TI TPS61260DRVR

TPS61260, TPS61261
SLVSA99 – MAY 2011
www.ti.com
TINY LOW INPUT VOLTAGE BOOST CONVERTER
FEATURES
•
•
•
1
•
•
2
•
•
•
•
•
•
•
•
•
•
Up to 95% Efficiency
More than 50 mA Output Current at 3.3 V (VIN
> 0.9 V)
Input Voltage Range from 0.8 V to 4.0 V
Fixed and Adjustable Output Voltage Options
from 1.8 V to 4.0 V
Programmable Average Output Current from
10 mA to 100 mA
Up to 700 mA Switch Current Rating
Power Save Mode for Improved Efficiency at
Low Output Power
Low Quiescent Current
Dynamic Switch Current Limit
Advanced Softstart
Quasi Fixed Frequency Operation at 2.5 MHz
Output Overvoltage Protection
Load Disconnect During Shutdown
Undervoltage Lockout
Available in a 2 × 2 mm, 6-pin SON Package
APPLICATIONS
•
•
•
•
•
•
•
All single or dual cell Alkaline, NiCd or NiMH
Battery Powered Products
High Output Impedance Battery (Coin Cells)
Powered Products
Personal Medical Products
High Power LED's
Wireless Pointing Devices
Wireless Headsets
Industrial Metering Equipment
DESCRIPTION
The TPS6126x devices provide a power supply solution for products powered by either single or dual cell
alkaline, NiCd or NiMH battery. Its unique advanced softstart makes it also suitable for products powered by high
output impedance battery types, like coin cells. Output currents can go as high as 100 mA while using a single
cell alkaline battery, and discharge it down to 0.8 V or lower. The boost converter is based on a quasi fixed
frequency, pulse-width-modulation (PWM) controller using synchronous rectification to obtain maximum
efficiency. At low load currents, the converter enters Power Save Mode to ensure high efficiency over a wide
load current range. The maximum average current in the switches is limited to a programmable value which can
go as high as 700 mA. The output voltage is programmable using an external resistor divider, or is fixed
internally on the chip. In addition to that the average output current can be programmed as well. The converter
will then regulate the programmed output voltage or the programmed output current which ever demands lower
output power. The converter can be disabled to minimize battery drain. During shutdown, the load is
disconnected from the battery. The device is packaged in a 6-pin SON PowerPAD™ package measuring 2 × 2
mm (DRV).
L1
4.7 µH
VIN
0.8 V to 4.0 V
VOUT
L
R1
VIN
C1
10 µF
FB
C2
10µF
VOUT
R2
EN
GND
RI
R3
TPS61260
1
2
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.
PowerPAD is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2011, Texas Instruments Incorporated
TPS61260, TPS61261
SLVSA99 – MAY 2011
www.ti.com
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.
AVAILABLE DEVICE OPTIONS (1)
TA
–40°C to 85°C
(1)
(2)
OUTPUT VOLTAGE
DC/DC
PACKAGE MARKING
Adjustable
QWD
3.3 V
QWE
PART NUMBER (2)
PACKAGE
TPS61260DRV
6-Pin SON
TPS61261DRV
Contact the factory to check availability of other fixed output voltage versions.
For detailed ordering information please check the PACKAGE OPTION ADDENDUM section at the end of this datasheet.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
Voltage range (2)
Temperature range
ESD rating (3)
(1)
(2)
(3)
MIN
MAX
UNIT
VIN, L, VOUT, EN, FB
–0.3
5.0
V
RI
–0.3
3.6
V
Operating virtual junction, TJ
–40
150
°C
Storage, Tstg
–65
150
°C
2
kV
0.5
kV
Human Body Model - (HBM)
Charge Device Model - (CDM)
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 my affect device reliability.
All voltages are with respect to network ground terminal.
ESD testing is performed according to the respective JESD22 JEDEC standard.
THERMAL INFORMATION
THERMAL METRIC
(1)
TPS61260,
TPS61261
DRV
UNITS
6 PINS
θJA
Junction-to-ambient thermal resistance
89
θJC(top)
Junction-to-case(top) thermal resistance
100
θJB
Junction-to-board thermal resistance
35
ψJT
Junction-to-top characterization parameter
2
ψJB
Junction-to-board characterization parameter
36
θJC(bottom)
Junction-to-case(bottom) thermal resistance
8
(1)
2
°C/W
For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953.
