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TPS61087
SLVS821E – MAY 2008 – REVISED MAY 2019
TPS61087 650-kHz,1.2-MHz, 18.5-V Step-Up DC-DC Converter With 3.2-A Switch
1 Features
3 Description
•
•
•
The TPS61087 is a high-frequency, high-efficiency
DC-DC converter with an integrated 3.2-A, 0.13-Ω
power switch capable of providing an output voltage
up to 18.5 V. The selectable frequency of 650 kHz or
1.2 MHz allows the use of small external inductors
and capacitors and provides fast transient response.
The external compensation allows optimization of the
application for specific conditions. A capacitor
connected to the soft-start pin minimizes inrush
current at startup.
1
•
•
•
•
2.5-V to 6-V Input Voltage Range
18.5-V Boost Converter With 3.2-A Switch Current
650-kHz, 1.2-MHz Selectable Switching
Frequency
Adjustable Soft-Start
Thermal Shutdown
Undervoltage Lockout
10-Pin QFN and Thin QFN Packages
Device Information(1)
2 Applications
•
•
•
•
•
•
•
PART NUMBER
Handheld Devices
GPS Receivers
Digital Still Cameras
Portable Applications
DSL Modems
PCMCIA Cards
TFT LCD Bias Supply
TPS61087
PACKAGE
VSON (10)
BODY SIZE (NOM)
3.00 mm × 3.00 mm
WSON (10)
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic
L
3.3 mH
VIN
2.5 V to 6 V
Cin
2* 10 mF
16 V
8
Cby
1 mF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
TPS61087
D
SL22
6
VS
15 V/500 mA
R1
200 kW
7
Cout
4* 10 mF
25 V
2
R2
18 kW
1
Rcomp
100 kW
10
Css
100 nF
Ccomp
820 pF
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.
TPS61087
SLVS821E – MAY 2008 – REVISED MAY 2019
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
4
4
6.1
6.2
6.3
6.4
6.5
6.6
4
5
5
5
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 9
7.1 Overview ................................................................... 9
7.2 Functional Block Diagram ......................................... 9
7.3 Feature Description................................................. 10
7.4 Device Functional Modes........................................ 10
8
Application and Implementation ........................ 11
8.1 Application Information............................................ 11
8.2 Typical Application ................................................. 11
8.3 System Examples ................................................... 17
9 Power Supply Recommendations...................... 22
10 Layout................................................................... 22
10.1 Layout Guidelines ................................................. 22
10.2 Layout Example .................................................... 23
11 Device and Documentation Support ................. 24
11.1
11.2
11.3
11.4
Third-Party Products Disclaimer ...........................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
24
24
24
24
12 Mechanical, Packaging, and Orderable
Information ........................................................... 24
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision D (August 2014) to Revision E
Page
•
Changed device number from TPS61085 (typo) to TPS61087 (correct) in the Application Information description
paragraph. ........................................................................................................................................................................... 11
•
Changed device number from TPS61085 (typo) to TPS61087 (correct) in the Power Supply Recommendations
section. ................................................................................................................................................................................. 22
Changes from Revision C (July 2013) to Revision D
•
Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section .................................................................................................. 1
Changes from Revision B (March 2010) to Revision C
•
Page
Page
Added VIH Test Condition for EN, VIN = 2.5 V to 4.3 V........................................................................................................... 6
Changes from Revision A (June 2008) to Revision B
Page
•
Added DSC package to PIN ASSIGNMENT .......................................................................................................................... 4
•
Deleted Lead temperature from Absolute Maximum Ratings................................................................................................. 4
•
Changed fosc to fS in Electrical Characteristics Boost Converter Oscillator Frequency .......................................................... 6
•
Changed FREQ = high to FREQ = VIN in Electrical Characteristics Boost Converter Oscillator Frequency ......................... 6
•
Changed FREQ = low to FREQ = GND in Electrical Characteristics Boost Converter Oscillator Frequency ....................... 6
•
Added Maximum load current vs. Input voltage graph ........................................................................................................... 6
•
Added Maximum load current vs. Input voltage graph ........................................................................................................... 6
•
Changed f to fS and Frequency to Oscillator Frequency in Figure 6 ..................................................................................... 7
•
Changed f to fS and Frequency to Oscillator Frequency in Figure 7 ..................................................................................... 7
•
Changed the text in the Detailed Description. ........................................................................................................................ 9
•
Changed "inductor current ripple is below 20%" to " inductor current ripple is below 35%" ............................................... 13
2
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•
SLVS821E – MAY 2008 – REVISED MAY 2019
Added output capacitor calculation....................................................................................................................................... 15
Changes from Original (May 2008) to Revision A
•
Page
Added text to the Detailed Description - following the Block Diagram ................................................................................... 9
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SLVS821E – MAY 2008 – REVISED MAY 2019
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5 Pin Configuration and Functions
DRC (VSON), DSC (WSON) Package
10 Pins, 3 mm × 3 mm × 1 mm
Top View
COMP
SS
FREQ
FB
EN
Thermal
Pad
IN
AGND
SW
PGND
SW
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
AGND
4,
Thermal
Pad
Analog ground
COMP
1
I/O
EN
3
I
Shutdown control input. Connect this pin to logic high level to enable the device
FB
2
I
Feedback pin
FREQ
9
I
Frequency select pin. The power switch operates at 650 kHz if FREQ is connected to GND and at 1.2 MHz
if FREQ is connected to IN
IN
8
I
Input supply pin
Compensation pin
PGND
5
SS
10
O
Power ground
Soft-start control pin. Connect a capacitor to this pin if soft-start needed. Open = no soft-start
SW
6, 7
I
Switch pin
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
Input voltage range IN (2)
–0.3
7.0
V
Voltage range on pins EN, FB, SS, FREQ, COMP
–0.3
7.0
V
Voltage on pin SW
–0.3
20
V
Continuous power dissipation
See Thermal Information
Operating junction temperature range
–40
150
°C
Storage temperature range
–65
150
°C
(1)
(2)
4
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
All voltage values are with respect to network ground terminal.
