for peak current-mode control.
7.2 Functional Block Diagram
Linear
Regulator
2M
VIN
1
3
3
CIN
EN
CBST
CINint
1
2.2 uH VOUT
VREF
3
RFBT
CSS
2
350 kHz
PWM
SS
COUT
FB
2
Comp
RFBB
AGND
Regulator IC
EP/
PGND
Internal Passives
7.3 Feature Description
7.3.1 Output Overvoltage Protection
If the voltage at FB is greater than a 0.86-V internal reference, the output of the error amplifier is pulled toward
ground, causing VOUT to fall.
7.3.2 Current Limit
The LMZ12008 is protected by both low-side (LS) and high-side (HS) current limit circuitry. The LS current limit
detection is carried out during the OFF-time by monitoring the current through the LS 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 13 A (typical) the
current limit comparator disables the start of the next switching period. Switching cycles are prohibited until
current drops below the limit.
NOTE
DC current limit is dependent on duty cycle as illustrated in the graph in the Typical
Characteristics section.
14
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Feature Description (continued)
The HS current limit monitors the current of top side MOSFET. Once HS current limit is detected (16 A typical) ,
the HS MOSFET is shutoff immediately, until the next cycle. Exceeding HS current limit causes VOUT to fall.
Typical behavior of exceeding LS current limit is that fSW drops to 1/2 of the operating frequency.
7.3.3 Thermal Protection
The junction temperature of the LMZ12008 must 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 VOUT 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 150°C (typical hysteresis = 15°C)
the SS pin is released, VOUT rises smoothly, and normal operation resumes.
Applications requiring maximum output current especially those at high input voltage may require additional
derating at elevated temperatures.
7.3.4 Prebiased Start-Up
The LMZ12008 will properly start up into a prebiased output. This start-up situation is common in multiple rail
logic applications where current paths may exist between different power rails during the start-up sequence.
Figure 45 shows proper behavior in this mode. Trace one is Enable going high. Trace two is 1.8-V prebias rising
to 3.3 V. Trace three is the SS voltage with a CSS= 0.47 µF. Rise-time determined by CSS.
Figure 45. Prebiased Start-Up
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, inductor
current is maintained to an average value equaling IOUT. In DCM the low-side switch will turn off when the
inductor current falls to zero, this causes the inductor current to resonate. Although it is in DCM, the current is
allowed to go slightly negative to charge the bootstrap capacitor.
In CCM, current flows through the inductor through the entire switching cycle and never falls to zero during the
OFF-time.
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Device Functional Modes (continued)
Figure 46 is a comparison pair of waveforms showing both the CCM (upper) and DCM operating modes.
VIN = 12 V, VO = 3.3 V, IO = 3 A / 0.3 A
Figure 46. CCM and DCM Operating Modes
The approximate formula for determining the DCM/CCM boundary is as follows:
(VIN - VOUT) x D
IDCB =
2 x L x fSW
(1)
The inductor internal to the module is 2.2 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 (ΔiL). ΔiL can be calculated with:
(VIN - VOUT) x D
'iL =
L x fSW
where
•
•
VIN is the maximum input voltage
and fSW is typically 359 kHz.
(2)
If the output current IOUT is determined by assuming that IOUT = IL, the higher and lower peak of ΔiL can be
determined.
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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 LMZ12008 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 8 A. The following design procedure can be used to select
components for the LMZ12008. 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. Please go to www.ti.com for more details.
8.2 Typical Application
CIN6
(OPT)
+
CIN5
VOUT
SS
FB
PGND
AGND
V IN
EN
VIN
LMZ12008
V OUT
RENT
(OPT)
CIN2,3,4
CIN1
D1
5.1V
(OPT)
CO 3,4
CSS
RENB
CO1
(OPT)
CO 2
CO5
(OPT)
LOAD
(OPT)
RFBB
RFBT
Figure 47. Typical Application Schematic Diagram
8.2.1 Design Requirements
For this example the following application parameters exist.
