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TPS61093
SLVS992D – SEPTEMBER 2009 – REVISED APRIL 2019
TPS61093 Low-Input Boost Converter With Integrated Power Diode and
Input/Output Isolation
1 Features
3 Description
•
•
•
•
•
•
•
•
•
•
The TPS61093 is a 1.2-MHz, fixed-frequency boost
converter designed for high integration and high
reliability. The IC integrates a 20-V power switch,
input/output isolation switch, and power diode. When
the output current exceeds the overload limit, the
isolation switch of the IC opens up to disconnect the
output from the input, thus protecting the IC and the
input supply. The isolation switch also disconnects
the output from the input during shutdown to minimize
leakage current. When the IC is shut down, the
output capacitor is discharged to a low voltage level
by internal diodes. Other protection features include
1.1-A peak overcurrent protection (OCP) at each
cycle, output overvoltage protection (OVP), thermal
shutdown, and undervoltage lockout (UVLO).
1
Input range: 1.6 V to 6 V
Integrated power diode and isolation FET
20-V Internal switch FET with 1.1-A current
Fixed 1.2-MHz switching frequency
Efficiency at 15-V output up to 88%
Overload and overvoltage protection
Programmable soft start-up
Load discharge path after IC shutdown
2.5 mm × 2.5 mm × 0.8 mm WSON package
Create a custom design using the TPS61093 with
the WEBENCH® Power Designer
2 Applications
•
•
•
With its 1.6-V minimum input voltage, the IC can be
powered by two alkaline batteries, a single Li-ion
battery, or 3.3-V and 5-V regulated supply. The
output can be boosted up to 17 V. The TPS61093 is
available in 2.5 mm × 2.5 mm VSON package with
thermal pad.
Glucose meters
OLED power supplies
3.3-V to 12-V, 5-V to 12-V Boost converters
Device Information(1)
PART NUMBER
TPS61093
PACKAGE
WSON (10)
BODY SIZE (NOM)
2.50 mm × 2.50 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Simplified Schematic
VI 1.6 V to 6 V
L1
10 mH
C1
4.7 mF
C3
R3
200 kW
TPS61093
VIN
SW
CP1
VO
CP2
OUT
100 nF
C5
1 mF
EN
FB
SS
GND
C2
0.1 mF
VO 15 V/50 mA
R1
294 kW
C4
1 mF
R2
10.2 kW
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.
TPS61093
SLVS992D – SEPTEMBER 2009 – REVISED APRIL 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
3
3
6.1
6.2
6.3
6.4
6.5
6.6
3
4
4
4
5
5
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 7
7.1 Overview ................................................................... 7
7.2 Functional Block Diagram ......................................... 7
7.3 Feature Description................................................... 8
7.4 Device Functional Modes.......................................... 8
8
Application and Implementation .......................... 9
8.1 Application Information.............................................. 9
8.2 Typical Applications .................................................. 9
9 Power Supply Recommendations...................... 17
10 Layout................................................................... 17
10.1 Layout Guidelines ................................................. 17
10.2 Layout Example .................................................... 17
11 Device and Documentation Support ................. 18
11.1
11.2
11.3
11.4
11.5
11.6
Device Support......................................................
Receiving Notification of Documentation Updates
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
18
18
18
18
18
19
12 Mechanical, Packaging, and Orderable
Information ........................................................... 19
4 Revision History
Changes from Revision C (June 2015) to Revision D
Page
•
Added links for Webench ....................................................................................................................................................... 1
•
Changed Shutdown and Load Discharge output voltage value from "3.3 V" to "4.3 V"......................................................... 8
Changes from Revision B (December 2014) to Revision C
Page
•
Changed Features From: VSON package To: WSON Package ............................................................................................ 1
•
Changed the pinout title From "QFN Package 10 Pins" To: "DSK Package 10 Pins (WSON)" ............................................ 3
•
Changed "VSON" to "WSON" in the Thermal Information table ........................................................................................... 5
•
Deleted the Dissipation Ratings table..................................................................................................................................... 5
Changes from Revision A (October 2009) to Revision B
•
Page
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 Original (September 2009) to Revision A
Page
•
Added information to OPERATION description...................................................................................................................... 7
•
Changed Output Program description .................................................................................................................................. 10
•
Changed Output Program equations.................................................................................................................................... 10
2
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5 Pin Configuration and Functions
DSK Package
10 Pins (WSON)
Top View
10
VO
9
SW
8
OUT
CP1 4
7
FB
EN 5
6
SS
GND 1
VIN 2
CP2 3
Thermal
Pad
Pin Functions
PIN
NAME
NO.
