Texas Instruments TPS54327DDA, TPS54327DRCT Schematic [ru]

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SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

TPS54327 3-A Output Single Synchronous Step-Down Switcher

With Integrated FET

1 Features 3 Description

1

• D-CAP2™ Mode Enables Fast Transient
Response

• Low-Output Ripple and Allows Ceramic Output
Capacitor

• Wide VINInput Voltage Range: 4.5 V to 18 V

• Output Voltage Range: 0.76 V to 7 V

• Highly Efficient Integrated FETs Optimized
for Lower Duty Cycle Applications
– 100 mΩ (High-Side) and 70 mΩ (Low-Side)

• High Efficiency, Less Than 10 μA at shutdown

• High Initial Bandgap Reference Accuracy

• Adjustable Soft Start

• Prebiased Soft Start

• 700-kHz Switching Frequency (fSW)

• Cycle-By-Cycle Overcurrent Limit

The TPS54327 device is an adaptive on-time D­CAP2™ mode synchronous buck converter.
TheTPS54327 enables system designers to complete
the suite of various end equipment’s power bus
regulators with a cost effective, low component count,
low standby current solution. The main control loop
for the TPS54327 uses the D-CAP2 mode control
which provides a fast transient response with no
external compensation components. The TPS54327
also has a proprietary circuit that enables the device
to adopt to both low equivalent series resistance
(ESR) output capacitors, such as POSCAP or SP­CAP, and ultra-low ESR ceramic capacitors. The
device operates from 4.5-V to 18-V VIN input. The
output voltage can be programmed between 0.76 V
and 7 V. The device also features an adjustable soft
start time. The TPS54327 is available in the 8-pin
DDA package and 10-pin DRC, and is designed to
operate from –40°C to 85°C.

TPS54327

2 Applications

Device Information

(1)

• Wide Range of Applications for Low Voltage PART NUMBER PACKAGE BODY SIZE (NOM)
System

– Digital TV Power Supply VSON (10) 3.00 mm × 3.00 mm
– High Definition Blu-ray Disc™ Players
– Networking Home Terminal

TPS54327

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

HSOP (8) 4.89 mm × 3.90 mm

– Digital Set Top Box (STB)

Simplified Schematic TPS54327 Transient Response

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.

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

www.ti.com

Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description ............................................................. 1

4 Revision History..................................................... 2

5 Pin Configuration and Functions......................... 3

6 Specifications......................................................... 4

6.1 Absolute Maximum Ratings ...................................... 4

6.2 ESD Ratings.............................................................. 4

6.3 Recommended Operating Conditions....................... 4

6.4 Thermal Information.................................................. 5

6.5 Electrical Characteristics........................................... 5

6.6 Typical Characteristics.............................................. 6

7 Detailed Description .............................................. 7

7.1 Overview................................................................... 7

7.2 Functional Block Diagram ......................................... 7

7.3 Feature Description................................................... 7

7.4 Device Functional Modes.......................................... 9

8 Application and Implementation........................ 10

8.1 Application Information............................................ 10

8.2 Typical Application ................................................. 10

9 Power Supply Recommendations...................... 14

10 Layout................................................................... 14

10.1 Layout Guidelines ................................................. 14

10.2 Layout Examples................................................... 15

10.3 Thermal Considerations........................................ 17

11 Device and Documentation Support................. 18

11.1 Documentation Support ........................................ 18

11.2 Community Resources.......................................... 18

11.3 Trademarks........................................................... 18

11.4 Electrostatic Discharge Caution............................ 18

11.5 Glossary................................................................ 18

12 Mechanical, Packaging, and Orderable

Information........................................................... 18

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision B (January 2012) to Revision C 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

• Removed Ordering Information table .................................................................................................................................... 1

Changes from Revision A (October 2011) to Revision B Page

• Removed (SWIFT™) from the data sheet title ....................................................................................................................... 1

• Added "and 10-pin DRC" to the DESCRIPTION.................................................................................................................... 1

• Added the DRC-10 Pin package pin out ................................................................................................................................ 3

• Changed the VBST(vs SW) MAX value From: 6V to 6.5V in the Abs Max Ratings table ..................................................... 4

• Changed the VBST(vs SW) MAX value From: 5.7V to 6V in the ROC table......................................................................... 4