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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
Machine model (MM)
±200
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 500-V HBM is possible with the necessary precautions. Pins listed as ±2000 V may actually have higher performance.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Manufacturing with
less than 250-V CDM is possible with the necessary precautions. Pins listed as ±500 V may actually have higher performance.
6.3 Recommended Operating Conditions
MIN
VIN
Input voltage range
VS
Boost output voltage range
TA
Operating free-air temperature
TJ
Operating junction temperature
NOM
MAX
UNIT
2.5
6
V
VIN + 0.5
18.5
V
–40
85
°C
–40
125
°C
6.4 Thermal Information
TPS61087
THERMAL METRIC (1)
DRC
DSC
10 PINS
10 PINS
UNIT
RθJA
Junction-to-ambient thermal resistance
54.7
55.3
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
67.2
84.8
°C/W
RθJB
Junction-to-board thermal resistance
29.6
29.7
°C/W
ψJT
Junction-to-top characterization parameter
2.3
5.4
°C/W
ψJB
Junction-to-board characterization parameter
29.8
29.8
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
15.6
10.9
°C/W
(1)
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
6.5 Electrical Characteristics
VIN = 5 V, EN = VIN, VS = 15 V, TA = –40°C to 85°C, typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
6
V
75
100
μA
1
μA
2.4
V
SUPPLY
VIN
Input voltage range
IQ
Operating quiescent current into IN
Device not switching, VFB = 1.3 V
2.5
ISDVIN
Shutdown current into IN
EN = GND
VUVLO
Undervoltage lockout threshold
VIN falling
TSD
Thermal shutdown
TSDHYS
Thermal shutdown hysteresis
VIN rising
Temperature rising
2.5
°C
14
°C
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150
5
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Electrical Characteristics (continued)
VIN = 5 V, EN = VIN, VS = 15 V, TA = –40°C to 85°C, typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
LOGIC SIGNALS EN, FREQ
VIN = 2.5 V to 6.0 V
2
VIH
High-level input voltage
VIL
Low-level input voltage
VIN = 2.5 V to 6.0 V
0.5
V
IINLEAK
Input leakage current
EN = FREQ = GND
0.1
μA
18.5
V
Valid only for EN, VIN = 2.5 V to 4.3 V
V
1.6
BOOST CONVERTER
VS
Boost output voltage
VIN +
0.5
VFB
Feedback regulation voltage
1.230
gm
Transconductance error amplifier
IFB
Feedback input bias current
rDS(on)
N-channel MOSFET on-resistance
ISWLEAK
SW leakage current
ILIM
N-Channel MOSFET current limit
ISS
Soft-start current
fS
Oscillator frequency
1.238
1.246
107
VFB = 1.238 V
0.1
VIN = VGS = 5 V, ISW = current limit
0.13
0.18
VIN = VGS = 3V, ISW = current limit
0.16
0.23
EN = GND, VSW = VIN = 6.0V
V
μA/V
2
μA
Ω
μA
3.2
4.0
4.8
A
7
10
13
μA
FREQ = VIN
0.9
1.2
1.5
MHz
FREQ = GND
480
650
820
VSS = 1.238 V
Line regulation
VIN = 2.5 V to 6.0 V, IOUT = 10 mA
Load regulation
VIN = 5.0 V, IOUT = 1 mA to 1 A
kHz
0.0002
%/V
0.11
%/A
6.6 Typical Characteristics
The typical characteristics are measured with the inductors 7447789003 3.3 µH (high frequency) or 74454068 6.8 µH (low
frequency) from Wurth and the rectifier diode SL22.