CP1, CP2
3, 4
I/O
DESCRIPTION
Connect to flying capacitor for internal charge pump.
EN
5
I
Enable pin (HIGH = enable). When the pin is pulled low for 1 ms, the IC turns off and consumes less
than 1-μA current.
FB
7
I
Voltage feedback pin for output regulation, 0.5-V regulated voltage. An external resistor divider
connected to this pin programs the regulated output voltage.
GND
1
–
Ground of the IC.
OUT
8
O
Isolation switch is between this pin and VO pin. Connect load to this pin for input/output isolation during
IC shutdown. See Without Isolation FET for the tradeoff between isolation and efficiency.
SS
6
I
Soft start pin. A RC network connecting to the SS pin programs soft start timing. See Start-Up.
SW
9
I
Switching node of the IC where the internal PWM switch operates.
Thermal Pad
–
–
It should be soldered to the ground plane. If possible, use thermal via to connect to ground plane for
ideal power dissipation.
VIN
2
I
IC Supply voltage input.
VO
10
O
Output of the boost converter. When the output voltage exceeds the overvoltage protection (OVP)
threshold, the power switch turns off until VO drops below the overvoltage protection hysteresis.
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature (unless otherwise noted)
Supply voltage on pin VIN
(2)
MAX
UNIT
–0.3
7
V
–0.3
7
V
Voltage on pin CP1 and FB (2)
–0.3
3
V
–0.3
20
V
–40
85
°C
150
°C
150
°C
Voltage on pin SW, VO, and OUT
(2)
Operating temperature
TJ
Maximum operating junction temperature
Tstg
Storage temperature
(2)
MIN
Voltage on pins CP2, EN, and SS (2)
TA
(1)
(1)
–55
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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SLVS992D – SEPTEMBER 2009 – REVISED APRIL 2019
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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)
±750
UNIT
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
6
UNIT
Vi
Input voltage range
Vo
Output voltage range at VO pin
L
Inductor (1)
2.2
Cin
Input capacitor
4.7
Co
Output capacitor at OUT pin (1)
Cfly
Flying capacitor at CP1 and CP2 pins
TJ
Operating junction temperature
–40
125
°C
TA
Operating free-air temperature
–40
85
°C
(1)
1.6
MAX
4.7
V
17
V
10
μH
μF
1
10
10
μF
nF
These values are recommended values that have been successfully tested in several applications. Other values may be acceptable in
other applications but should be fully tested by the user.
6.4 Thermal Information
TPS61093
THERMAL METRIC
(1)
WSON
UNIT
10 PINS
RθJA
Junction-to-ambient thermal resistance
49.2
RθJC(top)
Junction-to-case (top) thermal resistance
63.3
RθJB
Junction-to-board thermal resistance
23.4
ψJT
Junction-to-top characterization parameter
1.1
ψJB
Junction-to-board characterization parameter
23.0
RθJC(bot)
Junction-to-case (bottom) thermal resistance
5.7
(1)
4
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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6.5 Electrical Characteristics
VIN = 3.6 V, EN = VIN, TA = –40°C to 85°C, typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
0.9
1.5
mA
1
μA
SUPPLY CURRENT
VIN
Input voltage range, VIN
IQ
Operating quiescent current into VIN
Device PWM switching no load
1.6
ISD
Shutdown current
EN = GND, VIN = 6 V
UVLO
Undervoltage lockout threshold
VIN falling
Vhys
Undervoltage lockout hysterisis
6
1.5
1.55
50
V
V
mV
ENABLE AND PWM CONTROL
VENH
EN logic high voltage
VIN = 1.6 V to 6 V
VENL
EN logic low voltage
VIN = 1.6 V to 6 V
REN
EN pull down resistor
Toff
EN pulse width to shutdown
1.2
V
0.3
400
800
EN high to low
V
1600
kΩ
1
ms
VOLTAGE CONTROL
VREF
Voltage feedback regulation voltage
IFB
Voltage feedback input bias current
fS
