CSD86350Q5D - Texas Instruments · t gr v in p gnd v sw t g b g s0474-01 enable enable pwm gnd bst drvh ll drvl driver ic csd86350q5d v dd v i v o v dd control fet sync fet pwm p0116-01

Output Current (A)

Effic

iency (

%)

Pow

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Loss (

W)

0 5 10 15 20 2540 0

50 1

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G029

VGS = 5VVIN = 12VVOUT = 1.3VLOUT = 0.3,HfSW = 500kHzTA = 25C

TGR

VIN

PGND

VSW

TG

BG

S0474-01

ENABLE

ENABLE

PWM

GND

BST

DRVH

LL

DRVL

CSD86350Q5DDriver IC

VDD VI

VO

VDD

ControlFET

SyncFET

PWM

P0116-01

1

2

3 VSW

VSW

VSW

4 BG5TGR

6TG

PGND

(Pin 9)

7VIN

8VIN

Product

Folder

Sample &Buy

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Documents

Tools &

Software

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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.

CSD86350Q5DSLPS223F –MAY 2010–REVISED OCTOBER 2016

CSD86350Q5D Synchronous Buck NexFET™ Power Block

1

1 Features1• Half-Bridge Power Block• 90% System Efficiency at 25 A• Up to 40-A Operation• High-Frequency Operation (up to 1.5 MHz)• High-Density SON 5-mm × 6-mm Footprint• Optimized for 5-V Gate Drive• Low-Switching Losses• Ultra-Low Inductance Package• RoHS Compliant• Halogen Free• Lead-Free Terminal Plating

2 Applications• Synchronous Buck Converters

– High-Frequency Applications– High-Current, Low-Duty Cycle Applications

• Multiphase Synchronous Buck Converters• POL DC-DC Converters• IMVP, VRM, and VRD Applications

3 DescriptionThe CSD86350Q5D NexFET™ power block is anoptimized design for synchronous buck applicationsoffering high-current, high-efficiency, and high-frequency capability in a small 5-mm × 6-mm outline.Optimized for 5-V gate drive applications, this productoffers a flexible solution capable of offering a high-density power supply when paired with any 5-V gatedrive from an external controller/driver.

.

Top View

.

Device Information(1)

DEVICE MEDIA QTY PACKAGE SHIP

CSD86350Q5D 13-Inch Reel 2500 SON5.00-mm × 6.00-mm

Plastic Package

TapeandReelCSD86350Q5DT 7-Inch Reel 250

(1) For all available packages, see the orderable addendum atthe end of the data sheet.

.

.

Typical Circuit Typical Power Block Efficiencyand Power Loss

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Product Folder Links: CSD86350Q5D

Submit Documentation Feedback Copyright © 2010–2016, Texas Instruments Incorporated

Table of Contents1 Features .................................................................. 12 Applications ........................................................... 13 Description ............................................................. 14 Revision History..................................................... 25 Specifications......................................................... 4

5.1 Absolute Maximum Ratings ...................................... 45.2 Recommended Operating Conditions....................... 45.3 Thermal Information .................................................. 45.4 Power Block Performance ........................................ 45.5 Electrical Characteristics........................................... 55.6 Typical Power Block Device Characteristics............. 65.7 Typical Power Block MOSFET Characteristics......... 8

6 Application and Implementation ........................ 116.1 Application Information............................................ 11

7 Layout ................................................................... 167.1 Layout Guidelines ................................................... 167.2 Layout Example ...................................................... 17

8 Device and Documentation Support.................. 188.1 Documentation Support .......................................... 188.2 Receiving Notification of Documentation Updates.. 188.3 Community Resources............................................ 188.4 Trademarks ............................................................. 188.5 Glossary .................................................................. 18

9 Mechanical, Packaging, and OrderableInformation ........................................................... 199.1 Q5D Package Dimensions...................................... 199.2 Land Pattern Recommendation .............................. 209.3 Stencil Recommendation ........................................ 209.4 Q5D Tape and Reel Information............................. 21

4 Revision HistoryNOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision E (October 2011) to Revision F Page

• Added small reel option .......................................................................................................................................................... 1• Added footnote for pulsed current rating ................................................................................................................................ 4• Changed Recommended PCB Design Overview section to Layout section ........................................................................ 16• Added Device and Documentation Support section............................................................................................................. 18• Changed MECHANICAL DATA section to Mechanical, Packaging, and Orderable Information section ............................ 19