• VIN Range = Up to 20 V
• VOUT = 0.8 V to 6 V
• IOUT = 8 A
8.2.2 Detailed Design Procedure
The LMZ12008 is fully supported by WEBENCH which offers: component selection, electrical and thermal
simulations. Additionally, there are both evaluation and demonstration boards that may be used as a starting
point for design. The following list of steps can be used to manually design the LMZ12008 application.
All references to values refer to the typical applications schematic Figure 47.
1.
2.
3.
4.
5.
6.
Select minimum operating VIN with enable divider resistors
Program VOUT with FB resistor divider selection
Select COUT
Select CIN
Determine module power dissipation
Layout PCB for required thermal performance
8.2.2.1 Enable Divider, RENT, RENB and RENH Selection
Internal to the module is a 2-MΩ pullup resistor connected from VIN to Enable. For applications not requiring
precision undervoltage lockout (UVLO), the Enable input may be left open circuit and the internal resistor will
always enable the module. In such case, the internal UVLO occurs typically at 4.3V (VIN rising).
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Typical Application (continued)
In applications with separate supervisory circuits Enable can be directly interfaced to a logic source. In the case
of sequencing supplies, the divider is connected to a rail that becomes active earlier in the power-up cycle than
the LMZ12008 output rail.
Enable provides a precise 1.274-V threshold to allow direct logic drive or connection to a voltage divider from a
higher enable voltage such as VIN. Additionally there is 13 μA (typical) of switched offset current allowing
programmable hysteresis. See Figure 48.
The function of the enable divider is to allow the designer to choose an input voltage below which the circuit will
be disabled. This implements the feature of a programmable UVLO. The two resistors must be chosen based on
the following ratio:
RENT / RENB = (VIN UVLO / 1.274 V) – 1
(3)
The LMZ12008 typical application shows 12.7 kΩ for RENB and 42.2 kΩ for RENT resulting in a rising UVLO of
5.51 V. This divider presents 4.62 V to the EN input when VIN is raised to 20 V. This upper voltage must always
be checked, making sure that it never exceeds the Abs Max 5.5-V limit for Enable. A 5.1-V Zener clamp can be
applied in cases where the upper voltage would exceed the EN input's range of operation. The Zener clamp is
not required if the target application prohibits the maximum Enable input voltage from being exceeded.
Additional enable voltage hysteresis can be added with the inclusion of RENH. It is possible to select values for
RENT and RENB such that RENH is a value of zero allowing it to be omitted from the design.
Rising threshold can be calculated as follows:
VEN(rising) = 1.274 ( 1 + (RENT|| 2 meg)/ RENB)
(4)
Whereas the falling threshold level can be calculated using:
VEN(falling) = VEN(rising) – 13 µA ( RENT|| 2 meg || RENTB + RENH )
VIN
(5)
INT-VCC (5V)
13 PA
2.0M
RENT
42.2k
RENH
ENABLE
RUN
100:
5.1V
RENB
12.7k
1.274V
Figure 48. Enable Input Detail
8.2.2.2 Output Voltage Selection
Output voltage is determined by a divider of two resistors connected between VOUT and AGND. The midpoint of
the divider is connected to the FB input.
The regulated output voltage determined by the external divider resistors RFBT and RFBB is:
VOUT = 0.795 V × (1 + RFBT / RFBB)
(6)
Rearranging terms; the ratio of the feedback resistors for a desired output voltage is:
RFBT / RFBB = (VOUT / 0.795V) – 1
(7)
These resistors must generally be chosen from values in the range of 1.0 kΩ to 10.0 kΩ.
For VOUT = 0.8 V the FB pin can be connected to the output directly and RFBB can be set to 8.06 kΩ to provide
minimum output load.
Table 1 lists the values for RFBT , and RFBB.
