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TPS563249
SLVSE54A – APRIL 2018 – REVISED DECEMBER 2018
TPS563249 17-V, 3-A, Constant 1.4-MHz Synchronous Step-Down Voltage Regulator
1 Features
3 Description
•
•
The TPS563249 is a simple, easy-to-use, 3 A
synchronous step-down converter in SOT-23
package.
1
•
•
•
•
•
•
•
•
•
•
•
3-A Converter Integrated 70-mΩ and 30-mΩ FETs
D-CAP3™ Mode Control with Fast Transient
Response
Input Voltage Range: 4.5 V to 17 V
Output Voltage Range: 0.6 V to 7 V
Forced Continuous Conduction Mode
Constant 1.4-MHz Switching Frequency
Low Shutdown Current Less than 10 µA
1% Feedback Voltage Accuracy (25ºC)
Startup from Pre-Biased Output Voltage
Cycle-by-Cycle Overcurrent Limit
Hiccup-mode Overcurrent Protection
Non-Latch UVP and TSD Protections
Fixed Soft Start: 1.7 ms
2 Applications
•
•
•
•
•
Broadband Modem
Access Point Networks
Wireless Routers
Surveillance
TV, Set-Top Boxes
The device is optimized to operate with minimum
external component counts and also optimized to
achieve low standby current.
This switching regulator employs D-CAP3 mode
control providing a fast transient response and
supporting both low-equivalent series resistance
(ESR) output capacitors such as specialty polymer
and ultra-low ESR ceramic capacitors with no
external compensation components.
TPS563249 operates in Forced Continuous
Conduction Mode (FCCM), which maintains fixed 1.4
MHz switching frequency during light load operation
and eliminates system interference. The TPS563249
is available in a 6-pin 1.6-mm × 2.9-mm SOT (DDC)
package, and specified from a –40°C to 125°C
junction temperature.
Device Information(1)
PART NUMBER
TPS563249
PACKAGE
SOT-23-THIN (6)
BODY SIZE (NOM)
1.60 mm × 2.90 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
SPACER
SPACER
Simplified Schematic
TPS563249 Efficiency
Efficiency at 12V input
TPS563249
2
VOUT
COUT
3
VIN
CIN
GND VBST
SW
EN
VIN
VFB
6
5
4
90%
EN
80%
VOUT
Efficiency
1
100%
70%
60%
Vout = 0.9V
Vout = 1.05V
Vout = 1.2V
Vout = 1.5V
Vout = 1.8V
Vout = 2.5V
Vout = 3.3V
Vout = 5V
50%
40%
30%
20%
0
0.5
1
1.5
2
Output Current (A)
2.5
3
D001
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.
TPS563249
SLVSE54A – APRIL 2018 – REVISED DECEMBER 2018
www.ti.com
Table of Contents
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
7.4 Device Functional Modes........................................ 11
8
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Application ................................................. 12
9 Power Supply Recommendations...................... 16
10 Layout................................................................... 17
10.1 Layout Guidelines ................................................. 17
10.2 Layout Example .................................................... 17
11 Device and Documentation Support ................. 18
11.1
11.2
11.3
11.4
11.5
Detailed Description .............................................. 9
7.1 Overview ................................................................... 9
7.2 Functional Block Diagram ......................................... 9
7.3 Feature Description................................................... 9
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
18
18
18
18
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.
2
DATE
REVISION
NOTES
December 2018
*
Initial release.
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5 Pin Configuration and Functions
DDC Package
6-Pin SOT
Top View
GND
1
6
VBST
SW
2
5
EN
VIN
3
4
VFB
Not to scale
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
EN
5
I
Enable input control. Active high and must be pulled up to enable the device.
GND
1
—
Ground pin Source terminal of low-side power NFET as well as the ground terminal for controller
circuit. Connect sensitive VFB to this GND at a single point.
SW
2
O
Switch node connection between high-side NFET and low-side NFET.
