TPS61097-33
V
0.9 V to 3.3V
IN
VOUT
EN
L
GND
VIN
L1
C1
C2
V
+3.3V
OUT
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
LOW INPUT VOLTAGE SYNCHRONOUS BOOST CONVERTER
WITH LOW QUIESCENT CURRENT
1FEATURES
• Up to 95% Efficiency at Typical Operating • Small 2.8-mm x 2.9-mm 5-Pin SOT-23 Package
Conditions (6-Pin for Adjustable)
• Connection from Battery to Load via Bypass APPLICATIONS
Switch in Shutdown Mode • MSP430 Applications
• Typical Shutdown Current Less Than 5 nA • All Single-Cell, Two-Cell, and Three-Cell
• Typical Quiescent Current Less Than 5 μAAlkaline, NiCd, NiMH, or Single-Cell Li-Battery
• Operating Input Voltage Range Powered Products
From 0.9 V to 5.5 V • Personal Medical Products
• Fixed Output Voltage Options • Fuel Cell and Solar Cell Powered Products
From 1.8 V to 5.0 V • PDAs
• Power-Save Mode for Improved Efficiency at • Mobile Applications
Low Output Power • White LEDs
• Overtemperature Protection
DESCRIPTION
The TPS61097 provide a power supply solution for products powered by either a single-cell, two-cell, or
three-cell alkaline, NiCd, or NiMH, or one-cell Li-Ion or Li-polymer battery. They can also be used in fuel cell or
solar cell powered devices where the capability of handling low input voltages is essential. Possible output
currents depend on the input-to-output voltage ratio. The devices provides output currents up to 100 mA at a
3.3-V output while using a single-cell Li-Ion or Li-Polymer battery. The boost converter is based on a
current-mode controller using synchronous rectification to obtain maximum efficiency. The maximum average
input current is limited to a value of 350 mA. The output voltage can be programmed by an external resistor
divider, or it is fixed internally on the chip. The converter can be disabled to minimize battery drain. During
shutdown, the battery is connected to the load to enable battery backup of critical functions on the load. The
fixed output device is packaged in a 5-pin SOT-23 package (DBV) measuring 2.8 mm × 2.9 mm. The adjustable
output version (TPS61097-01) is packaged in a 6-pin SOT-23 (DBV).
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
UNLESS OTHERWISE NOTED this document contains Copyright © 2009, Texas Instruments Incorporated
PRODUCTION DATA information current as of publication date.
Products conform to specifications per the terms of Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
AVAILABLE DEVICE OPTIONS(1) (2)
OUTPUT ORDERABLE
TAVOLTAGE PACKAGE(3) TOP-SIDE MARKING
PART NUMBER
DC/DC
Reel of 3000 TPS61097-01DBVR
Adjustable 6-pin SOT-23 – DBV PREVIEW
Reel of 250 TPS61097-01DBVT
Reel of 3000 TPS61097-18DBVR
1.8 V 5-pin SOT-23 – DBV PREVIEW
Reel of 250 TPS61097-18DBVT
Reel of 3000 TPS61097-27DBVR
2.7 V 5-pin SOT-23 – DBV PREVIEW
Reel of 250 TPS61097-27DBVT
–40°C to 85°C Reel of 3000 TPS61097-30DBVR
3.0 V 5-pin SOT-23 – DBV PREVIEW
Reel of 250 TPS61097-30DBVT
Reel of 3000 TPS61097-33DBVR
3.3 V 5-pin SOT-23 – DBV YC4L
Reel of 250 TPS61097-33DBVT
Reel of 3000 TPS61097-50DBVR
5.0 V 5-pin SOT-23 – DBV PREVIEW
Reel of 250 TPS61097-50DBVT
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
(2) Contact the factory for availability of other fixed output voltage versions.
(3) Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.
2Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted)(1)
VIInput voltage range VIN, L, VOUT, EN, FB –0.3 V to 7 V
Isc Short-circuit current 400 mA
TJJunction temperature range –40°C to 150°C
Tstg Storage temperature range –65°C to 150°C
ESD Electrostatic discharge rating Human-Body Model (HBM) (2) 2000 V
(1) 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.