Table 1. Table of Graphs
FIGURE
IOUT(max)
Maximum load current
vs. Input voltage at High frequency (1.2 MHz)
Figure 1
IOUT(max)
Maximum load current
vs. Input voltage at Low frequency (650 kHz)
Figure 2
η
Efficiency
vs. Load current, VS = 15 V, VIN = 5 V
Figure 3
η
Efficiency
vs. Load current, VS = 9 V, VIN = 3.3 V
Figure 4
Supply current
vs. Supply voltage
Figure 5
Oscillator frequency
vs. Load current
Figure 6
Oscillator frequency
vs. Supply voltage
Figure 7
6
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3.0
3.0
fS = 1.2 Mhz
2.5
VOUT = 9 V
2.0
VOUT = 12 V
1.5
VOUT = 15 V
1.0
VOUT = 18.5 V
0.5
IOUT - Maximum Load Current - A
IOUT - Maximum Load Current - A
fS = 650 kHz
2.5
2.0
VOUT = 9 V
VOUT = 12 V
1.5
1.0
VOUT = 18.5 V
0.5
VOUT = 15 V
0.0
2.5
3.0
3.5
4.0
4.5
5.5
5.0
0.0
2.5
6.0
3.0
3.5
4.0
4.5
5.0
5.5
6.0
VIN - Input Voltage - V
VIN - Input Voltage - V
Figure 1. Maximum Load Current vs Input Voltage
Figure 2. Maximum Load Current vs Input Voltage
100
100
90
90
80
fS = 1.2 Mhz
70
L = 3.3 mH
Efficiency - %
Efficiency - %
fS = 1.2 Mhz
70
60
50
40
L = 3.3 mH
60
50
40
30
30
20
20
VIN = 5 V
VS = 15 V
10
0
0.0 0.1
VIN = 3.3 V
VS = 9 V
10
0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
IOUT - Load Current - A
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
IOUT - Load Current - A
Figure 3. Efficiency vs Load Current
Figure 4. Efficiency vs Load Current
1600
2.0
1.8
SWITCHING
fS = 1.2 Mhz
1.6
L = 3.3 mH
1.4
1400
fS - Oscillator Frequency - kHz
ICC - Supply Current - mA
L = 6.8 mH
80
fS = 650 kHz
L = 6.8 mH
SWITCHING
fS = 650 kHz
1.2
L = 6.8 mH
1.0
0.8
0.6
0.4
0.2
0
2.5
fS = 650 kHz
3.5
4.0
4.5
5.0
VCC - Supply Voltage - V
L = 3.3 mH
1200
1000
800
FREQ = GND
L = 6.8 mH
600
400
VIN = 5 V
VS = 15 V
200
NOT SWITCHING
3.0
FREQ = VIN
5.5
6.0
0
0.0 0.1
0.2
0.3
0.4 0.5 0.6
0.7 0.8 0.9
1.0
IOUT - Load Current - mA
Figure 5. Supply Current vs Supply Voltage
Figure 6. Oscillator Frequency vs Load Current
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1400
VS = 15 V / 200 mA
fS - Oscillator Frequency - kHz
1200
FREQ = VIN
L = 3.3 mH
1000
800
600
FREQ = GND
L = 6.8 mH
400
200
0
2.5
3
3.5
4
4.5
5
VCC - Supply Voltage - V
5.5
6
Figure 7. Oscillator Frequency vs Supply Voltage
8
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7 Detailed Description
7.1 Overview
The boost converter is designed for output voltages of up to 18.5 V with a switch peak current limit of 3.2 A
minimum. The device, which operates in a current mode scheme with quasi-constant frequency, is externally
compensated for maximum flexibility and stability. The switching frequency is selectable between 650 kHz and
1.2 MHz, and the minimum input voltage is 2.5 V. To limit the inrush current at start-up, a soft-start pin is
available.
The novel topology of the TPS60187 boost converter uses adaptive off-time to provide superior load and line
transient responses. This topology also operates over a wider range of applications than conventional converters.
The selectable switching frequency offers the possibility to optimize the design either for the use of small-sized
components (1.2 MHz) or for higher system efficiency (650 kHz). However, the frequency changes slightly
because the voltage drop across the rDS(on) has some influence on the current and voltage measurement and
thus on the on-time (the off-time remains constant).
The converter operates in continuous conduction mode (CCM) as soon as the input current increases above half
the ripple current in the inductor, for lower load currents it switches into discontinuous conduction mode (DCM). If
the load is further reduced, the part starts to skip pulses to maintain the output voltage.
