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TPS61086
SLVSA05B – AUGUST 2009 – REVISED AUGUST 2015
TPS61086 18.5-V PFM – PWM Step-Up DC – DC Converter With 2.0-A Switch
1
1 Features
•
•
•
•
•
•
•
•
3 Description
2.3-V to 6.0-V Input Voltage Range
18.5-V Boost Converter With 2.0-A Switch Current
1.2-MHz Switching Frequency
Power Save Mode for Improved Efficiency at LowOutput Power or Forced PWM
Adjustable Soft-Start
Thermal Shutdown
Undervoltage Lockout
10-Pin VSON Package
The TPS61086 device is a high-frequency, highefficiency DC-to-DC converter with an integrated 2.0A, 0.13-Ω power switch capable of providing an
output voltage up to 18.5 V. The implemented boost
converter is based on a fixed frequency of 1.2-MHz,
pulse-width-modulation (PWM) controller that allows
the use of small external inductors and capacitors
and provides fast transient response.
At light-load, the device can operate in Power Save
Mode with pulse-frequency-modulation (PFM) to
improve the efficiency while keeping a low-output
voltage ripple. For very noise-sensitive applications,
the device can be forced to PWM Mode operation
over the entire load range by pulling the MODE pin
high. The external compensation allows optimizing
the application for specific conditions. A capacitor
connected to the soft-start pin minimizes inrush
current at start-up.
2 Applications
•
•
•
•
•
•
•
Handheld Devices
GPS Receivers
Digital Still Cameras
Portable Applications
DSL Modems
PCMCIA Cards
TFT LCD Bias Supply
Device Information(1)
PART NUMBER
TPS61086
PACKAGE
VSON (10)
BODY SIZE (NOM)
3.00 mm × 3.00 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
L
3.3 mH
VIN
2.5 V to 6 V
Cin
10 mF
16 V
8
Cby
1 mF
16 V
3
9
4
5
IN
SW
EN
SW
MODE
FB
AGND
COMP
PGND
SS
TPS61086
6
D
PMEG2010AEH
VS
12 V
R1
156 kW
7
Cout
2* 10 mF
25 V
2
R2
18 kW
1
Rcomp
68 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.
TPS61086
SLVSA05B – AUGUST 2009 – REVISED AUGUST 2015
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 ..............................................
Detailed Description .............................................. 8
7.1 Overview ................................................................... 8
7.2 Functional Block Diagram ......................................... 8
7.3 Feature Description................................................... 8
7.4 Device Functional Modes.......................................... 9
8
Application and Implementation ........................ 10
8.1 Application Information............................................ 10
8.2 Typical Applications ................................................ 10
8.3 System Examples ................................................... 18
9 Power Supply Recommendations...................... 21
10 Layout................................................................... 21
10.1 Layout Guidelines ................................................. 21
10.2 Layout Example .................................................... 21
11 Device and Documentation Support ................. 22
11.1
11.2
11.3
11.4
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
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 A (June 2015) to Revision B
Page
•
Changed "FREQ" to "MODE" in Absolute Maximum Ratings table ...................................................................................... 4
•
Changed "mA" to "A" in X-axis label for Figure 4 .................................................................................................................. 6
•
Changed VS from "12V/50 mA" to "12V/500 mA" in Figure 7. ............................................................................................ 10
Changes from Original (August 2009) to Revision A
Page
•
Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional
Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section .............................. 1
•
Deleted Ordering Information table ....................................................................................................................................... 1
2
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SLVSA05B – AUGUST 2009 – REVISED AUGUST 2015
5 Pin Configuration and Functions
DRC Package
10-Pin VSON
Top View
COMP
SS
FB
EN
MODE
Thermal
Pad
IN
AGND
SW
PGND
SW
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
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
PGND
SW
IN
MODE
SS
4
Thermal Pad
5
6
7
8
9
10
Compensation pin
—
Analog ground
—
Power ground
—
Switch pin
—
Input supply pin
I
—
Operating mode selection pin. MODE = 'high' for forced PWM operation. MODE = 'low' for PFM
operation
Soft-start control pin. Connect a capacitor to this pin if soft-start needed. Open = no soft-start
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
Input voltage IN (2)
–0.3
7
V
Voltage on pins EN, FB, SS, MODE, COMP
–0.3
7
V
Voltage on pin SW
–0.3
20
V
Operating junction temperature
–40
150
°C
Storage temperature
–65
150
°C
(1)
(2)
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.