Oscillator frequency
Dmax
Maximum duty cycle
Tmin_on
Minimum on pulse width
0.49
VFB = 0.1 V, TA = 85°C
0.5
1.0
1.2
90%
93%
0.51
V
100
nA
1.4
MHz
65
ns
POWER SWITCH, ISOLATION FET
RDS(ON)N
N-channel MOSFET on-resistance
VIN = 3 V
0.25
0.4
Ω
RDS(ON)iso
Isolation FET on-resistance
VO = 5 V
2.5
4
Ω
VO = 3.5 V
4.5
ILN_N
N-channel leakage current
VDS = 20 V, TA = 25°C
1
μA
ILN_iso
Isolation FET leakage current
VDS = 20 V, TA = 25°C
1
μA
VF
Power diode forward voltage
Current = 500 mA
0.8
V
OC, ILIM, OVP SC AND SS
ILIM
N-Channel MOSFET current limit
Vovp
Overvoltage protection threshold
Vovp_hys
Overvoltage protection hysteresis
IOL
Overload protection
Measured on the VO pin
0.9
1.1
18
19
1.5
A
0.6
V
200
300
mA
V
THERMAL SHUTDOWN
Tshutdown
Thermal shutdown threshold
150
°C
Thysteresis
Thermal shutdown hysteresis
15
°C
6.6 Typical Characteristics
Table 1. Table Of Graphs
Figure 1, L = TOKO #A915_Y-100M, unless otherwise noted
FIGURE
η
Efficiency
vs Load current at OUT = 15 V
Figure 1
η
Efficiency
vs Load current at OUT = 10 V
Figure 2
VFB
FB voltage
vs Free-air temperature
Figure 3
VFB
FB voltage
vs Input voltage
Figure 4
ILIM
Switch current limit
vs Free-air temperature
Figure 5
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100
100
OUT = 15 V
95
85
85
80
80
75
VI = 2.5 V
70
VI =1.8 V
65
70
60
55
50
50
45
45
100
40
1
1000
VI = 2.5 V
VI =1.8 V
65
55
10
VI = 3.3 V
75
60
40
1
VI = 4.2 V
90
VI = 3.3 V
Efficiency - %
Efficiency - %
90
OUT = 10 V
95
VI = 4.2 V
10
Load - mA
100
1000
Load - mA
Figure 1. Efficiency vs Load
Figure 2. Efficiency vs Load
0.502
502
501.5
0.501
VFB - mV
VFB - V
501
0.5
500.5
500
0.499
499.5
0.498
-40
-20
0
20
40
60
80
TA - Free-Air Temperature - ºC
100
120
499
1.6
Figure 3. FB Voltage vs Free-Air Temperature
2
2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6
VI - Input Voltage - V
6
Figure 4. FB Voltage vs Input Voltage
1.3
ILIM - A
1.2
1.1
1
0.9
0.8
-40
-20
0
20
40
60
80
TA - Free-Air Temperature - ºC
100
120
Figure 5. Switch Current Limit vs Free-Air Temperature
6
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7 Detailed Description
7.1 Overview
The TPS61093 is a highly integrated boost regulator for up to 17-V output. In addition to the on-chip 1-A PWM
switch and power diode, this IC also integrates an output-side isolation switch as shown in the functional block
diagram. One common issue with conventional boost regulators is the conduction path from input to output even
when the PWM switch is turned off. It creates three problems, which are inrush current during start-up, output
leakage current during shutdown, and excessive overload current. In the TPS61093, the isolation switch turns off
under shutdown-mode and overload conditions, thereby opening the current path. However, shorting the VO and
OUT pins bypasses the isolation switch and enhances efficiency. Because the isolation switch is on the output
side, the IC's VIN pin and power stage input power (up to 10 V) can be separated.
The TPS61093 adopts current-mode control with constant pulse-width-modulation (PWM) frequency. The
switching frequency is fixed at 1.2 MHz typical. PWM operation turns on the PWM switch at the beginning of
each switching cycle. The input voltage is applied across the inductor and the inductor current ramps up. In this
mode, the output capacitor is discharged by the load current. When the inductor current hits the threshold set by
the error amplifier output, the PWM switch is turned off, and the power diode is forward-biased. The inductor
transfers its stored energy to replenish the output capacitor. This operation repeats in the next switching cycle.