(2) ESD testing is performed according to the respective JESD22 JEDEC standard.
DISSIPATION RATINGS TABLE
THERMAL RESISTANCE POWER RATING DERATING FACTOR ABOVE
PACKAGE θJA TA≤25°C TA= 25°C
DBV 255°C/W 390 mW -3.92 mW/°C
RECOMMENDED OPERATING CONDITIONS MIN MAX UNIT
VIN Supply voltage at VIN 0.9 5.5 V
VOUT Adjustable output voltage 1.8 5.5 V
TAOperating free air temperature range –40 85 °C
TJOperating junction temperature range –40 125 °C
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 3
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
ELECTRICAL CHARACTERISTICS
over recommended free-air temperature range and over recommended input voltage range (typical at an ambient temperature
range of 25°C) (unless otherwise noted)
DC/DC STAGE
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
VIN Input voltage 0.9 5.5 V
TPS61097-01 output voltage
VOUT VIN < VOUT 1.8 5.0 V
range
VFB TPS61097-01 feedback voltage VIN = 1.2 V , IOUT = 10 mA 1.16 1.20 1.24 V
TPS61097-18 VIN = 1.2 V , IOUT = 10 mA 1.75 1.80 1.85
TPS61097-27 VIN = 1.2 V , IOUT = 10 mA 2.62 2.70 2.78
VOUT TPS61097-30 VIN = 1.2 V , IOUT = 10 mA 2.91 3.00 3.09 V
TPS61097-33 VIN = 1.2 V , IOUT = 10 mA 3.20 3.30 3.40
TPS61097-50 VIN = 2.4 V , IOUT = 10 mA 4.85 5.00 5.15
ISW Switch current limit VOUT = 3.3 V 200 350 475 mA
Rectifying switch on resistance VOUT = 3.3 V 1.0 Ω
Main switch on resistance VOUT = 3.3 V 1.0 Ω
Bypass switch on resistance VIN = 1.2 IOUT = 100 mA 3.4 Ω
Line regulation VIN < VOUT, VIN = 1.2 V to 1.8 V, IOUT = 10 mA 0.5%
Load regulation VIN < VOUT, IOUT = 10 mA to 50 mA, VIN = 1.8 V 0.5%
VIN 1 2.5 μA
IQQuiescent current IO= 0 mA, VEN = VIN = 1.2 V, VOUT = 3.4V
VOUT 4 6.5 μA
ISD Shutdown current VIN VEN = 0 V, VIN = 1.2 V, IOUT = 0 mA 0.005 0.15 μA
Leakage current into L VEN = 0 V, VIN = 1.2 V, VL= 1.2 V 0.01 1 μA
CONTROL STAGE
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
EN input current EN = 0 V or EN = VIN 0.01 0.1 μA
VIL Logic low level, EN falling edge 0.65 V
VIN +
VIH Logic high level, EN rising edge 0.78 V
1.0 V
Overvoltage protection threshold TPS61097-01 5.5 6.5 7 V
Overtemperature protection 150 °C
Overtemperature hysteresis 20 °C
VUVLO Undervoltage lock-out threshold for turn off VIN decreasing 0.5 0.7
4Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
1
2
3
5
4
L
VOUTEN
GNDGND
VIN
FIXED OUTPUT VOLTAGE
DBV PACKAGE
(TOP VIEW)
ADJUSTABLE OUTPUT VOLAGE
DBV PACKAGE
(TOP VIEW)
1
2
3
6
4
L
VOUTEN
GND
VIN
5FB
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
PIN ASSIGNMENTS
Terminal Functions
TERMINAL
NO. I/O DESCRIPTION
NAME Adjus
Fixed table
VIN 1 1 I Boost converter input voltage
GND 2 2 Control / logic ground
EN 3 3 I Enable input (1 = enabled, 0 = disabled). EN must be actively terminated high or low.