VBST
6
O
Supply input for the high-side NFET gate drive circuit. Connect 0.1 µF capacitor between VBST
and SW pins.
VFB
4
I
Converter feedback input. Connect to output voltage with feedback resistor divider.
VIN
3
I
Input voltage supply pin. The drain terminal of high-side power NFET.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
Input voltage
MIN
MAX
VIN
–0.3
19
V
VBST
–0.3
24.5
V
VBST (10 ns transient)
–0.3
26.5
V
VBST (vs SW)
–0.3
5.5
V
VFB
–0.3
5.5
V
–2
19
V
SW (10 ns transient)
–3.5
21
V
EN
SW
UNIT
-0.3
VIN + 0.3
V
Operating junction temperature, TJ
–40
150
°C
Storage temperature, Tstg
–55
150
°C
(1)
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
6.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
±2000
Charged-device model (CDM), per JEDEC specification JESD22C101 (2)
±500
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
VIN
Supply input voltage range
EN
TJ
NOM
MAX
UNIT
4.5
17
V
EN Input voltage range
–0.1
VIN
V
Operating junction temperature
–40
125
°C
6.4 Thermal Information
TPS563249
THERMAL METRIC (1)
DDC (SOT)
UNIT
6 PINS
RθJA
Junction-to-ambient thermal resistance
117.1
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
57.3
°C/W
RθJB
Junction-to-board thermal resistance
31.2
°C/W
ψJT
Junction-to-top characterization parameter
11.2
°C/W
ψJB
Junction-to-board characterization parameter
31.3
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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6.5 Electrical Characteristics
TJ = –40°C to 125°C, VIN = 12 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
2.5
10
µA
1.27
1.34
V
SUPPLY CURRENT
IVIN(SDN)
Shutdown supply current
VIN current, EN = 0 V, TJ = 25°C
LOGIC THRESHOLD
VENH
Enable threshold
Rising
VENL
Enable threshold
Falling
1.08
1.15
REN
EN pin resistance to GND
VEN = 1 V
800
1000
1200
kΩ
594
600
606
mV
588
600
612
mV
0
±50
nA
V
VFB VOLTAGE AND DISCHARGE RESISTANCE
TJ = 25°C
VFB
FB voltage
IFB
FB input current
VFB = 0.7 V
RDS(on)h
High-side switch resistance
TJ = 25°C
70
mΩ
RDS(on)l
Low-side switch resistance
TJ = 25°C
30
mΩ
MOSFET
CURRENT LIMIT
Iocl_h_source
High side FET source
Current limit
5.5
6.3
7.1
A
Iocl_l_source
Low side FET source
Current limit
3.1
3.9
4.7
A
Iocl_l_sink
Low side FET sink Current
limit
1.1
1.7
A
THERMAL SHUTDOWN
TSDN
Thermal shutdown
threshold (1)
Shutdown temperature
160
Hysteresis
°C
25
ON-TIME TIMER CONTROL
tON(MIN)
Minimum on time (1)
tOFF(MIN)
Minimum off time
VIN = 12 V, load = 3 A
50
ns
250
ns
1.7
ms
SOFT START
tss
Soft-start time
Internal soft-start time
FREQUENCY
Fsw
Switching frequency
1250
1400
1550
kHz
OUTPUT UNDERVOLTAGE PROTECTION
VUVP
Output UVP threshold
tUVPDLY
UVP propagation delay
tHIC
UVP protection Hiccup Time
before restart
Hiccup detect (H > L)
65%
0.36
ms
25
ms
UVLO
Wake up VIN voltage
UVLO
UVLO threshold
Shutdown VIN voltage
Hysteresis VIN voltage
(1)
4.2
3.6
4.4
3.8
V
0.4
Not production tested.
