TI CSD87588N Csd87588n synchronous buck nexfet power block ii Datasheet

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CSD87588N
SLPS384D – MARCH 2013 – REVISED APRIL 2015
CSD87588N Synchronous Buck NexFET™ Power Block II
1 Features
3 Description
•
•
•
•
•
•
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The CSD87588N NexFET™ power block II is a
highly-optimized design for synchronous buck
applications offering high current and high efficiency
capability in a small 5 mm × 2.5 mm outline.
Optimized for 5 V gate drive applications, this product
offers an efficient and flexible solution capable of
providing a high density power supply when paired
with any 5 V gate driver from an external
controller/driver.
1
Half-Bridge Power Block
90% System Efficiency at 20 A
Up to 25 A Operation
High Density – 5 mm x 2.5 mm LGA Footprint
Double Side Cooling Capability
Ultra-Low Profile – 0.48 mm Max
Optimized for 5 V Gate Drive
Low Switching Losses
Low Inductance Package
RoHS Compliant
Halogen Free
Pb Free
TEXT ADDED FOR SPACING
Ordering Information(1)
•
•
Media
Qty
13-Inch Reel
2500
CSD87588NT
7-Inch Reel
250
Synchronous Buck Converters
– High-Current, Low Duty Cycle Applications
Multiphase Synchronous Buck Converters
POL DC-DC Converters
5 x 2.5 LGA
Tape and
Reel
Typical Power Block Efficiency and Power Loss
VIN
VDD
Ship
TEXT ADDED FOR SPACING
Typical Circuit
VDD
Package
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
2 Applications
•
Device
CSD87588N
100
7
90
6
BOOT
VIN
DRVH
VSW
ENABLE
PWM
ENABLE
PWM
VOUT
LL
BG
DRVL
PGND
Driver IC
VGS = 5V
VIN = 12V
VOUT = 1.3V
LOUT = 0.29µH
fSW = 500kHz
TA = 25ºC
80
Efficiency (%)
GND
70
60
5
4
3
50
2
40
1
Power Loss (W)
TG
CSD87588N
30
0
5
10
15
Output Current (A)
20
25
0
G001
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.
CSD87588N
SLPS384D – MARCH 2013 – REVISED APRIL 2015
www.ti.com
Table of Contents
1
2
3
4
5
6
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Specifications.........................................................
1
1
1
2
3
5.1
5.2
5.3
5.4
5.5
5.6
5.7
3
3
3
4
4
5
7
Absolute Maximum Ratings ......................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Power Block Performance ........................................
Electrical Characteristics...........................................
Typical Power Block Device Characteristics.............
Typical Power Block MOSFET Characteristics.........
Application and Implementation ........................ 10
6.1 Application Information............................................ 10
7
Layout ................................................................... 13
7.1 Layout Guidelines ................................................... 13
7.2 Layout Example ...................................................... 13
8
Device and Documentation Support.................. 14
8.1 Trademarks ............................................................. 14
8.2 Electrostatic Discharge Caution .............................. 14
8.3 Glossary .................................................................. 14
9
Mechanical, Packaging, and Orderable
Information ........................................................... 15
9.1
9.2
9.3
9.4
9.5
9.6
CSD87588N Package Dimensions ......................... 15
Land Pattern Recommendation .............................. 16
Stencil Recommendation (100 µm)......................... 16
Stencil Recommendation (125 µm)......................... 17
Pin Drawing............................................................. 17
CSD87588N Embossed Carrier Tape Dimensions. 18
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (June 2014) to Revision D
Page
•
Changed capacitance units to read pF in Figure 15 ............................................................................................................. 8
•
Changed capacitance units to read pF in Figure 16 ............................................................................................................. 8
Changes from Revision B (January 2014) to Revision C
•
Page
Changed "Pb-Free Terminal Plating" feature to state "Pb Free" ........................................................................................... 1
Changes from Revision A (May 2013) to Revision B
Page
•
Added small reel info .............................................................................................................................................................. 1
•
Updated Figure 5.................................................................................................................................................................... 5
•
Updated Figure 6.................................................................................................................................................................... 5
•
Updated Figure 7.................................................................................................................................................................... 5
•
Updated Figure 8.................................................................................................................................................................... 5
•
Changed figure reference to Figure 29 in electrical performance ........................................................................................ 13
Changes from Original (March 2013) to Revision A
•
2
Page
Changed RθJC-PCBTo: RθJC in the Thermal Information table................................................................................................... 3
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Copyright © 2013–2015, Texas Instruments Incorporated
CSD87588N
www.ti.com
SLPS384D – MARCH 2013 – REVISED APRIL 2015
5 Specifications
5.1 Absolute Maximum Ratings
TA = 25°C (unless otherwise noted)
(1)
VIN to PGND
MIN
MAX
–0.8
30
VSW to PGND
Voltage
UNIT
30
VSW to PGND (10 ns)
32
TG to VSW
–20
20
BG to PGND
–20
20
V
IDM
Pulsed Current Rating (2)
PD
Power Dissipation (3)
EAS
Avalanche Energy
TJ
Operating Junction
–55
150
°C
Tstg
Storage Temperature Range
–55
150
°C
(1)
(2)
(3)
Sync FET, ID = 45, L = 0.1 mH
50
A
6
W
101
Control FET, ID = 26, L = 0.1 mH
34
mJ
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated is not implied. Exposure to
absolute-maximum-rated conditions for extended periods may affect device reliability.
