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TPS61087-Q1
SLVSB50C – DECEMBER 2011 – REVISED JUNE 2020
TPS61087-Q1 650-kHz or 1.2-MHz, 18.5-V Step-Up DC-DC Converter With 3.2-A Switch
1 Features
3 Description
•
•
The TPS61087-Q1 is a high-frequency, highefficiency DC-to-DC converter with an integrated
3.2‑A, 0.13-Ω power switch that is 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 optimizing the application for
specific conditions. A capacitor connected to the softstart pin minimizes inrush current at start-up.
1
•
•
•
•
•
•
•
Qualified for automotive applications
Functional Safety-Capable
– Documentation available to aid functional
safety system design
2.5-V to 6-V Input voltage range
18.5-V Boost converter with 3.2-A switch current
650-kHz or 1.2-MHz Selectable switching
frequency
Adjustable soft start
Thermal shutdown
Undervoltage lockout
10-Pin VQFN package with wettable flanks
Device Information(1)
PART NUMBER
TPS61087-Q1
•
•
•
BODY SIZE (NOM)
3.00 mm x 3.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
2 Applications
•
PACKAGE
VSON (10)
Automotive infotainment clusters
– Instrument clusters, head units
– Radio, navigation
– Audio amplifiers
Automotive body electronics
– Body control modules
– Gateway
Telemetrics and eCall
Advanced driver assistance system (ADAS)
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
COMP
AGND
PGND
SS
TPS61087-Q1
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-Q1
SLVSB50C – DECEMBER 2011 – REVISED JUNE 2020
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
3
6.1
6.2
6.3
6.4
6.5
6.6
3
4
4
4
4
5
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1
7.2
7.3
7.4
Overview ...................................................................
Functional Block Diagram .........................................
Feature Description...................................................
Device Functional Modes..........................................
7
7
8
8
8
Application and Implementation .......................... 9
8.1 Application Information.............................................. 9
8.2 Typical Applications .................................................. 9
9 Power Supply Recommendations...................... 20
10 Layout................................................................... 20
10.1 Layout Guidelines ................................................. 20
10.2 Layout Example .................................................... 21
11 Device and Documentation Support ................. 22
11.1
11.2
11.3
11.4
11.5
11.6
11.7
Device Support......................................................
Documentation Support ........................................
Receiving Notification of Documentation Updates
Support Resources ...............................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
22
22
22
22
22
22
22
12 Mechanical, Packaging, and Orderable
Information ........................................................... 22
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (June 2020) to Revision C
•
Page
Added functional safety bullet to the Features ...................................................................................................................... 1
Changes from Revision A (June 2016) to Revision B
Page
•
Changed ESD Ratings table to use AEC-Q100 specification ................................................................................................ 4
•
Added the Documentation Support and Receiving Notification of Documentation Updates sections ................................. 22
Changes from Original (December 2011) to Revision A
•
2
Page
Added Applications section, Device Information table, Table of Contents, Revision History section, Specifications
section, ESD Ratings table, Thermal Information table, Detailed Description section, Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section .................................................................................................. 1
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SLVSB50C – DECEMBER 2011 – REVISED JUNE 2020
5 Pin Configuration and Functions
DRC and WDRC Packages
10 Pin VSON
Top View
COMP
1
FB
2
10
Thermal
Pad
SS
9
FREQ
8
IN
EN
3
AGND
4
7
SW
PGND
5
6
SW
Not to scale
Pin Functions
PIN
I/O
DESCRIPTION
NAME
NO.
COMP
1
I/O
FB
2
I
Feedback pin
EN
3
I
Shutdown control input. Connect this pin to logic high level to enable the device
AGND
4
—
Analog ground
PGND
5
—
Power ground
6, 7
I
Switch pin
IN
8
I
Input supply 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.
SS
10
O
Soft-start control pin. Connect a capacitor to this pin if soft start is needed. Open = no soft start
—
Ground
SW
Thermal Pad
Compensation pin
6 Specifications
6.1 Absolute Maximum Ratings
See
(1)
MIN
MAX
UNIT
IN
–0.3
7
V
EN, FB, SS, FREQ, COMP
–0.3
7
SW
–0.3
20
Operating junction temperature, TJ
–40
150
°C
Storage temperature, Tstg
–65
150
°C
Input voltage range (2)
Voltage range
(1)
(2)
V
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.