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6.6 Typical Characteristics
2.96
610
2.94
608
2.92
606
2.9
604
FB Voltage (mV)
VIN Shutdown Current (uA)
VIN = 12 V (unless otherwise noted)
2.88
2.86
2.84
2.82
602
600
598
596
2.8
594
2.78
592
2.76
-40
-20
0
20
40
60
80
Junction Temperature (°C)
100
120
590
-40
140
Figure 1. Shutdown Current vs Junction Temperature
20
40
60
80
Junction Temperature (°C)
100
120
140
D001
1.18
1.17
EN Threshold - Falling (V)
1.29
EN Threshold - Rising (V)
0
Figure 2. VFB Voltage vs Junction Temperature
1.3
1.28
1.27
1.26
1.25
1.24
-40
-20
D001
1.16
1.15
1.14
1.13
1.12
1.11
-20
0
20
40
60
80
Junction Temperature (°C)
100
120
1.1
-40
140
-20
0
D001
Figure 3. EN Rising threshold vs Junction Temperature
20
40
60
80
Junction Temperature (°C)
100
120
140
D001
Figure 4. EN Falling threshold vs Junction Temperature
110
60
100
50
/RZ 6LGH 5GVBRQ P
+LJK 6LGH 5GVBRQ P
90
80
70
60
50
40
30
20
40
30
-40
-20
0
20
40
60
80
Junction Temperature (°C)
100
120
140
-20
D001
Figure 5. High-Side Rds(On) vs Junction Temperature
6
10
-40
0
20
40
60
80
Junction Temperature (°C)
100
120
140
D001
Figure 6. Low-Side Rds(On) vs Junction Temperature
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Typical Characteristics (continued)
VIN = 12 V (unless otherwise noted)
5.2
3.4
3.3
5
Output Voltage (V)
Output Voltage (V)
3.2
3.1
3
2.9
4.8
4.6
4.4
2.8
4.2
2.7
Iout = 3A
Iout = 1.5A
2.6
4.6
Iout = 3A
Iout = 1.5A
4
4.8
5
5.2
5.4
5.6
Input Voltage (V)
5.8
6
6.2
7
80%
80%
70%
70%
60%
60%
50%
40%
10%
9
D001
40%
Vin = 5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
10%
0
0
0
0.5
1
0.9 V Efficiency
1.5
2
Output Current (A)
L = 0.56 µH
2.5
3
0
(Wurth:7443835600
56)
80%
70%
70%
60%
60%
Efficiency
80%
50%
40%
L = 0.56 µH
3
D001
(Wurth:7443835600
56)
40%
Vin = 5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
10%
0
2.5
50%
30%
Vin = 5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
10%
1.5
2
Output Current (A)
Figure 10. Efficiency vs Output Current, VOUT = 1.05 V
90%
20%
1
1.05 V Efficiency
90%
30%
0.5
D001
Figure 9. Efficiency vs Output Current, VOUT = 0.9 V
Efficiency
8.5
50%
30%
Vin = 5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
8
Input Voltage (V)
Figure 8. Dropout for 5 V Output Voltage
90%
Efficiency
Efficiency
Figure 7. Dropout for 3.3 V Output Voltage
90%
30%
7.5
D001
0
0
0.5
1.2 V Efficiency
1
1.5
2
Output Current (A)
L = 0.68 µH
2.5
3
0
0.5
D001
(Wurth:7443835600
68)
Figure 11. Efficiency vs Output Current, VOUT = 1.2 V
1.5 V Efficiency
1
1.5
2
Output Current (A)
L = 0.68 µH
2.5
3
D001
(Wurth:7443835600
68)
Figure 12. Efficiency vs Output Current, VOUT = 1.5 V
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Typical Characteristics (continued)
100%
100%
90%
90%
80%
80%
70%
70%
60%
60%
Efficiency
Efficiency
VIN = 12 V (unless otherwise noted)
50%
40%
30%
10%
10%
0
0
0.5
1
1.8 V Efficiency
1.5
2
Output Current (A)
L = 1 µH
2.5
3
0
(Wurth:744311100)
90%
80%
80%
70%
70%
60%
60%
Efficiency
90%
50%
40%
L = 1 µH
2.5
3
D001
(Wurth:744311100)
50%
40%
30%
Vin = 6.5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
10%
1.5
2
Output Current (A)
Figure 14. Efficiency vs Output Current, VOUT= 2.5 V
100%
20%
1
2.5 V Efficiency
100%
30%
0.5
D001
Figure 13. Efficiency vs Output Current, VOUT = 1.8 V
Efficiency
Vin = 5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
0
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
10%
0
0
0
0.5
3.3 V Efficiency
1
1.5
2
Output Current (A)
L = 1.5 µH
2.5
3
0
0.5
D001
(Wurth:744311150)
Figure 15. Efficiency vs Output Current, VOUT= 3.3 V
8
40%
30%