The error amplifier compares the FB-pin voltage with an internal reference, and its output determines the duty
cycle of the PWM switching. This closed-loop system requires frequency compensation for stable operation. The
device has a built-in compensation circuit that can accommodate a wide range of input and output voltages. To
avoid the sub-harmonic oscillation intrinsic to current-mode control, the IC also integrates slope compensation,
which adds an artificial slope to the current ramp.
7.2 Functional Block Diagram
FB
EN
CP2
CP1
SW
OUT
VO
Soft
Startup
Ref.
C/P
EA
Gate
Driver
PWM Control
Gate
Driver
EN
Precharge
On/off control
Oscillator
Ramp
Generator
+
SS
Current Sensor
GND
VIN
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7.3 Feature Description
7.3.1 Shutdown and Load Discharge
When the EN pin is pulled low for 1 ms, the IC stops the PWM switch and turns off the isolation switch, providing
isolation between input and output. The internal current path consisting of the isolation switch’s body diode and
several parasitic diodes quickly discharges the output voltage to less than 4.3 V. Afterwards, the voltage is slowly
discharged to zero by the leakage current. This protects the IC and the external components from high voltage in
shutdown mode.
In shutdown mode, less than 1 μA of input current is consumed by the IC.
7.3.2 Overload and Overvoltage Protection
If the overload current passing through the isolation switch is above the overload limit (IOL) for 3-μs (typical), the
TPS61093 is switched off until the fault is cleared and the EN pin toggles. The function only is triggered 52 ms
after the IC is enabled.
To prevent the PWM switch and the output capacitor from exceeding maximum voltage ratings, an overvoltage
protection circuit turns off the boost switch as soon as the output voltage at the VO pin exceeds the OVP
threshold. Simultaneously, the IC opens the isolation switch. The regulator resumes PWM switching after the VO
pin voltage falls 0.6 V below the threshold.
7.3.3 UVLO
An undervoltage lockout prevents improper operation of the device for input voltages below 1.55 V. When the
input voltage is below the undervoltage threshold, the entire device, including the PWM and isolation switches,
remains off.
7.3.4 Thermal Shutdown
An internal thermal shutdown turns off the isolation and PWM switches when the typical junction temperature of
150°C is exceeded. The thermal shutdown has a hysteresis of 15°C, typical.
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.
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 device is a step up DC-DC converter with a PWM switch, a power diode and an input/output isolation switch
integrated. TPS61093 supports up to 17-V output with the input range from 1.6 V to 6 V. The TPS61093 adopts
the current-mode control with constant pulse-width-modulation (PWM) frequency. The switching frequency is
fixed at 1.2 MHz typical. The isolation switch disconnects the output from the input during shutdown to minimize
leakage current. However, shorting the VO and OUT pins bypasses the isolation switch and enhances efficiency.
The following design procedure can be used to select component values for the TPS61093.
8.2 Typical Applications
8.2.1 15 V Output Boost Converter
Vin 1.8V to 6V
L1
10mH
C1
TPS61093
4.7mF
C3 100nF
R3
200kW
VIN
SW
CP1
VO
CP2
OUT
EN
FB
SS
GND
C2 0.1mF
C5
1 mF
Vo 15V/50mA
R1
294kW
C6
10nF
C4
100mF
R2
10.2kW
Figure 6. 15 V Boost Converter with 100 µF Output Capacitor
8.2.1.1 Design Requirements
Table 2. Design Parameters
PARAMETERS
VALUES
Input voltage
4.2 V
Output voltage
15 V
Operating frequency
1.2 MHz
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8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Custom Design With WEBENCH® Tools
Click here to create a custom design using the TPS61093 device with the WEBENCH® Power Designer.
1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements.
2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial.
3. Compare the generated design with other possible solutions from Texas Instruments.
The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time
pricing and component availability.