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 JESD22-C101 (2)
±500
Machine Model
±200
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. 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. Pins listed as ±500 V
may actually have higher performance.
6.3 Recommended Operating Conditions
MIN
VIN
Input voltage
VS
Boost output voltage
TA
TJ
MAX
UNIT
2.3
6
VIN + 0.5
18.5
V
V
Operating free-air temperature
–40
85
°C
Operating junction temperature
–40
125
°C
6.4 Thermal Information
TPS61086
THERMAL METRIC (1)
DRC (VSON)
UNIT
10 PINS
RθJA
Junction-to-ambient thermal resistance
54.7
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
67.2
°C/W
RθJB
Junction-to-board thermal resistance
29.6
°C/W
ψJT
Junction-to-top characterization parameter
2.3
°C/W
ψJB
Junction-to-board characterization parameter
29.8
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
15.6
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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6.5 Electrical Characteristics
VIN = 3.3 V, EN = IN, VS = 12 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
V
SUPPLY
VIN
Input voltage range
IQ
Operating quiescent current into IN
Device not switching, VFB = 1.3 V
ISDVIN
Shutdown current into IN
EN = GND
VUVLO
Undervoltage lockout threshold
VIN falling
2.2
VIN rising
2.3
TSD
Thermal shutdown
TSDHYS
Thermal shutdown hysteresis
2.3
Temperature rising
V
150
°C
14
°C
LOGIC SIGNALS EN, FREQ
VIH
High level input voltage
VIN = 2.3 V to 6 V
2
V
VIL
Low level input voltage
VIN = 2.3 V to 6 V
0.5
V
IINLEAK
Input leakage current
EN = GND
0.1
μA
18.5
V
BOOST CONVERTER
VS
Boost output voltage
VFB
Feedback regulation voltage
gm
Transconductance error amplifier
IFB
Feedback input bias current
VFB = 1.238 V
rDS(on)
N-channel MOSFET on-resistance
VIN = VGS = 5 V, ISW = current
limit
0.13
0.2
VIN = VGS = 3.3 V, ISW = current
limit
0.16
0.23
2
2.6
3.2
A
7
10
13
μA
1.2
1.5
MHz
ISWLEAK
SW leakage current
ILIM
N-channel MOSFET current limit
ISS
Soft-start current
fS
Oscillator frequency
VIN + 0.5
1.23
1.238
1.246
VIN = 2.3 V to 6 V, IOUT = 10 mA
Load regulation
VIN = 3.3 V, IOUT = 1 mA to 400
mA
Ω
μA
10
0.9
Line regulation
μA
0.1
EN = GND, VSW = 6 V
VSS = 1.238 V
V
μA/V
107
0.0002
0.11
%/V
%/A
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6.6 Typical Characteristics
The typical characteristics are measured with the inductor CDRH6D12 3.3 µH from Sumida and the rectifier diode SL22.