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Typical Application (continued)
Table 1. Typical Application Bill of Materials
REF DES
DESCRIPTION
CASE SIZE
MANUFACTURER
U1
SIMPLE SWITCHER
PFM-11
Texas Instruments
MANUFACTURER P/N
LMZ12008TZ
CIN1,6 (OPT)
0.047 µF, 50 V, X7R
1206
Yageo America
CC1206KRX7R9BB473
UMK325BJ106MM-T
CIN2,3,4
10 µF, 50 V, X7R
1210
Taiyo Yuden
CIN5 (OPT)
CAP, AL, 150 µF, 50 V
Radial G
Panasonic
EEE-FK1H151P
CO1,5 (OPT)
0.047 µF, 50 V, X7R
1206
Yageo America
CC1206KRX7R9BB473
CO2 (OPT)
47 µF, 10 V, X7R
1210
Murata
GRM32ER61A476KE20L
CO3,4
330 μF, 6.3 V, 0.015 Ω
CAPSMT_6_UE
Kemet
T520D337M006ATE015
RFBT
3.32 kΩ
0805
Panasonic
ERJ-6ENF3321V
RFBB
1.07 kΩ
0805
Panasonic
ERJ-6ENF1071V
ERJ-6ENF4222V
RENT
42.2 kΩ
0805
Panasonic
RENB
12.7 kΩ
0805
Panasonic
ERJ-6ENF1272V
CSS
0.47 μF, ±10%, X7R, 16 V
0805
AVX
0805YC474KAT2A
D1 (OPT)
5.1 V, 0.5 W
SOD-123
Diodes Inc.
MMSZ5231BS-7-F
8.2.2.3 Soft-Start Capacitor 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.
Upon turnon, after all UVLO conditions have been passed, an internal 1.6-ms circuit slowly ramps the SS input to
implement internal soft start. If 1.6 ms is an adequate turnon time then the Css capacitor can be left unpopulated.
Longer soft-start periods are achieved by adding an external capacitor to this input.
Soft-start duration is given by the formula:
tSS = VREF × CSS / Iss = 0.795 V × CSS / 50 µA
(8)
This equation can be rearranged as follows:
CSS = tSS × 50 μA / 0.795 V
(9)
Using a 0.22-μF capacitor results in 3.5-ms typical soft-start duration; and 0.47-μF results in 7.5 ms typical. 0.47
μF is a recommended initial value.
As the soft-start input exceeds 0.795 V the output of the power stage will be in regulation and the 50-μA current
is deactivated. The following conditions will reset the soft-start capacitor by discharging the SS input to ground
with an internal current sink.
•
•
•
The Enable input being pulled low
A thermal shutdown condition
VIN falling below 4.3 V (typical) and triggering the VCC UVLO
8.2.2.4 Tracking Supply Divider Option
The tracking function allows the module to be connected as a slave supply to a primary voltage rail (often the
3.3-V system rail) where the slave module output voltage is lower than that of the master. Proper configuration
allows the slave rail to power up coincident with the master rail such that the voltage difference between the rails
during ramp-up is small (that is, < 0.15 V typical). The values for the tracking resistive divider must be selected
such that the effect of the internal 50-µA current source is minimized. In most cases the ratio of the tracking
divider resistors is the same as the ratio of the output voltage setting divider. Proper operation in tracking mode
dictates the soft-start time of the slave rail be shorter than the master rail; a condition that is easy to satisfy since
the CSS cap is replaced by RTKB. The tracking function is only supported for the power up interval of the master
supply; once the SS/TRK rises past 0.795 V the input is no longer enabled and the 50-µA internal current source
is switched off.
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3.3V Master
2.5Vout
Int VCC
50 PA
Rtkt
226
Rfbt
2.26k
SS
FB
Rtkb
107
Rfbb
1.07k
Figure 49. Tracking Option Input Detail
8.2.2.5 COUT Selection
None of the required COUT output capacitance is contained within the module. A minimum value ranging from 330
μF for 6-VOUT to 660 μF for 1.2-VOUT applications is required based on the values of internal compensation in the
error amplifier. These minimum values can be decreased if the effective capacitor ESR is higher than 15 mΩ.