In most cases, these actions are available:
• Run electrical simulations to see important waveforms and circuit performance
• Run thermal simulations to understand board thermal performance
• Export customized schematic and layout into popular CAD formats
• Print PDF reports for the design, and share the design with colleagues
Get more information about WEBENCH tools at www.ti.com/WEBENCH.
8.2.1.2.2 Output Program
To program the output voltage, select the values of R1 and R2 (see Figure 7) according to Equation 1.
æ R1 ö
Vout = 0.5 V ´ ç
+1÷
è R2 ø
æ Vout
ö
R1 = R2 ´ ç
- 1÷
è 0.5 V
ø
(1)
A recommended value for R2 is approximately 10 kΩ which sets the current in the resistor divider chain to 0.5
V/10 kΩ = 50 μA. The output voltage tolerance depends on the VFB accuracy and the resistor divider.
C2
C2
VO
OUT
TPS61093
VO
Cff
Option
R1
C4
OUT
TPS61093
FB
R1
Cff
Option
FB
R2
R2
(a) With isolation FET
(b) Without isolation FET
Figure 7. Resistor Divider to Program Output Voltage
8.2.1.2.3 Without Isolation FET
The efficiency of the TPS61093 can be improved by connecting the load to the VO pin instead of the OUT pin.
The power loss in the isolation FET is then negligible, as shown in Figure 8. The tradeoffs when bypassing the
isolation FET are:
• Leakage path between input and output causes the output to be a diode drop below the input voltage when
the IC is in shutdown
• No overload circuit protection
When the load is connected to the VO pin, the output capacitor on the VO pin must be above 1 μF.
10
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100
95
90
Without isolation
85
Efficiency - %
80
With isolation
75
70
65
60
55
50
45
40
0
50
100
150
200
Load - mA
250
300
Figure 8. Efficiency vs Load
8.2.1.2.4 Start-Up
The TPS61093 turns on the isolation FET and PWM switch when the EN pin is pulled high. During the soft-start
period, the R and C network on the SS pin is charged by an internal bias current of 5 μA (typical). The RC
network sets the reference voltage ramp up slope. Because the output voltage follows the reference voltage via
the FB pin, the output voltage rise time follows the SS pin voltage until the SS pin voltage reaches 0.5 V. The
soft-start time is given by Equation 2.
0.5 V ´ C5
tSS =
5 mA
where
•
C5 is the capacitor connected to the SS pin
(2)
When the EN pin is pulled low to switch the IC off, the SS pin voltage is discharged to zero by the resistor R3.
The discharge period depends on the RC time constant. Note that if the SS pin voltage is not discharged to zero
before the IC is enabled again, the soft start circuit may not slow the output voltage startup and may not reduce
the startup inrush current.
8.2.1.2.5 Switch Duty Cycle
The maximum switch duty cycle (D) of the TPS61093 is 90% (minimum). The duty cycle of a boost converter
under continuous conduction mode (CCM) is given by:
Vout + 0.8 V - Vin
D=
Vout + 0.8 V
(3)
The duty cycle must be lower than the specification in the application; otherwise the output voltage cannot be
regulated.
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The TPS61093 has a minimum ON pulse width once the PWM switch is turned on. As the output current drops,
the device enters discontinuous conduction mode (DCM). If the output current drops extremely low, causing the
ON time to be reduced to the minimum ON time, the TPS61093 enters pulse-skipping mode. In this mode, the
device keeps the power switch off for several switching cycles to keep the output voltage in regulation. See
Figure 14. The output current when the IC enters skipping mode is calculated with Equation 4.
Iout_skip =
2
Vin2 ´ Tmin_on
´ fSW
2 ´ (Vout + 0.8V - Vin) ´ L
where
•
•
•
Tmin_on = Minimum ON pulse width specification (typically 65-ns);
L = Selected inductor value;
fSW = Converter switching frequency (typically 1.2-MHz)
(4)
8.2.1.2.6 Inductor Selection
Because the selection of the inductor affects steady state operation, transient behavior, and loop stability, the
inductor is the most important component in power regulator design. There are three important inductor
specifications, inductor value, saturation current, and dc resistance. Considering inductor value alone is not
enough.
The saturation current of the inductor should be higher than the peak switch current as calculated in Equation 5.