All voltage values are with respect to network ground terminal.
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SLVSB50C – DECEMBER 2011 – REVISED JUNE 2020
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6.2 ESD Ratings
VALUE
V(ESD)
(1)
Electrostatic discharge
Human-body model (HBM), per AEC Q100-002 (1)
±2000
Charged-device model (CDM), per AEC Q100-011
±1000
UNIT
V
AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
VIN
Input voltage range
VS
Boost output voltage range
TA
Operating free-air temperature
MIN
MAX
2.5
6
UNIT
VIN + 0.5
18.5
V
–40
125
°C
V
6.4 Thermal Information
TPS61087-Q1
THERMAL METRIC (1)
DRC (VSON)
WDRC (VSON)
10 PINS
10 PINS
UNIT
RθJA
Junction-to-ambient thermal resistance
57
51.8
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
84.5
81.3
°C/W
RθJB
Junction-to-board thermal resistance
31.5
26.2
°C/W
ψJT
Junction-to-top characterization parameter
5.9
4.4
°C/W
ψJB
Junction-to-board characterization parameter
31.6
26.4
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
13
7.6
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
6.5 Electrical Characteristics
VIN = 5 V, EN = VIN, VS = 15 V, TA = TJ = –40°C to 125°C, typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
6
V
75
100
μA
4
μA
V
SUPPLY
VIN
Input voltage range
IQ
Operating quiescent current into IN pin
Device not switching, VFB = 1.3 V
ISDVIN
Shutdown current into IN pin
EN = GND
VUVLO
Undervoltage lockout threshold
VIN falling
2.4
VIN rising
2.5
TSD
Thermal shutdown
TSDHYS
Thermal shutdown hysteresis
2.5
Temperature rising
V
150
°C
14
°C
LOGIC SIGNALS EN, FREQ
VIH
High level input voltage
VIN = 2.5 V to 6 V
VIL
Low level input voltage
VIN = 2.5 V to 6 V
0.5
V
IINLEAK
Input leakage current
EN = FREQ = GND
0.1
μA
4
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Electrical Characteristics (continued)
VIN = 5 V, EN = VIN, VS = 15 V, TA = TJ = –40°C to 125°C, typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
18.5
V
1.25
V
BOOST CONVERTER
VS
Boost output voltage
VFB
Feedback regulation voltage
VIN + 0.5
gm
Transconductance error amplifier
IFB
Feedback input bias current
1.23
1.238
107
μA/V
VFB = 1.238 V
rDS(on)
N-channel MOSFET on-resistance
ISWLEAK
SW leakage current
ILIM
N-Channel MOSFET current limit
ISS
Soft-start current
fS
Oscillator frequency
0.1
μA
VIN = VGS = 5 V, ISW = current limit
0.13
0.18
VIN = VGS = 3 V, ISW = current limit
0.16
0.23
3.2
4
4.8
A
7
10
13
μA
MHz
EN = GND, VSW = VIN = 6 V
Ω
2
VSS = 1.238 V
FREQ = VIN
0.9
1.2
1.5
FREQ = GND
480
650
820
Line regulation
VIN = 2.5 V to 6 V, IOUT = 10 mA
Load regulation
VIN = 5 V, IOUT = 1 mA to 1 A
μA
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
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
3.0
3.0
fS = 650 kHz
2.5
IOUT - Maximum Load Current - A
IOUT - Maximum Load Current - A
fS = 1.2 Mhz
2.0
VOUT = 9 V
VOUT = 12 V
1.5
1.0
VOUT = 18.5 V
0.5
2.5
VOUT = 9 V
2.0
VOUT = 12 V
1.5
VOUT = 15 V
1.0
VOUT = 18.5 V
0.5
VOUT = 15 V
0.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
0.0
2.5
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
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Typical Characteristics (continued)
100
100
90
90
80
fS = 1.2 Mhz
70
L = 3.3 mH
L = 6.8 mH
80
fS = 650 kHz
fS = 1.2 Mhz
70
Efficiency - %
L = 6.8 mH
Efficiency - %
fS = 650 kHz
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 4. Efficiency vs Load Current
Figure 3. Efficiency vs Load Current
1600
1.8
SWITCHING
fS = 1.2 Mhz
1.6
L = 3.3 mH
1400
1.4
fS - Oscillator Frequency - kHz
ICC - Supply Current - mA
2.0
SWITCHING
fS = 650 kHz
1.2
L = 6.8 mH
1.0
0.8
0.6
0.4
0.2
0
2.5
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
3.5
4.0
4.5
5.0
VCC - Supply Voltage - V
5.5
0