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TPS61260, TPS61261
SLVSA99 – MAY 2011
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RECOMMENDED OPERATING CONDITIONS
MIN
NOM
MAX UNIT
Supply voltage at VIN
0.8
4.0
V
Operating free air temperature range, TA
–40
85
°C
Operating junction temperature range, TJ
–40
125
°C
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)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
DC/DC STAGE
VI
Input voltage range
VI
Minimum input voltage for startup
VO
TPS61260 output voltage range
VFB
TPS61260 feedback voltage
0.8
1.8
-40°C < TJ < 85°C
TPS61261 output voltage
ISW
IOUT
Iq
IS
4.0
V
0.8
V
4.0
V
495
500
505
mV
3.27
3.3
3.33
V
7x
Average switch current limit
mA
IOUT
High side switch on resistance
VIN = 1.2 V, VOUT = 3.3 V
Low side switch on resistance
VIN = 1.2 V, VOUT = 3.3 V
1000
mΩ
250
mΩ
Maximum output voltage line regulation
0.5%
Maximum output voltage load regulation
0.5%
Average output current programming range
100
mA
Average output current
RI = 10 kΩ, TA = 25 °C, VIN < VOUT
10
19
20
21
mA
Average output current
RI = 10 kΩ, 0°C < TJ < 60°C, VIN < VOUT
18
20
22
mA
4
7
μA
25
40
μA
Maximum average output current line regulation
0.5%
Maximum average output current load regulation
0.5%
Quiescent
current
VIN
VOUT
IO = 0 mA, VEN = VIN = 1.2 V,
VOUT = 3.3 V
TPS61261 FB input impedance
VEN = HIGH
Shutdown current
VEN = 0 V, VIN = 1.2 V
1
MΩ
0.1
1.5
0.7
0.8
μA
CONTROL STAGE
UVLO
Under voltage lockout threshold
VIN voltage decreasing
0.6
Under voltage lockout threshold hysteresis
200
VIL
EN input low voltage
VIN ≤ 1.8 V, -40°C < TJ < 85°C
VIL
EN input low voltage
VIN > 1.8 V, -40°C < TJ < 85°C
VIH
EN input high voltage
VIN ≤ 1.5 V
0.8 ×
VIN
VIH
EN input high voltage
VIN > 1.5 V
1.2
EN input current
Clamped on GND or VIN
Output overvoltage protection
Copyright © 2011, Texas Instruments Incorporated
V
mV
0.2 ×
VIN
V
0.1
μA
4.5
V
V
0.01
4.0
0.36
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PIN ASSIGNMENTS
DRV PACKAGE
(TOP VIEW)
we
r
Pa
d
GND
Po
RI
EN
FB
GND
VIN
L
VOUT
Pin Functions
PIN
NAME
NO.
I/O
DESCRIPTION
EN
2
I
Enable input. (1 enabled, 0 disabled), must be actively tied high or low.
FB
3
I
Voltage feedback of adjustable versions, must be connected to VOUT on fixed output voltage
versions
L
5
I
Connection for Inductor
RI
1
VIN
6
I
Supply voltage for control stage
VOUT
4
O
Boost converter output
GND
PowerPAD™
4
Average output current programming input. A resistor with a value between 2 kΩ and 20 kΩ must be
connected between RI pin and GND.
Must be soldered to achieve appropriate power dissipation. Must be connected to GND.