• Changed UVLO MIn Value From: 0.19 V To: 0.17 V............................................................................................................. 5

• Added Added a conditions statement "VIN = 12 V, TA = 25°C" to the TYPICAL CHARACTERISTICS............................... 6

• Changed Figure 10 title From: 1.05-V, 50-mA to 2-A LOAD TRANSIENT RESPONSE To: 1.05-V, 0-A to 3-A LOAD

TRANSIENT RESPONSE .................................................................................................................................................... 12

• Changed Figure 12 Figure Title From: (IO= 2 A) To: (IO= 3 A)........................................................................................... 12

• Changed Figure 13 Figure Title From: (IO= 2 A) To: (IO= 3 A)........................................................................................... 12

• Added Figure 17 ................................................................................................................................................................... 16

Changes from Original (November 2010) to Revision A Page

• Changed Pin 6 (SW) Description In the Pin Functions table ................................................................................................ 3

• Changed the V

Min value From: 2 V To: 1.6 V in the Logic Threshold section................................................................ 5

ENH

• Changed Figure 4................................................................................................................................................................... 6

• Changed Equation 1............................................................................................................................................................... 8

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1

2

3

4

5

6

7

8

SW

GND

VBST

VIN

EN

VFB

VREG5

SS

TPS54327

(DDA)

PowerPAD

EN

VFB

VREG5

SS

GND

VIN

VIN

VBST

SW

SW

Exposed

Thermal

Die PAD

on

Underside

PGND

1

2

3

4

5

10

9

8

7

6

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5 Pin Configuration and Functions

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

DDA Package

8-Pin HSOP

Top View

DRC Package

10-Pin VSON

Top View

Pin Functions

PIN

NAME HSOP VSON

EN 1 1 I Enable input control. Active high.
VFB 2 2 I Converter feedback input. Connect to output voltage with feedback resistor divider.

VREG5 3 3 O
SS 4 4 O Soft-start control. An external capacitor should be connected to GND.
GND 5 5 G
SW 6 6, 7 O Switch node connection between high-side NFET and low-side NFET.

VBST 7 8 I between VBST and SW pins. An internal diode is connected between VREG5 and

VIN 8 9, 10 P Input voltage supply pin.
PowerPAD Back side — G
Exposed

thermal — Back side G
pad

TYPE DESCRIPTION

5.5 V power supply output. A capacitor (typical 1 µF) should be connected to GND.
VREG5 is not active when EN is low.

Ground pin. Power ground return for switching circuit. Connect sensitive SS and VFB
returns to GND at a single point.

Supply input for the high-side FET gate drive circuit. Connect 0.1µF capacitor
VBST.

PowerPAD of the package. Must be soldered to achieve appropriate dissipation. Must
be connected to GND.

Thermal pad of the package. PGND power ground return of internal low-side FET.
Must be soldered to achieve appropriate dissipation.

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SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

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6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)

VIN, EN –0.3 20 V
VBST –0.3 26 V
VBST (10 ns transient) –0.3 28 V

Input voltage VBST (vs SW) –0.3 6.5 V

VFB, SS –0.3 6.5 V
SW –2 20 V
SW (10 ns transient) –3 22 V

Output voltage

Voltage from GND to thermal pad, V
Operating junction temperature, T
Storage temperature, T

(1) 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 under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

VREG5 –0.3 6.5 V
GND –0.3 0.3 V

diff

J

stg

(1)

MIN MAX UNIT

–0.2 0.2 V

–40 150 °C
–55 150 °C

6.2 ESD Ratings

V

(ESD)

Electrostatic discharge V

Human body model (HBM), per ANSI/ESDA/JEDEC JS-001
Charged-device model (CDM), per JEDEC specification JESD22-C101

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

(1)

(2)

6.3 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)

MIN MAX UNIT

V

V

V
I

O

T
T

Supply input voltage 4.5 18 V

IN

VBST –0.1 24
VBST (10 ns transient) –0.1 27
VBST(vs SW) –0.1 6
SS –0.1 5.7

Input voltage EN –0.1 18 V

I

VFB –0.1 5.5
SW –1.8 18
SW (10 ns transient) –3 21
GND –0.1 0.1

Output voltage VREG5 –0.1 5.7 V

O

Output Current I
Operating free-air temperature –40 85 °C

A

Operating junction temperature –40 150 °C

J

VREG5

0 10 mA

VALUE UNIT

±2000

±500

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SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