Changes from Revision D (September 2011) to Revision E Page

• Changed "DIM a" Millimeter Max value From: 1.55 To: 1.5 and Inches Max value From: 0.061 To: 0.059........................ 19

Changes from Revision C (November 2010) to Revision D Page

• Replace RDS(on) with ZDS(on) ..................................................................................................................................................... 5• Added Equivalent System Performance section .................................................................................................................. 11• Added Electrical Performance bullet .................................................................................................................................... 16

Changes from Revision B (September 2010) to Revision C Page

• Added the Stencil Recommendation illustration................................................................................................................... 20

Changes from Revision A (May 2010) to Revision B Page

• Updated Figure 6.................................................................................................................................................................... 6• Updated Figure 7.................................................................................................................................................................... 6• Updated Figure 8.................................................................................................................................................................... 6• Updated Figure 9.................................................................................................................................................................... 6


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CSD86350Q5Dwww.ti.com SLPS223F –MAY 2010–REVISED OCTOBER 2016


Submit Documentation FeedbackCopyright © 2010–2016, Texas Instruments Incorporated

Changes from Original (May 2010) to Revision A Page

• Changed graph title From: TYPICAL EFFICIENCY vs POWER LOSS To: TYPICAL POWER BLOCK EFFICIENCYand POWER LOSS ................................................................................................................................................................ 1

• Updated the Land Pattern Recommendation illustration...................................................................................................... 20


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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratingsonly, and functional operation of the device at these or any other conditions beyond those indicated in the Recommended OperatingConditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) Pulse duration ≤ 50 µs, duty cycle ≤ 1%.

5 Specifications

5.1 Absolute Maximum RatingsTA = 25°C (unless otherwise noted) (1)

MIN MAX UNIT

VoltageVIN to PGND –0.8 25

VTG to TGR –8 10BG to PGND –8 10

Pulsed current rating, IDM(2) 120 A

Power dissipation, PD 13 W

Avalanche energy, EASSync FET, ID = 100 A, L = 0.1 mH 500

mJControl FET, ID = 58 A, L = 0.1 mH 168

Operating junction, TJ –55 150 °CStorage temperature, TSTG –55 150 °C

5.2 Recommended Operating ConditionsTA = 25° (unless otherwise noted)

MIN MAX UNITVGS Gate drive voltage 4.5 8 VVIN Input supply voltage 22 VfSW Switching frequency CBST = 0.1 μF (min) 200 1500 kHz

Operating current 40 ATJ Operating temperature 125 °C

(1) Device mounted on FR4 material with 1-in2 (6.45-cm2) Cu.(2) RθJC is determined with the device mounted on a 1-in2 (6.45-cm2), 2 oz (0.071-mm) thick Cu pad on a 1.5-in × 1.5-in

(3.81-cm × 3.81-cm), 0.06-in (1.52-mm) thick FR4 board. RθJC is specified by design while RθJA is determined by the user’s boarddesign.

5.3 Thermal InformationTA = 25°C (unless otherwise stated)

THERMAL METRIC MIN TYP MAX UNIT

RθJAJunction-to-ambient thermal resistance (min Cu) (1) (2) 102 °C/WJunction-to-ambient thermal resistance (max Cu) (1) (2) 50 °C/W

RθJCJunction-to-case thermal resistance (top of package) (2) 20 °C/WJunction-to-case thermal resistance (PGND pin) (2) 2 °C/W

(1) Measurement made with six 10-µF (TDK C3216X5R1C106KT or equivalent) ceramic capacitors placed across VIN to PGND pins andusing a high-current 5-V driver IC.

5.4 Power Block PerformanceTA = 25° (unless otherwise noted)

PARAMETER CONDITIONS MIN TYP MAX UNIT

PLOSS Power loss (1)

VIN = 12 V, VGS = 5 V,VOUT = 1.3 V, IOUT = 25 A,fSW = 500 kHz,LOUT = 0.3 µH, TJ = 25°C

2.8 W

IQVIN VIN quiescent current TG to TGR = 0 VBG to PGND = 0 V 10 µA


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86350 5x6 QFN TTA MIN Rev1

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HS

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HS

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(1) Specified by design.