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SLVSA99 – MAY 2011
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FUNCTIONAL BLOCK DIAGRAM (TPS61260)
L
VOUT
Current
Sensor
VIN
VOUT
Gate
Control
+
_
Modulator
+
_
+
-
VIN
VOUT
Device
Control
EN
FB
VREF
RI
GND
FUNCTIONAL BLOCK DIAGRAM (TPS61261)
L
VOUT
Current
Sensor
VIN
VOUT
Gate
Control
Modulator
FB
+
_
+
_
VIN
EN
GND
Copyright © 2011, Texas Instruments Incorporated
Device
Control
VOUT
+
-
VREF
RI
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TYPICAL CHARACTERISTICS
TABLE OF GRAPHS
DESCRIPTION
FIGURE
Maximum output current
Efficiency
vs Input voltage (TPS61260, VOUT = {1.8 V; 2.5 V; 4.0 V})
1
vs Input voltage (TPS61261, VOUT = 3.3 V)
2
vs Output current (TPS61260, VOUT = {1.8 V; 2.5 V; 4.0 V})
3
vs Output current (TPS61261, VOUT = 3.3 V)
4
vs Input voltage (TPS61260, VOUT = 1.8 V, IOUT = {10; 20; 50 mA})
5
vs Input voltage (TPS61260, VOUT = 2.5 V, IOUT = {10; 20; 50 mA})
6
vs Input voltage (TPS61260, VOUT = 4.0 V, IOUT = {10; 20; 50; 100 mA})
7
vs Input voltage (TPS61261, VOUT = 3.3V, IOUT = {10; 20; 50 mA})
8
Output current
vs Resistance at RI
9
Output voltage
vs Output current (TPS61260, VOUT = 1.8 V)
10
vs Output current (TPS61260, VOUT = 2.5 V)
11
vs Output current (TPS61260, VOUT = 4.0 V)
12
vs Output current (TPS61261, VOUT = 3.3V)
13
Output current
vs Output voltage
14
Waveforms
Load transient response (TPS61261, Load change from 5 mA to 45 mA)
15
Line transient response (TPS61261, Iout = 50 mA, VIN change from 1.0 V to 1.5 V)
16
Startup after enable (TPS61261, VOUT = 3.3V, VIN = 1.2 V, Iout = 10 mA)
17
Startup after enable (TPS61261, VOUT = 3.3V, VIN = 2.5 V, Iout = 10 mA)
18
110
110
100
100
90
90
80
70
60
50
40
30
VOUT = 1.8 V
VOUT = 2.5 V
VOUT = 4.0 V
20
10
0
0.8
R3 = 2 kΩ
1.2
1.6
2.0
2.4
2.8
Input Voltage (V)
Figure 1.
6
MAXIMUM OUTPUT CURRENT
vs
INPUT VOLTAGE
Output Current (mA)
Output Current (mA)
MAXIMUM OUTPUT CURRENT
vs
INPUT VOLTAGE
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3.2
3.6
80
70
60
50
40
30
20
10
4.0
G000
0
0.8
R3 = 2 kΩ
1.2
VOUT = 3.3 V
1.6
2.0
2.4
2.8
Input Voltage (V)
3.2
3.6
4.0
G000
Figure 2.
Copyright © 2011, Texas Instruments Incorporated
TPS61260, TPS61261
SLVSA99 – MAY 2011
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EFFICIENCY
vs
OUTPUT CURRENT
100
100
90
90
80
80
70
70
Efficiency (%)
Efficiency (%)
EFFICIENCY
vs
OUTPUT CURRENT
60
50
40
30
VIN = 1.2 V
40
0.1
1
Output Current (mA)
10
20
10
100
Figure 3.
Figure 4.
EFFICIENCY
vs
INPUT VOLTAGE
EFFICIENCY
vs
INPUT VOLTAGE
100
90
90
80
80
70
70
60
50
40
30
10
100
G000
60
50
40
30
IOUT =10 mA
IOUT =20 mA
IOUT =50 mA
20
0
0.8
1
Output Current (mA)
G000
100
10
VOUT =3.3 V
VIN = 1.2 V
0
0.01
0.1
Efficiency (%)
Efficiency (%)
0
0.01
VOUT =1.8 V
1.0
1.2
1.4
1.6
1.8
Input Voltage (V)
2.0
2.2
IOUT =10 mA
IOUT =20 mA
IOUT =50 mA
20
10
0
0.8
2.4
G000
VOUT = 2.5 V
1.0
1.2
1.4
1.6 1.8 2.0 2.2
Input Voltage (V)
Figure 5.
Figure 6.