6.4 Thermal Information

TPS54327

THERMAL METRIC

(1)

DDA (HSOP) DRC (VSON) UNIT

8 PINS 10 PINS

R

θJA

R

θJC(top)

R

θJB

ψ

JT

ψ

JB

R

θJC(bot)

Junction-to-ambient thermal resistance 42.1 43.9 °C/W
Junction-to-case (top) thermal resistance 50.9 55.4 °C/W
Junction-to-board thermal resistance 31.8 18.9 °C/W
Junction-to-top characterization parameter 5 0.7 °C/W
Junction-to-board characterization parameter 13.5 19.1 °C/W
Junction-to-case (bottom) thermal resistance 7.1 5.3 °C/W

(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report, SPRA953.

6.5 Electrical Characteristics

over operating free-air temperature range VIN= 12 V (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SUPPLY CURRENT

I

VIN

I

VINSDN

Operating - non-switching supply current 800 1200 μA
Shutdown supply current VINcurrent, TA= 25°C, EN = 0 V 1.8 10 μA

LOGIC THRESHOLD

V

ENH

V

ENL

EN high-level input voltage EN 1.6 V
EN low-level input voltage EN 0.45 V

VFBVOLTAGE AND DISCHARGE RESISTANCE

V

FBTH

I

VFB

V

REG5

V

VREG5

V

LN5

V

LD5

I

VREG5

VFBthreshold voltage TA= 25°C, VO= 1.05 V, continuous mode 749 765 781 mV
VFBinput current VFB= 0.8 V, TA= 25°C 0 ±0.1 μA

OUTPUT

V

output voltage 5.2 5.5 5.7 V

REG5

Line regulation 6 V < VIN< 18 V, I
Load regulation 0 mA < I
Output current VIN= 6 V, V

MOSFET

R

DS(on)h

R

DS(on)l

High-side switch resistance 25°C, V
Low-side switch resistance 25°C 70 mΩ

CURRENT LIMIT

I

ocl

Current limit L out = 1.5 μH

THERMAL SHUTDOWN

T

SDN

Thermal shutdown threshold °C

ON-TIME TIMER CONTROL

t

ON

t

OFF(MIN)

ON-time VIN= 12 V, VO= 1.05 V 150 ns
Minimum OFF-time TA= 25°C, VFB= 0.7 V 260 310 ns

SOFT START

I
I

SSC
SSD

SS charge current VSS= 0 V 1.4 2 2.6 μA
SS discharge current VSS= 0.5 V 0.05 0.1 mA

UVLO

UVLO UVLO threshold V

(1) Not production tested.

VINcurrent, TA= 25°C, EN = 5 V,
VFB= 0.8 V

TA= 25°C, 6 V < VIN< 18 V,
0 < I

Shutdown temperature
Hysteresis

Wakeup V
Hysteresis V

< 5 mA

VREG5

= 5 mA 25 mV

VREG5

< 5 mA 100 mV

VREG5

= 4 V, TA= 25°C 60 mA

REG5

- SW = 5.5 V 100 mΩ

BST

(1)

, TA= -20ºC to 85ºC 3.5 4.2 5.7 A

(1)

(1)

voltage 3.45 3.75 4.05

REG5

voltage 0.17 0.32 0.45

REG5

165

30

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400

450

500

550

600

650

700

750

800

850

900

0 5 10 15 20

V -InputVoltage-V

IN

f -SwitchingFrequency-kHz

s

V =1.8V

O

V =1.05V

O

I =1 A

O

V =3.3V

O

400

450

500

550

600

650

700

750

800

850

900

0 0.5 1 1.5 2 2.5 3

I -OutputCurrent- A

O

f -SwitchingFrequency-kHz

s

V =3.3V

O

V =1.8V

O

V =1.05V

O

0

10

20

30

40

50

60

70

80

90

100

0 2 4 6 8 10 12 14 16 18 20

EN-InputVoltage-V

V =18V

IN

EN-InputCurrent- Am

40

50

60

70

80

90

100

0.0 0.5 1.0 1.5 2.0 2.5 3.0

V = 1.8 V

OUT

V = 2.5 V

OUT

V = 3.3 V

OUT

I - Output Current - A

OUT

Efficiency - %

0

200

400

600

800

1000

1200

-50

0

50 100 150

T - Junction Temperature - °C

j

I - Supply Current - µA

VIN

0

2.0

4.0

6.0

8.0

10.0

-50

0

50 100 150

T - Junction Temperature - °C

j

I - Supply Current - µA

VINSDN

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

6.6 Typical Characteristics

VIN = 12 V, TA= 25°C (unless otherwise noted)