5.5 Electrical CharacteristicsTA = 25°C (unless otherwise stated)

PARAMETER TEST CONDITIONSQ1 Control FET Q2 Sync FET

UNITMIN TYP MAX MIN TYP MAX

STATIC CHARACTERISTICSBVDSS Drain-to-source voltage VGS = 0 V, IDS = 250 μA 25 25 VIDSS Drain-to-source leakage current VGS = 0 V, VDS = 20 V 1 1 μAIGSS Gate-to-source leakage current VDS = 0 V, VGS = +10 / –8 V 100 100 nAVGS(th) Gate-to-source threshold voltage VDS = VGS, IDS = 250 μA 0.9 1.4 2.1 0.9 1.1 1.6 V

ZDS(on) Drain-to-source on impedanceVIN = 12 V, VDD = 5 V,VOUT = 1.3 V, IOUT = 25 A,fSW = 500 kHz, LOUT = 0.3 µH

5 1.1 mΩ

gfs Transconductance VDS = 10 V, IDS = 20 A 103 132 SDYNAMIC CHARACTERISTICSCISS Input capacitance (1)

VGS = 0 V, VDS = 12.5 V,f = 1 MHz

1440 1870 3080 4000 pFCOSS Output capacitance (1) 645 840 1550 2015 pFCRSS Reverse transfer capacitance (1) 22 29 45 59 pFRG Series gate resistance (1) 1.4 2.8 1.4 2.8 Ω

Qg Gate charge total (4.5 V) (1)

VDS = 12.5 V,IDS = 20 A

8.2 10.7 19.4 25 nCQgd Gate charge – gate-to-drain 1 2.5 nCQgs Gate charge – gate-to-source 3.2 5.1 nCQg(th) Gate charge at Vth 1.9 2.8 nCQOSS Output charge VDS = 12 V, VGS = 0 V 9.9 28 nCtd(on) Turnon delay time

VDS = 12.5 V, VGS = 4.5 V,IDS = 20 A, RG = 2 Ω

8 9 nstr Rise time 21 23 nstd(off) Turnoff delay time 9 24 nstf Fall time 2.3 21 nsDIODE CHARACTERISTICSVSD Diode forward voltage IDS = 20 A, VGS = 0 V 0.85 1 0.77 1 VQrr Reverse recovery charge Vdd = 12 V, IF = 20 A,

di/dt = 300 A/μs16 40 nC

trr Reverse recovery time 22 32 ns

Max RθJA = 50°C/Wwhen mounted on 1-in2

(6.45-cm2) of 2-oz(0.071-mm) thick Cu.

Max RθJA = 102°C/Wwhen mounted onminimum pad area of2-oz (0.071-mm) thickCu.


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Board Temperature (C)

Outp

ut C

urr

ent (A

)

0 20 40 60 80 100 120 1400

5

10

15

20

25

30

35

40

45

50

5

15

25

35

45

G005

VIN = 12VVGS = 5VVOUT = 1.3V fSW = 500kHzLOUT = 0.3)H

Ambient Temperature (C)

Outp

ut C

urr

ent (A

)

0 10 20 30 40 50 60 70 80 900

5

10

15

20

25

30

35

40

45

50

5

15

25

35

45

G003

VIN = 12VVGS = 5VVOUT = 1.3V fSW = 500kHzLOUT = 0.3*H

400LFM200LFM100LFMNat Conv

Ambient Temperature (C)

Outp

ut C

urr

ent (A

)

0 10 20 30 40 50 60 70 80 900

5

10

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25

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G004


400LFM200LFM100LFMNat Conv

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Pow

er

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0 5 10 15 20 25 30 35 400

1

2

3

4

5

6

7

8

9

10

1

3

5

7

9

G001


Junction Temperature (C)

Pow

er

Loss, N

orm

aliz

ed

50 25 0 25 50 75 100 125 1500.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1

G002

VIN = 12VVGS = 5VVOUT = 1.3V fSW = 500kHzLOUT = 0.31H

6




(1) The Typical Power Block System Characteristic curves are based on measurements made on a PCB design with dimensions of 4 in (W)× 3.5 in (L) x 0.062 in (H) and 6 copper layers of 1-oz copper thickness. See Application and Implementation for detailed explanation.

