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TPS61291
SLVSBX9A – SEPTEMBER 2014 – REVISED SEPTEMBER 2014

TPS61291 Low Iq Boost Converter with Bypass Operation
1 Features
•
•
•
•
•
•
•
•
1

•
•
•
•
•

In bypass mode the integrated feedback divider
network for boost mode operation is disconnectedfrom the output and the quiescent current
consumption drops down to only 15nA (typical).

Input Voltage Range 0.9V to 5V
Startup Voltage 1.5V at 20mA Load
Pin Selectable Output Voltages: 3.3V, 3V, 2.5V
15nA typical Quiescent Current in Bypass Mode
5.7μA typical Quiescent Current in Boost Mode
Bypass Switch from VIN to VOUT
IOUT > 200mA at 3.3V VOUT, VIN = 1.8V
Internal Feedback Divider Disconnect (Bypass
Mode)
Controlled Bypass Transition Prevents Reverse
Current into Battery
Power-Save Mode at Light Loads
Overtemperature Protection
Redundant Overvoltage Protection
Small 2mm x 2mm SON 6-pin package

In boost mode the device provides a minimum output
current of 200mA at 3.3V VOUT from 1.8V VIN. The
boost mode is used for system components which
require a regulated supply voltage and cannot directly
operate from the input source. The boost converter isbased on a current-mode controller usingsynchronous rectification to obtain maximum
efficiency and consumes typically 5.7uA from theoutput. During startup of the boost converter, the
VSEL pin is read out and the integrated feedback
network sets the output voltage to 2.5V, 3V or 3.3V.
Bypass mode or boost mode operation is controlled
by the system via the EN/BYP pin.
The device integrates an enhanced bypass mode
control to prevent charge, stored in the output
capacitor during boost mode operation, from flowing
back to the input and charging the battery.

2 Applications••••

Metering (Gas, Water, Smart Meters)
Remote Controls
Home Security / Home Automation
Single 3V Li-MnO2 or 2 x 1.5V Alkaline Cell
Powered Applications

The device is packaged in a small 6-pin SON
package (DRV) measuring 2.0mm × 2.0mm x
0.75mm.
Device Information(1)PART NUMBER

PACKAGEBODY SIZE (NOM)

3 Description

TPS61291

SON (6)2.00 mm x 2.00 mm

The TPS61291 is a boost converter with pin
selectable output voltages and an integrated bypass
mode. In bypass operation, the device provides a
direct path from the input to the system and allows a
low power micro controller (MCU) such as the
MSP430 to operate directly from a single 3V Li-MnO2
battery or dual alkaline battery cells.

(1) For all available packages, see the orderable addendum atthe end of the datasheet.

Simplified Schematic and Efficiency Curves
100

TPS61291

2 x 1.5V Alkaline /1 x 3V Li-MnO2
+
+
-

+
-

VBAT
CIN
10mF

SW

VOUT =
Step upconverter VOUT VBAT / 3.3V

VIN

COUT
22mF

Bypass

VSEL
GND

95

Subsystem

90

VCC = 3.3V

MCU
(VCC = VBAT or 3.3V)

85
Efficiency [%]L = 3.3mH

80
75
VIN = 1.2V

70

VIN = 1.8V

EN/BYP

65

VIN = 2.5V

60

VIN = 3.0V

55
50
0.01

0.1

1

10

100

Output Current IOUT [mA]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.

TPS61291
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Table of Contents
1
2
3
4
5
6

Features .................................................................. 1
Applications ........................................................... 1
Description ............................................................. 1
Revision History..................................................... 2
Pin Configuration and Functions ......................... 3
Specifications......................................................... 4
6.1
6.2
6.3
6.4
6.5
6.6

7

Absolute Maximum Ratings ...................................... 4
Handling Ratings....................................................... 4
Recommended Operating Conditions....................... 4
Thermal Information ................................................. 4
Electrical Characteristics........................................... 5
Typical Characteristics .............................................. 6

Detailed Description .............................................. 7
7.1 Overview ................................................................... 7
7.2 Functional Block Diagram ......................................... 7
7.3 Feature Description................................................... 7

7.4 Device Functional Modes.......................................... 88

Applications and Implementation ...................... 10
8.1 Application Information............................................ 10
8.2 Typical Application .................................................. 10