0.0 0.1
6.0
0.2
0.3
0.4 0.5 0.6
0.7 0.8 0.9
1.0
IOUT - Load Current - mA
Figure 6. Oscillator Frequency vs Load Current
Figure 5. Supply Current vs Supply Voltage
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
6
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7 Detailed Description
7.1 Overview
The TPS61087-Q1 boost converter is designed for output voltages 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 from 650 kHz
to 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 TPS61087-Q1 boost converter using adaptive OFF-time provides superior load and
line transient responses and operates also 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).
Depending on the load current, the converter operates in continuous conduction mode (CCM), discontinuous
conduction mode (DCM), or pulse skip mode 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 = 1.24 V
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 SS pin 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. As the size of the capacitor increases, the ramp of the current limit slows and the soft-start time
increases. 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 switching frequency of the device is set using the frequency select pin (FREQ) to 650 kHz (FREQ = low) or
1.2 MHz (FREQ = high). Higher switching frequency improves load transient response but slightly reduces the
efficiency. Another benefit of higher switching frequency is a lower output ripple voltage. Unless light load
efficiency is a major concern, TI recommends using a 1.2-MHz switching frequency.
7.3.3 Undervoltage Lockout (UVLO)
To avoid misoperation of the device at low input voltages, an undervoltage lockout is included, which 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, the converter switches into discontinuous conduction
mode (DCM). If the load is further reduced, the part starts to skip pulses to maintain the output voltage.
8
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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-Q1 is designed for output voltages 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 from 650 kHz to
1.2 MHz, and the input voltage range is from 2.3 V to 6 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-Q1
as a voltage regulating boost converter.
8.2 Typical Applications
8.2.1 Typical Application Circuit: 5 V to 15 V (fS = 1.2 MHz)
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
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
TPS61087-Q1
Css
100 nF
Ccomp
820 pF
Figure 8. 5-V to 15-V (fS = 1.2 MHz) Application Diagram
8.2.1.1 Design Requirements
For this design example, use the parameters shown in Table 2.
Table 2. Design Parameters
PARAMETER
Input voltage
EXAMPLE VALUE
5 V ± 20%
Output voltage
15 V
Output current
900 mA
Switching frequency
1.2 MHz
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8.2.1.2 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%).
Duty cycle (D) is calculated with Equation 1.
D = 1-
VIN ×h
VS
(1)
Maximum output current (Iout(max)) is calculated with Equation 2.
DI
æ
I out (max) = ç I LIM (min) - L
2
è
ö
÷ × (1 - D )
ø
(2)
Peak switch current in application (Iswpeak) is calculated with Equation 3.
I swpeak =
I
DI L
+ out
2 1- D
(3)
The inductor peak-to-peak ripple current (ΔIL) is calculated with Equation 4.
DI L =
VIN × D
fS × L
where
•
•
•
•
•
•
VIN is the minimum input voltage.
VS is the output voltage.
ILIM(min) is the converter switch current limit (minimum switch current limit = 3.2 A).
fS is the converter switching frequency (typically 1.2 MHz or 650 kHz).
L is the selected inductor value.
η is the estimated converter efficiency (use the number from the efficiency plots or 90% as an estimation).