5.6 Typical Power Block Device CharacteristicsTJ = 125°C, unless stated otherwise.

Figure 1. Power Loss vs Output Current Figure 2. Normalized Power Loss vs Temperature

Figure 3. Safe Operating Area – PCB Vertical Mount (1) Figure 4. Safe Operating Area – PCB Horizontal Mount (1)

Figure 5. Typical Safe Operating Area (1)


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Output Voltage (V)

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Loss, N

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0.5 0.9 1.3 1.7 2.1 2.5 2.9 3.3 3.7 4.1 4.5 4.9 5.30.8

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1.3

1.4

1.5

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200 350 500 650 800 950 1100 1250 1400 15500.6

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0.8

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1

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1.4

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Input Voltage (V)

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2 4 6 8 10 12 14 16 18 20 22

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7




Typical Power Block Device Characteristics (continued)TJ = 125°C, unless stated otherwise.

Figure 6. Normalized Power Loss vs Switching Frequency Figure 7. Normalized Power Loss vs Input Voltage

Figure 8. Normalized Power Loss vs Output Voltage Figure 9. Normalized Power Loss vs Output Inductance


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5.7 Typical Power Block MOSFET CharacteristicsTA = 25°C, unless stated otherwise.

Figure 10. Control MOSFET Saturation Figure 11. Sync MOSFET Saturation

Figure 12. Control MOSFET Transfer Figure 13. Sync MOSFET Transfer

Figure 14. Control MOSFET Gate Charge Figure 15. Sync MOSFET Gate Charge


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Typical Power Block MOSFET Characteristics (continued)TA = 25°C, unless stated otherwise.

Figure 16. Control MOSFET Capacitance Figure 17. Sync MOSFET Capacitance

Figure 18. Control MOSFET VGS(th) Figure 19. Sync MOSFET VGS(th)

Figure 20. Control MOSFET RDS(on) vs VGS Figure 21. Sync MOSFET RDS(on) vs VGS


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Typical Power Block MOSFET Characteristics (continued)TA = 25°C, unless stated otherwise.

Figure 22. Control MOSFET Normalized RDS(on) Figure 23. Sync MOSFET Normalized RDS(on)

Figure 24. Control MOSFET Body Diode Figure 25. Sync MOSFET Body Diode

Figure 26. Control MOSFET Unclamped Inductive Switching Figure 27. Sync MOSFET Unclamped Inductive Switching


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6 Application and Implementation

NOTEInformation in the following applications sections is not part of the TI componentspecification, and TI does not warrant its accuracy or completeness. TI’s customers areresponsible for determining suitability of components for their purposes. Customers shouldvalidate and test their design implementation to confirm system functionality.

6.1 Application Information

6.1.1 Equivalent System PerformanceMany of today’s high-performance computing systems require low-power consumption in an effort to reducesystem operating temperatures and improve overall system efficiency. This has created a major emphasis onimproving the conversion efficiency of today’s synchronous buck topology. In particular, there has been anemphasis in improving the performance of the critical power semiconductor in the power stage of this application(see Figure 28). As such, optimization of the power semiconductors in these applications, needs to go beyondsimply reducing RDS(ON).

Figure 28. Equivalent System Schematic

The CSD86350Q5D is part of TI’s power block product family which is a highly optimized product for use in asynchronous buck topology requiring high-current, high-efficiency, and high-frequency. It incorporates TI’s latestgeneration silicon which has been optimized for switching performance, as well as minimizing losses associatedwith QGD, QGS, and QRR. Furthermore, TI’s patented packaging technology has minimized losses by nearlyeliminating parasitic elements between the control FET and sync FET connections (see Figure 29). A keychallenge solved by TI’s patented packaging technology is the system-level impact of Common SourceInductance (CSI). CSI greatly impedes the switching characteristics of any MOSFET which in turn increasesswitching losses and reduces system efficiency. As a result, the effects of CSI need to be considered during theMOSFET selection process. In addition, standard MOSFET switching loss equations used to predict systemefficiency need to be modified in order to account for the effects of CSI. Further details behind the effects of CSIand modification of switching loss equations are outlined in Power Loss Calculation With Common SourceInductance Consideration for Synchronous Buck Converters (SLPA009).