9 Power Supply Recommendations...................... 16
10 Layout................................................................... 16
10.1 Layout Guidelines ................................................. 16
10.2 Layout Example .................................................... 16

11 Device and Documentation Support ................. 17
11.1
11.2
11.3
11.4
11.5

Device Support .................................................... 17
Documentation Support ........................................ 17
Trademarks ........................................................... 17
Electrostatic Discharge Caution ............................ 17
Glossary ................................................................ 17

12 Mechanical, Packaging, and Orderable
Information ........................................................... 17

4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Original (September 2014) to Revision A

Page

•

Changed "Bypass Mode Operation" description ................................................................................................................... 9•

Added sub-section "Controlled Transition into Bypass Mode" .............................................................................................. 9•

Added NOTE to the "Application and Implementation" section. .......................................................................................... 10•

Changed "List of Inductors" table ........................................................................................................................................ 112

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5 Pin Configuration and Functions

SW
VOUT
VIN

1
2
3

TH E
ER XP
M OS
A ED
L
PA
D

DRV Package
6 Pin
Top View

6
5
4

GND
VSEL
EN/BYP

Pin Functions
PIN
NAME

NO.

I/O

DESCRIPTION

SW

1

I

Switch node of the converter. Connect the inductor between this pin and the input capacitor
CIN.

VOUT

2

O

Boost converter output. Connect the output capacitor COUT between this pin and GND close
to the device.

VIN

3

PWR

Input voltage supply pin for the boost converter. Connect the input capacitor CIN between
this pin and GND as close as possible to the device.

EN/BYP

4

I

Control pin of the device. A high level enables the boost mode operation. A low leveldisables the boost converter and enables bypass mode operation. EN/BYP must be actively
terminated high or low. Usually, this pin is controlled by the MCU in the system.

VSEL

5

I

Output voltage selection pin. The logic level of this pin is read out during startup andinternally latched. Connect this pin only to GND, VOUT, or leave it floating.

GND

6

PWR

Ground pin of the device.

NC

Not electrically connected to the IC, but must be soldered to achieve specified thermal
performance. Connect this pad to the GND pin and use it as a central GND plane.

EXPOSEDTHERMAL
PAD

Output Voltage Setting
EN/BYP Pin

VSEL Pin at Startup

VOUT

Mode

high

GND

3.3V

Boost Mode Operation

high

VOUT

3.0V

high

floating

2.5V

low

GND / VOUT / floating

VOUT = VIN (Bypass Mode)

Bypass Mode Operation

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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
Pin Voltage Range (2)

(1)
(2)

MIN

MAX

VIN

-0.3

5.5

UNIT

SW

-0.3

7

EN/BYP, VOUT

-0.3

5.5

VSEL

-0.3

VOUT +
0.3V

Output Current

In Bypass Operation (EN/BYP = GND)

TJ

Maximum Junction Temperature

-40

V

250

mA

150

°C

Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltage values are with respect to network ground terminal GND.

6.2 Handling Ratings
Tstg

V(ESD)

(1)
(2)

MIN

MAX

–65

150

Human body model (HBM) per ANSI/ESDA/JEDEC
JS-001, all pins (1)-22Charged device model (CDM), per JEDEC
specification JESD22-C101, all pins (2)

-0.5

0.5

Storage temperature range

Electrostatic discharge

UNIT
°C

kV

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
VIN

NOM

MAX

Supply voltage for startup

1.5

Supply voltage range (once device has started)

0.9

5
VOUT

Supply voltage range for step up conversion (once device has started)

0.9

TA

Operating ambient temperature

-40

85

TJ

Operating junction temperature

–40

125

UNIT
V

°C

6.4 Thermal Information
TPS61291
THERMAL METRIC (1)DRV (2x2 SON)UNIT

6 PINS
RθJA

Junction-to-ambient thermal resistance

71.2

RθJCtopJunction-to-case (top) thermal resistance

93.5

RθJB

Junction-to-board thermal resistance

46.7

ψJT

Junction-to-top characterization parameter

2.5

ψJB

Junction-to-board characterization parameter

41.1

RθJCbot

Junction-to-case (bottom) thermal resistance

11.1

(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
TA = –40°C to 85°C. Typical values are at TA = 25°C (unless otherwise noted)
PARAMETERTEST CONDITIONS