Figure 1. VIN Current vs Junction Temperature Figure 2. VIN Shutdown Current vs Junction Temperature

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Figure 3. EN Current vs EN Voltage

Figure 5. Switching Frequency vs Input Voltage

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Figure 4. Efficiency vs Output Current

Figure 6. Switching Frequency vs Output Current

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SW

VBST

EN

VFB

GND

VO

4

5

6

2

1

7

VIN

SS

VIN

VREG5

EN

Logic

SW

PGND

Protection

Logic

Ref

SS

UVLO

UVLO

Softstart

SS

REF

TSD

Ref

VREG5

8

VIN

Ceramic

Capacitor

3

SGND

SGND

PGND

PWM

+

-

+

OCP

+

-

VREG5

XCON

VREG5

Control Logic

1 shot

ON

TPS54327

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SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

7 Detailed Description

7.1 Overview

The TPS54327 device is a 3-A synchronous step-down (buck) converter with two integrated N-channel
MOSFETs. It operates using D-CAP2 mode control. The fast transient response of D-CAP2 control reduces the
output capacitance required to meet a specific level of performance. Proprietary internal circuitry allows the use
of low ESR output capacitors including ceramic and special polymer types.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 PWM Operation

The main control loop of the TPS54327 is an adaptive ON-time pulse width modulation (PWM) controller that
supports a proprietary D-CAP2 mode control. D-CAP2 mode control combines constant on-time control with an
internal compensation circuit for pseudo-fixed frequency and low external component count configuration with
both low ESR and ceramic output capacitors. It is stable even with virtually no ripple at the output.

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C6(nF) x V x 1.1

C6(nF) x 0.765 x 1.1

REF

t (ms) = =

SS

I ( A ) 2

SS

m

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

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Feature Description (continued)

At the beginning of each cycle, the high-side MOSFET is turned on. This MOSFET is turned off after internal one
shot timer expires. This one shot is set by the converter input voltage, VIN, and the output voltage, VO, to
maintain a pseudo-fixed frequency over the input voltage range, hence it is called adaptive on-time control. The
one-shot timer is reset and the high-side MOSFET is turned on again when the feedback voltage falls below the
reference voltage. An internal ramp is added to reference voltage to simulate output ripple, eliminating the need
for ESR induced output ripple from D-CAP2 mode control.

7.3.2 PWM Frequency and Adaptive ON-Time Control

TPS54327 uses an adaptive on-time control scheme and does not have a dedicated on-board oscillator. The
TPS54327 runs with a pseudo-constant frequency of 700 kHz by using the input voltage and output voltage to
set the on-time one-shot timer. The on-time is inversely proportional to the input voltage and proportional to the
output voltage, therefore, when the duty ratio is VOUT/VIN, the frequency is constant.

7.3.3 Soft-Start and Prebiased Soft-Start

The soft start function is adjustable. When the EN pin becomes high, 2-μA current begins charging the capacitor
which is connected from the SS pin to GND. Smooth control of the output voltage is maintained during start up.
The equation for the slow start time is shown in Equation 1. VFB voltage is 0.765 V and SS pin source current is
2 μA.

(1)

The TPS54327 contains a unique circuit to prevent current from being pulled from the output during start-up if the
output is prebiased. When the soft-start commands a voltage higher than the prebias level (internal soft start
becomes greater than feedback voltage VFB), the controller slowly activates synchronous rectification by starting
the first low side FET gate driver pulses with a narrow on-time. It then increments that on-time on a cycle-by­cycle basis until it coincides with the time dictated by (1-D), where D is the duty cycle of the converter. This
scheme prevents the initial sinking of the prebias output, and ensure that the out voltage (VO) starts and ramps
up smoothly into regulation and the control loop is given time to transition from prebiased start-up to normal
mode operation.