VOUT 4 4 O Boost converter output
L 5 6 I Connection for inductor
FB – 5 I (Adjustable versions) Voltage feedback of adjustable versions.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 5
N
BypassSwitch
Control
P
VOUT
EN
L
Rectifying
Switch
Overvoltage
Protection
Bypass
Switch
StartupCircuit
VIN
ControlLogic
ThermalShutdown
Undervoltage
Lockout
N
Driver
Current
Sense
GND
Main
Switch
1.20V
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
FUNCTIONAL BLOCK DIAGRAM (FIXED OUTPUT VERSION)
6Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
N
BypassSwitch
Control
P
VOUT
EN
L
Rectifying
Switch
Overvoltage
Protection
Bypass
Switch
StartupCircuit
VIN
ControlLogic
ThermalShutdown
Undervoltage
Lockout
N
Driver
Current
Sense
GND
Main
Switch
1.20V
FB
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
FUNCTIONAL BLOCK DIAGRAM (ADJUSTABLE OUTPUT VERSION)
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 7
TPS61097-33
V
0.9 V to 3.3V
IN
VOUT
EN
L
GND
VIN
L1
C1
C2
V
+3.3V
OUT
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
PARAMETER MEASUREMENT INFORMATION
C1 10 μF
C2 10 μF
L 10 μH
Table 1. List of Components
REFERENCE MANUFACTURER PART NO.
C1 Murata GRM319R61A106KE19 10μF 10V X5R 1206 20%
C2 Murata GRM319R61A106KE19 10μF 10V X5R 1206 20%
L1 Coilcraft DO3314-103MLC
8Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
0
10
20
30
40
50
60
70
80
90
100
0.1 1 10 100
IO– Output Current – mA
Efficiency – %
COUT = 10 µF, ceramic
L = 10 µH
V = 3 V
IN
V = 2.5 V
IN
V = 1.8 V
IN
V = 1.5 V
IN
V = 1.2 V
IN
V = 0.9 V
IN
0.00
0.05
0.10
0.15
0.20
0.25
0.9 1.2 1.5 1.8 2.1 2.4 2.7 3
VI– Input Voltage – V
IO(max) – Maximum Output Current – A
COUT = 10 µF, ceramic
L = 10 µH
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
TYPICAL CHARACTERISTICS
Table 2. Table of Graphs
FIGURE
Maximum Output Current vs Input Voltage 1
vs Output Current 2
Efficiency vs Input Voltage 3
vs Input Voltage (Device Enabled, No Output Load, VOUT = 3.3 V) 4
Input Current vs Input Voltage (Device Disabled, No Output Load) 5
vs Temperature 6
Startup Voltage vs Output Current 7
vs Output Current 8
Output Voltage vs Input Voltage 9
Output Voltage Ripple 10
Load Transient Response 11
Line Transient Response 12
Waveforms Switching Waveform, Continuous Mode 13
Switching Waveform, Discontinuous Mode 14
Startup After Enable (VIN = 1.2 V, IOUT = 10 mA) 15
Startup After Enable (VIN = 1.8 V, IOUT = 10 mA) 16
MAXIMUM OUTPUT CURRENT EFFICIENCY
vs vs
INPUT VOLTAGE OUTPUT CURRENT
Figure 1. Figure 2.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 9
0
10
20
30
40
50
60
70
80
90
100
0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0
VIN – Input Voltage – V
Efficiency – %
COUT = 10 µF, ceramic
L = 10 µH
I = 100 mA
OUT
I = 10 mA
OUT
I = 100 µA
OUT
I = 50 mA
OUT
I = 5 mA
OUT
0
2
4
6
8
10
12
14
16
18
20
0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.6 3.9 4.2
VIN – Input Voltage – V
IIN – Input Current – µA
Device Enabled
No Output Load
VOUT = 3.3 V
0
20
40
60
80
100
120
0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.6 3.9 4.2
VIN – Input Voltage – V
IIN – Input Current – nA
Device Disabled
No Output Load
0.706
0.708
0.710
0.712
0.714
0.716
0.718
0.720
-40 -25 -10 5 20 35 50 65 80
TA– Temperature – °C
Startup Voltage – V
VIN = 1.8 V
No Load
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
EFFICIENCY INPUT CURRENT
vs vs
INPUT VOLTAGE INPUT VOLTAGE
Figure 3. Figure 4.