A Low ESR (15 mΩ) tantalum, organic semiconductor or specialty polymer capacitor types in parallel with a 47nF X7R ceramic capacitor for high-frequency noise reduction is recommended for obtaining lowest ripple. The
output capacitor COUT may consist of several capacitors in parallel placed in close proximity to the module. The
output voltage ripple of the module depends on the equivalent series resistance (ESR) of the capacitor bank, and
can be calculated by multiplying the ripple current of the module by the effective impedance of your chosen
output capacitors (for ripple current calculation, see Equation 2. Electrolytic capacitors will have large ESR and
lead to larger output ripple than ceramic or polymer types. For this reason a combination of ceramic and polymer
capacitors is recommended for low output ripple performance.
The output capacitor assembly must also meet the worst case ripple current rating of ΔiL, as calculated in
Equation 2 below. Loop response verification is also valuable to confirm closed loop behavior.
For applications with dynamic load steps; Equation 10 provides a good first pass approximation of COUT for load
transient requirements.
Istep
COUT t
('VOUT - ISTEP x ESR) x (
fSW
)
VOUT
(10)
For 12 VIN, 3.3 VOUT, a transient voltage of 5% of VOUT = 0.165 V (ΔVOUT), a 7A load step (ISTEP), an output
capacitor effective ESR of 3 mΩ, and a switching frequency of 350 kHz (fSW):
7A
COUT t
(0.165V - 7A x 0.003) x (
350e3
)
3.3V
t 458 PF
(11)
NOTE
The stability requirement for minimum output capacitance must always be met.
One recommended output capacitor combination is two 330-μF, 15-mΩ ESR tantalum polymer capacitors
connected in parallel with a 47-µF 6.3-V X5R ceramic. This combination provides excellent performance that may
exceed the requirements of certain applications. Additionally some small 47-nF ceramic capacitors can be used
for high frequency EMI suppression.
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8.2.2.6 CIN Selection
The LMZ12008 module contains two internal ceramic input capacitors. Additional input capacitance is required
external to the module to handle the input ripple current of the application. The input capacitor can be several
capacitors in parallel. This input capacitance must be located in very close proximity to the module. Input
capacitor selection is generally directed to satisfy the input ripple current requirements rather than by
capacitance value. Input ripple current rating is dictated by Equation 12:
ICIN-RMS = IOUT x D(1-D)
where
D ≊ VOUT / 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 × VOUT.
Recommended minimum input capacitance is 30-µF X7R (or X5R) 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 derating of the capacitor selected.
NOTE
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 parameter.
If the system design requires a certain minimum value of peak-to-peak input ripple voltage (ΔVIN) to be
maintained then Equation 13 may be used.
CIN 8
IOUT x D x (1 - D)
fSW x 'VIN
(13)
If ΔVIN is 200 mV or 1.66% of VIN for a 12-V input to 3.3-V output application and fSW = 350 kHz then:
8A x §
CIN 8
3.3V · § 3.3V·
x 1© 12V ¹ © 12V ¹
350 kHz x 200 mV
8 22.4 µF
(14)
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. The LMZ12008 typical applications schematic
and evaluation board include a 150-μF 50-V aluminum capacitor for this function. There are many situations
where this capacitor is not necessary.