7.2 Functional Block Diagram
VIN
VS
EN
SS
IN
SW
FREQ
SW
Current limit
and
Soft Start
tOFF Generator
AGND
Bias Vref = 1.238V
UVLO
Thermal Shutdown
tON
PWM
Generator
Gate Driver of
Power
Transistor
COMP
GM Amplifier
FB
Vref
PGND
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7.3 Feature Description
7.3.1 Soft-Start
The boost converter has an adjustable soft-start to prevent high inrush current during start-up. To minimize the
inrush current during start-up an external capacitor, connected to the soft-start pin SS and charged with a
constant current, is used to slowly ramp up the internal current limit of the boost converter. When the EN pin is
pulled high, the soft-start capacitor CSS is immediately charged to 0.3 V. The capacitor is then charged at a
constant current of 10 μA typically until the output of the boost converter VS has reached its Power Good
threshold (roughly 98% of VS nominal value). During this time, the SS voltage directly controls the peak inductor
current, starting with 0 A at VSS = 0.3 V up to the full current limit at VSS = 800 mV. The maximum load current is
available after the soft-start is completed. The larger the capacitor the slower the ramp of the current limit and the
longer the soft-start time. A 100-nF capacitor is usually sufficient for most of the applications. When the EN pin is
pulled low, the soft-start capacitor is discharged to ground.
7.3.2 Frequency Select Pin (FREQ)
The frequency select pin FREQ allows to set the switching frequency of the device to 650 kHz (FREQ = low) or
1.2 MHz (FREQ = high). Higher switching frequency improves load transient response but reduces slightly the
efficiency. The other benefits of higher switching frequency are a lower output ripple voltage. The use of a 1.2MHz switching frequency is recommended unless light load efficiency is a major concern.
7.3.3 Undervoltage Lockout (UVLO)
To avoid mis-operation of the device at low input voltages an undervoltage lockout is included that disables the
device, if the input voltage falls below 2.4 V.
7.3.4 Thermal Shutdown
A thermal shutdown is implemented to prevent damages due to excessive heat and power dissipation. Typically
the thermal shutdown happens at a junction temperature of 150°C. When the thermal shutdown is triggered the
device stops switching until the junction temperature falls below typically 136°C. Then the device starts switching
again.
7.3.5 Overvoltage Prevention
If overvoltage is detected on the FB pin (typically 3% above the nominal value of 1.238 V) the part stops
switching immediately until the voltage on this pin drops to its nominal value. This prevents overvoltage on the
output and secures the circuits connected to the output from excessive overvoltage.
7.4 Device Functional Modes
The converter operates in continuous conduction mode (CCM) as soon as the input current increases above half
the ripple current in the inductor, for lower load currents it switches into discontinuous conduction mode (DCM). If
the load is further reduced, the part starts to skip pulses to maintain the output voltage.
10
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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 TPS61087 is designed for output voltages up to 18.5 V with a switch peak current limit of 2.0-A minimum.
The device, which operates in a current mode scheme with quasi-constant frequency, is externally compensated
for maximum flexibility and stability. The switching frequency is selectable between 650 kHz and 1.2 MHz, and
the input voltage range is 2.3 V to 6.0 V. To control the inrush current at start-up a soft-start pin is available. The
following section provides a step-by-step design approach for configuring the TPS61087 as a voltage regulating
boost converter.
8.2 Typical Application
L
3.3 µH
VIN
5 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
TPS61087
VS
15 V/900 mA max.
D
SL22
6
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
100 kΩ
10
Css
100 nF
Ccomp
820 pF
Figure 8. Typical Application, 5 V to 15 V (fS = 1.2 MHz)
8.2.1 Design Requirements
Table 2. TPS61087 15-V Output Design Requirements
PARAMETERS
VALUES
Input Voltage
5 V ± 20%
Output Voltage
15 V
Output Current
900 mA
Switching Frequency
1.2 MHz
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8.2.2 Detailed Design Procedure
The first step in the design procedure is to verify that the maximum possible output current of the boost converter
supports the specific application requirements. A simple approach is to estimate the converter efficiency, by
taking the efficiency numbers from the provided efficiency curves or to use a worst case assumption for the
expected efficiency, for example, 90%.
1. Duty cycle, D:
D = 1-
VIN ×h
VS
(1)
2. Maximum output current, Iout(max) :
DI
æ
I out (max) = ç I LIM (min) - L
2
è
ö
÷ × (1 - D )
ø
(2)
3. Peak switch current in application, Iswpeak :
I swpeak =
I
DI L
+ out
2 1- D
(3)
with the inductor peak-to-peak ripple current, ΔIL
DI L =
VIN × D
fS × L
(4)
and
VIN
Minimum input voltage
VS
Output voltage
ILIM(min)
Converter switch current limit (minimum switch current limit = 3.2 A)
fS
Converter switching frequency (typically 1.2 MHz or 650 kHz)
L
Selected inductor value
η
Estimated converter efficiency (use the number from the efficiency plots or 90% as an estimation)
The peak switch current is the steady state peak switch current that the integrated switch, inductor and external
Schottky diode has to be able to handle. The calculation must be done for the minimum input voltage where the
peak switch current is the highest.