Vin = 5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
50%
5 V Efficiency
1
1.5
2
Output Current (A)
L = 1.5 µH
2.5
3
D001
(Wurth:744311150)
Figure 16. Efficiency vs Output Current, VOUT = 5 V
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7 Detailed Description
7.1 Overview
The TPS563249 is a 3-A synchronous step-down converter. The proprietary D-CAP3 mode control supports low
ESR output capacitors such as specialty polymer capacitors and multi-layer ceramic capacitors without complex
external compensation circuits. The fast transient response of D-CAP3 mode control can reduce the output
capacitance required to meet a specific level of performance.
7.2 Functional Block Diagram
EN 5
VUVP
+
UVP
Hiccup
Control Logic
3
VIN
6
BST
2
SW
1
GND
VREG5
Regulator
UVLO
FB 4
Voltage
Reference
+
+
+
+
SS
Soft Start
PWM
HS
Ripple Injection
One-Shot
XCON
VREG5
TSD
OCL
threshold
LS
OCL
+
+
NOC
threshold
NOC
7.3 Feature Description
7.3.1 Adaptive On-Time Control and PWM Operation
The main control loop of the TPS563249 is adaptive on-time pulse width modulation (PWM) controller that
supports a proprietary D-CAP3 mode control. The D-CAP3 mode control combines adaptive 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.
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 duration is set proportional to the converter input voltage, VIN, and inversely
proportional to 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-CAP3 mode control.
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Feature Description (continued)
7.3.2 Soft Start and Pre-Biased Soft Start
The TPS563249 has an internal 1.7-ms soft-start. When the EN pin becomes high, the internal soft-start function
begins ramping up the reference voltage to the PWM comparator.
If the output capacitor is pre-biased at startup, the devices initiate switching and start ramping up only after the
internal reference voltage becomes greater than the feedback voltage VFB. This scheme ensures that the
converters ramp up smoothly into regulation point.
7.3.3 Current Protection
There are three kinds of current protection in TPS563249: High-side FET source current limit, low-side FET
source current limit, and low-side FET sink current limit.
The output over-current limit (OCL) is implemented using a cycle-by-cycle valley detect control circuit. The switch
current is monitored during the OFF state by measuring the low-side FET drain to source voltage. This voltage is
proportional to the switch current. To improve accuracy, the voltage sensing is temperature compensated.
During the on time of the low-side FET switch, the inductor current flow through low-side FET and decreases
linearly. The average value of the inductor current is the load current IOUT. If the monitored current is above the
low-side FET source current limit level, the converter maintains low-side FET on and delays the creation of a
new set pulse, even the voltage feedback loop requires one, until the current cross the low-side FET source
current limit level. In subsequent switching cycles, the on-time is set to a fixed value and the current is monitored
in the same manner.
There are some important considerations for this type of over-current protection. The load current is higher than
the over-current threshold by one half of the peak-to-peak inductor ripple current. 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 VFB voltage falls below the UVP
threshold voltage, the UVP comparator detects it. And then, the device will shut down after the UVP delay time
(typically 0.36 ms) and re-start after the hiccup time (typically 25 ms).