INPUT CURRENT STARTUP VOLTAGE
vs vs
INPUT VOLTAGE TEMPERATURE
Figure 5. Figure 6.
10 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
0.700
0.705
0.710
0.715
0.720
0.725
0 1 10 100
IOUT – Output Current – mA
Startup Voltage – V
VIN = 1.8 V
0
1
2
3
4
5
6
0 1 2 3 4 5 6
VIN – Input Voltage – V
VOUT – Ouput Voltage – V
Device disabled
RLOAD = 1k
RLOAD = 122
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
STARTUP VOLTAGE OUTPUT VOLTAGE
vs vs
OUTPUT CURRENT OUTPUT CURRENT
Figure 7. Figure 8.
OUTPUT VOLTAGE
vs
INPUT VOLTAGE
Figure 9.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 11
Inductor Current
VOUT
V = 1.8 V
I = 50 mA
C = 10 µF, ceramic
L = 10 µH
IN
OUT
OUT
VOUT
V = 1.2 V
I = 6 mA to 50 mA
IN
OUT
IOUT
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
OUTPUT VOLTAGE RIPPLE
Figure 10.
LOAD TRANSIENT RESPONSE
Figure 11.
12 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
VOUT
V = 1.8 V to 2.4 V
R = 100
IN
LOAD W
V
Offset 1.8 V
IN
VOUT
V = 1.8 V
I = 50 mA
IN
OUT
Inductor Current
Inductor Voltage
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
LINE TRANSIENT RESPONSE
Figure 12.
SWITCHING WAVEFORM, CONTINUOUS MODE
Figure 13.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 13
Inductor Voltage
V = 1.8 V
I = 10 mA
IN
OUT
Inductor Current
VOUT
VOUT
VEN
V = 1.2 V
I = 10 mA
IN
OUT
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
SWITCHING WAVEFORM, DISCONTINUOUS MODE
Figure 14.
STARTUP AFTER ENABLE
Figure 15.
14 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
VOUT
VEN
V = 1.8 V
I = 10 mA
IN
OUT
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
STARTUP AFTER ENABLE
Figure 16.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 15
IL
t
200mA
(typ.)
ContinuousCurrentOperation DiscontinuousCurrentOperation
200mA
(typ.)
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
DETAILED DESCRIPTION
Operation
The TPS61097 is a high performance, high efficient family of switching boost converters. To achieve high
efficiency the power stage is realized as a synchronous boost topology. For the power switching two actively
controlled low RDSon power MOSFETs are implemented.
Controller Circuit
The device is controlled by a hysteretic current mode controller. This controller regulates the output voltage by
keeping the inductor ripple current constant in the range of 200 mA and adjusting the offset of this inductor
current depending on the output load. If the required average input current is lower than the average inductor
current defined by this constant ripple the inductor current goes discontinuous to keep the efficiency high at low
load conditions.
Figure 17. Hysteretic Current Operation
The output voltage VOUT is monitored via the feedback network which is connected to the voltage error amplifier.
To regulate the output voltage, the voltage error amplifier compares this feedback voltage to the internal voltage
reference and adjusts the required offset of the inductor current accordingly. For fixed output voltage versions,
the feedback function is connected internally. A resistive divider network is required to set the output voltage with
the adjustable option.
The self oscillating hysteretic current mode architecture is inherently stable and allows fast response to load
variations. It also allows using inductors and capacitors over a wide value range.
Device Enable and Shutdown Mode
The device is enabled when EN is set high and shut down when EN is low. During shutdown, the converter stops
switching and all internal control circuitry is turned off.