7.3.4 Current Protection

The output overcurrent protection (OCP) is implemented using a cycle-by-cycle valley detect control circuit. The
switch current is monitored by measuring the low-side FET switch voltage between the SW pin and GND. This
voltage is proportional to the switch current. To improve accuracy, the voltage sensing is temperature
compensated.

During the on time of the high-side FET switch, the switch current increases at a linear rate determined by Vin,
Vout, the on-time and the output inductor value. During the on time of the low-side FET switch, this current
decreases linearly. The average value of the switch current is the load current I

. The TPS54327 constantly

OUT

monitors the low-side FET switch voltage, which is proportional to the switch current, during the low-side on-time.
If the measured voltage is above the voltage proportional to the current limit, an internal counter is incremented
per each SW cycle and the converter maintains the low-side switch on until the measured voltage is below the
voltage corresponding to the current limit at which time the switching cycle is terminated and a new switching
cycle begins. In subsequent switching cycles, the on-time is set to a fixed value and the current is monitored in
the same manner. If the overcurrent condition exists for 7 consecutive switching cycles, the internal OCL
threshold is set to a lower level, reducing the available output current. When a switching cycle occurs where the
switch current is not above the lower OCL threshold, the counter is reset and the OCL limit is returned to the
higher value.

There are some important considerations for this type of overcurrent protection. The load current one half of the
peak-to-peak inductor current higher than the overcurrent threshold. Also when the current is being limited, the
output voltage tends to fall as the demanded load current may be higher than the current available from the
converter. This may cause the output voltage to fall. When the overcurrent condition is removed, the output
voltage will return to the regulated value. This protection is nonlatching.

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Feature Description (continued)

7.3.5 UVLO Protection

Undervoltage lock out protection (UVLO) monitors the voltage of the V

pin. When the V

REG5

voltage is lower

REG5

than UVLO threshold voltage, the TPS54327 is shut off. This is protection is non-latching.

7.3.6 Thermal Shutdown

TPS54327 monitors the temperature of itself. If the temperature exceeds the threshold value (typically 165°C),
the device is shut off. This is non-latch protection.

7.4 Device Functional Modes

7.4.1 Normal Operation

When the input voltage is above the UVLO threshold and the EN voltage is above the enable threshold, the
TPS54327 device operates in normal switching mode. Normal continuous conduction mode(CCM) occurs when
the minimum switch current is above 0 A. In CM, the TPS54327 device operates at a quasi-fixed frequency of
650 kHz.

7.4.2 Forced CCM Operation

When the TPS54327 device is in normal CCM operating mode and switch current falls below 0 A, the device
begins operating in forced CCM.

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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 TPS54327 device is used as a step converter that converts a voltage of 4.5 V to 18 V to a lower voltage.

WEBENCH software is available to aid in the design and analysis of circuits.

8.2 Typical Application

Figure 7. Schematic Diagram

8.2.1 Design Requirements

Use the parameters in Table 1 for this application.

Table 1. TPS54327EVM-686 Performance Specifications Summary

PARAMETERS TEST CONDITIONS MIN TYP MAX UNIT

Input voltage range (VIN) 4.5 12 18 V
Output voltage 1.05 V
Operating frequency VIN= 12 V, IO= 1 A 675 kHz
Output current range 0 3 A

8.2.2 Detailed Design Procedure

To begin the design process, you must know a few application parameters:

• Input voltage range

• Output voltage

• Output current

• Output voltage ripple

• Input voltage ripple

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2 2

=

IPP

Lo(RMS) O

1

+

12

I I I

lpp

= +

Ipeak

O

2

I

I I

V V

V

IN(max)

OUT

OUT

= x

IPP

V L x

IN(max)

O SW

-

I

f

F =

P

OUT OUT

1

2 L x Cp

V = 0.765 x

OUT

R1

1 +

R2

æ ö

÷

ç

÷

ç

÷

÷

ç

è ø

TPS54327

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SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

8.2.2.1 Output Voltage Resistors Selection

The output voltage is set with a resistor divider from the output node to the VFB pin. TI recommends using 1%
tolerance or better divider resistors. Start by using Equation 2 to calculate V

OUT

.

To improve efficiency at very light loads consider using larger value resistors, too high of resistance will be more
susceptible to noise and voltage errors from the VFB input current will be more noticeable.