When the over current condition is removed, the output voltage returns to the regulated value.
During the on time of the high-side FET switch, the inductor current flow through high-side FET and increases at
a linear rate determined by VIN, VOUT, the on-time and the output inductor value. The switch current is compared
with high-side FET source current limit after a short blanking time. If the cross-limit event detected before the one
shot timer expires, the high-side FET is turn off immediately, and is not allowed on in the following 1 µS period.
TPS563249 works in Forced Continuous Conduction Mode (FCCM). To support light load operation, the current
flowing through low-side FET is allowed to be negative, which means the current flow from drain to source of
low-side FET. This negative current is compared with low-side FET sink current limit to prevent device from being
over-current damaged. Once the sink current cross limit, the low-side FET is turn off immediately. Both high-side
FET and low-side FET will keep off until the VFB voltage falls below reference voltage.
7.3.4 Undervoltage Lockout (UVLO) Protection
UVLO protection monitors the internal regulator voltage. When the voltage is lower than UVLO threshold voltage,
the device is shut off. This protection is non-latching.
7.3.5 Thermal Shutdown
The device monitors the temperature of itself. If the temperature exceeds the thermal shutdown threshold value
(typically 160°C), the device will shut off. This is a non-latch protection. The device will resume normal working
once the temperature return below the recovery threshold value (typically 135°C).
10
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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
TPS563249 can operate in the continuous conduction mode (CCM) at a fixed frequency of 1.4 MHz. If EN pin is
driven by a control signal, the required power on sequence is that applying input voltage at VIN pin firstly, then
pull EN pin high. Be sure that the EN pin voltage isn't higher than VIN pin voltage. If EN pin is not used, it can be
tied to VIN pin directly.
7.4.2 Standby Operation
TPS563249 can be placed in standby by asserting the EN pin low.
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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 device is a typical step-down DC-DC converter. It is typically used to convert a higher dc voltage to a lower
dc voltage with a maximum available output current of 3 A. The following design procedure can be used to select
component values for the TPS563249. Alternately, the WEBENCH® software may be used to generate a
complete design. The WEBENCH software uses an iterative design procedure and accesses a comprehensive
database of components when generating a design. This section presents a simplified discussion of the design
process.
8.2 Typical Application
The application schematic in Figure 17 was developed to meet the previous requirements. This circuit is
available as the evaluation module (EVM). The sections provide the design procedure.
Figure 17 shows the TPS563249 6.5-V to 17-V input, 3.3-V output converter schematic.
C7 0.1 F
1
VOUT = 3.3V/3A
L1
2
VOUT
R4 0
GND
VBST
SW
EN
VIN
VFB
6
R3 10 k
5
EN
1.5 H
C9
22 F
C8
NC
3
4
VOUT
R1 45.3 k
R2
10 k
1
C1
10 F
C2
NC
C3
0.1 F
Not Installed
C4
1
VIN
1
Figure 17. 3.3-V/3-A Reference Design
12
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Typical Application (continued)
8.2.1 Design Requirements
Table 1 shows the design parameters for this application.
Table 1. Design Parameters
PARAMETER
EXAMPLE VALUE
Input voltage range
6.5 to 17 V
Output voltage
3.3 V
Transient response, 1.5-A load step
ΔVOUT = ±5%
Input ripple voltage
400 mV
Output ripple voltage
100 mV
Output current rating
3A
Operating frequency
1.4 MHz
8.2.2 Detailed Design Procedure
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 to use 1%
tolerance or better divider resistors. Start by using Equation 1 to calculate VOUT.
Too high of resistance is more susceptible to noise, and voltage errors from the VFB input current is more
noticeable.