Pulse Duration ≤50 µs, duty cycle ≤0.01
Device mounted on FR4 material with 1 inch2 (6.45 cm2) Cu
5.2 Recommended Operating Conditions
TA = 25°C (unless otherwise noted)
VGS
Gate Drive Voltage
VIN
Input Supply Voltage
ƒSW
Switching Frequency
Operating Current
TJ
MIN
MAX
4.5
16
24
CBST = 0.1 μF (min)
200
1500
UNIT
V
V
kHz
No Airflow
25
A
With Airflow (200 LFM)
30
A
With Airflow + Heat Sink
35
A
125
°C
Operating Temperature
5.3 Thermal Information
TA = 25°C (unless otherwise stated)
THERMAL METRIC
RθJA
RθJC
(1)
(2)
Junction-to-ambient thermal resistance (Min Cu)
Junction-to-ambient thermal resistance (Max Cu)
(1)
TYP
MAX
UNIT
170
(2) (1)
Junction-to-case thermal resistance (Top of package)
Junction-to-case thermal resistance (PGND Pin)
MIN
(1)
(1)
70
3.7
°C/W
1.25
RθJC is determined with the device mounted on a 1 inch2 (6.45 cm2), 2 oz. (0.071 mm thick) Cu pad on a 1.5 inches × 1.5 inches
(3.81 cm × 3.81 cm), 0.06 inch (1.52 mm) thick FR4 board. RθJC is specified by design while RθJA is determined by the user’s board
design.
Device mounted on FR4 material with 1 inch2 (6.45 cm2) Cu.
Copyright © 2013–2015, Texas Instruments Incorporated
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5.4 Power Block Performance
TA = 25°C (unless otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
PLOSS
Power Loss (1)
VIN = 12 V, VGS = 5 V
VOUT = 1.3 V, IOUT = 15 A
ƒSW = 500 kHz
LOUT = 0.29 µH, TJ = 25ºC
2.1
W
IQVIN
VIN Quiescent Current
TG to TGR = 0 V
BG to PGND = 0 V
10
µA
(1)
Measurement made with six 10 µF (TDK C3216X5R1C106KT or equivalent) ceramic capacitors placed across VIN to PGND pins and
using a high current 5 V driver IC.