Bypass Switch
The TPS61097 contains a P-channel MOSFET (Bypass Switch) in parallel with the synchronous rectifying
MOSFET. When the IC is enabled (EN = VIH), the Bypass Switch is turned off to allow the IC to work as a
standard boost converter. When the IC is disabled (EN = VIL) the Bypass Switch is turned on to provide a direct,
low impedance connection from the input voltage (at the L pin) to the load (VOUT). The Bypass Switch is not
impacted by Undervoltage lockout, Overvoltage or Thermal shutdown.
Startup
After the EN pin is tied high, the device starts to operate. If the input voltage is not high enough to supply the
control circuit properly a startup oscillator starts to operate the switches. During this phase the switching
frequency is controlled by the oscillator and the maximum switch current is limited. As soon as the device has
built up the output voltage to about 1.8 V, high enough for supplying the control circuit, the device switches to its
normal hysteretic current mode operation. The startup time depends on input voltage and load current.
Operation at Output Overload
If in normal boost operation the inductor current reaches the internal switch current limit threshold the main
switch is turned off to stop further increase of the input current.
In this case the output voltage will decrease since the device can not provide sufficient power to maintain the set
output voltage.
16 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
TPS61097
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SLVS872B –JUNE 2009–REVISED DECEMBER 2009
If the output voltage drops below the input voltage the backgate diode of the rectifying switch gets forward biased
and current starts flow through it. Because this diode cannot be turned off, the load current is only limited by the
remaining DC resistances. As soon as the overload condition is removed, the converter automatically resumes
normal operation and enters the appropriate soft start mode depending on the operating conditions.
Undervoltage Lockout
An undervoltage lockout function stops the operation of the converter if the input voltage drops below the typical
undervoltage lockout threshold. This function is implemented in order to prevent malfunctioning of the converter.
The undervoltage lockout function has no control of the Bypass Switch. If the Bypass Switch is enabled (EN =
VIL) there is no impact during an undervoltage condition, the Bypass Switch remains on.
Overvoltage Protection
If, for any reason, TPS61097-01 output voltage is not properly connected to the input of the voltage amplifier, the
IC cannot control the output voltage. Therefore an overvoltage protection is implemented to keep the output
voltage from exceeding the absolute maximum voltage ratings of the IC and to protect the load. For this
protection the TPS61097-01 output voltage is also monitored internally. In case it reaches the internally
programmed threshold of 6.5 V typically the voltage amplifier regulates the output voltage to this value.
If the TPS61097-01 is used to drive LEDs, this feature protects the circuit if the LED fails.
Overtemperature Protection
The device has a built-in temperature sensor which monitors the internal IC temperature. If the temperature
exceeds the programmed threshold (150 °C typical), the device stops operating. As soon as the IC temperature
has decreased below the programmed threshold, it starts operating again. There is a built-in hysteresis to avoid
unstable operation at IC temperatures at the overtemperature threshold.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 17
R1 = R2 × VOUT
VFB
– 1
TPS61097-01
V
0.9 V to VOUT
IN
VOUT
EN
L
GND
VIN
L1
R2
R1
C1
C2
V
1.8 V to 5.5 V
OUT
FB
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
APPLICATION INFORMATION
Design Procedure
The TPS61097 DC/DC converters are intended for systems powered by a single up to triple cell Alkaline, NiCd,
NiMH battery with a typical terminal voltage between 0.9 V and 5.5 V. They can also be used in systems
powered by one-cell Li-Ion or Li-Polymer with a typical voltage between 2.5 V and 4.2 V. Additionally, any other
voltage source like solar cells or fuel cells with a typical output voltage between 0.9 V and 5.5 V can power
systems where the TPS61097 is used. The TPS61097 does not down-regulate VIN; therefore, if VIN is greater
than VOUT, VOUT tracks VIN.