MIN

TYP

MAX

UNIT

SUPPLY
VIN
IQ

Startup voltage

VOUT = 3.3V, IOUT = 20mA

Input voltage range

Operating voltage range

Quiescent current in boost mode

VIN
VOUT

Quiescent current in bypass mode

VIN

1.5
0.9

IOUT = 0 mA, VEN/BYP = VIN = 1.8 V, VOUT =3.3V, device not switching

V

5
0.4

1.5

5.7

9

VEN/BYP = low, VIN = 3 V, IOUT = 0 mA

0.015

0.5

μA
μA

ILkSW

Leakage current into SW

VEN/BYP = low, VIN = 1.2 V, VSW = 1.2 V

0.01

0.5

VUVLO

Undervoltage lockout threshold

VIN decreasing

0.65

0.9

Overtemperature protection

TJ rising

140

°C

20

°C

Overtemperature hysteresis

V

INPUTS
IIN

EN/BYP, input current

EN/BYP = low or EN/BYP = VIN

0.01

VIN ≤ 1.5 V
VIL

EN/BYP, input low voltage
5 V > VIN > 1.5 V
VIN ≤ 1.5 V

0.1

μA

0.2 ×
VIN

V

0.3
0.8 ×
VIN

V

VIH

EN/BYP, input high voltage

VIL

VSEL, input low voltage

VEN/BYP = high

VIH

VSEL, input high voltage

VEN/BYP = highIIN

VSEL, input current

VEN/BYP = high, VSEL = VOUT = 3V

0.01

Rectifying switch on resistance

VOUT = 3.3 V

0.6Ω

Main switch on resistance

VOUT = 3.3 V

0.4Ω

Bypass switch on resistance

VIN = 1.8V, IOUT = 50 mA, EN/BYP = low

1.2

Switch current limit

VOUT = 3.3V

Output voltage accuracy

VIN = 1.8V, IOUT = 10 mA, VOUT 3.3V, 3.0V,
2.5V, EN/BYP = highLine regulation

VOUT = 3.3V, VIN = 2V to 3.0V, IOUT = 50
mA, EN/BYP = high

+0.15

%/V

Load regulation

VIN = 2V, VOUT = 3.3V, IOUT = 1 mA to 200
mA, EN/BYP = high-0.007%/mA

Output overvoltage protection

VOUT rising, EN/BYP = high

5 V > VIN > 1.5 V

1.2
0.3

V

VOUT 0.3

V
μA

0.1

POWER SWITCHESRDS(ON)
ISW

Ω

700

1000

1300

mA

-2

+1

+4

%

OUTPUT

VOUT

VOVP

5.4

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6.6 Typical Characteristics
0.14

1
VIN = 1.8V

VIN = 3.3V

0.8

Quiescent Current IQ into VIN [mA]

Bypass Mode Quiescent Current IQ [mA]

0.12

VIN = 1.8V

VIN = 2.5V

0.9

0.1

0.08

0.06

0.04

VIN = 2.5V

0.7
0.6
0.5
0.4
0.3
0.2

0.02

0.1
0

0
-40

-20

0

20

40

60

80

100

-40

-20

0

Temperature T A [°C]

20

40

60

80

C001

EN/BYP = low

VSEL = low

IOUT = 0mA

Figure 1. Quiescent Current IQ into VIN Pin in Bypass Mode

C001

EN/BYP = high

1.6
VIN 1.8V

VOUT = 2.6V
VOUT = 3.1V

7

1.4

VOUT = 3.4V
1.2

6
RDSON Bypass Switch [W]Quiescent Current IQ into VOUT [mA]

Boost mode operation
Device not switching

Figure 2. Quiescent Current IQ into VIN Pin in Boost Mode

8

5
4
3

1
0.8
0.6

2

0.4

1

0.2
0

0
-40

-20

0

20

40

60

80

-40

100

-20

0

EN/BYP = high
IOUT = 0mA

40

60

80

Boost mode operation
Device not switching

100

C001

Figure 3. Quiescent Current IQ into VOUT Pin in Boost Mode

Figure 4. RDSON Bypass Switch

1

1

0.9

0.9

0.8

0.8

0.7

0.7

RDSON Rectifier Switch [W]

RDSON Main Switch [W ]20

Temperature T A [°C]

Temperature T A [°C]]

0.6
0.5
0.4
0.3

0.6
0.5
0.4
0.3

0.2

0.2

0.1

0.1
0

0
-40

-20

0

20

40

60

80

100

-40

-20

0

20

40

60

80

100

Temperature T A [°C]

Temperature T A [°C]

VOUT = 3.3V
Figure 5. RDSON Main Switch

6100

Temperature TA [°C]

C001

VOUT = 3.3V
Figure 6. RDSON Rectifier Switch

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7 Detailed Description
7.1 Overview
The TPS61291 provides two operating modes: high efficiency boost mode to generate an output voltage higher
than the input voltage and bypass mode, which connects the output of the device directly to the input.