5.5 Electrical Characteristics
TA = 25°C (unless otherwise stated)
PARAMETER
TEST CONDITIONS
Q1 FET
MIN
TYP
Q2 FET
MAX
MIN
TYP
MAX
UNIT
STATIC CHARACTERISTICS
BVDSS
Drain-to-Source Voltage
VGS = 0 V, IDS = 250 μA
IDSS
Drain-to-Source Leakage Current
VGS = 0 V, VDS = 24 V
IGSS
Gate-to-Source Leakage Current
VDS = 0 V, VGS = 20
VGS(th)
Gate-to-Source Threshold Voltage VDS = VGS, IDS = 250 μA
RDS(on)
Drain-to-Source On Resistance
gƒs
Transconductance
30
30
1.1
V
1
1
μA
100
100
nA
1.9
V
1.9
1.1
VGS = 4.5 V, IDS = 15 A
10.4
12.5
3.5
4.2
VGS = 10 V, IDS = 15 A
8
9.6
2.9
3.5
VDS = 10 V, IDS = 15 A
43
93
mΩ
S
DYNAMIC CHARACTERISTICS
(1)
CISS
Input Capacitance
COSS
Output Capacitance
(1)
CRSS
Reverse Transfer Capacitance
RG
Series Gate Resistance
Qg
Gate Charge Total (4.5 V)
Qgd
Gate Charge - Gate-to-Drain
Qgs
Gate Charge - Gate-to-Source
Qg(th)
Gate Charge at Vth
QOSS
Output Charge
td(on)
Turn On Delay Time
tr
Rise Time
td(off)
Turn Off Delay Time
tƒ
Fall Time
(1)
VGS = 0 V, VDS = 15 V,
ƒ = 1 MHz
(1)
(1)
VDS = 15 V,
IDS = 15 A
VDD = 12 V, VGS = 0 V
VDS = 15 V, VGS = 4.5 V,
IDS = 15 A, RG = 2 Ω
566
736
2310
3000
pF
341
444
682
887
pF
10.3
13.4
62
80.4
pF
1.2
2.4
1.1
2.2
Ω
3.2
4.1
13.7
17.9
nC
0.7
4.3
nC
1.4
4.3
nC
0.8
2.8
nC
7
18.6
nC
7.3
12.1
ns
31.6
36.7
ns
10.2
20.1
ns
5.0
6.3
ns
DIODE CHARACTERISTICS
VSD
Diode Forward Voltage
IDS = 15 A, VGS = 0 V
0.85
0.78
V
Qrr
Reverse Recovery Charge
26.7
nC
Reverse Recovery Time
Vdd = 15 V, IF = 15 A,
di/dt = 300 A/μs
12.5
trr
16
23
ns
(1)
4
Specified by design
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SLPS384D – MARCH 2013 – REVISED APRIL 2015
Max RθJA = 70°C/W
when mounted on
1 inch2 (6.45 cm2) of
2 oz. (0.071 mm thick)
Cu.
Max RθJA = 170°C/W
when mounted on
minimum pad area of
2 oz. (0.071 mm thick)
Cu.
5.6 Typical Power Block Device Characteristics
TJ = 125°C, unless stated otherwise.The Typical Power Block System Characteristic curves Figure 3 and Figure 4 are based
on measurements made on a PCB design with dimensions of 4.0 inches (W) × 3.5 inches (L) × 0.062 inch (H) and 6 copper
layers of 1 oz. copper thickness. See Application and Implementation for detailed explanation.
8
1.1
VIN = 12V
VGS = 5V
VOUT = 1.3V
fSW = 500kHz
LOUT = 0.29µH
Power Loss (W)
6
5
4
3
2
1
3
5
7
9
11 13 15 17
Output Current (A)
19
21
23
0.8
0.7
0.5
−50
25
25
25
Output Current (A)
30
20
15
10
0
400LFM
200LFM
100LFM
Nat Conv
0
10
20
30
40
50
60
70
Ambient Temperature (ºC)
25
50
75
100
Junction Temperature (ºC)
80
125
150
G001
20
15
VIN = 12V
VGS = 5V
VOUT = 1.3V
fSW = 500kHz
LOUT = 0.29µH
10
5
90
G001
Figure 3. Safe Operating Area – PCB Horizontal Mount
Copyright © 2013–2015, Texas Instruments Incorporated
0
Figure 2. Normalized Power Loss vs Temperature
30
5
−25
G001
Figure 1. Power Loss vs Output Current
Output Current (A)
0.9
0.6
1
0
VIN = 12V
VGS = 5V
VOUT = 1.3V
fSW = 500kHz
LOUT = 0.29µH
1
Power Loss, Normalized
7
0
0
20
40
60
80
100
Board Temperature (ºC)
120
140
G001
Figure 4. Typical Safe Operating Area
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Typical Power Block Device Characteristics (continued)
1.4
2.6
1.35