8.2.2.1 Inductor Selection
The TPS61087 is designed to work with a wide range of inductors. The main parameter for the inductor selection
is the saturation current of the inductor which should be higher than the peak switch current as calculated in the
Detailed Design Procedure section with additional margin to cover for heavy load transients. An alternative, more
conservative, is to choose an inductor with a saturation current at least as high as the maximum switch current
limit of 4.8 A. The other important parameter is the inductor DC resistance. Usually the lower the DC resistance
the higher the efficiency. It is important to note that the inductor DC resistance is not the only parameter
determining the efficiency. Especially for a boost converter where the inductor is the energy storage element, the
type and core material of the inductor influences the efficiency as well. At high switching frequencies of 1.2 MHz
inductor core losses, proximity effects and skin effects become more important. Usually an inductor with a larger
form factor gives higher efficiency. The efficiency difference between different inductors can vary between 2% to
10%. For the TPS61087, inductor values between 3 μH and 6 μH are a good choice with a switching frequency
of 1.2 MHz, typically 3.3 μH. At 650 kHz TI recommends inductors between 6 μH and 13 μH, typically 6.8 μH.
Possible inductors are shown in Table 3.
12
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Typically, TI recommends an inductor current ripple below 35% of the average inductor current. Therefore, the
following equation can be used to calculate the inductor value, L:
2
æ V ö æ V -V
L = ç IN ÷ × ç S IN
è VS ø è I out × f S
ö æ h ö
÷×ç
÷
ø è 0.35 ø
(5)
with
VIN
Minimum input voltage
VS
Output voltage
Iout
Maximum output current in the application
fS
Converter switching frequency (typically 1.2 MHz or 650 kHz)
η
Estimated converter efficiency (use the number from the efficiency plots or 90% as an estimation)
Table 3. Inductor Selection
L
(μH)
SUPPLIER
COMPONENT
CODE
SIZE
(L×W×H mm)
DCR TYP
(mΩ)
Isat (A)
4.2
Sumida
CDRH5D28
5.7 × 5.7 × 3
23
2.2
4.7
5
Wurth Elektronik
7447785004
5.9 × 6.2 × 3.3
60
2.5
Coilcraft
MSS7341
7.3 × 7.3 × 4.1
24
5
2.9
Sumida
CDRH6D28
7×7×3
23
2.4
1.2 MHz
4.6
Sumida
CDR7D28
7.6 × 7.6 × 3
38
3.15
4.7
Wurth Elektronik
7447789004
7.3 × 7.3 × 3.2
33
3.9
3.3
Wurth Elektronik
7447789003
7.3 × 7.3 × 3.2
30
4.2
10
Wurth Elektronik
744778910
7.3 × 7.3 × 3.2
51
2.2
10
Sumida
CDRH8D28
8.3 × 8.3 × 3
36
2.7
6.8
Sumida
CDRH6D26HPNP
7 × 7 × 2.8
52
2.9
6.2
Sumida
CDRH8D58
8.3 × 8.3 × 6
25
3.3
10
Coilcraft
DS3316P
12.95 × 9.40 ×
5.08
80
3.5
10
Sumida
CDRH8D43
8.3 × 8.3 × 4.5
29
4
6.8
Wurth Elektronik
74454068
12.7 × 10 × 4.9
55
4.1
650 kHz
8.2.2.2 Rectifier Diode Selection
To achieve high efficiency a Schottky type should be used for the rectifier diode. The reverse voltage rating
should be higher than the maximum output voltage of the converter. The averaged rectified forward current Iavg ,
the Schottky diode needs to be rated for, is equal to the output current Iout :
I avg = I out
(6)
Usually a Schottky diode with 2-A maximum average rectified forward current rating is sufficient for most
applications. The Schottky rectifier can be selected with lower forward current capability depending on the output
current Iout but has to be able to dissipate the power. The dissipated power, PD , is the average rectified forward
current times the diode forward voltage, Vforward .
PD = I avg × V forward
(7)
Typically, the diode should be able to dissipate around 500 mW depending on the load current and forward
voltage.