7.2 Functional Block Diagram

BypassSwitch

P

VIN

SW

VOUT

N

Rectifying
SwitchVOUT
Driver
VIN
N

Bypass Switch
Control
Control Logic

EN/BYP

Main
SwitchCurrent
Sense

Startup Circuit
VIN
Undervoltage
Lockout
Overvoltage
Protection
BYP/EN
Reference Vref

Vref

GND

Voltage Error
Amplifiervoltage selection logic

Thermal Shutdown

VSEL

integrated FB divider
network with disconnect

7.3 Feature Description
7.3.1 Bypass / Boost Mode Operation EN/BYP
The EN/BYP pin selects the operating mode of the device. With the EN/BYP pin pulled low, the device operates
in bypass mode. With a high level on the EN/BYP pin, the device operates as a boost converter. The EN/BYP
pin is usually controlled by an I/O pin of a MCU, powered from the output of the TPS61291 and should not be left
floating. See Figure 8. See also sections Boost Mode Operation and Bypass Mode Operation for more detailed
descriptions.

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Feature Description (continued)
7.3.2 Output Voltage Selection VSEL
In boost mode operation, the device supports three internally set output voltages: 2.5V, 3V and 3.3V. Leaving the
VSEL pin open sets the output voltage to 2.5V, VSEL = VOUT to 3.0V and VSEL= GND to 3.3V. The VSEL pin
condition is detected during the startup of the boost converter and internally latched. For proper operation, it must
be connected to either GND, VOUT or left floating. Depending on the VSEL condition, an integrated feedback
divider network is selected. Changing the VSEL pin condition during operation does not change the output
voltage.
7.3.3 Feedback Divider Disconnect
In boost mode operation, the integrated feedback divider network, which is required for regulation, is connectedto the VOUT pin. To achieve the low quiescent current in bypass mode, the integrated feedback divider network
is disconnected from the output pin VOUT.
7.3.4 Undervoltage Lockout
An undervoltage lockout function stops the operation of the boost converter if the input voltage drops below theundervoltage lockout threshold. This function is implemented in order to prevent malfunction of the boost
converter. The undervoltage lockout function has no control of the bypass switch.
7.3.5 Overtemperature Protection
The device has a built-in temperature sensor which monitors the internal junction temperature in boost mode
operation. If the junction temperature exceeds the threshold (140 °C typical), the device stops operating. As soon
as the junction temperature has decreased below the programmed threshold, it starts operating again. There is abuilt-in hysteresis to avoid unstable operation at IC temperatures at the overtemperature threshold. The
overtemperature protection is not active in bypass mode operation.
7.3.6 Overvoltage Protection
In boost mode operation (EB/BYP = high), the device features a redundant over voltage protection circuit (OVP),
which is independent from the reference, the regulation loop and feedback divider network. The redundant overvoltage protection circuit limits the output voltage to typically 5.4V. The over voltage protection can only limit theoutput voltage in boost mode operation, when the input voltage VIN is smaller than the output voltage VOUT.

7.4 Device Functional Modes
7.4.1 Boost Mode Operation
The device is enabled and operates in boost mode operation when the EN/BYP pin is set high. The bypass
switch is turned off once the boost converter has started switching.
In boost mode operation, 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 300 mA and adjusting the offsetof 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. To achieve high efficiency, the power stage is realized as a synchronous
boost topology.