Table 1. Table of Graphs
FIGURE
η
Efficiency vs Load current- PFM
VIN = 3.3 V, VS = 9 V, 12 V, 15 V
Figure 1
η
Efficiencyvs Load current - Forced PWM
VIN = 3.3 V, VS = 9 V, 12 V, 15 V
Figure 2
Iout(max)
Maximum output current
fS
Switching frequency - Forced PWM
vs Load current, VIN = 3.3 V, VS = 12 V
Figure 4
fS
Switching frequency - Forced PWM
vs Supply voltage, VS = 12 V, Iout = 200 mA
Figure 5
Supply current
vs Supply voltage,VIN = 3.3 V, VS = 12 V
Figure 6
Figure 3
100
100
VS = 9 V
90
80
80
VS = 15 V
70
VS = 12 V
Efficiency - %
Efficiency - %
70
60
50
40
VS = 12 V
50
40
30
FREQ = GND
VIN = 3.3 V
L = 3.3 µH
20
10
1
0.1
10
100
IO - Output Current - mA
FREQ = VIN
VIN = 3.3 V
L = 3.3 µH
20
10
0
1000
Figure 1. PFM Mode Efficiency vs Output Current
10
100
IO - Output Current - mA
1
1000
Figure 2. Force PWM Mode Efficiency vs Output Current
1600
1.6
VS = 9 V
1.4
1.2
1200
VS = 12 V
1.0
0.8
0.6
VS = 15 V
0.4
VS = 18.5 V
0.2
MODE = VIN
Forced PWM
L = 3.3 µH
1400
f - Frequency - kHz
IO - Output current - A
VS = 15 V
60
30
0
VS = 9 V
90
1000
800
600
400
VIN = 3.3 V
VS = 12 V
200
L = 3.3 µH
0.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
VIN - Supply voltage - V
6.0
0.1
0.2
0.3
0.4
0.5
0.6
IO - Load current - A
Figure 3. Output Current vs Supply Voltage
6
0
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Figure 4. Frequency vs Load Current
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1400
2.5
1200
f - Frequency - kHz
ICC - Supply Current - mA
MODE = VIN
Forced PWM
L = 3.3 µH
1000
800
600
400
2.0
MODE = VIN
Forced PWM
1.5
MODE = GND
(PFM)
1.0
0.5
200
VIN = 3.3 V
VS = 12 V/50 mA
VS = 12 V / 200 mA
0
2.5
3.0
3.5
4.0
4.5 5.0
VCC - Supply Voltage - V
5.5
0
6.0
Figure 5. Frequency vs Supply Voltage
2.0
2.5
3.0
3.5 4.0 4.5 5.0 5.5
VCC - Supply Voltage - V
6.0
Figure 6. Supply Current vs Supply Voltage
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7 Detailed Description
7.1 Overview
The boost converter 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 fixed to 1.2 MHz and the minimum
input voltage is 2.3 V. To limit the inrush current at start-up a soft-start pin is available.
TPS61086 boost converter’s novel topology using adaptive OFF-time provides superior load and line transient
responses and operates also over a wider range of applications than conventional converters.
7.2 Functional Block Diagram
VIN
VS
IN
EN
SW
MODE
SW
Current limit
and
Soft Start
SS
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
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 (90% 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.
8
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Feature Description (continued)
7.3.2 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 2.2 V.
7.3.3 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.
7.3.4 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
7.4.1 Power Save Mode
Connecting the MODE pin to GND (or any low logic level) enables the Power Save Mode operation. The
converter operates in quasi fixed frequency PWM (Pulse Width Modulation) mode at moderate to heavy load and
in the PFM (Pulse Frequency Modulation) mode during light loads, which maintains high efficiency over a wide
load current range.
In PFM mode the converter is skipping switch pulses. However, within a PFM pulse, the switching frequency is
still fixed to 1.2 MHz typically and the duty cycle determined by the input and output voltage. Therefore, the
inductor peak current will remain constant for a defined application. With an increasing output load current, the
PFM pulses become closer and closer (the PFM mode frequency gets higher) until no pulse is skipped anymore:
the device operates then in CCM (Continuous Conduction Mode) with normal PWM mode.
The PFM mode frequency (between each PFM pulse) depends on the load current, the external components like
the inductor or the output capacitor values as well as the output voltage. The device enters Power Save Mode as
the inductor peak current falls below a 0.6A typically and switches until VS is 1% higher than its nominal value.
The converter stops switching when VS = VS + 0.5%. The output voltage will thenrefore oscillate between 0.5%
and 1% more than its nominal value which will provide excellent transient response to sudden load change, since
the output voltage drop will be reduced due to this slight positive offset (see Figure 12).