Programming the Output Voltage
Within the TPS61097 family, there are fixed and adjustable output voltage versions available. For the adjustable
output voltage versions, an external resistor divider is used to adjust the output voltage. The resistor divider must
be connected between VOUT, FB, and GND. When the output voltage is regulated properly, the typical value of
the voltage at the FB pin is 1.2 V. The maximum recommended value for the output voltage is 5.5 V. The current
through the resistive divider should be about 100 times greater than the current into the FB pin. The typical
current into the FB pin is 0.01 μA, and the voltage across the resistor between FB and GND, R2, is typically 1.2
V. Based on those two values, the recommended value for R2 should be lower than 500 kΩ, in order to set the
divider current at 1 μA or higher. It is recommended to keep the value for this resistor in the range of 100 kΩ.
Equation 1 calculates the value of R1 to set the desired output voltage:
(1)
As an example, if an output voltage of 2.5 V is needed, a 162-kΩresistor should be chosen for R1 when a
150-kΩhas been selected for R2.
Figure 18. Typical Application Circuit for Adjustable Output Voltage Option
Adjustable Bypass Switching
The EN pin can be set up as a low voltage control for the bypass switch. By setting the desired ratio of R1 and
R2, the TPS61097 can be set to switch on the bypass at a defined voltage level on VIN. For example, setting R1
and R2 to 200K Ωwould set VEN to half of VIN. The voltage level of VIN engaging the bypass switch is based on
the VIL level of EN (0.65 V). If VIN is less than 1.30 V then the bypass switch will be enabled. For VIN values
above 1.50 V (50% of VIH) the bypass switch is disabled.
18 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
TPS61097-33
V
0.9 V to 3.3V
IN
VOUT
EN
L
GND
VIN
L1
R2
R1
C1
C2
V
+3.3V
OUT
´
´
´
IN OUT IN
OUT
V (V - V )
1
L = f 200 mA V
´
ì
ï´
í
ï
î
OUT OUT
IN
L,MAX
V I + 100 mA; continous current operation
0.8 V
I =
200 mA; discontinuous current operation
´
> ´
OUT OUT
IN
V I 0.8 100 mA
V
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
Figure 19. Adjustable Bypass Switching
Inductor Selection
To make sure that the TPS61097 devices can operate, a suitable inductor must be connected between pin VIN
and pin L. Inductor values of 4.7 μH show good performance over the whole input and output voltage range .
Choosing other inductance values affects the switching frequency fproportional to 1/L as shown in Equation 2.
(2)
Choosing inductor values higher than 4.7 μH can improve efficiency due to reduced switching frequency and
therefore with reduced switching losses. Using inductor values below 2.2 μH is not recommended.
Having selected an inductance value, the peak current for the inductor in steady state operation can be
calculated. Equation 3 gives the peak current estimate.
(3)
IL,MAX is the inductor's required minimum current rating. Note that load transient or over current conditions may
require an even higher current rating.
Equation 4 provides an easy way to estimate whether the device is operating in continuous or discontinuous
operation. As long as the equation is true, continuous operation is typically established. If the equation becomes
false, discontinuous operation is typically established.
(4)
Due to the use of current hysteretic control in the TPS61097, the series resistance of the inductor can impact the
operation of the main switch. There is a simple calculation that can ensure proper operation of the TPS61097
boost converter. The relationship between the series resistance (RIN), the input voltage (VIN) and the switch
current limit (ISW) is shown in Equation 5.
RIN < VIN / ISW (5) (5)
Examples:
ISW = 400 mA, VIN = 2.5 V (6) (6)
In Equation 6, RIN < 2.5 V / 400 mA; therefore, RIN must be less than 6.25 Ω.
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 19
³ ´
2
L
C
2
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
ISW = 400 mA, VIN = 1.8 V (7) (7)
In Equation 7, RIN < 1.8 V / 400 mA; therefore, RIN must be less than 4.5 Ω.