IL

Continuous Current Operation
IIN

Discontinuous Current Operation
Ilpp =
300 mA (typ.)Ilpp =
300 mA (typ.)tFigure 7. Hysteretic Current Operation

8

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Device Functional Modes (continued)
The output voltage VOUT is monitored via the integrated feedback network which is connected to the voltage error
amplifier. To regulate the output voltage, the voltage error amplifier compares this feedback voltage to theinternal voltage reference and adjusts the required offset of the inductor current accordingly.
The hysteretic current mode architecture allows fast response to load variations.
7.4.2 Bypass Mode Operation
The TPS61291 includes a P-channel MOSFET (Bypass Switch) between the VIN and VOUT pins. When the IC
is disabled (EN/BYP = low), bypass mode is activated to provide a direct, low impedance connection from the
input voltage (at the VIN pin) to the load (VOUT). The bypass switch is not impacted by undervoltage lockout, or
thermal shutdown. The bypass switch is not current-limit controlled. In bypass operation, the OVP circuit isdisabled.
7.4.3 Controlled Transition into Bypass Mode
When changing from boost mode into bypass mode, the output capacitor is usually charged up to a higher
voltage than the battery voltage VBAT. In order to prevent current flowing from the output capacitor COUT via thebypass switch into the battery (reverse battery current), the internal bypass control circuit delays the bypass
switch activation until the output voltage VOUT has decreased to the input voltage level.
7.4.4 Operation at Output Overload
If the peak inductor current reaches the internal switch current limit threshold in boost mode operation, the main
switch is turned off to stop a further increase of the input current. In this case the output voltage will decreasesince the device cannot provide sufficient power to maintain the set output voltage. If the output voltage drops
below the input voltage, the backgate diode of the rectifying switch gets forward biased and current starts to flow
through it. Because this diode cannot be turned off, the load current is only limited by the remaining DC
resistance. As soon as the overload condition is removed, the converter automatically resumes normal operationand enters the appropriate soft start mode depending on the operating conditions.
7.4.5 Startup
After the EN/BYP 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 switchingfrequency is controlled by the oscillator and the switch current is limited. As soon as the device has built up theoutput voltage to about 1.8 V, high enough for supplying the control circuit, the device switches to its normal
hysteretic current mode operation.

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8 Applications 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 TPS61291 is a boost converter with pin selectable output voltages and an integrated bypass mode. In
bypass operation, the device provides a direct path from the input to the system and allows a low power microcontroller (MCU) to operate directly from a single 3V Li-MnO2 battery or dual alkaline battery cells. In bypass
mode, the quiescent current consumption is typically only 15nA and supports low power modes of MCUs such as
the MSP430. In boost mode operation, the device provides a regulated output voltage (e.g. 3.3V) to supply
circuits which require a higher voltage than provided by the battery. See Figure 8.
The device also extends battery life in applications which can run partially directly from the battery, but need aboost conversion to maintain sufficient system voltage when the battery voltage drops due to discharge. In thiscase, the system runs off the battery in bypass mode operation until the battery voltage trips the minimum
system operating voltage. Then the system turns on the boost converter, providing a sufficient output voltage
down to the cut off voltage of the battery. See Figure 9 and Figure 26.

8.2 Typical Application
TPS61291
L = 3.3mH

2 x 1.5V Alkaline /1 x 3V Li-MnO2++-

Subsystem

VOUT =
Step upconverter VOUT VBAT / 3.3V

VIN

COUT
22mF

Bypass

CIN
10mF

+
-

SW

VCC = 3.3V

MCU
(VCC = VBAT or 3.3V)

VSEL
GND

EN/BYP

Figure 8. Typical Application Circuit with Regulated 3.3V VOUT / VBAT

L = 3.3mH

2 x 1.5V Alkaline /1 x 3V Li-MnO2
+
+
-

VBAT
CIN

+
-

NC

TPS61291

SystemVOUT =
Step upV/ 2.5VBAT
converter VOUT

MCU + ADC

COUT

SubsystemSW
VIN

BypassVSEL
GND

EN/BYP

EN/BYP set high
@ VBAT = 2.2V

Minimum VCC for System: 2.2V
Bypass Mode:
VOUT = VBAT (for VBAT > 2.2V)
Boost Mode:
VOUT = 2.5V (for VBAT < 2.2V)

Figure 9. Bypass Mode / Boost Mode Operation to Maintain Sufficient System Voltage
8.2.1 Design Requirements
The TPS61291 is a highly integrated boost converter. The output voltage is set internally via a VSEL pin without
any additional components. For operation, only an input capacitor, output capacitor, and an inductor are required.
Table 1 shows the components used for the application characteristic curves.