(4)
The peak switch current is the steady state peak switch current that the integrated switch, inductor, and external
Schottky diode must be able to handle. The calculation must be done for the minimum input voltage where the
peak switch current is the highest.
8.2.1.2.1 Inductor Selection
The TPS61087-Q1 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 must be higher than the peak switch current as
calculated in Equation 3 with additional margin to cover for heavy load transients. A more conservative
alternative 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. As the DC resistance decreases, the
efficiency usually increases. 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. An inductor with a larger form
factor usually gives higher efficiency. The efficiency difference between different inductors can vary from 2% to
10%. For the TPS61087-Q1, inductor values from 3 μH to 6 μH are a good choice with a switching frequency of
1.2 MHz, typically 3.3 μH. At 650 kHz, TI recommends inductors from 6 μH to 13 μH, typically 6.8 μH. See
Table 3 for inductor selection. Customers must verify and validate selected components for suitability with their
application.
10
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TI recommends that the inductor current ripple is below 35% of the average inductor current. Equation 5 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
where
•
Iout is the maximum output current in the application.
(5)
Table 3. Inductor Selection
INDUCTOR
VALUE
TYPICAL DCR
Isat
SUPPLIER
SIZE (L × W × H mm)
COMPONENT CODE
4.2 µH
23 mΩ
2.2 A
Sumida
5.7 × 5.7 × 3
CDRH5D28
4.7 µH
60 mΩ
2.5 A
Wurth Elektronik
5.9 × 6.2 × 3.3
7447785004
5 µH
24 mΩ
2.9 A
Coilcraft
7.3 × 7.3 × 4.1
MSS7341
5 µH
23 mΩ
2.4 A
Sumida
7×7×3
CDRH6D28
4.6 µH
38 mΩ
3.15 A
Sumida
7.6 × 7.6 × 3
CDR7D28
4.7 µH
33 mΩ
3.9 A
Wurth Elektronik
7.3 × 7.3 × 3.2
7447789004
3.3 µH
30 mΩ
4.2 A
Wurth Elektronik
7.3 × 7.3 × 3.2
7447789003
10 µH
51 mΩ
2.2 A
Wurth Elektronik
7.3 × 7.3 × 3.2
744778910
1.2 MHz
650 kHz
10 µH
36 mΩ
2.7 A
Sumida
8.3 × 8.3 × 3
CDRH8D28
6.8 µH
52 mΩ
2.9 A
Sumida
7 × 7 × 2.8
CDRH6D26HPNP
6.2 µH
25 mΩ
3.3 A
Sumida
8.3 × 8.3 × 6
CDRH8D58
10 µH
80 mΩ
3.5 A
Coilcraft
12.95 × 9.4 × 5.08
DS3316P
10 µH
29 mΩ
4A
Sumida
8.3 × 8.3 × 4.5
CDRH8D43
6.8 µH
55 mΩ
4.1 A
Wurth Elektronik
12.7 × 10 × 4.9
74454068
8.2.1.2.2 Rectifier Diode Selection
To achieve high efficiency, a Schottky type must be used for the rectifier diode. The reverse voltage rating must
be higher than the maximum output voltage of the converter. The averaged rectified forward current (Iavg), the
Schottky diode must 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 but must 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 must be able to dissipate around 500 mW, depending on the load current and forward
voltage. See Table 4 for diode selection. Customers must verify and validate selected components for suitability
with their application.
Table 4. Rectifier Diode Selection
Iavg
VR
Vforward
SUPPLIER
2A
20 V
0.44 V
Vishay Semiconductor
COMPONENT CODE
SL22
2A
20 V
0.5 V
Fairchild Semiconductor
SS22
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8.2.1.2.3 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 shown in Equation 8:
VS
V
R 2 = FB » 18k W
70 m A
æ V
ö
R1 = R 2 × ç S - 1÷
è VFB
ø
R1
VFB
VFB = 1.238V
R2
(8)
8.2.1.2.4 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.
Equation 9 can be used to calculate RCOMP and CCOMP.
RCOMP =
110 × VIN × VS × Cout
L × I out
CCOMP =
Vs × Cout
7.5 × I out × RCOMP
where
•
Cout is the output capacitance.