R1
VOUT 0.6 u (1
)
R2
(1)
8.2.2.2 Output Filter Selection
The LC filter used as the output filter has double pole at:
1
fP
2S LOUT u COUT
(2)
At low frequencies, the overall loop gain is set by the output set-point resistor divider network and the internal
gain of the device. The low frequency phase is 180°. At the output filter pole frequency, the gain rolls off at a –40
dB per decade rate and the phase drops rapidly. D-CAP3 introduces a high frequency zero that reduces the gain
roll off to –20 dB per decade and increases the phase to 90° one decade above the zero frequency. The inductor
and capacitor for the output filter must be selected so that the double pole of Equation 2 is located below the
high frequency zero but close enough that the phase boost provided by 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)
L1 (µH)
MIN
TYP
MAX
C8 + C9 (µF)
1
6.65
10.0
0.33
0.56
1
10 to 44
1.05
7.5
10.0
0.33
0.56
1
10 to 44
1.2
10
10.0
0.47
0.68
1.5
10 to 44
1.5
15
10.0
0.47
0.82
1.5
10 to 44
1.8
20
10.0
0.56
1
2.2
10 to 44
2.5
31.6
10.0
0.68
1
2.2
10 to 44
3.3
45.3
10.0
0.82
1.5
3.3
10 to 44
5
73.2
10.0
1
1.5
3.3
10 to 44
6.5
97.6
10.0
1
1.5
3.3
10 to 44
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The inductor peak-to-peak ripple current, peak current and RMS current are calculated using Equation 3,
Equation 4, and Equation 5. 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.
VIN(MAX) VOUT
VOUT
IlP P
u
VIN(MAX)
LO u fSW
(3)
IlPEAK
IlP P
2
IO
IO2
ILO(RMS)
(4)
1
IlP
12
2
P
(5)
For this design example, the calculated peak current is 3.63 A and the calculated RMS current is 3.02 A. The
inductor used is a WE 744311150 with a rated current of 11 A.
The capacitor value and ESR determines the amount of output voltage ripple. The TPS563249 is intended for
use with ceramic or other low ESR capacitors. Recommended values range from 10 µF to 44 µF. Use Equation 6
to determine the required RMS current rating for the output capacitor.
ICO(RMS)
VOUT u VIN
VOUT
12 u VIN u LO u fSW
(6)
For this design one Murata GRM31CR61A226KE19 22-µF output capacitor is used. The typical ESR is 2 mΩ.
The calculated RMS current is 0.365 A and output capacitor is rated for 4 A.
8.2.2.3 Input Capacitor Selection
The TPS563249 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. An additional 0.1-µF
capacitor (C3) from pin 3 to ground is optional to provide additional high frequency filtering. The capacitor voltage
rating needs to 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 to use a ceramic capacitor.
8.2.2.5 Dropout
With a constant 1.4-MHz switching frequency, there is a minimum input voltage limit for a given output voltage to
be regulated. This is due to the minimum off time limit. If the input voltage less than the minimum input voltage
limit, the output voltage drops accordingly, which is called dropout condition. Figure 7 and Figure 8 show the
typical dropout curve for 3.3 V and 5 V output voltage with 3 A and 1.5 A load respectively. Equation 7 can be
used to estimate this minimum input voltage limit.