10

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Typical Application (continued)
Table 1. Components for Application Characteristic Curves (1)(1)

Reference

Description

TPS61291

Low Iq Boost Converter with
Bypass Operation

Value

Manufacturer
Texas Instruments

CIN

Input capacitor

10µF

Murata

GRM219R61A106KE44D

COUT

Output capacitor

22µF

Murata

GRM21BR60J226ME39L

L

Inductor

3.3µH

Coilcraft

LPS3314 3R3

See the Third-Party Products Disclaimer in the Device Support section.

8.2.2 Detailed Design Procedure
The external components have to fulfill the needs of the application but also the stability criteria of the device's
control loop. The TPS61291 is optimized to work within a range of L and C combinations. The LC output filter
inductance and capacitance must be considered together. The output capacitor sets the corner frequency of theconverter while the inductor creates a Right-Half-Plane-Zero degrading the stability of the converter.
Consequently with a larger inductor a bigger capacitor has to be used to guarantee a stable loop. Table 2 shows
the output filter component selection.
Table 2. Recommended LC Output Filter Combinations
Output voltage[V]
3.3 / 3.0
2.5
(1)
(2)
(3)

Output capacitor value [µF] (2)Inductor value [µH] (1)2222 + 102 x 22

(3)

√

√

√

√

√

(3)

√

√

3.3

√

4.7
2.2

√

3.3

Inductor tolerance and current de-rating is anticipated. The effective inductance can vary by 20% and -30%.
Capacitance tolerance and bias voltage de-rating is anticipated. The effective capacitance can vary by 20% and -50%.
This LC combination is the standard value and recommended for most applications.

8.2.2.1 Inductor Selection
The device is optimized to operate with a 3.3µH inductor value. Other inductor values can be used, per Table 2.
The maximum inductor current can be approximated by the ILMAX, from Equation 1. For proper operation, theinductor needs to be rated for a saturation current which is higher than the switch current limit of typically 1A.
Table 3 lists inductors that have been tested with the TPS61291.
V´I
IL max : = OUT OUT + 150 mA continuous current operation
0.8 ´ VIN

IL max : = 300 mA

discontinuous current operation(1)

Table 3. List of Inductors (1)(1)

INDUCTANCEDIMENSIONS [mm3]

TYPE

3.3

3.3 x 3.3 x 1.3

LPS3314

3.3

2.95 x 2.95 x 1.4

LPS3015

3.3

3 x 2.5 x 1.5

VLF302515

TDK

3.3

2 x 2 x 1.2

MDMK2020T3R3M

Taiyo Yuden

3.3

2.5 x 2.0 x 1.2

DFE252012

Toko

3.3

3.0 x 3.0 x 1.574438335033

Würth

SUPPLIER
Coilcraft

See the Third-Party Products Disclaimer in the Device Support section.

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8.2.2.2 Input and Output Capacitor Selection
For best output and input voltage filtering, low ESR X5R or X7R ceramic capacitors are recommended. The input
capacitor minimizes input voltage ripple, suppresses input voltage spikes and provides a stable system rail forthe device. At least a 10μF or larger input capacitor is recommended for operation. In applications in which thepower source (e.g. certain battery chemistries) shows an internal resistance characteristic, a larger input
capacitor might be used to buffer the supply voltage for the TPS61291. The recommended typical output
capacitor value is 22 μF and can vary as outlined in the output filter selection Table 2.

12

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100

100

95

95

90

90

85

85
Efficiency [%]Efficiency [%]8.2.3 Application Curves

80
75
VIN = 1.2V

70

80
75

VIN = 1.2V

70

VIN = 1.8V

VIN = 1.8V
65

VIN = 2.5V

60

VIN = 3.0V

VIN = 2.5V

65

VIN = 2.7V
60
55

55
50
0.01

0.1

1

10

50
0.01

100

0.1

1

10

100

Output Current IOUT [mA]

Output Current IOUT [mA]

C002

C002

EN/BYP = highL = 3.3µH

VSEL = GND

EN/BYP = highL = 3.3µH

VSEL = VOUT

Figure 11. Efficiency vs IOUT, VOUT = 3.0V

Figure 10. Efficiency vs IOUT, VOUT = 3.3V
100

3.399

95

Output Voltage VOUT [V]90

Efficiency [%]