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http://www.ti.com/lit/pdf/SLPA009


74

76

78

80

82

84

86

88

90

92

94

96

0 5 10 15 20 25 30 35 40 45Output Current (A)

Effi

cien

cy (

%)

PowerBlock HS/LS RDS(ON) = 5mΩ/2mΩDiscrete HS/LS RDS(ON) = 5mΩ/2mΩDiscrete HS/LS RDS(ON) = 5mΩ/1.1mΩ

VGS = 5VVIN = 12VVOUT = 1.3VLOUT = 0.3µHfSW = 500kHzTA = 25ºC

0

1

2

3

4

5

6

7

8

9

10

0 5 10 15 20 25 30 35 40 45Output Current (A)

Pow

er L

oss

(W)

PowerBlock HS/LS RDS(ON) = 5mΩ/2mΩDiscrete HS/LS RDS(ON) = 5mΩ/2mΩDiscrete HS/LS RDS(ON) = 5mΩ/1.1mΩ

VGS = 5VVIN = 12VVOUT = 1.3VLOUT = 0.3µHfSW = 500kHzTA = 25ºC

12




Application Information (continued)

Figure 29. Elimination of Parasitic Inductances

The combination of TI’s latest generation silicon and optimized packaging technology has created abenchmarking solution that outperforms industry standard MOSFET chipsets of similar RDS(ON) and MOSFETchipsets with lower RDS(ON). Figure 30 and Figure 31 compare the efficiency and power loss performance of theCSD86350Q5D versus industry standard MOSFET chipsets commonly used in this type of application. Thiscomparison purely focuses on the efficiency and generated loss of the power semiconductors only. Theperformance of CSD86350Q5D clearly highlights the importance of considering the effective AC on-impedance(ZDS(ON)) during the MOSFET selection process of any new design. Simply normalizing to traditional MOSFETRDS(ON) specifications is not an indicator of the actual in-circuit performance when using TI’s power blocktechnology.

Figure 30. Efficiency Figure 31. Power Loss


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Application Information (continued)Table 1 below compares the traditional DC measured RDS(ON) of CSD86350Q5D versus its ZDS(ON). Thiscomparison takes into account the improved efficiency associated with TI’s patented packaging technology. Assuch, when comparing TI’s power block products to individually packaged discrete MOSFETs or dual MOSFETsin a standard package, the in-circuit switching performance of the solution must be considered. In this example,individually packaged discrete MOSFETs or dual MOSFETs in a standard package would need to have DCmeasured RDS(ON) values that are equivalent to CSD86350Q5D’s ZDS(ON) value in order to have the sameefficiency performance at full load. Mid to light-load efficiency will still be lower with individually packaged discreteMOSFETs or dual MOSFETs in a standard package.

Table 1. Comparison of RDS(ON) vs. ZDS(ON)

PARAMETERHS LS

TYP MAX TYP MAXEffective AC on-impedance (ZDS(ON)), VGS = 5 V 5 — 1.1 —

DC measured RDS(ON), VGS = 4.5 V 5 6.6 2 2.7

The CSD86350Q5D NexFET™ power block is an optimized design for synchronous buck applications using 5-Vgate drive. The control FET and sync FET silicon are parametrically tuned to yield the lowest power loss andhighest system efficiency. As a result, a new rating method is needed which is tailored towards a more systems-centric environment. System-level performance curves such as power loss, Safe Operating Area (SOA), andnormalized graphs allow engineers to predict the product performance in the actual application.

6.1.2 Power Loss CurvesMOSFET centric parameters such as RDS(ON) and Qgd are needed to estimate the loss generated by the devices.In an effort to simplify the design process for engineers, Texas Instruments has provided measured power lossperformance curves. Figure 1 plots the power loss of the CSD86350Q5D as a function of load current. This curveis measured by configuring and running the CSD86350Q5D as it would be in the final application (seeFigure 32).The measured power loss is the CSD86350Q5D loss and consists of both input conversion loss andgate drive loss. Equation 1 is used to generate the power loss curve.