1.25
2.2
1.2
1.7
1.15
1.3
1.3
1.1
0.9
1.05
0.4
−0.4
1
0.0
−0.9
400 600 800 1000 1200 1400 1600 1800
Switching Frequency (kHz)
0.95
0.95
0.4
0.0
0
G001
Figure 5. Normalized Power Loss vs Switching Frequency
5.1
3.4
1.4
VIN = 12V
VGS = 5V
fSW = 500kHz
LOUT = 0.29µH
IOUT = 25A
1.2
1
0.8
1.3
1.8
2.3 2.8 3.3 3.8
Output Voltage (V)
4.3
4.8
1.7
0
−1.7
5.3
Figure 7. Normalized Power Loss vs Output Voltage
6
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Power Loss, Normalized
1.6
SOA Temperature Adj (ºC)
Power Loss, Normalized
6.9
6
8
10 12 14 16
Input Voltage (V)
18
20
22
24
1.04
VIN = 12V
VGS = 5V
VOUT = 1.3V
fSW = 500kHz
IOUT = 25A
1.08
1.06
0.87
0.69
0.52
1.04
0.35
1.02
0.17
0
1
0.98
−0.17
0.96
−0.35
0.94
G001
−0.4
G001
1.12
1.1
1.8
4
Figure 6. Normalized Power Loss vs Input Voltage
8.6
2
2
0
−0.52
100 200 300 400 500 600 700 800 900 1000 1100
Output Inductance (nH)
SOA Temperature Adj (ºC)
1
0.8
0.3
2.2
1.15
0.9
VIN = 12V
VGS = 5V
VOUT = 1.3V
LOUT = 0.29µH
IOUT = 25A
200
2.6
1.7
1.1
0
1.3
1.25
3.0
1.2
1.05
0.9
3.5
VGS = 5V
VOUT = 1.3V
LOUT = 0.29µH
fSW = 500kHz
IOUT = 25A
SOA Temperature Adj (ºC)
3.0
1.3
Power Loss, Normalized
1.35
SOA Temperature Adj (ºC)
Power Loss, Normalized
TJ = 125°C, unless stated otherwise.The Typical Power Block System Characteristic curves Figure 3 and Figure 4 are based
on measurements made on a PCB design with dimensions of 4.0 inches (W) × 3.5 inches (L) × 0.062 inch (H) and 6 copper
layers of 1 oz. copper thickness. See Application and Implementation for detailed explanation.
G001
Figure 8. Normalized Power Loss vs Output Inductance
Copyright © 2013–2015, Texas Instruments Incorporated
CSD87588N
www.ti.com
SLPS384D – MARCH 2013 – REVISED APRIL 2015
5.7 Typical Power Block MOSFET Characteristics
50
200
45
180
IDS - Drain-to-Source Current (A)
IDS - Drain-to-Source Current (A)
TA = 25°C, unless stated otherwise.
40
35
30
25
20
15
VGS = 8.0V
VGS = 4.5V
VGS = 4.0V
10
5
0
0
0.2
0.4
0.6
0.8
VDS - Drain-to-Source Voltage (V)
160
140
120
100
80
60
20
0
1
VGS = 8.0V
VGS = 4.5V
VGS = 4.0V
40
0
Figure 9. Control MOSFET Saturation
IDS - Drain-to-Source Current (A)
IDS - Drain-to-Source Current (A)
VDS = 5V
1
0.1
0.01
0.001
TC = 125°C
TC = 25°C
TC = −55°C
0.0001
1.2
G001
0
0.5
1
1.5
2
2.5
VGS - Gate-to-Source Voltage (V)
3
VDS = 5V
100
10
1
0.1
0.01
TC = 125°C
TC = 25°C
TC = −55°C
0.001
0.0001
0.5
1
G001
Figure 11. Control MOSFET Transfer
1.5
2
2.5
VGS - Gate-to-Source Voltage (V)
3
G001
Figure 12. Sync MOSFET Transfer
10
10
ID = 15A
VDS = 15V
9
VGS - Gate-to-Source Voltage (V)
VGS - Gate-to-Source Voltage (V)
1
1000
10
8
7
6
5
4
3
2
1
0
0.4
0.6
0.8
VDS - Drain-to-Source Voltage (V)
Figure 10. Sync MOSFET Saturation
100
0.00001
0.2
G001
0
1
2
3
4
5
Qg - Gate Charge (nC)
6
7
Figure 13. Control MOSFET Gate Charge
Copyright © 2013–2015, Texas Instruments Incorporated
8
G001
ID = 15A
VDS = 15V
9
8
7
6
5
4
3
2
1
0
0
5
10
15
20
Qg - Gate Charge (nC)
25
30
G001
Figure 14. Sync MOSFET Gate Charge
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Typical Power Block MOSFET Characteristics (continued)
TA = 25°C, unless stated otherwise.