(9)
Make sure that RCOMP < 120 kΩ and CCOMP > 820 pF, independent of the results of the above formulas.
See Table 5 for dedicated compensation networks giving an improved load transient response. These
conservative RCOMP and CCOMP values for certain inductors, input, and output voltages provide 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 must be performed in parallel
with the load transient response monitoring of TPS61087-Q1.
Standard values of RCOMP = 16 kΩ and CCOMP = 2.7 nF works for the majority of the applications.
Table 5. Recommended Compensation Network Values at High and 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
VIN ± 20%
RCOMP
CCOMP
5V
100 kΩ
820 pF
3.3 V
91 kΩ
1.2 nF
5V
68 kΩ
820 pF
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
8.2.1.2.5 Input Capacitor Selection
TI recommends low-ESR ceramic capacitors for good input voltage filtering. The TPS61087-Q1 has an analog
input (IN). Therefore, TI recommends placing a 1-μF bypass capacitor 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 for output capacitor selection. Customers must verify
and validate selected components for suitability with their application.
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8.2.1.2.6 Output Capacitor Selection
TI recommends low-ESR ceramic capacitors for best output voltage filtering. Four 10-μF (or two 22-µF) ceramic
output capacitors work for most of the applications. Higher capacitor values can be used to improve the load
transient response. See Table 6 for output capacitor selection. DC voltage derating factor must also be
considered while choosing capacitors. Customers must verify and validate selected components for suitability
with their application.
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, use Equation 10.
DVC =
VS - VIN I out
×
VS × f S Cout
DVC _ ESR = I L ( peak ) × RC _ ESR
where
•
•
•
•
ΔVC is the output voltage ripple dependent on output capacitance, output current, and switching frequency.
ΔVC_ESR is the output voltage ripple due to output capacitors ESR (equivalent series resistance).
Iswpeak is the inductor peak switch current in the application.
RC_ESR is the output capacitors equivalent series resistance (ESR).
(10)
ΔVC_ESR can be neglected in many cases because ceramic capacitors provide low ESR.
8.2.2 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
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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
L = 3.3 mH
Rcomp = 150 kW
Ccomp = 820 pF
IOUT = 100 mA - 500 mA
COUT = 40 mF
IOUT = 100 mA - 500 mA
IOUT
200 mA/div
IOUT
200 mA/div
200 ms/div
200 ms/div
Figure 12. Load Transient Response Low Frequency
(650 kHz)
Figure 11. Load Transient Response High Frequency
(1.2 MHz)
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
14
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8.2.3 Other Application Circuit Examples
Figure 14 to Figure 22 show application circuit examples using the TPS61087-Q1 device. These circuits must be
fully validated and tested by customers before using these circuits in their designs. TI does not warrant the
accuracy or completeness of these circuits, nor does TI accept any responsibility for them.
L
6.8 µH
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
AGND
COMP
PGND
SS
6
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
51 kΩ
10
Css
100 nF
TPS61087-Q1
fS = 650 kHz
VS
15 V/900 mA max.
D
SL22
Ccomp
1.5 nF
VS = 15 V
IOUT(max) = 900 mA
Figure 14. 5-V to 15-V Application Diagram
L
3.3 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.
R1
110 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
39 kΩ
10
TPS61087-Q1
fS = 1.2 MHz
D
SL22
6
Css
100 nF
Ccomp
1.2 nF
VS = 9 V
IOUT(max) = 950 mA
Figure 15. 3.3-V to 9-V Application Diagram
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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