7.4.2 Forced PWM Mode
Pulling the MODE pin high forces the converter to operate in a continuous PWM mode evan at light load
currents. The advantage is that the converter operates with a quai constant frequency that allows simple filtering
of the swithcing frequency for noise-sensitive applications. In this mode and at light load, the efficiency is lower
compared to the Power Save Mode.
For additional flexibility, it is possible to switch from Power Save Mode to Forced PWM Mode during operation.
This allows efficient power management by adjusting the operation of the converter to the specific system
requirements.
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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 TPS61086 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 fixed to 1.2 MHz and the minimum input voltage
is 2.3 V. To limit the inrush current at start-up, a soft-start pin is available.
TPS61086 boost converter's novel topology using adaptive off-time provides superior load and line transient
responses and operates also over a wider range of applications than conventional converters.
8.2 Typical Applications
8.2.1 3.3-V to 12-V Boost Converter With PFM Mode at Light Load
L
3.3 µH
VIN
3.3 V ± 20%
8
Cin
10 µF
16 V
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
MODE
FB
COMP
AGND
PGND
SS
VS
12 V/500 mA
D
PMEG2010AEH
6
R1
156 kΩ
7
Cout
2*10 µF
25 V
2
R2
18 kΩ
1
Rcomp
68kΩ
10
TPS61086
Ccomp
1.2 nF
Css
100 nF
Figure 7. Typical Application, 3.3 V to 12 V (PFM Mode)
8.2.1.1 Design Requirements
For this example, the design parameters are listed in Table 2.
Table 2. Design Parameters
10
DESIGN PARAMETERS
EXAMPLE VALUES
Input Voltage
3.3 V ± 20%
Output Voltage
12 V
Output Current
500 mA
Operation Mode at Light Load
PFM
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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%.
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
where
•
•
•
•
•
•
VIN is Minimum input voltage.
VS is Output voltage.
ILIM(min) is Converter switch current limit (minimum switch current limit = 2.0 A).
fS is Converter switching frequency (typically 1.2 MHz).
L is Selected inductor value.
η is Estimated converter efficiency (please 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 has to be able to handle. The calculation must be done for the minimum input voltage where the
peak switch current is the highest.
8.2.1.2.1 Inductor Selection
The TPS61086 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 3.2 A. The other important parameter is the inductor DC resistance. Usually the lower the DC resistance
the higher the efficiency.
NOTE
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.
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 TPS61086, inductor values between 3 μH and 6 μH are a good
choice. Possible inductors are shown in Table 3.
Typically, TI recommends that the inductor current ripple is below 35% of the average inductor current. The
following equation can therefore be used to calculate the inductor value, L:
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2
æ V ö æ V -V ö æ h ö
L = ç IN ÷ × ç S IN ÷ × ç
÷
è VS ø è I out × f S ø è 0.35 ø
where
•
•
•
•
•
VIN is Minimum input voltage.
VS is Output voltage.
Iout is Maximum output current in the application.
fS is Converter switching frequency (typically 1.2 MHz).
η is Estimated converter efficiency (please use the number from the efficiency plots or 90% as an estimation.
(5)
Table 3. Inductor Selection
L
(μH)
SUPPLIER
3.3
Sumida
4.7
Sumida
3.3
Sumida
3.3
Sumida
4.7
5
COMPONENT
CODE
SIZE
(L×W×H mm)
DCR TYP
(mΩ)
Isat (A)
CDH38D09
4x4x1
240
1.25
CDPH36D13
5 x 5 x 1.5
155
1.36
CDPH4D19F
5.2 x 5.2 x 2
33
1.5
CDRH6D12
6.7 x 6.7 x 1.5
62
2.2
Würth Elektronik
7447785004
5.9 x 6.2 x 3.3
60
2.5
Coilcraft
MSS7341
7.3 x 7.3 x 4.1
24
2.9
8.2.1.2.2 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 1-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.