EFFICIENCY
vs
INPUT VOLTAGE
EFFICIENCY
vs
INPUT VOLTAGE
100
100
90
90
80
80
70
70
Efficiency (%)
Efficiency (%)
50
30
VOUT = 1.8 V
VOUT = 2.5 V
VOUT = 4.0 V
20
10
60
60
50
40
30
IOUT =10 mA
IOUT =20 mA
IOUT =50 mA
IOUT =100 mA
20
10
VOUT = 4.0 V
0
0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0
Input Voltage (V)
G000
Figure 7.
Copyright © 2011, Texas Instruments Incorporated
2.4
2.6
2.8
3.0
G000
60
50
40
30
IOUT =10 mA
IOUT =20 mA
IOUT =50 mA
20
10
VOUT = 3.3 V
0
0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8
Input Voltage (V)
G000
Figure 8.
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OUTPUT CURRENT
vs
RESISTANCE AT RI
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
1.854
100
90
1.836
Output Voltage (V)
Output Current (mA)
80
70
60
50
40
30
20
0
2.0
1.782
4.0
6.0
8.0
10.0 12.0 14.0
Resistance (kΩ)
16.0
18.0
VIN = 1.2 V, VOUT = 1.8 V, R3 = 2 kΩ
1.746
0.01
0.1
1
Output Current (mA)
20.0
G000
Figure 9.
Figure 10.
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
2.575
4.12
2.55
4.08
Output Voltage (V)
Output Voltage (V)
1.8
1.764
10
2.525
2.5
2.475
2.45
2.425
0.01
100
G000
4.04
4
3.96
0.1
1
Output Current (mA)
10
VIN = 1.2 V, VOUT = 4.0 V, R3 = 2 kΩ
3.88
0.01
0.1
1
Output Current (mA)
100
G000
Figure 11.
Figure 12.
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
OUTPUT CURRENT
vs
OUTPUT VOLTAGE
3.399
10
100
G000
22
21.5
Output Current (mA)
3.366
3.333
3.3
3.267
3.234
21
20.5
20
19.5
19
18.5
VIN = 1.2 V, VOUT = 3.3 V, R3 = 2 kΩ
3.201
0.01
0.1
1
Output Current (mA)
Figure 13.
8
10
3.92
VIN = 1.2 V, VOUT = 2.5 V, R3 = 2 kΩ
Output Voltage (V)
1.818
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VIN = 1.2 V, R3 = 10 kΩ
10
100
G000
18
1.8
2.0
2.2
2.4
2.6
2.8
Output Voltage (V)
3.0
3.2
G000
Figure 14.
Copyright © 2011, Texas Instruments Incorporated
TPS61260, TPS61261
SLVSA99 – MAY 2011
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LOAD TRANSIENT RESPONSE
LINE TRANSIENT RESPONSE
Input Voltage
1 V/div, DC
Output Current
20 mA/div, DC
Output Voltage
100 mV/div, AC
Output Voltage
100 mV/div, AC
Inductor Current
200 mA/div, DC
VIN = 1.2 V, VOUT = 3.3 V, IOUT = 5 mA to 45 mA
VIN = 1.0 V to 1.5 V, VOUT = 3.3 V, IOUT = 50 mA
Time 2 ms/div
Figure 15.
Inductor Current
100 mA/div, DC
Time 2 ms/div
Figure 16.
STARTUP AFTER ENABLE
STARTUP AFTER ENABLE
Enable Voltage
1 V/div, DC
Enable Voltage
1 V/div, DC
Output Voltage
2 V/div, DC
Output Voltage
2 V/div, DC
Inductor Current
200 mA/div, DC
Inductor Current
200 mA/div, DC
Output Current
10 mA/div, DC
Output Current
10 mA/div, DC
VIN = 1.2 V, VOUT = 3.3 V
VIN = 2.5 V, VOUT = 3.3 V
Time 400 ms/div
Time 400 ms/div
Figure 17.
Figure 18.