(2)

8.2.2.2 Output Filter Selection

The output filter used with the TPS54327 is an LC circuit. This LC filter has double pole at:

(3)

At low frequencies, the overall loop gain is set by the output set-point resistor divider network and the internal
gain of the TPS54327. The low-frequency phase is 180 degrees. At the output filter pole frequency, the gain rolls
off at a -40 dB per decade rate and the phase drops rapidly. D-CAP2™ introduces a high-frequency zero that
reduces the gain roll off to -20 dB per decade and increases the phase to 90 degrees one decade above the
zero frequency. The inductor and capacitor selected for the output filter must be selected so that the double pole
of Equation 3 is located below the high-frequency zero but close enough that the phase boost provided be the
high-frequency zero provides adequate phase margin for a stable circuit. To meet this requirement use the
values recommended in Table 2

Table 2. Recommended Component Values

OUTPUT VOLTAGE (V) R1 (kΩ) R2 (kΩ) C4 (pF) L1 (µH) C8 + C9 (µF)

1 6.81 22.1 1.5 22 to 68

1.05 8.25 22.1 1.5 22 to 68

1.2 12.7 22.1 1.5 22 to 68

1.8 30.1 22.1 5 - 22 2.2 22 to 68

2.5 49.9 22.1 5 - 22 2.2 22 to 68

3.3 73.2 22.1 5 - 22 2.2 22 to 68
5 124 22.1 5 - 22 3.3 22 to 68

6.5 165 22.1 5 - 22 3.3 22 to 68

Because the DC gain is dependent on the output voltage, the required inductor value will increase as the output
voltage increases. For higher output voltages above 1.8 V, additional phase boost can be achieved by adding a
feed forward capacitor (C4) in parallel with R1

The inductor peak-to-peak ripple current, peak current and RMS current are calculated using Equation 4,

Equation 5 and Equation 6. The inductor saturation current rating must be greater than the calculated peak

current and the RMS or heating current rating must be greater than the calculated RMS current. Use 700 kHz for
fSW.

Use 700 kHz for fSW. Make sure the chosen inductor is rated for the peak current of Equation 5 and the RMS
current of Equation 6.

(4)

For this design example, the calculated peak current is 3.47 A and the calculated RMS current is 3.01 A. The
inductor used is a TDK SPM6530-1R5M100 with a peak current rating of 11.5 A and an RMS current rating of

11 A.

Copyright © 2010–2015, Texas Instruments Incorporated Submit Documentation Feedback 11

(5)

(6)

Product Folder Links: TPS54327

0 5 10 15 20

V -InputVoltage-V

I

1.04

1.05

1.06

1.07

1.08

V -OutputVoltage-V

O

I =1 A

O

I =0 A

O

0 0.5 1 1.5 2 2.5 3

I -OutputCurrent- A

O

1.04

1.05

1.06

1.07

1.08

V -OutputVoltage-V

O

V =12V

IN

V =18V

IN

V =5V

IN

IN

OUT OUT

=

Co(RMS)

IN

O SW

V x (V - V )

12 x V x L x

I

f

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

www.ti.com

The capacitor value and ESR determines the amount of output voltage ripple. The TPS54327 is intended for use
with ceramic or other low ESR capacitors. Recommended values range from 22uF to 68uF. Use Equation 7 to
determine the required RMS current rating for the output capacitor.

(7)

For this design two TDK C3216X5R0J226M 22-µF output capacitors are used. The typical ESR is 2 mΩ each.
The calculated RMS current is 0.271 A and each output capacitor is rated for 4 A.

8.2.2.3 Input Capacitor Selection

The TPS54327 requires an input decoupling capacitor and a bulk capacitor is needed depending on the
application. TI recommends a ceramic capacitor over 10 μF for the decoupling capacitor. TI also recommends
connecting an additional 0.1-µF capacitor from pin 14 to ground to improve the stability of the overcurrent limit
function. The capacitor voltage rating must be greater than the maximum input voltage.

8.2.2.4 Bootstrap Capacitor Selection

A 0.1 µF. ceramic capacitor must be connected between the VBST to SW pin for proper operation. TI
recommends using a ceramic capacitor.