6
Cout
4* 10 µF
25 V
R1
110 kΩ
7
2
FREQ
FB
AGND
COMP
PGND
SS
R2
18 kΩ
1
Rcomp
18 kΩ
10
Css
100 nF
TPS61087-Q1
fS = 650 kHz
VS
9 V/950 mA max.
D
SL22
Ccomp
2.7 nF
VS = 9 V
IOUT(max) = 950 mA
Figure 16. 3.3-V to 9-V Application Diagram
Riso
10 kW
L
6.8 µH
Cby
1 µF/16 V
VIN
5 V ± 20%
8
Cin
2* 10 µF/
16 V
3
9
Enable
4
SW
IN
SW
EN
FREQ
FB
AGND
COMP
PGND
SS
5
TPS61087-Q1
fS = 650 kHz
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
VS = 15 V
IOUT = 300 mA
Figure 17. Diagram for Application With External Load Disconnect Switch
16
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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
VS
15 V/900 mA max.
6
Dz
BZX84C 18V
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
Rlimit
110 Ω
1
R2
18 kΩ
Rcomp
51 kΩ
10
Css
100 nF
TPS61087-Q1
fS = 650 kHz
Overvoltage
Protection
VS = 15 V
Ccomp
1.5 nF
IOUT(max) = 900 mA
Figure 18. Application Diagram for 5 V to 15 V With Overvoltage Protection
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T2
BC850B
3·Vs
VGL
-7 V/20 mA
T1
BC857B
-Vs
R8
6.8 kΩ
C13
1 µF/
35 V
C16
470 nF/
50 V
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
Cby
1 µF/
16 V
VIN
5 V ± 20%
Cin
2*10 µF/
16 V
D
SL22
8
IN
SW
EN
SW
3
7
9
FB
4
Cout
4*10µF/
25V
R2
18 kΩ
1
AGND
COMP
PGND
SS
TPS61087-Q1
fS = 1.2 MHz
R1
200 kΩ
2
FREQ
5
VS
15 V/500 mA
6
Rcomp
100 kΩ
10
Css
100 nF
Ccomp
820 pF
VS = 15 V
IOUT = 500 mA
Figure 19. Application Diagram for 5 V to 15 V for TFT LCD With External Charge Pumps (VGH, VGL)
18
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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-Q1
Css
100 nF
fS = 650 kHz
Rsense
15 Ω
Ccomp
1.5 nF
IOUT = 500 mA
Figure 20. Application Diagram 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
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-Q1
fS = 650 kHz
D
SL22
Rlimit
110 Ω
1
Rcomp
51 kΩ
10
Css
100 nF
Rsense
15 Ω
Ccomp
1.5 nF
IOUT = 500 mA
Figure 21. Application Diagram 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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L
6.8 µH
optional
VIN
5 V ± 20%
Cby
1 µF/ 16 V
6
8
Cin
2* 10 µF/
16 V
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-Q1
fS = 650 kHz
R1
Rlimit
110 Ω
180 kΩ
1
10
Css
100 nF
Rsense
15 Ω
Rcomp
51 kΩ
Ccomp
1.5 nF
Cout
4* 10 µF/
25 V
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
IOUT = 500 mA
Figure 22. Application Diagram 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-Q1 is designed to operate from an input voltage supply range from 2.3 V to 6 V. The power
supply to the TPS61087-Q1 must have a current rating according to the supply voltage, output voltage, and
output current of the TPS61087-Q1.
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 can show stability problems as
well as EMI problems.
Figure 23 provides an example of layout design with the TPS61087-Q1 device.
• Use wide and short traces for the main current path and for the power ground tracks.
• The input capacitor, output capacitor, and the inductor must 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 must 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.
20
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10.2 Layout Example
6
7
8
9
VOUT
10
VIN
TPS61087-Q1
4
5
3
1
2
GND
Figure 23. TPS61087-Q1 Layout Example
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11 Device and Documentation Support
11.1 Device Support
11.1.1 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 Documentation Support
11.2.1 Related Documentation
For related documentation see the following:
• Performing Accurate PFM Mode Efficiency Measurements
• QFN/SON PCB Attachment
11.3 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.
11.4 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is 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.
11.5 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.6 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.
11.7 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)
TPS61087QDRCRQ1
ACTIVE
VSON
DRC
10
3000
RoHS & Green
NIPDAU
Level-3-260C-168 HR
-40 to 125
PMOQ
TPS61087QWDRCRQ1
ACTIVE
VSON
DRC
10
3000
RoHS & Green
SN
Level-3-260C-168 HR
-40 to 125
11ZC
(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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