PARAMETER MEASUREMENT INFORMATION
L1
VOUT
L
VOUT
R1
VIN
VIN
C2
FB
R2
C1
EN
GND
RI
R3
TPS61260
Table 1. List of Components
REFERENCE
DESCRIPTION
MANUFACTURER
TPS6126 0 / 1
Texas Instruments
L1
4.7 μH, 2.5 mm x 2 mm
LQM2HPN4R7MG0, Murata
C1
10 μF 6.3V, 0603, X5R ceramic
GRM188R60J106KME84D, Murata
C2
10 μF 6.3V, 0603, X5R ceramic
GRM188R60J106KME84D, Murata
R1
Depending on the output voltage at TPS61260, 0 Ω at TPS61261
R2
Depending on the output voltage at TPS61260, not used at TPS61261
R3
Depending on the output current
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DETAILED DESCRIPTION
Controller Circuit
The controlling circuit of the device is based on a current mode topology. The inductor current is regulated by a
fast current regulator loop which is controlled by a voltage control loop or a reference current. The controller also
uses input and output voltage feedforward. Changes of input and output voltage are monitored and immediately
can change the duty cycle in the modulator to achieve a fast response to those errors. The voltage error amplifier
gets its feedback input from the FB pin. At adjustable output voltages, a resistive voltage divider must be
connected to that pin. At fixed output voltages, FB must be connected to the output voltage to directly sense the
voltage. Fixed output voltage versions use a trimmed internal resistive divider. The feedback voltage will be
compared with the internal reference voltage to generate a stable and accurate output voltage. The reference
current for average output current control is programmed with a resistor connected between RI and GND.
The programming of the average output current also affects the maximum switch current in the main switch
which basically is the input current. The lower the average output current is programmed, the lower the maximum
input current will be. Now, maximum input power can be controlled as well as the maximum peak current to
achieve a safe and stable operation under all possible conditions. Since switch current and inductor current have
the same level smaller inductors can be used when lower average output currents are programmed.
Synchronous Boost Operation and Down Conversion Mode
The device uses 3 internal N-channel MOSFETs to maintain synchronous power conversion at all possible
operating conditions. This enables the device to keep high efficiency over a wide input voltage and output power
range. Using 2 rectifying switches also enables the device to control the output voltage and current at conditions
when the input voltage is higher than the actual output voltage. This for example happens at output short circuit
conditions, during startup or if the supply voltage is just higher than the regulated output voltage. In this down
conversion mode the rectifying switch works in a linear mode.
In difference to a standard boost converter technology the implemented 3 switch topology enables the output to
be disconnected from the input during device shutdown.
Power Save Mode
At normal load conditions with continuous inductor current the device operates at a quasi fixed frequency. If the
load gets lower the inductor current decreases and gets discontinuous. If this happens and the load is further
decreased the device lowers the switching frequency and turns off parts of the control to minimize internal power
consumption. The output voltage is controlled by a low power comparator at a level about 1% higher than the
nominal output voltage. If the output voltage reaches the nominal value or drops below it, the device control is
turned on again to handle the new load condition.
Accurate average output current regulation requires continuous inductor current. This means that there will be no
power save mode during current regulation.
Dynamic Current Limit
To protect the device and the application the inductor current is limited internally on the IC. At nominal operating
conditions, this current limit is constant at the programmed value. If the supply voltage at VIN drops to values
close to the undervoltage lockout threshold, the device stops operating. This can happen when the input power
source becomes weak. Increasing output impedance, when the batteries are almost discharged, or an additional
heavy pulse load is connected to the battery can cause such VIN voltage drops. If the voltage at VIN recovers
the device starts operating again. This way the average input current is reduced if the output impedance of the
power source is causing the voltage drop, allowing the system to stay in operation at a decreased output power.
Device Enable
The device is put into operation when EN is set high. It is put into a shutdown mode when EN is set to GND. In
shutdown mode, the regulator stops switching, all internal control circuitry is switched off, and the load is
disconnected from the input. This means that the output voltage can drop below the input voltage during
shutdown. During start-up of the converter, the duty cycle and the peak current are limited in order to avoid high
peak currents flowing from the input.