8.2.2.5 VREG5 Capacitor Selection

A 1-µF ceramic capacitor must be connected between the VREG5 to GND pin for proper operation. TI
recommends using a ceramic capacitor.

8.2.3 Application Curves

Figure 8. 1.05-V Output Voltage vs Output Current

Figure 9. 1.05-V Output Voltage vs Input Voltage

12 Submit Documentation Feedback Copyright © 2010–2015, Texas Instruments Incorporated

Product Folder Links: TPS54327

0.0 0.5 1.0 1.5 2.0 2.5 3.0

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

VIN = 12 V

VIN = 5 V

Output Current (A)

Efficiency (%)

0.001 0.01 0.1 1 10

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

VIN = 12 V

VIN = 5 V

Output Current (A)

Efficiency (%)

V (10mV/div)

O

V =1.05V

O

SW(5V/div)

V =1.05V

O

V (50mV/div)

IN

SW(5V/div)

EN(10V/div)

VREG5(5V/div)

1ms/div)

Vout(0.5V/div)

Vout(50mV/div)

Iout(2 A/div)

100 s/divm

www.ti.com

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

Figure 10. 1.05-V, 0-A to 3-A Load Transient Response

Figure 11. Start-Up Wave Form

Figure 12. Voltage Ripple at Output (IO= 3 A) Figure 13. Voltage Ripple at Input (IO= 3 A)

Figure 14. TPS54327EVM-686 Efficiency Figure 15. TPS54327EVM-686 Light Load Efficiency

Copyright © 2010–2015, Texas Instruments Incorporated Submit Documentation Feedback 13

Product Folder Links: TPS54327

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

www.ti.com

9 Power Supply Recommendations

The TPS54327 device is designed to operate from input supply voltage in the range of 4.5 V to 18 V. Buck
converters require the input voltage to be higher than the output voltage. in this case, the maximum
recommended operating duty cycle is 65%. Using that criteria, the minimum recommended input voltage is
Vo/0.65.

10 Layout

10.1 Layout Guidelines

1. Keep the input switching current loop as small as possible.

2. Keep the SW node as physically small and short as possible to minimize parasitic capacitance and
inductance and to minimize radiated emissions. Kelvin connections should be brought from the output to the
feedback pin of the device.

3. Keep analog and non-switching components away from switching components.

4. Make a single point connection from the signal ground to power ground.

5. Do not allow switching current to flow under the device.

6. Keep the pattern lines for VIN and PGND broad.

7. Exposed pad of device must be connected to PGND with solder.

8. VREG5 capacitor should be placed near the device, and connected PGND.

9. Output capacitor should be connected to a broad pattern of the PGND.

10. Voltage feedback loop should be as short as possible, and preferably with ground shield.

11. Lower resistor of the voltage divider which is connected to the VFB pin should be tied to SGND.

12. Providing sufficient via is preferable for VIN, SW and PGND connection.

13. PCB pattern for VIN, SW, and PGND should be as broad as possible.

14. VIN Capacitor should be placed as near as possible to the device.

14 Submit Documentation Feedback Copyright © 2010–2015, Texas Instruments Incorporated

Product Folder Links: TPS54327

VFB

VREG5

SS

GND

EN

VIN

VBST

SW

EXPOSED
THERMAL PAD
AREA

BOOST
CAPACITOR

VOUT

VIA to Ground Plane

OUTPUT
INDUCTOR

OUTPUT
FILTER
CAPACITOR

SLOW
START
CAP

ANALOG
GROUND
TRACE

VIN
INPUT
BYPASS
CAPACITOR

VIN

FEEDBACK
RESISTORS

TO ENABLE
CONTROL

POWER GROUND

BIAS
CAP

Connection to
POWER GROUND
on internal or
bottom layer

VIN
HIGH FREQENCY
BYPASS
CAPACITOR

www.ti.com

10.2 Layout Examples

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

Figure 16. PCB Layout

Copyright © 2010–2015, Texas Instruments Incorporated Submit Documentation Feedback 15