85

80
75
VIN = 1.2V

70

VIN = 1.8V

65

3.366

3.333
VIN = 1.2V
VIN = 1.8V

VIN = 2.2V

3.300

VIN = 2.5V

60

VIN = 3.0V

55
50
0.01

0.1

1

10

3.267
0.01

100

0.1

Output Current IOUT [mA]

1

10

100

Output Current IOUT[mA]
C006

C001

EN/BYP = highL = 3.3µH

VSEL = open

3.090

2.575

3.060

2.550

3.030

VIN = 1.2V
3.000

L = 3.3µH

2.525

VIN = 1.2V
VIN = 1.8V

2.500

VIN = 1.8V

VIN = 2.2V

VIN = 2.5V

2.970
0.01

0.1

1

10

2.475
0.01

100

Output Current IOUT [mA]

0.1

1

10

L = 3.3µH

100

Output Current IOUT [mA]C005

EN/BYP = high

VSEL = GND

Figure 13. Output Voltage vs Output Current VOUT = 3.3V

Output Voltage VOUT [V]Output Voltage VOUT [V]Figure 12. Efficiency vs IOUT, VOUT = 2.5V

EN/BYP = high

VSEL = VOUT

Figure 14. Output Voltage vs Output Current VOUT = 3.0V

C004

EN/BYP = highL = 3.3µH

VSEL = open

Figure 15. Output Voltage vs Output Current VOUT = 2.5V

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35

0.600

T A = 25°C

T A = 85°C
25

0.400

0.300

Input Current IIN [uA]

Maximum Output Current IOUTMAX [A]T A = -40°C

30

0.500

VOUT = 2.5V
VOUT = 3.0V
VOUT = 3.3V

0.200

20

15

10
0.100

5

0.000

0
0.5

1.0

1.5

2.0

2.5

3.0

3.5

0.9

1.4

1.9

Input Voltage VIN [V]

2.4

2.9

Input Voltage VIN [V]
C001

EN/BYP = highL = 3.3µH

ISW = 1000mA (typical)
Boost mode operation

Figure 16. Maximum Output Current

VOUT = 3.3 V
IOUT = 0 mA

L = 3.3 µH

COUT = 22 µF
Device switching

Figure 17. Supply Current vs. VIN, VOUT = 3.3V, IOUT = 0mA

3530
T A = 25°C

T A = 25°C

T A = -40°C

30

T A = -40°C

25

T A = 85°C

T A = 85°C

Input Current IIN [uA]

Input Current IIN [uA]

25

20

15

20

15

10

10
5

5

0

0
0.9

1.4

1.9

2.4

2.9

0.9

1.4

Input Voltage VIN [V]

VOUT = 3.0 V
IOUT = 0 mA

L = 3.3 µH

COUT = 22 µF
Device switching

Figure 18. Supply Current vs. VIN, VOUT = 3.0V, IOUT = 0mA

VIN = 2.0 V
VOUT = 3.3 V

L = 3.3 µH
IOUT = 15mA

VOUT = 2.5 V
IOUT = 0 mA

2.4

L = 3.3 µH

COUT = 22 µF
Device switching

Figure 19. Supply Current vs. VIN, VOUT = 2.5V, IOUT = 0mA

COUT = 22 µF
VSEL = GND
EN/BYP = highFigure 20. Discontinuous Conduction Mode Operation,
VOUT = 3.3V

14

1.9
Input Voltage VIN [V]

VIN = 1.8 V
VOUT = 3.3 V
VSEL = GND

L = 3.3 µH

COUT = 22 µF
IOUT = 150 mA
EN/BYP = highFigure 21. Continuous Conduction Mode Operation,
VOUT = 3.3V

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VIN = 1.8V
VOUT = 3.3V

L = 3.3µH

COUT = 22 µF
VSEL = GND
ILOAD 20mA /150mA

VIN = 1.8V
VOUT = 3.3V

Figure 22. Load Transient Response

L = 3.3µH

COUT = 22 µF
VSEL = GND
ILOAD 1mA/200mA

Figure 23. AC Load Sweep

Boost operation
Bypass switch activation
when VOUT is discharged to VIN level
Bypass mode