Table 4. Rectifier Diode Selection
12
CURRENT
RATING Iavg
Vr
Vforward/Iavg
SUPPLIER
750 mA
20 V
0.425 V / 1 A
Fairchild Semiconductor
FYV0704S
SOT 23
1A
20 V
0.39 V / 1 A
NXP
PMEG2010AEH
SOD 123
1A
20 V
0.5 V / 1 A
Vishay Semiconductor
SS12
SMA
1A
20 V
0.44 V / 1 A
Vishay Semiconductor
MSS1P2L
µ -SMP
2A
20 V
0.44 V / 2 A
Vishay Semiconductor
SL22
SMB
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CODE
PACKAGE
TYPE
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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:
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.
Standard values of RCOMP = 16 kΩ and CCOMP = 2.7 nF will work for the majority of the applications.
Please refer to 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
where
•
•
•
•
•
VIN is Minimum input voltage.
VS is Output voltage.
Cout is Output capacitance.
L is Inductor value, for example, 3.3 μH or 4.7 μH.
Iout is Maximum output current in the application.
(9)
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
L
VS
15 V
3.3 μH
12 V
9V
VIN ± 20%
RCOMP
CCOMP
820 pF
5V
100 kΩ
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
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 TPS61086.
8.2.1.2.5 Input Capacitor Selection
For good input voltage filtering low-ESR ceramic capacitors are recommended. TPS61086 has an analog input
IN. Therefore, a 1-μF bypass is highly recommended as close as possible to the IC from IN to GND.
One 10-μF ceramic input capacitors are sufficient for most of the applications. For better input voltage filtering
this value can be increased. Refer to Table 6 and typical applications for input capacitor recommendation
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8.2.1.2.6 Output Capacitor Selection
For best output voltage filtering a low-ESR output capacitor like ceramic capcaitor is recommended. Two to 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. Refer to Table 6 for the selection of the output capacitor.
Table 6. Rectifier Input and Output Capacitor Selection
CAPACITOR/SI
ZE
VOLTAGE RATING
SUPPLIER
COMPONENT CODE
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
CIN
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
where
•
•
•
•
•
•
•
•
ΔVC is Output voltage ripple dependent on output capacitance,output current and switching frequency.
VS is Output voltage.
VIN is Minimum input voltage of boost converter.
fS is Converter switching frequency (typically 1.2 MHz).
Iout is Output capacitance.
ΔVC_ESR is Output voltage ripple due to output capacitors ESR (equivalent series resistance).
ISWPEAK is Inductor peak switch current in the application.
RC_ESR is Output capacitors equivalent series resistance (ESR).
(10)
ΔVC_ESR can be neglected in many cases since ceramic capacitors provide very low ESR.
8.2.1.3 Application Curves
VSW
5 V/div
VSW
5 V/div
VS_AC
50 mV/div
VS_AC
50 mV/div
Il
0.5 A/div
Il
0.5 A/div
VIN = 3.3 V, VS = 12 V/50 mA
VIN = 3.3 V, VS = 12 V/50 mA
10 µs/div
10 µs/div
Figure 8. PFM Mode Switching Pulse
14
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Figure 9. PFM Mode Switching Pulses
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VSW
10 V/div
VSW
10 V/div
VS_AC
50 mV/div
VS_AC
50 mV/div
Il
0.5 A/div
Il
1 A/div
VIN = 3.3 V
VS = 12 V/300 mA
VIN = 3.3 V, VS = 12 V/4 mA
100 µs/div
400 ns/div
Figure 10. PFM Mode - Light Load
Figure 11. Forced PWM / PFM Mode - Heavy Load
VIN
2 V/div
VS_AC
50 mV/div
COUT = 40 µF
L = 3.3 µH
Rcomp = 16 kΩ
Ccomp = 2.7 nF
COUT = 40 µF
L = 3.3 µH
Rcomp = 16 kΩ
Ccomp = 2.7 nF
VS_AC
200 mV/div
IOUT
50 mA/div
VIN = 3.3 V
VS = 12 V/50 mA - 150 mA
VIN = 2.3 V - 6.0V
VS = 12 V/0 mA
400 µs/div
400 µs/div
Figure 12. Load Transient Response PFM Mode
Figure 13. Line Transient Response Light Load
VIN = 3.3 V
VS = 12 V / 300 mA
EN
5 V/div
VS
5 V/div
IL
1 A/div
CSS = 100 nF
2 ms/div
Figure 14. Soft-Start
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8.2.2 3.3-V to 12-V Boost Converter With Forced PWM Mode at Light Load