(VIN x IIN) + (VDD x IDD) – (VSW_AVG x IOUT) = Power Loss (1)

The power loss curve in Figure 1 is measured at the maximum recommended junction temperatures of 125°Cunder isothermal test conditions.

6.1.3 Safe Operating Area (SOA) CurvesThe SOA curves in the CSD86350Q5D data sheet provides guidance on the temperature boundaries within anoperating system by incorporating the thermal resistance and system power loss. Figure 3 to Figure 5 outline thetemperature and airflow conditions required for a given load current. The area under the curve dictates the safeoperating area. All the curves are based on measurements made on a PCB design with dimensions of 4 in (W) ×3.5 in (L) × 0.062 in (T) and 6 copper layers of 1-oz copper thickness.

6.1.4 Normalized CurvesThe normalized curves in the CSD86350Q5D data sheet provides guidance on the power loss and SOAadjustments based on their application specific needs. These curves show how the power loss and SOAboundaries will adjust for a given set of systems conditions. The primary Y-axis is the normalized change inpower loss and the secondary Y-axis is the change in system temperature required in order to comply with theSOA curve. The change in power loss is a multiplier for the power loss curve and the change in temperature issubtracted from the SOA curve.


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PWM

ENABLE

PWM

GND

BST

DRVH

LL

DRVL

CSD86350Q5DDriver IC

VDD

Gate DriveCurrent (I )DD

Input Current (I )IN

Input Voltage (V )IN

Output Current (I )OUT

TGR

VIN

PGND

VI

VOVSW

TG

BG

Gate DriveVoltage (V )DD

VDDA

V

V

V

ControlFET

SyncFET

AveragingCircuit

Averaged SwitchedNode Voltage

(VSW_AVG)

A

S0475-01

A

14




Figure 32. Typical Application

6.1.5 Calculating Power Loss and SOAThe user can estimate product loss and SOA boundaries by arithmetic means (see Design Example). Thoughthe power loss and SOA curves in this data sheet are taken for a specific set of test conditions, the followingprocedure will outline the steps the user should take to predict product performance for any set of systemconditions.

6.1.5.1 Design ExampleOperating Conditions:• Output Current = 25 A• Input Voltage = 7 V• Output Voltage = 1 V• Switching Frequency = 800 kHz• Inductor = 0.2 µH

6.1.5.2 Calculating Power Loss• Power loss at 25 A = 3.5 W (Figure 1)• Normalized power loss for input voltage ≈ 1.07 (Figure 7)• Normalized power loss for output voltage ≈ 0.95 (Figure 8)• Normalized power loss for switching frequency ≈ 1.11 (Figure 6)• Normalized power loss for output inductor ≈ 1.07 (Figure 9)• Final calculated power loss = 3.5 W × 1.07 × 0.95 × 1.11 × 1.07 ≈ 4.23 W

6.1.5.3 Calculating SOA Adjustments• SOA adjustment for input voltage ≈ 2°C (Figure 7)• SOA adjustment for output voltage ≈ –1.3°C (Figure 8)• SOA adjustment for switching frequency ≈ 2.8°C (Figure 6)• SOA adjustment for output inductor ≈ 1.6°C (Figure 9)• Final calculated SOA adjustment = 2 + (–1.3) + 2.8 + 1.6 ≈ 5.1°CIn the design example above, the estimated power loss of the CSD86350Q5D would increase to 4.23 W. Inaddition, the maximum allowable board and/or ambient temperature would have to decrease by 5.1°C. Figure 33graphically 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.


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Board Temperature (°C)0 20 40 60 80 100 120 140

0

5

10

15

20

25

30

35

40

45

50

G028

V = 12VIN

V = 5VGS

V = 1.3VOUT

f = 500kHzSW

L = 0.3 mHOUT

Outp

ut

Curr

ent

(A)

1

2

3

15




3. Adjust the SOA board/ambient temperature by subtracting the temperature adjustment value.

In the design example, the SOA temperature adjustment yields a reduction in allowable board/ambienttemperature of 5.1°C. In the event the adjustment value is a negative number, subtracting the negative numberwould yield an increase in allowable board/ambient temperature.