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Table 4. Rectifier Diode Selection
CURRENT
RATING Iavg
Vr
Vforward/Iavg
SUPPLIER
COMPONENT CODE
2A
20 V
0.44 V / 2 A
Vishay Semiconductor
SL22
2A
20 V
0.5 V / 2 A
Fairchild Semiconductor
SS22
8.2.2.3 Setting the Output Voltage
The output voltage is set by an external resistor divider. Typically, a minimum current of 50 μA flowing through
the feedback divider gives good accuracy and noise covering. A standard low-side resistor of 18 kΩ is typically
selected. The resistors are then calculated as:
VS
R2 =
VFB
» 18k W
70 m A
æ V
ö
R1 = R 2 × ç S - 1÷
V
è FB
ø
R1
VFB
VFB = 1.238V
R2
(8)
8.2.2.4 Compensation (COMP)
The regulator loop can be compensated by adjusting the external components connected to the COMP pin. The
COMP pin is the output of the internal transconductance error amplifier.
Standard values of RCOMP = 16 kΩ and CCOMP = 2.7 nF will work for the majority of the applications.
See Table 5 for dedicated compensation networks giving an improved load transient response. The following
equations can be used to calculate RCOMP and CCOMP :
RCOMP =
110 × VIN × VS × Cout
L × I out
CCOMP =
Vs × Cout
7.5 × I out × RCOMP
(9)
with
VIN
Minimum input voltage
VS
Output voltage
Cout
Output capacitance
L
Inductor value, for example, 3.3 μH or 6.8 μH
Iout
Maximum output current in the application
Make sure that RCOMP < 120 kΩ and CCOMP> 820 pF, independent of the results of the above formulas.
Table 5. Recommended Compensation Network Values at High/Low Frequency
FREQUENCY
L
VS
15 V
High (1.2 MHz)
3.3 μH
12 V
9V
15 V
Low (650 kHz)
6.8 μH
12 V
9V
14
VIN ± 20%
RCOMP
CCOMP
5V
100 kΩ
820 pF
3.3 V
91 kΩ
1.2 nF
820 pF
5V
68 kΩ
3.3 V
68 kΩ
1.2 nF
5V
39 kΩ
820 pF
3.3 V
39 kΩ
1.2 nF
5V
51 kΩ
1.5 nF
3.3 V
47 kΩ
2.7 nF
5V
33 kΩ
1.5 nF
3.3 V
33 kΩ
2.7 nF
5V
18 kΩ
1.5 nF
3.3 V
18 kΩ
2.7 nF
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Table 5 gives conservative RCOMP and CCOMP values for certain inductors, input and output voltages providing a
very stable system. For a faster response time, a higher RCOMP value can be used to enlarge the bandwidth, as
well as a slightly lower value of CCOMP to keep enough phase margin. These adjustments should be performed in
parallel with the load transient response monitoring of TPS61087.
8.2.2.5 Input Capacitor Selection
For good input voltage filtering low ESR ceramic capacitors are recommended. TPS61087 has an analog input
IN. Therefore, a 1-μF bypass is highly recommended as close as possible to the IC from IN to GND.
Two 10-μF (or one 22-μF) ceramic input capacitors are sufficient for most of the applications. For better input
voltage filtering this value can be increased. See Table 6 and typical applications for input capacitor
recommendation.
8.2.2.6 Output Capacitor Selection
For best output voltage filtering a low ESR output capacitor like ceramic capcaitor is recommended. Four 10-μF
ceramic output capacitors (or two-22 μF) work for most of the applications. Higher capacitor values can be used
to improve the load transient response. See Table 6 for the selection of the output capacitor.
Table 6. Rectifier Input and Output Capacitor Selection
CAPACITOR/SIZE
VOLTAGE RATING
SUPPLIER
COMPONENT CODE
CIN
22 μF/1206
16 V
Taiyo Yuden
EMK316 BJ 226ML
IN bypass
1 μF/0603
16 V
Taiyo Yuden
EMK107 BJ 105KA
COUT
10 μF/1206
25 V
Taiyo Yuden
TMK316 BJ 106KL
To calculate the output voltage ripple, the following equation can be used:
DVC =
VS - VIN I out
×
VS × f S Cout
DVC _ ESR = I L ( peak ) × RC _ ESR
(10)
with
ΔVC
Output voltage ripple dependent on output capacitance,output current and switching frequency
VS
Output voltage
VIN
Minimum input voltage of boost converter
fS
Converter switching frequency (typically 1.2 MHz or 650 kHz)
Iout
Output capacitance
ΔVC_ESR
Output voltage ripple due to output capacitors ESR (equivalent series resistance)
ISWPEAK
Inductor peak switch current in the application
RC_ESR
Output capacitors equivalent series resistance (ESR)
ΔVC_ESR can be neglected in many cases since ceramic capacitors provide low ESR.