L
3.3 µH
VIN
3.3 V ± 20%
8
Cin
10 µF
16 V
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
MODE
FB
AGND
COMP
PGND
SS
VS
12 V/500 mA max.
D
PMEG2010AEH
6
R1
156 kΩ
7
Cout
10 µF
25 V
2
R2
18 kΩ
1
Rcomp
68kΩ
10
TPS61086
Ccomp
1.2 nF
Css
100 nF
Figure 15. Typical Application, 3.3 V to 12 V (Force PWM Mode)
8.2.2.1 Design Requirements
For this example, the design parameters are listed in Table 7.
Table 7. Design Parameters
16
DESIGN PARAMETERS
EXAMPLE VALUES
Input Voltage
3.3 V ± 20%
Output Voltage
12 V
Output Current
500 mA
Operation Mode at Light Load
Forced PWM
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8.2.2.2 Detailed Design Procedure
Refer to Detailed Design Procedure in the 3.3-V to 12-V Boost Converter With PFM Mode at Light Load section.
8.2.2.3 Application Curves
VSW
10 V/div
VSW
10 V/div
VS_AC
50 mV/div
VS_AC
50 mV/div
Il
0.5 A/div
Il
1 A/div
VIN = 3.3 V
VS = 12 V/300 mA
VIN = 3.3 V, VS = 12 V/4 mA
100 µs/div
400 ns/div
Figure 16. Forced PWM Mode - Light Load
Figure 17. Forced PWM / PFM Mode - Heavy Load
VIN
2 V/div
VS_AC
100 mV/div
COUT = 40 µF
L = 3.3 µH
Rcomp = 16 kΩ
Ccomp = 2.7 nF
COUT = 40 µF
L = 3.3 µH
Rcomp = 16 kΩ
Ccomp = 2.7 nF
VS_AC
200 mV/div
IOUT
50 mA/div
VIN = 2.3 V - 6.0V
VS = 12 V/150 mA
VIN = 3.3 V
VS = 12 V/50 mA - 150 mA
400 µs/div
400 µs/div
Figure 18. Load Transient Response Force PWM Mode
Figure 19. Line Transient Response Heavy Load
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8.3 System Examples
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
C20
1 µF/
35 V
C19
470 nF/
50 V
D8
BZX84C7V5
Vgh
26.5 V / 20 mA
D9
BZX84C27V
L
3.3 µH
Cby
1 µF/
16 V
VIN
5 V ± 20%
D
SL22
8
IN
SW
EN
SW
3
Cin
2*10 µF/
16 V
7
9
Cout
R1
200 kΩ
4*10µF/
25V
2
MODE
FB
4
5
VS
15 V/500 mA
6
R2
18 kΩ
1
AGND
COMP
PGND
SS
Rcomp
100 kΩ
10
TPS61086
Ccomp
820 pF
Css
100 nF
Figure 20. Typical Application 5 V to 15 V (Force PWM Mode) for TFT LCD With External Charge Pumps
(VGH, VGL)
Riso
10 kW
L
3.3 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
MODE
FB
AGND
COMP
PGND
SS
5
TPS61086
6
VS
15 V/50 mA
BC857C
D
PMEG2010AEH
Ciso
1 µF/ 25 V
7
R1
200 kΩ
2
Cout
4*10 µF/
25 V
R2
18 kΩ
1
Rcomp
100 kΩ
10
Css
100 nF
Ccomp
820 pF
Figure 21. Typical Application With External Load Disconnect Switch
18
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System Examples (continued)
L
3.3 µH
Overvoltage
D
PMEG2010AEH Protection
VIN
3.3 V ± 20%
8
Cin
10 µF
16 V
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
MODE
6
Dz
BZX84C 18V
7
FB
COMP
AGND
PGND
VS
15 V/30 mA
SS
R1
200 kΩ
Cout
10 µF
25 V
2
Rlimit
110 Ω
1
Rcomp
91 kΩ
10
Css
100 nF
TPS61086
R2
18 kΩ
Ccomp
1.2 nF
Figure 22. Typical Application, 3.3 V to 15 V (PFM Mode) With Overvoltage Protection
L
3.3 µH
optional
VIN
3.3 V ± 20%
Cin
10 µF/
16 V
Cby
1 µF/ 16 V
6
8
3
9
4
5
IN
SW
EN
SW
D
PMEG2010AEH
Dz
BZX84C
18 V
VS
300 mA
3S3P wLED
LW E67C
7
Cout