Product Folder Links: TPS54327

VFB

VREG5

SS

GND

EN VIN

VBST

SW

EXPOSED
THERMAL PAD
AREA

BOOST
CAPACITOR

VOUT

VIA to Ground Plane

OUTPUT
INDUCTOR

OUTPUT
FILTER
CAPACITOR

SLOW
START
CAP

ANALOG
GROUND
TRACE

VIN
INPUT
BYPASS
CAPACITOR

VIN

FEEDBACK
RESISTORS

TO ENABLE
CONTROL

POWER GROUND

BIAS
CAP

Connection to
POWER GROUND
on internal or
bottom layer

VIN
HIGH FREQENCY
BYPASS
CAPACITOR

VIN

SW

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

Layout Examples (continued)

www.ti.com

Figure 17. PCB Layout for the DRC Package

16 Submit Documentation Feedback Copyright © 2010–2015, Texas Instruments Incorporated

Product Folder Links: TPS54327

TPS54327

www.ti.com

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

10.3 Thermal Considerations

This 8-pin DDA package incorporates an exposed thermal pad that is designed to be directly attached to an
external heatsink. The thermal pad must be soldered directly to the printed-circuit board (PCB). After soldering,
the PCB can be used as a heatsink. In addition, through the use of thermal vias, the thermal pad can be
attached directly to the appropriate copper plane shown in the electrical schematic for the device, or alternatively,
can be attached to a special heatsink structure designed into the PCB. This design optimizes the heat transfer
from the integrated circuit (IC).

For additional information on the exposed thermal pad and how to use the advantage of its heat dissipating
abilities, see the technical brief, PowerPAD™ Thermally Enhanced Package (SLMA002), and the application
brief, PowerPAD™ Made Easy (SLMA004).

The exposed thermal pad dimensions for this package are shown in the following illustration.

Figure 18. Thermal Pad Dimensions (Top View)

Copyright © 2010–2015, Texas Instruments Incorporated Submit Documentation Feedback 17

Product Folder Links: TPS54327

TPS54327

SLVSAG1C –DECEMBER 2010–REVISED DECEMBER 2015

www.ti.com

11 Device and Documentation Support

11.1 Documentation Support

11.1.1 Related Documentation

For related documentation see the following:

• PowerPAD™ Thermally Enhanced Package, SLMA002

• PowerPAD™ Made Easy, SLMA004

11.2 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

11.3 Trademarks

D-CAP2, E2E are trademarks of Texas Instruments.
Blu-ray Disc is a trademark of Blu-ray Disc Association.
All other trademarks are the property of their respective owners.

11.4 Electrostatic Discharge Caution

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.

11.5 Glossary

SLYZ022 — TI Glossary.

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

12 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

18 Submit Documentation Feedback Copyright © 2010–2015, Texas Instruments Incorporated

Product Folder Links: TPS54327

PACKAGE OPTION ADDENDUM

www.ti.com

27-Sep-2015

PACKAGING INFORMATION

Orderable Device Status

TPS54327DDA ACTIVE SO PowerPAD DDA 8 75 Green (RoHS

TPS54327DDAR ACTIVE SO PowerPAD DDA 8 2500 Green (RoHS

TPS54327DRCR ACTIVE VSON DRC 10 3000 Green (RoHS

TPS54327DRCT ACTIVE VSON DRC 10 250 Green (RoHS

(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.

Package Type Package

(1)

Drawing

Pins Package

Qty

Eco Plan

(2)

& no Sb/Br)

& no Sb/Br)

& no Sb/Br)

& no Sb/Br)

Lead/Ball Finish

(6)

CU NIPDAUAG | Call TI Level-2-260C-1 YEAR -40 to 85 54327

CU NIPDAUAG | Call TI Level-2-260C-1 YEAR -40 to 85 54327

CU NIPDAU Level-2-260C-1 YEAR -40 to 85 54327

CU NIPDAU Level-2-260C-1 YEAR -40 to 85 54327

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

(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.

Samples

Addendum-Page 1

PACKAGE OPTION ADDENDUM

www.ti.com

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.

27-Sep-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 16-Oct-2015

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

TPS54327DRCR VSON DRC 10 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2

TPS54327DRCT VSON DRC 10 250 180.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2

Type

Package
Drawing

Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

A0

(mm)B0(mm)K0(mm)P1(mm)W(mm)

Pin1

Quadrant

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com 16-Oct-2015

*All dimensions are nominal

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

TPS54327DRCR VSON DRC 10 3000 367.0 367.0 35.0
TPS54327DRCT VSON DRC 10 250 210.0 185.0 35.0

Pack Materials-Page 2

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