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8.2.3 Application Curves
VSW
10 V/div
VSW
10 V/div
VS_AC
50 mV/div
VS_AC
50 mV/div
VIN = 5 V
VS = 15 V/2 mA
FREQ = VIN
Il
1 A/div
VIN = 5 V
VS = 15 V/500 mA
FREQ = VIN
IL
500 mA/div
200 ns/div
200 ns/div
Figure 9. PWM Switching Discontinuous Conduction Mode
Figure 10. PWM Switching Continuous Conduction Mode
VIN = 5 V
VS = 15 V
VIN = 5 V
VS = 15 V
VS_AC
100 mV/div
L = 6.8 mH
Rcomp = 110 kW
Ccomp = 1 nF
VS_AC
100 mV/div
COUT = 40 mF
IOUT = 100 mA - 500 mA
COUT = 40 mF
L = 3.3 mH
Rcomp = 150 kW
Ccomp = 820 pF
IOUT = 100 mA - 500 mA
IOUT
200 mA/div
IOUT
200 mA/div
200 ms/div
200 ms/div
Figure 11. Load Transient Response High Frequency
(1.2 MHz)
Figure 12. Load Transient Response Low Frequency
(650 kHz)
EN
5 V/div
VIN = 5 V
VS = 15 V/500 mA
VS
5 V/div
IL
1 A/div
CSS = 100 nF
2 ms/div
Figure 13. Soft-Start
16
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8.3 System Examples
8.3.1 General Boost Application Circuits
L
6.8 µH
VIN
5 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
VS
15 V/900 mA max.
D
SL22
6
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
51 kΩ
10
Css
100 nF
TPS61087
Ccomp
1.5 nF
Figure 14. Typical Application, 5 V to 15 V (fS = 650 kHz)
L
3.3 µH
VIN
3.3 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
TPS61087
D
SL22
6
VS
9 V/950 mA max.
R1
110 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
39 kΩ
10
Css
100 nF
Ccomp
1.2 nF
Figure 15. Typical Application, 3.3 V to 9 V (fS = 1.2 MHz)
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System Examples (continued)
L
6.8 µH
VIN
3.3 V ± 20%
8
Cin
2* 10 µF
16 V
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
VS
9 V/950 mA max.
D
SL22
6
R1
110 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
18 kΩ
10
Css
100 nF
TPS61087
Ccomp
2.7 nF
Figure 16. Typical Application, 3.3 V to 9 V (fS = 650 kHz)
Riso
10 kW
L
6.8 µH
VIN
5 V ± 20%
Cin
2* 10 µF/
16 V
Cby
1 µF/16 V
8
3
9
Enable
4
SW
IN
SW
EN
FREQ
FB
AGND
COMP
PGND
SS
5
TPS61087
VS
15 V/300 mA
BC857C
D
SL22
6
Ciso
1 µF/ 25 V
7
R1
200 kΩ
2
Cout
4*10 µF/
25 V
R2
18 kΩ
1
Rcomp
51 kΩ
10
Css
100 nF
Ccomp
1.5 nF
Figure 17. Typical Application With External Load Disconnect Switch
18
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System Examples (continued)
L
6.8 µH
D
SL22
VIN
5 V ± 20%
8
Cin
2* 10 µF
16 V
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
COMP
AGND
PGND
SS
TPS61087
Overvoltage
Protection
VS
15 V/900 mA max.
6
Dz
BZX84C 18V
7
R1
200 kΩ
Cout
4* 10 µF
25 V
2
Rlimit
110 Ω
1
R2
18 kΩ
Rcomp
51 kΩ
10
Css
100 nF
Ccomp
1.5 nF
Figure 18. Typical Application, 5 V to 15 V (fS = 1.2 MHz) With Overvoltage Protection
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System Examples (continued)
8.3.2 TFT LCD Application
T2
BC850B
3·Vs
VGL
-7 V/20 mA
T1
BC857B
R8
6.8 kΩ
C13
1 µF/
35 V
C16
470 nF/
50 V
-Vs
C14
470 nF/
25 V
D4
BAV99
C15
470 nF/
50 V
D3
BAV99
C18
470 nF/
50 V
R10
13 kΩ
2·Vs
C17
470 nF/
50 V
D2
BAV99
D8
BZX84C7V5
Vgh
26.5 V/20 mA
C20
1 µF/
35 V
C19
470 nF/
50 V
D9
BZX84C27V
L
3.3 µH
VIN
5 V ± 20%
Cin
2*10 µF/
16 V
Cby
1 µF/
16 V
D
SL22
8
IN
SW
EN
SW
3
7
9
R1
200 kΩ
Cout
4*10µF/
25V
2
FREQ
FB
4
5
VS
15 V/500 mA
6
R2
18 kΩ
1
AGND
COMP
PGND
SS
TPS61087
Rcomp
100 kΩ
10
Css
100 nF
Ccomp
820 pF
Figure 19. Typical Application 5 V to 15 V (fS = 1.2 MHz) for TFT LCD With External Charge Pumps
(VGH, VGL)
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System Examples (continued)
8.3.3 White LED Applications
L
6.8 µH
optional
VIN
5 V ± 20%
Cin
2* 10 µF/
16 V
Cby
1 µF/ 16 V
6
8
3
9
4
5
IN
SW
EN
SW
D
SL22
Dz
BZX84C 18 V
VS
500 mA
3S3P wLED
LW E67C
7
Cout
4* 10 µF/
25 V
2
FREQ
FB
AGND
COMP
PGND
SS
Rlimit
110 Ω
1
Rcomp
51 kΩ
10