2* 10 µF/
25 V
2
MODE
FB
AGND
COMP
PGND
SS
TPS61086
Rlimit
110 Ω
1
Rcomp
68 kΩ
10
Css
100 nF
Rsense
15 Ω
Ccomp
1.2 nF
Figure 23. Simple Application (3.3-V Input Voltage - Forced PWM Mode) for wLED Supply (3S3P) (With
Optional Clamping Zener Diode)
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System Examples (continued)
L
3.3 µH
optional
VIN
3.3 V ± 20%
Cby
1 µF/ 16 V
6
8
Cin
10 µF/
16 V
3
9
4
PWM
100 Hz to 500 Hz
5
IN
SW
EN
SW
D
PMEG2010AEH
Dz
BZX84C
18 V
VS
300 mA
3S3P wLED
LW E67C
7
Cout
2* 10 µF/
25 V
2
MODE
FB
AGND
COMP
PGND
SS
Rlimit
110 Ω
1
Rsense
15 Ω
Rcomp
68 kΩ
10
TPS61086
Ccomp
1.2 nF
Css
100 nF
Figure 24. Simple Application (3.3-V Input Voltage - Forced PWM Mode) for wLED Supply (3S3P) With
Adjustable Brightness Control Using a PWM Signal on the Enable Pin (With Optional Clamping Zener
Diode)
L
3.3 µH
optional
VIN
3.3 V ± 20%
Cby
1 µF/ 16 V
6
8
D
PMEG2010AEH
Dz
BZX84C
VS
300 mA
3S3P wLED
LW E67C
SW
IN
18 V
Cin
10 µF/
16 V
3
9
4
5
7
EN
Cout
2* 10 µF/
25 V
SW
2
MODE
FB
AGND
COMP
PGND
SS
TPS61086
R1
180 kΩ
Rlimit
110 Ω
1
10
Css
100 nF
Rcomp
68 kΩ
Ccomp
1.2 nF
R2
127 kΩ
Rsense
15 Ω
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 25. Simple Application (3.3-V Input Voltage - Forced PWM Mode) for wLED Supply (3S3P) With
Adjustable Brightness Control Using an Analog Signal on the Feedback Pin (With Optional Clamping
Zener Diode)
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9 Power Supply Recommendations
The TPS61086 is designed to operate from an input voltage supply range between 2.3 V and 6.0 V. The power
supply to the TPS61086 needs to have a current rating according to the supply voltage, output voltage, and
output current of the TPS61086.
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 connecting to the PGND terminal and a different one for control
ground connecting to the AGND terminal to minimize the effects of ground noise. Connect these ground nodes at
the PGND 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 IC's SW and PGND terminal.
10.2 Layout Example
VIN
SW
SW
6
5
7
IN
MODE
9
PGND
EN
AGND
5
2
3
FB
4
1
TPS61086
COMP
GND
8
10
SS
VOUT
Figure 26. TPS61086 Layout Example
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11 Device and Documentation Support
11.1 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.
11.2 Trademarks
E2E is a trademark of Texas Instruments.
All other 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.
22
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PACKAGE OPTION ADDENDUM
www.ti.com
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)
TPS61086DRCR
ACTIVE
VSON
DRC
10
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PSRI
TPS61086DRCT
ACTIVE
VSON
DRC
10
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
PSRI
(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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