10000
10000
1000
C − Capacitance (pF)
C − Capacitance (pF)
Ciss = Cgd + Cgs
Coss = Cds + Cgd
Crss = Cgd
100
10
1
0
5
10
15
20
25
VDS - Drain-to-Source Voltage (V)
1000
100
10
1
30
Ciss = Cgd + Cgs
Coss = Cds + Cgd
Crss = Cgd
0
ID = 250µA
0.9
0.8
−75
−25
25
75
125
TC - Case Temperature (ºC)
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
175
−25
G001
Figure 17. Control MOSFET VGS(th)
25
75
125
TC - Case Temperature (ºC)
175
G001
Figure 18. Sync MOSFET VGS(th)
ID = 15A
27
RDS(on) - On-State Resistance (mΩ)
RDS(on) - On-State Resistance (mΩ)
G001
10
24
21
18
15
12
9
6
TC = 25°C
TC = 125ºC
3
0
1
2
3
4
5
6
7
8
VGS - Gate-to- Source Voltage (V)
9
Figure 19. Control MOSFET RDS(on) vs VGS
8
30
ID = 250µA
0.7
0.6
−75
30
0
10
15
20
25
VDS - Drain-to-Source Voltage (V)
Figure 16. Sync MOSFET Capacitance
VGS(th) - Threshold Voltage (V)
VGS(th) - Threshold Voltage (V)
Figure 15. Control MOSFET Capacitance
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
5
G001
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G001
ID = 15A
9
8
7
6
5
4
3
2
TC = 25°C
TC = 125ºC
1
0
0
1
2
3
4
5
6
7
8
VGS - Gate-to- Source Voltage (V)
9
10
G001
Figure 20. Sync MOSFET RDS(on) vs VGS
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CSD87588N
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SLPS384D – MARCH 2013 – REVISED APRIL 2015
Typical Power Block MOSFET Characteristics (continued)
TA = 25°C, unless stated otherwise.
ID = 15A
VGS = 8V
1
0.9
0.8
0.7
0.6
−75
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
Normalized On-State Resistance
Normalized On-State Resistance
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
−25
25
75
125
TC - Case Temperature (ºC)
ID = 15A
VGS = 8V
1
0.9
0.8
0.7
0.6
−75
175
G001
Figure 21. Control MOSFET Normalized RDS(on)
ISD − Source-to-Drain Current (A)
ISD − Source-to-Drain Current (A)
175
G001
100
10
1
0.1
0.01
0.001
TC = 25°C
TC = 125°C
0
0.2
0.4
0.6
0.8
VSD − Source-to-Drain Voltage (V)
1
10
1
0.1
0.01
0.001
0.0001
TC = 25°C
TC = 125°C
0
G001
Figure 23. Control MOSFET Body Diode
1
G001
I(AV) - Peak Avalanche Current (A)
100
10
TC = 25°C
TC = 125°C
1
0.01
0.2
0.4
0.6
0.8
VSD − Source-to-Drain Voltage (V)
Figure 24. Sync MOSFET Body Diode
100
I(AV) - Peak Avalanche Current (A)
25
75
125
TC - Case Temperature (ºC)
Figure 22. Sync MOSFET Normalized RDS(on)
100
0.0001
−25
0.1
t(AV) - Time in Avalanche (ms)
1
G001
Figure 25. Control MOSFET Unclamped Inductive Switching
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10
TC = 25°C
TC = 125°C
1
0.01
0.1
t(AV) - Time in Avalanche (ms)
1
G001
Figure 26. Sync MOSFET Unclamped Inductive Switching
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6 Application and Implementation
6.1 Application Information
The CSD87588N NexFET power block is an optimized design for synchronous buck applications using 5 V gate
drive. The Control FET and Sync FET silicon are parametrically tuned to yield the lowest power loss and highest
system efficiency. As a result, a new rating method is needed which is tailored toward a more systems-centric
environment. System-level performance curves such as Power Loss, Safe Operating Area, and normalized
graphs allow engineers to predict the product performance in the actual application.
6.1.1 Power Loss Curves
MOSFET-centric parameters such as RDS(ON) and Qgd are needed to estimate the loss generated by the devices.
To simplify the design process for engineers, TI has provided measured power loss performance curves.
Figure 1 plots the power loss of the CSD87588N as a function of load current. This curve is measured by
configuring and running the CSD87588N as it would be in the final application (see Figure 27). The measured
power loss is the CSD87588N loss and consists of both input conversion loss and gate drive loss. Equation 1 is
used to generate the power loss curve.