DI
IL_peak = IL_DC + L
2
Vout ´ Iout
IL_DC =
Vin ´ h
1
DIL =
é
1
1 öù
æ
êL ´ ¦ SW ´ ç Vout + 0.8 V - VIN + VIN ÷ ú
è
øû
ë
where
•
•
•
•
IL_peak = Peak switch current
IL_DC = Inductor average current
ΔIL = Inductor peak to peak current
η = Estimated converter efficiency
(5)
Normally, it is advisable to work with an inductor peak-to-peak current of less than 30% of the average inductor
current. A smaller ripple from a larger valued inductor reduces the magnetic hysteresis losses in the inductor and
EMI. But in the same way, load transient response time is increased. Also, the inductor value should not be
outside the 2.2 μH to 10 μH range in the recommended operating conditions table. Otherwise, the internal slope
compensation and loop compensation components are unable to maintain small signal control loop stability over
the entire load range. Table 3 lists the recommended inductor for the TPS61093.
Table 3. Recommended Inductors for the TPS61093
12
PART NUMBER
L (μH)
DCR MAX (mΩ)
SATURATION
CURRENT (A)
SIZE (L×W×H mm)
VENDOR
#A915_Y-4R7M
4.7
45
1.5
5.2x5.2x3.0
Toko
#A915_Y-100M
10
90
1.09
5.2x5.2x3.0
Toko
VLS4012-4R7M
4.7
132
1.1
4.0x4.0x1.2
TDK
VLS4012-100M
10
240
0.82
4.0x4.0x1.2
TDK
CDRH3D23/HP
10
198
1.02
4.0x4.0x2.5
Sumida
LPS5030-103ML
10
127
1.4
5.0x5.0x3.0
Coilcraft
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Product Folder Links: TPS61093
TPS61093
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SLVS992D – SEPTEMBER 2009 – REVISED APRIL 2019
8.2.1.2.7 Input and Output Capacitor Selection
The output capacitor is mainly selected to meet the requirements for output ripple and loop stability. This ripple
voltage is related to the capacitor’s capacitance and its equivalent series resistance (ESR). Assuming a ceramic
capacitor with zero ESR, the minimum capacitance needed for a given ripple can be calculated by:
D ´ Iout
Cout =
Fs ´ Vripple
where
•
Vripple = peak to peak output ripple
(6)
The ESR impact on the output ripple must be considered if tantalum or electrolytic capacitors are used.
Care must be taken when evaluating a ceramic capacitor’s derating under dc bias, aging, and ac signal. For
example, larger form factor capacitors (in 1206 size) have their self resonant frequencies in the range of the
switching frequency. So the effective capacitance is significantly lower. The dc bias can also significantly reduce
capacitance. A ceramic capacitor can lose as much as 50% of its capacitance at its rated voltage. Therefore,
always leave margin on the voltage rating to ensure adequate capacitance at the required output voltage.
A 4.7-μF (minimum) input capacitor is recommended. The output requires a capacitor in the range of 1 μF to 10
μF. The output capacitor affects the small signal control loop stability of the boost regulator. If the output
capacitor is below the range, the boost regulator can potentially become unstable.
The popular vendors for high value ceramic capacitors are:
• TDK (http://www.component.tdk.com/components.php)
• Murata (http://www.murata.com/cap/index.html)
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Product Folder Links: TPS61093
13
TPS61093
SLVS992D – SEPTEMBER 2009 – REVISED APRIL 2019
www.ti.com
8.2.1.2.8 Small Signal Stability
The TPS61093 integrates slope compensation and the RC compensation network for the internal error amplifier.
Most applications are control loop stable if the recommended inductor and input/output capacitors are used. For
those few applications that require components outside the recommended values, the internal error amplifier’s
gain and phase are presented in Figure 9.
80
180
VFB
VEA
135
Phase
60
90
Gain - dB
45
20
Gain
0
fzea
0
fp-ea
-45
Phase - deg
40
-90
-20
-135
-40
10
100
1k
10k
f - Frequency - Hz
100k
-180
1M
Figure 9. Bode Plot of Error Amplifier Gain and Phase
The RC compensation network generates a pole fp-ea of 57 kHz and a zero fz-ea of 1.9 kHz, shown in Figure 9.
Use Equation 7 to calculate the output pole, fP, of the boost converter. If fP
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