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8.2.3 Application Curves
100
10
OUTPUT CURRENT (A)
EFFICIENCY (%)
90
80
70
60
50
12Vin
40
0
1
2
3
4
5
6
OUTPUT CURRENT (A)
8
6
4
2
0
7
8
JA = 9.9 °C/W
20 30 40 50 60 70 80 90 100 110 120
AMBIENT TEMPERATURE (°C)
VIN = 12 V, VOUT = 3.3 V
VIN = 12 V, VOUT = 3.3 V
Figure 51. Thermal Derating Curve
Figure 50. Efficiency
50
AMPLITUDE (dB V/m)
45
40
35
30
25
20
15
10
5
0
Horizontal Peak
Vertical Peak
Class B Limit
Class A Limit
0 100 200 300 400 500 600 700 800 9001000
FREQUENCY (MHz)
VIN = 12 V, VOUT = 5 V,
IOUT = 8 A
Figure 52. Radiated EMI (EN 55022)
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9 Power Supply Recommendations
The LMZ12008 device is designed to operate from an input voltage supply range between 6 V and 20 V. This
input supply must be well regulated and able to withstand maximum input current and maintain a stable voltage.
The resistance of the input supply rail must be low enough that an input current transient does not cause a high
enough drop at the LMZ12008 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 LMZ12008, 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. A good layout example is shown in
Figure 55
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 as
shown in Figure 53. 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 (CIN) is placed at a distance away
from the LMZ12008. Therefore place CIN as close as possible to the LMZ12008 VIN and PGND exposed
pad. This will minimize the high di/dt area and reduce radiated EMI. Additionally, grounding for both the input
and output capacitor must consist of a localized top side plane that connects to the PGND exposed pad
(EP).
2. Have a single point ground.
The ground connections for the feedback, soft-start, and enable components must be routed to the AGND
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. Additionally provide a single point ground connection from pin 4 (AGND) to EP/PGND.
3. Minimize trace length to the FB pin.
Both feedback resistors, RFBT and RFBB must be located close to the FB pin. Since the FB node is high
impedance, maintain the copper area as small as possible. The traces from RFBT, RFBB must be routed away
from the body of the LMZ12008 to minimize possible noise pickup.
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 multiple copper layers, these thermal vias can also be connected to inner layer heatspreading ground planes. For best results use a 10 × 10 via array or larger with a minimum via diameter of 8
mil thermal vias spaced 46.8 mil (1.5 mm). Ensure enough copper area is used for heat-sinking to keep the
junction temperature below 125°C.
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10.2 Layout Examples
VOUT
VIN
VOUT
VIN
High
di/dt
CIN
COUT
PGND
Loop 2
Loop 1
Figure 53. Critical Current Loops to Minimize
Top View
Thermal Vias
GND
GND
3
4 5
6 7 8 9 10 11
AGND
EN
NC
SS
FB
AGND
COUT
VOUT
VOUT
2
VIN
VIN
EPAD
1
AGND
VIN
CIN
VOUT
CSS
RFBT
Enable >
CFF
Connect EN on middle or
bottom layer
RFBB
GND Plane
Figure 54. PCB Layout Guide
24
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Layout Examples (continued)
Figure 55. Top View of Evaluation PCB
Figure 56. Bottom View of Evaluation PCB
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10.3 Power Dissipation and Thermal Considerations
When calculating module dissipation use the maximum input voltage and the average output current for the
application. Many common operating conditions are provided in the characteristic curves such that less common
applications can be derived through interpolation. In all designs, the junction temperature must be kept below the
rated maximum of 125°C.
For the design case of VIN = 12 V, VOUT = 3.3 V, IOUT = 8 A, and TA-MAX = 50°C, the module must see a thermal
resistance from case to ambient (θCA) of less than:
TJ-MAX ± TA-MAX
- TJC
TCA <
PIC_LOSS
(15)
Given the typical thermal resistance from junction to case (θJC) to be 1.0°C/W. Use the 85°C power dissipation
curves in the Typical Characteristics section to estimate the PIC-LOSS for the application being designed. In this
application it is 3.9 W.