(VIN × IIN) + (VDD × IDD) – (VSW_AVG × IOUT) = Power Loss
(1)
The power loss curve in Figure 1 is measured at the maximum recommended junction temperatures of 125°C
under isothermal test conditions.
6.1.2 Safe Operating Curves (SOA)
The SOA curves in the CSD87588N data sheet provide guidance on the temperature boundaries within an
operating system by incorporating the thermal resistance and system power loss. Figure 3 to Figure 4 outline the
temperature and airflow conditions required for a given load current. The area under the curve dictates the safe
operating area. All the curves are based on measurements made on a PCB design with dimensions of 4 inches
(W) × 3.5 inches (L) × 0.062 inch (T) and 6 copper layers of 1 oz. copper thickness.
6.1.3 Normalized Curves
The normalized curves in the CSD87588N data sheet provides guidance on the Power Loss and SOA
adjustments based on their application-specific needs. These curves show how the power loss and SOA
boundaries adjust for a given set of systems conditions. The primary y-axis is the normalized change in power
loss and the secondary y-axis is the change in system temperature required in order to comply with the SOA
curve. The change in power loss is a multiplier for the Power Loss curve and the change in temperature is
subtracted from the SOA curve.
Input Current (IIN)
A
VDD
A
BOOT
VDD
V
VIN
Gate Drive V
Voltage (VDD)
VIN
DRVH
ENABLE
Input Voltage (VIN)
TG
Output Current (IOUT)
VSW
LL
PWM
PWM
DRVL
GND
Driver IC
A
VOUT
BG
PGND
CSD873588N
Averaging
Circuit
Averaged Switch
V Node Voltage
(VSW_AVG)
Figure 27. Typical Application
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Application Information (continued)
6.1.4 Calculating Power Loss and SOA
The user can estimate product loss and SOA boundaries by arithmetic means (see Design Example). Though
the Power Loss and SOA curves in this data sheet are taken for a specific set of test conditions, the following
procedure outlines the steps the user should take to predict product performance for any set of system
conditions.
6.1.4.1 Design Example
Operating Conditions:
• Output Current = 15 A
• Input Voltage = 7 V
• Output Voltage = 1 V
• Switching Frequency = 800 kHz
• Inductor = 0.2 µH
6.1.4.2 Calculating Power Loss
•
•
•
•
•
•
Power Loss at 15 A = 2.75 W (Figure 1)
Normalized Power Loss for input voltage ≈ 1.03 (Figure 6)
Normalized Power Loss for output voltage ≈ 0.94 (Figure 7)
Normalized Power Loss for switching frequency ≈ 1.08 (Figure 5)
Normalized Power Loss for output inductor ≈ 1.03 (Figure 8)
Final calculated Power Loss = 2.75 W × 1.05 × 0.95 × 1.05 × 1.05 ≈ 3.02 W
6.1.4.3 Calculating SOA Adjustments
•
•
•
•
•
SOA adjustment for input voltage ≈ 0.3ºC (Figure 6)
SOA adjustment for output voltage ≈ –0.5ºC (Figure 7)
SOA adjustment for switching frequency ≈ 0.7ºC (Figure 5)
SOA adjustment for output inductor ≈ 0.3ºC (Figure 8)
Final calculated SOA adjustment = 0.3 + (–0.5) + 0.7 + 0.3 ≈ 0.8ºC
In the previous design example, the estimated power loss of the CSD87588N would increase to 3.02 W. In
addition, the maximum allowable board and/or ambient temperature would have to decrease by 0.8ºC. Figure 28
graphically shows how the SOA curve would be adjusted accordingly.
1. Start by drawing a horizontal line from the application current to the SOA curve.
2. Draw a vertical line from the SOA curve intercept down to the board/ambient temperature.
3. Adjust the SOA board/ambient temperature by subtracting the temperature adjustment value.
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Application Information (continued)
In the design example, the SOA temperature adjustment yields a reduction in allowable board/ambient
temperature of 0.8ºC. In the event the adjustment value is a negative number, subtracting the negative number
would yield an increase in allowable board/ambient temperature.
Figure 28. Power Block SOA
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7 Layout
7.1 Layout Guidelines
There are two key system-level parameters that can be addressed with a proper PCB design: electrical and
thermal performance. Properly optimizing the PCB layout yields maximum performance in both areas. The
following sections provide a brief description on how to address each parameter.