Figure 33. Power Block SOA


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16




(1) Keong W. Kam, David Pommerenke, “EMI Analysis Methods for Synchronous Buck Converter EMI Root Cause Analysis”, University ofMissouri – Rolla

7 Layout

7.1 Layout GuidelinesThere are two key system-level parameters that can be addressed with a proper PCB design: electrical andthermal performance. Properly optimizing the PCB layout will yield maximum performance in both areas. A briefdescription on how to address each parameter is provided.

7.1.1 Electrical PerformanceThe power block has the ability to switch voltages at rates greater than 10 kV/µs. Special care must be thentaken with the PCB layout design and placement of the input capacitors, driver IC, and output inductor.• The placement of the input capacitors relative to the power block’s VIN and PGND pins 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 34).The example in Figure 34 uses 6 × 10-µF ceramic capacitors (TDK part C3216X5R1C106KT or equivalent).Notice there are ceramic capacitors on both sides of the board with an appropriate amount of viasinterconnecting both layers. In terms of priority of placement next to the power block, C5, C7, C19, and C8should follow in order.

• The driver IC should be placed relatively close to the power block gate pins. TG and BG should connect to theoutputs of the driver IC. The TGR pin serves as the return path of the high-side gate drive circuitry and shouldbe connected to the phase pin of the IC (sometimes called LX, LL, SW, PH, etc.). The bootstrap capacitor forthe driver IC will also connect to this pin.

• The switching node of the output inductor should be placed relatively close to the power block VSW pins.Minimizing the node length between these two components will reduce the PCB conduction losses andactually reduce the switching noise level. In the event the switch node waveform exhibits ringing that reachesundesirable levels, the use of a boost resistor or RC snubber can be an effective way to easily reduce thepeak ring level. The recommended boost resistor value will range between 1 Ω to 4.7 Ω depending on theoutput characteristics of driver IC used in conjunction with the power block. The RC snubber values canrange from 0.5 Ω to 2.2 Ω for the R and 330 pF to 2200 pF for the C. Please refer to Snubber Circuits:Theory, Design and Application (SLUP100) for more details on how to properly tune the RC snubber values.The RC snubber should be placed as close as possible to the VSW node and PGND see Figure 34. (1)

7.1.2 Thermal PerformanceThe power block has the ability to utilize the GND planes as the primary thermal path. As such, the use ofthermal vias is an effective way to pull away heat from the device and into the system board. Concerns of soldervoids and manufacturability problems can be addressed by the use of three basic tactics to minimize the amountof solder attach that will wick 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 34 uses vias with a 10-mil drill hole

and a 16-mil capture pad.• Tent the opposite side of the via with solder-mask.

In the end, the number and drill size of the thermal vias should align with the end user’s PCB design rules andmanufacturing capabilities.


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http://www.ti.com/lit/pdf/SLUP100


VIN

V SW

PGND

BG

TGTGR

VSW V SW

Output Inductor

Input Capacitors

Power Block

Input Capacitors

Output Capacitors

Driver IC

Bottom LayerTop Layer

RC Snubber

Power BlockLocation on Top

Layer

17




7.2 Layout Example

Figure 34. Recommended PCB Layout (Top Down View)


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18




8 Device and Documentation Support

8.1 Documentation Support

8.1.1 Related DocumentationFor related documentation see the following:• Power Loss Calculation With Common Source Inductance Consideration for Synchronous Buck Converters

(SLPA009)• Snubber Circuits: Theory, Design and Application (SLUP100)

8.2 Receiving Notification of Documentation UpdatesTo receive notification of documentation updates, navigate to the device product folder on ti.com. In the upperright corner, click on Alert me to register and receive a weekly digest of any product information that haschanged. For change details, review the revision history included in any revised document.

8.3 Community ResourcesThe following links connect to TI community resources. Linked contents are provided "AS IS" by the respectivecontributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms ofUse.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaborationamong engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and helpsolve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools andcontact information for technical support.

8.4 TrademarksNexFET, E2E are trademarks of Texas Instruments.All other trademarks are the property of their respective owners.