TCA <
125°C - 50°C
- 1.0 °C < 18.23 °C
3.9 W
W
W
(16)
To reach θCA = 18.23, the PCB is required to dissipate heat effectively. With no airflow and no external heat-sink,
a good estimate of the required board area covered by 2-oz. copper on both the top and bottom metal layers is:
Board Area_cm2 8
500 . °C x cm 2
TCA
W
(17)
As a result, approximately 27.42 square cm of 2-oz. copper on top and bottom layers is the minimum required
area for the example PCB design. This is 5.23 × 5.23 cm (2.06 × 2.06 in) square. The PCB copper heat sink
must be connected to the exposed pad. For best performance, use approximately 100, 8 mil thermal vias spaced
59 mil (1.5 mm) apart connect the top copper to the bottom copper.
Another way to estimate the temperature rise of a design is using θJA. An estimate of θJA for varying heat sinking
copper areas and airflows can be found in the typical applications curves. If our design required the same
operating conditions as before but had 225 LFPM of airflow. We locate the required θJA of
TJA <
TJ-MAX - TA-MAX
PIC_LOSS
TJA <
(125 - 50) °C
°C
< 19.23
3.9 W
W
(18)
On the θRA vs copper heatsinking curve, the copper area required for this application is now only 1 square
inches. The airflow reduced the required heat sinking area by a factor of four.
To reduce the heat sinking copper area further, this package is compatable with D3-PAK surface mount heat
sinks.
For an example of a high thermal performance PCB layout for SIMPLE SWITCHER power modules, refer to AN2093 SNVA460, AN-2084 SNVA456, AN-2125 SNVA473, AN-2020 SNVA422 and AN-2026 SNVA424.
10.4 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
• Stencil Thickness — 0.125 to 0.15 mm
• Reflow — Refer to solder paste supplier recommendation and optimized per board size and density
• Refer to Design Summary LMZ1xxx and LMZ2xxx Power Modules Family (SNAA214) for reflow information
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Power Module SMT Guidelines (continued)
•
Maximum number of reflows allowed is one
Figure 57. Sample Reflow Profile
Table 2. Sample Reflow Profile Table
PROBE
MAX TEMP
(°C)
REACHED
MAX TEMP
TIME ABOVE
235°C
REACHED
235°C
TIME ABOVE
245°C
REACHED
245°C
TIME ABOVE
260°C
REACHED
260°C
1
242.5
6.58
0.49
6.39
2
242.5
7.10
0.55
6.31
0.00
–
0.00
–
0.00
7.10
0.00
3
241.0
7.09
0.42
6.44
–
0.00
–
0.00
–
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.1.2 Development Support
For developmental support, see the following:
WEBENCH Tool, http://www.ti.com/webench
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation, see the following:
• AN-2027 Inverting Application for the LMZ14203 SIMPLE SWITCHER Power Module, (SNVA425)
• Absolute Maximum Ratings for Soldering, (SNOA549)
• AN-2024 LMZ1420x / LMZ1200x Evaluation Board (SNVA422)
• AN-2085 LMZ23605/03, LMZ22005/03 Evaluation Board (SNVA457)
• AN-2054 Evaluation Board for LM10000 - PowerWise AVS System Controller (SNVA437)
• AN-2020 Thermal Design By Insight, Not Hindsight (SNVA419)
• AN-2093 LMZ23610/8/6 and LMZ22010/8/6 Current Sharing Evaluation Board (SNVA460)
• AN-2026 Effect of PCB Design on Thermal Performance of SIMPLE SWITCHER Power Modules (SNVA424)
• Design Summary LMZ1xxx and LMZ2xxx Power Modules Family (SNAA214)
11.3 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.4 Trademarks
E2E is a trademark of Texas Instruments.
WEBENCH, SIMPLE SWITCHER are registered trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
11.5 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.
11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
28
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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
6-Feb-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LMZ12008TZ/NOPB
ACTIVE
PFM
NDY
11
32
RoHS & Green
SN
Level-3-245C-168 HR
-40 to 85
LMZ12008
LMZ12008TZE/NOPB
ACTIVE
PFM
NDY
11
250
RoHS & Green
SN
Level-3-245C-168 HR
-40 to 85
LMZ12008
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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