7.1.1 Electrical Performance
The CSD87588N has the ability to switch voltages at rates greater than 10 kV/µs. Take special care with the
PCB layout design and placement of the input capacitors, inductor, and output capacitors.
• The placement of the input capacitors relative to VIN and PGND pins of CSD87588N device should have the
highest priority during the component placement routine. It is critical to minimize these node lengths. As such,
ceramic input capacitors need to be placed as close as possible to the VIN and PGND pins (see Figure 29).
The example in Figure 29 uses 1 x 10 nF 0402 25 V and 4 x 10 μF 1206 25 V ceramic capacitors (TDK part
number C3216X5R1C106KT or equivalent). Notice there are ceramic capacitors on both sides of the board
with an appropriate amount of vias interconnecting both layers. In terms of priority of placement next to the
Power Stage C21, C5, C8, C19, and C18 should follow in order.
• The switching node of the output inductor should be placed relatively close to the Power Block II CSD87588N
VSW pins. Minimizing the VSW node length between these two components will reduce the PCB conduction
losses and actually reduce the switching noise level. See Figure 29. (1)
7.1.2 Thermal Performance
The CSD87588N has the ability to utilize the PGND planes as the primary thermal path. As such, the use of
thermal vias is an effective way to pull away heat from the device and into the system board. Concerns of solder
voids and manufacturability problems can be addressed by the use of three basic tactics to minimize the amount
of solder attach that wicks down the via barrel:
• Intentionally space out the vias from each other to avoid a cluster of holes in a given area.
• Use the smallest drill size allowed in your design. The example in Figure 29 uses vias with a 10 mil drill hole
and a 16 mil capture pad.
• Tent the opposite side of the via with solder-mask.
The number and drill size of the thermal vias should align with the end user’s PCB design rules and
manufacturing capabilities.
7.2 Layout Example
Figure 29. Recommended PCB Layout (Top Down View)
(1)
Keong W. Kam, David Pommerenke, “EMI Analysis Methods for Synchronous Buck Converter EMI Root Cause Analysis”, University of
Missouri – Rolla
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8 Device and Documentation Support
8.1 Trademarks
NexFET is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
8.2 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.
8.3 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
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9 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.
9.1 CSD87588N Package Dimensions
Pin Configuration
Position
Copyright © 2013–2015, Texas Instruments Incorporated
Designation
Pin 1
TG
Pin 2
VIN
Pin 3
PGND
Pin 4
BG
Pin 5
VSW
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2.500 REF PKG
1.238
2.108
2.500 REF PKG
9.2 Land Pattern Recommendation
1.250 REF PKG
0.858
2
0.000
0.238
0.538
0.858
3
5
0.238
0.538
1
4
2.000
0.500
0.800
1.120
0.000
0.758
PACKAGE
OUTLINE
1.960
1.640
1.492
1.250 REF PKG
9.3 Stencil Recommendation (100 µm)
Text For Spacing
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9.4 Stencil Recommendation (125 µm)
Text
For
Spacing
For recommended circuit layout for PCB designs, see application note SLPA005 – Reducing Ringing Through
PCB Layout Techniques.
9.5 Pin Drawing
87588N
TI YMS
LLLL E
Text For Spacing
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9.6 CSD87588N Embossed Carrier Tape Dimensions
(1)
Pin 1 is oriented in the top-left quadrant of the tape enclosure (closest to the carrier tape sprocket holes).
spacer
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PACKAGE OPTION ADDENDUM
www.ti.com
25-Feb-2015
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
CSD87588N
ACTIVE
PTAB
MPA
5
2500
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-1-260C-UNLIM
CSD87588NT
ACTIVE
PTAB
MPA
5
250
Green (RoHS
& no Sb/Br)
CU NIPDAU
Level-1-260C-UNLIM
Op Temp (°C)
Device Marking
(4/5)
-55 to 150
87588N
87588N
(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
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.
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
25-Feb-2015
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
24-Feb-2015
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
CSD87588N
PTAB
MPA
5
2500
330.0
12.4
2.8
5.3
0.55
8.0
12.0
Q1
CSD87588NT
PTAB
MPA
5
250
180.0
12.4
2.8
5.3
0.55
8.0
12.0
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
24-Feb-2015
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
CSD87588N
PTAB
MPA
5
2500
367.0
367.0
35.0
CSD87588NT
PTAB
MPA
5
250
210.0
185.0
35.0
Pack Materials-Page 2
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