8+0(/+0)
8176
+ :4@OH + 4. ; × +1 × kPKBB (IEJ ) F P@1 F P@2 o + (8@ + 4. × +1 ) × (P@1 + P@2 )
(
= 59
+ (4@OD + 4. ) × +1
1
F PKBB (IEJ )
(59
where
•
•
•
•
•
•
•
•
•
•
14
VOUT = target output voltage
FSW = maximum switching frequency including tolerance
toff(min) = minimum off time including tolerance
Rdsl = low side FET on resistance
Rdsh = high side FET on resistance
RL = inductor DC resistance
IO = maximum load current
td1 = dead time between high side FET off and low side FET on, 15nS typical
td2 = dead time between low side FET off and high side FET on, 10nS typical
Vd = forward voltage of low side FET body diode
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8.2.3 Application Curves
3.34
3.335
3.33
3.325
3.32
3.315
3.31
3.305
3.3
3.295
3.29
3.285
3.28
3.275
3.27
3.33
3.32
Output Voltage (V)
Output Voltage (V)
TA = 25°C, VIN = 12 V (unless otherwise noted)
3.31
3.3
3.29
3.28
3.27
Vin = 6.5V
Vin = 12V
Vin = 17V
0A Load
1.5A Load
3A Load
3.26
3.25
0
0.5
1
1.5
2
Output Current (A)
2.5
3
6
7
8
D001
Figure 18. Load Regulation
9
10 11 12 13
Input Voltage (V)
14
15
16
17
D001
Figure 19. Line Regulation
100%
90%
80%
Efficiency
70%
60%
50%
40%
30%
Vin = 6.5V
Vin = 9V
Vin = 12V
Vin = 15V
Vin = 17V
20%
10%
0
0
0.5
1
1.5
2
Output Current (A)
2.5
3
Iout = 3 A
Figure 21. Input Voltage Ripple
D001
Figure 20. Efficiency
IOUT = 0 A
Iout = 3 A
Figure 22. Output Voltage Ripple
Figure 23. Output Voltage Ripple
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Slew rate is 1.6 A/µS
Slew rate is 1.6 A/µS
Figure 24. Transient Response, 0.6 to 2.4 A
Figure 25. Transient Response, 0 to 3 A
IOUT = 3 A
IOUT = 0 A
Figure 27. Start-Up Relative to EN
Figure 26. Start Up Relative to VIN
IOUT = 3 A
IOUT = 0 A
Figure 28. Shutdown Relative to VIN
Figure 29. Shutdown Relative to EN
9 Power Supply Recommendations
TPS563249 is designed to operate from input supply voltage in the range of 4.5 V to 17 V. Buck converters
require the input voltage to be higher than the output voltage for proper operation.
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10 Layout
10.1 Layout Guidelines
1. VIN and GND traces should be as wide as possible to reduce trace impedance. The wide areas are also of
advantage from the view point of heat dissipation.
2. The input capacitor and output capacitor should be placed as close to the device as possible to minimize
trace impedance.
3. Provide sufficient vias for the input capacitor and output capacitor.
4. Keep the SW trace as physically short and wide as practical to minimize radiated emissions.
5. Do not suggest routing SW copper under the device.
6. A separate VOUT path should be connected to the upper feedback resistor.
7. Make a Kelvin connection to the GND pin for the feedback path.
8. Voltage feedback loop should be placed away from the high-voltage switching trace, and preferably has
ground shield.
9. The trace of the VFB node should be as small as possible to avoid noise coupling.
10. The GND trace between the output capacitor and the GND pin should be as wide as possible to minimize its
trace impedance.
10.2 Layout Example
Trace on the
bottom layer
GND
VOUT
Additional
Vias to the
GND plane
OUTPUT
CAPACITOR
BOOST
CAPACITOR
GND
BST
SW
EN
TO ENABLE
CONTROL
FEEDBACK
RESISTORS
OUTPUT
INDUCTOR
VIN
VIN
FB
GND trace under IC
On top layer
INPUT BYPASS
CAPACITOR
GND
Figure 30. Example Layout
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11 Device and Documentation Support
11.1 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
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-CAP3, E2E are trademarks of Texas Instruments.
WEBENCH is a registered trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.4 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
11.5 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
TPS563249DDCR
ACTIVE
SOT-23-THIN
DDC
6
3000
RoHS & Green
Call TI | SN
Level-1-260C-UNLIM
-40 to 125
249
TPS563249DDCT
ACTIVE
SOT-23-THIN
DDC
6
250
RoHS & Green
Call TI | SN
Level-1-260C-UNLIM
-40 to 125
249
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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