TPS61087
Css
100 nF
Rsense
15 Ω
Ccomp
1.5 nF
Figure 20. Simple Application (5 V Input Voltage) (fS = 650 kHz) for wLED Supply (3S3P) (With Optional
Clamping Zener Diode)
L
6.8 µH
optional
VIN
5 V ± 20%
Cin
2* 10 µF/
16 V
Cby
1 µF/ 16 V
3
9
4
PWM
100 Hz to 500 Hz
6
8
5
IN
SW
EN
SW
D
SL22
Dz
BZX84C 18 V
VS
500 mA
3S3P wLED
LW E67C
7
Cout
4* 10 µF/
25 V
2
FREQ
FB
AGND
COMP
PGND
SS
TPS61087
Rlimit
110 Ω
1
Rcomp
51 kΩ
10
Css
100 nF
Rsense
15 Ω
Ccomp
1.5 nF
Figure 21. Simple Application (5 V Input Voltage) (fS = 650 kHz) for wLED Supply (3S3P) With Adjustable
Brightness Control Using a PWM Signal on the Enable Pin
(With Optional Clamping Zener Diode)
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System Examples (continued)
L
6.8 µH
optional
VIN
5 V ± 20%
Cby
1 µF/ 16 V
Cin
2* 10 µF/
16 V
6
8
3
9
4
5
IN
SW
EN
SW
D
SL22
Dz
BZX84C 18 V
VS
500 mA
3S3P wLED
LW E67C
7
2
FREQ
FB
AGND
COMP
PGND
SS
TPS61087
R1
180 kΩ
Rlimit
110 Ω
1
10
Css
100 nF
Rcomp
51 kΩ
Ccomp
1.5 nF
Cout
4* 10 µF/
25 V
Rsense
15 Ω
R2
127 kΩ
Analog Brightness Control
3.3 V ~ wLED off
0 V ~ lLED = 30 mA (each string)
PWM Signal
Can be used swinging from 0 V to 3.3 V
Figure 22. Simple Application (5 V Input Voltage) (fS = 650 kHz) for wLED Supply (3S3P) With Adjustable
Brightness Control Using an Analog Signal on the Feedback Pin
(With Optional Clamping Zener Diode)
9 Power Supply Recommendations
The TPS61087 is designed to operate from an input voltage supply range from 2.3 V to 6.0 V. The power supply
to the TPS61087 must have a current rating according to the supply voltage, output voltage, and output current
of the TPS61087.
10 Layout
10.1 Layout Guidelines
For all switching power supplies, the layout is an important step in the design, especially at high peak currents
and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as
well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground
tracks. The input capacitor, output capacitor, and the inductor should be placed as close as possible to the IC.
Use a common ground node for power ground and a different one for control ground to minimize the effects of
ground noise. Connect these ground nodes at the GND terminal of the IC. The most critical current path for all
boost converters is from the switching FET, through the rectifier diode, then the output capacitors, and back to
ground of the switching FET. Therefore, the output capacitors and their traces should be placed on the same
board layer as the IC and as close as possible between the SW pin and the GND terminal of the IC..
22
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10.2 Layout Example
SW
SW
6
5
7
IN
8
9
10
EN
AGND
PGND
3
FB
5
2
4
1
TPS61087
COMP
GND
FREQ
VOUT
SS
VIN
Figure 23. TPS61087 Layout Example
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11 Device and Documentation Support
11.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.2 Trademarks
All trademarks are the property of their respective owners.
11.3 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.
11.4 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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13-Aug-2021
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)
TPS61087DRCR
ACTIVE
VSON
DRC
10
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PMOQ
TPS61087DRCRG4
ACTIVE
VSON
DRC
10
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PMOQ
TPS61087DRCT
ACTIVE
VSON
DRC
10
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PMOQ
TPS61087DSCR
ACTIVE
WSON
DSC
10
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PMWI
TPS61087DSCT
ACTIVE
WSON
DSC
10
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PMWI
(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