VIN = 2.5V/3V
VOUT = 3.3V

L = 3.3µH
VSEL = GND

COUT = 22 µF
Load =100Ω

Figure 24. Line Transient Response

VIN = 2.0V
VOUT = 3.3V

L = 3.3µH
VSEL = GND

COUT = 22 µF
RLOAD = 1kΩ

Figure 25. Boost Mode / Bypass Mode Transition

VIN
VOUT = 2.5V
VOUT
tracks VIN
VIN < 2.2V

EN/BYP control

IL

VIN = 0.9V to 3V
VOUT = 2.5V

VSEL = OpenILOAD = 5mA
EN/BYP externally controlled
Bypass / Boost mode operation

VIN = 2.0V
VOUT = 3.3V

Figure 26. Bypass / Boost Mode Operation

L = 3.3µH
VSEL = GND

COUT = 22 µF
RLOAD = 100ΩFigure 27. Startup in Boost Mode

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9 Power Supply Recommendations
The input power supply needs to have a current rating according to the supply voltage, output voltage and output
current of the TPS61291.

10 Layout10.1 Layout Guidelines
As for all switching power supplies, the layout is an important step in the design. Care must be taken in board
layout to get the specified performance. If the layout is not carefully done, the regulator could show poor line
and/or load regulation, stability issues as well as EMI problems. It is critical to provide a low inductance, low
impedance ground path. Therefore, use wide and short traces for the main current paths. In a boost converter,
the ripple current on the output is larger than the ripple current on the input. The output capacitor needs to beplaced as close as possible between the VOUT and the GND pins. The input capacitor should be placed as
close as possible to the VIN and GND pins. Place the inductor close by the IC and connect it with short and thicktraces to the IC. Avoid current loops to minimize radiated noise and stray fields. The exposed thermal pad of the
package and the GND pin must be connected. See Figure 28 for the recommended PCB layout.

10.2 Layout Example

2

Area: ~ 51 mm
VIN

VOUT

GND

U1
CIN

L

GND

COUT

Figure 28. Recommended PCB Layout

16

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SLVSBX9A – SEPTEMBER 2014 – REVISED SEPTEMBER 201411 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOTCONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHERALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.

11.2 Documentation Support
11.2.1 Related Documentation
TPS61291EVM-569 User's Guide, SLVUA29

11.3 Trademarks
11.4 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.

11.5 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 mostcurrent data available for the designated devices. This data is subject to change without notice and revision ofthis document. For browser-based versions of this data sheet, refer to the left-hand navigation.

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PACKAGE OPTION ADDENDUM

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28-Sep-2014

PACKAGING INFORMATION
Orderable Device

Status(1)

Package Type Package Pins Package
Drawing
Qty

Eco Plan

Lead/Ball Finish

MSL Peak Temp

(2)

(6)

(3)

Op Temp (°C)

Device Marking(4/5)

TPS61291DRVR

ACTIVE

SON

DRV

6

3000

Green (RoHS& no Sb/Br)

CU NIPDAU

Level-2-260C-1 YEAR

-40 to 85

PC4I

TPS61291DRVTACTIVE

SON

DRV

6

250

Green (RoHS& no Sb/Br)

CU NIPDAU

Level-2-260C-1 YEAR

-40 to 85

PC4I

(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 thatlead 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 weightin homogeneous material)(3)

MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4)

There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5)

Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuationof the previous line and the two combined represent the entire Device Marking for that device.
(6)

Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
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 andcontinues 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.

Addendum-Page 1

SamplesPACKAGE OPTION ADDENDUM

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28-Sep-2014

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.

Addendum-Page 2

PACKAGE MATERIALS INFORMATION
www.ti.com

1-Oct-2014

TAPE AND REEL INFORMATION*All dimensions are nominal

DevicePackage Package Pins
Type Drawing

SPQ

Reel
Reel
A0
Diameter Width (mm)(mm) W1 (mm)

B0
(mm)

K0
(mm)

P1
(mm)

W
Pin1
(mm) Quadrant

TPS61291DRVR

SON

DRV

6

3000

180.0

8.4

2.3

2.3

1.15

4.0

8.0

Q2

TPS61291DRVT

SON

DRV

6

250

180.0

8.4

2.3

2.3

1.15

4.0

8.0

Q2

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION
www.ti.com

1-Oct-2014*All dimensions are nominal

DevicePackage Type

Package Drawing

Pins

SPQ

Length (mm)Width (mm)Height (mm)TPS61291DRVR

SON

DRV

6

3000

210.0

185.0

35.0

TPS61291DRVT

SON

DRV

6

250

210.0

185.0

35.0

Pack Materials-Page 2

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