8.5 GlossarySLYZ022 — TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.


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http://www.ti.com/lit/pdf/SLYZ022

M0187-01

E1

E

q

c

56

78 1

23

4

L

d1

f

K

b

d3

L

E1

e

a

E2

D2

Top View Bottom View

Front View

Side View

5

9

67

8

12

34

qc1

D1

d2

d

Pinout

Position Designation

Pin 1 VIN

Pin 2 VIN

Pin 3 TG

Pin 4 TGR

Pin 5 BG

Pin 6 VSW

Pin 7 VSW

Pin 8 VSW

Pin 9 PGND

Exposed Tie Bar May Vary

19




9 Mechanical, Packaging, and Orderable InformationThe following pages include mechanical, packaging, and orderable information. This information is the mostcurrent data available for the designated devices. This data is subject to change without notice and revision ofthis document. For browser-based versions of this data sheet, refer to the left-hand navigation.

9.1 Q5D Package Dimensions

DIMMILLIMETERS INCHES

MIN MAX MIN MAXa 1.40 1.5 0.055 0.059b 0.360 0.460 0.014 0.018c 0.150 0.250 0.006 0.010

c1 0.150 0.250 0.006 0.010d 1.630 1.730 0.064 0.068d1 0.280 0.380 0.011 0.015d2 0.200 0.300 0.008 0.012d3 0.291 0.391 0.012 0.015D1 4.900 5.100 0.193 0.201D2 4.269 4.369 0.168 0.172E 4.900 5.100 0.193 0.201E1 5.900 6.100 0.232 0.240E2 3.106 3.206 0.122 0.126e 1.27 TYP 0.050 TYPf 0.396 0.496 0.016 0.020L 0.510 0.710 0.020 0.028θ 0.00 — — —K 0.812 TYP 0.032 TYP


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M0208-01

0.341 (0.013)

0.410 (0.016)

14

58

0.250 (0.010)

0.300 (0.012)

0.300 (0.012)

Stencil Opening0.300 (0.012)

0.950 (0.037)

PCB Pattern

1.290 (0.051)

0.610 (0.024)

1.680(0.066)

1.710(0.067)

M0188-01

0.650 (0.026)0.650 (0.026)

0.620 (0.024)0.620

(0.024)

0.415 (0.016)

14

58

0.345 (0.014)

3.480 (0.137)

0.850 (0.033) 0.850 (0.033)

0.530 (0.021)

0.400 (0.016)

6.240 (0.246)

1.920(0.076)

4.460(0.176)

4.460(0.176)

1.270(0.050)

20




9.2 Land Pattern Recommendation

NOTE: Dimensions are in mm (inches).

9.3 Stencil Recommendation

NOTE: Dimensions are in mm (inches).

.For recommended circuit layout for PCB designs, see Reducing Ringing Through PCB Layout Techniques(SLPA005).


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Ø 1.50+0.10–0.00

4.00 ±0.10 (See Note 1)

1.75 ±0.10

R 0.30 TYPØ 1.50 MINA0

K0

0.30 ±0.05

R 0.20 MAX

A0 = 5.30 ±0.10B0 = 6.50 ±0.10K0 = 1.90 ±0.10

M0191-01

2.00 ±0.05

8.00 ±0.10

B0

5.50 ±0.05

12.00 ±0.30

21




9.4 Q5D Tape and Reel Information

NOTES: 1. 10-sprocket hole-pitch cumulative tolerance ±0.2.2. Camber not to exceed 1 mm in 100 mm, noncumulative over 250 mm.3. Material: black static-dissipative polystyrene.4. All dimensions are in mm, unless otherwise specified.5. Thickness: 0.30 ±0.05 mm.6. MSL1 260°C (IR and convection) PbF reflow compatible.


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TAPE AND REEL INFORMATION

*All dimensions are nominal

Device PackageType

PackageDrawing

Pins SPQ ReelDiameter

(mm)

ReelWidth

W1 (mm)

A0(mm)

B0(mm)

K0(mm)

P1(mm)

W(mm)

Pin1Quadrant

CSD86350Q5D LSON-CLIP

DQY 8 2500 330.0 15.4 5.3 6.3 1.2 8.0 12.0 Q2

PACKAGE MATERIALS INFORMATION

www.ti.com 1-Nov-2017

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

CSD86350Q5D LSON-CLIP DQY 8 2500 335.0 335.0 32.0

PACKAGE MATERIALS INFORMATION

www.ti.com 1-Nov-2017

Pack Materials-Page 2

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