The following inductor series from different suppliers have been used with TPS61097 converters:
Table 3. List of Inductors
VENDOR INDUCTOR SERIES
Coilcraft DO3314
TDK NLC565050T
Taiyo Yuden CBC2012T
Capacitor Selection
Input Capacitor
The input capacitor should be at least 10-μF to improve transient behavior of the regulator and EMI behavior of
the total power supply circuit. The input capacitor should be a ceramic capacitor and be placed as close as
possible to the VIN and GND pins of the IC.
Output Capacitor
For the output capacitor C2, it is recommended to use small ceramic capacitors placed as close as possible to
the VOUT and GND pins of the IC. If, for any reason, the application requires the use of large capacitors which
can not be placed close to the IC, the use of a small ceramic capacitor with an capacitance value of around
2.2μF in parallel to the large one is recommended. This small capacitor should be placed as close as possible to
the VOUT and GND pins of the IC.
A minimum capacitance value of 4.7 μF should be used, 10 μF are recommended. If the inductor value exceeds
4.7 μH, the value of the output capacitance value needs to be half the inductance value or higher for stability
reasons, see Equation 8.
(8)
The TPS61097 is not sensitive to the ESR in terms of stability. Using low ESR capacitors, such as ceramic
capacitors, is recommended to minimize output voltage ripple. If heavy load changes are expected, the output
capacitor value should be increased to avoid output voltage drops during fast load transients.
Table 4. Recommended Output Capacitors
VENDOR CAPACITOR SERIES
Murata GRM188R60J106M47D 10μF 6.3V X5R 0603
Murata GRM319R61A106KE19 10μF 10V X5R 1206
20 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
TPS61097
www.ti.com
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
Layout Considerations
As 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 and output capacitor, as well as the inductor should be placed as close as possible to the IC.
Use a common ground node for power ground and a different one for control ground to minimize the effects of
ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC.
The feedback divider should be placed as close as possible to the control ground pin of the IC. To lay out the
control ground, it is recommended to use short traces as well, separated from the power ground traces. This
avoids ground shift problems, which can occur due to superimposition of power ground current and control
ground current.
Figure 20. Layout Schematic
Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 21
TPS61097
SLVS872B –JUNE 2009–REVISED DECEMBER 2009
www.ti.com
Figure 21. PCB Top View
Thermal Information
Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires
special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added
heat sinks and convection surfaces, and the presence of other heat-generating components affect the
power-dissipation limits of a given component.
Three basic approaches for enhancing thermal performance are listed below.
• Improving the power dissipation capability of the PCB design
• Improving the thermal coupling of the component to the PCB
• Introducing airflow in the system
The maximum recommended junction temperature (TJ) of the TPS61097 devices is 125°C. Specified regulator
operation is assured to a maximum ambient temperature TAof 85°C. Therefore, the maximum power dissipation
is about TBD mW. More power can be dissipated if the maximum ambient temperature of the application is
lower.
22 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated
PACKAGING INFORMATION
Orderable Device Status (1) Package
Type Package
Drawing Pins Package
Qty Eco Plan (2) Lead/Ball Finish MSL Peak Temp (3)
TPS61097-33DBVR ACTIVE SOT-23 DBV 5 3000 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
TPS61097-33DBVT ACTIVE SOT-23 DBV 5 250 Green (RoHS &
no Sb/Br) CU NIPDAU Level-1-260C-UNLIM
(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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
PACKAGE OPTION ADDENDUM
www.ti.com 11-Sep-2009
Addendum-Page 1
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
TPS61097-33DBVR SOT-23 DBV 5 3000 180.0 9.2 3.23 3.17 1.37 4.0 8.0 Q3
TPS61097-33DBVT SOT-23 DBV 5 250 180.0 9.2 3.23 3.17 1.37 4.0 8.0 Q3
PACKAGE MATERIALS INFORMATION
www.ti.com 11-Sep-2009
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
TPS61097-33DBVR SOT-23 DBV 5 3000 205.0 200.0 33.0
TPS61097-33DBVT SOT-23 DBV 5 250 205.0 200.0 33.0
PACKAGE MATERIALS INFORMATION
www.ti.com 11-Sep-2009
Pack Materials-Page 2
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