10
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Softstart and Short Circuit Protection
After being enabled, the device starts operating. Until the output voltage reaches about 0.4 V, the average output
current ramps up from zero to the programmed value, following the output voltage increasing. As soon as the
output current has reached the programmed value it stays regulated at that value until the load conditions
demand less current. This typically happens when the output capacitor is charged and the output voltage is
regulated.
During this start up the device can seamlessly change modes of operation. When the input voltage is higher than
the output voltage the device operates in a linear mode using the rectifying switches for control. If the input
voltage is lower than the output voltage it operates in a standard boost conversion mode. The boost conversion
is non synchronous when the output voltage is below approximately 1.8 V and it is synchronous if the output
voltage is higher than approximately 1.8 V.
At short circuit conditions at the output the output current is limited to the programmed average current. If the
short at the output causes the output voltage to drop below 0.4 V the average current decreases approximately
linearily with the output voltage down to zero.
Undervoltage Lockout
An undervoltage lockout function prevents device start-up if the supply voltage on VIN is lower than the
undervoltage lockout threshold defined in the ELECTRICAL CHARACTERISTICS table. When in operation, the
device automatically shuts down the power stage if the voltage on VIN drops below the undervoltage lockout
threshold. The device automatically restarts if the input voltage recovers to the minimum operating input voltage.
Output Overvoltage Protection
If for any reason the output voltage of the device exceeds its maximum recommended value the device stops
operating. It will continue operting as soon as the output voltage has dropped below this threshold.
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APPLICATION INFORMATION
PROGRAMMING THE OUTPUT VOLTAGE
Within the TPS6126x family there are fixed and adjustable output voltage versions available. To properly
configure the fixed output voltage devices, the FB pin is used to sense the output voltage. This means that it
must be connected directly to VOUT. At 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 500 mV. The maximum
recommended value for the output voltage is 4.0 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 500 mV. Based on these 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 also
recommended to keep the total value for the resistor divider, R1 + R2, in the range of 1 MΩ. From that, the value
of the resistor connected between VOUT and FB, R1, depending on the needed output voltage (VOUT), can be
calculated using Equation 1:
æV
ö
R1 = R2 × çç OUT - 1÷÷
è VFB
ø
(1)
L1
VOUT
L
VOUT
R1
VIN
VIN
C1
C2
FB
R2
EN
GND
RI
R3
TPS61260
Figure 19. Typical Application Circuit for Adjustable Output Voltage Option
PROGRAMMING THE OUTPUT CURRENT
The devices of the TPS6126x family also support average output current regulation. An external resistor is used
to program the average output current. The resistor must be connected between RI and GND. When the average
output current is regulated properly, the typical value of the voltage at the RI pin is 400 mV. The maximum
recommended value for the regulated average output current is 100 mA. The value of the resistor R3 should be
between 2 kΩ and 20 kΩ. It can be calculated, depending on the needed average output current (IOUT), using
Equation 2:
R3 =
200 V
IOUT
(2)
Accurate regulation of the average output current only is possible if the inductor current is continuous. Please
check the INDUCTOR SELECTION section to calculate the required parameters for selecting an appropriate
inductor.
INDUCTOR SELECTION
To properly configure the TPS6126x devices, an inductor must be connected between the supply voltage and pin
L. To estimate the minimum inductance value for accurate average output current regulation, Equation 3 can be
used.
L MIN
12
VIN2 × (VOUT - VIN )
=
× 0 .2 × μ s
2
× IOUT
VOUT
Submit Documentation Feedback
(3)
Copyright © 2011, Texas Instruments Incorporated
TPS61260, TPS61261
SLVSA99 – MAY 2011
www.ti.com
In Equation 3 the minimum inductance value required for accurate average output current regulation is
calculated. VIN is the input voltage. For typical applications which require voltage regulation the recommended
inductor value is 4.7 μH. Applications with higher inductance values will have lower light load efficiency. The
recommended range for the inductor value goes from 2.2 μH up to 22 μH. The current rating required for this
inductor depends on the programmed output current IOUT. Please refer to the ELECTRICAL CHARACTERISTICS
table for more details.
Table 2. List of Inductors
VENDOR
INDUCTOR SERIES
muRata
LQM2HP_G0
Toko
DFE252012C
Hitachi Metals
KSLI-252010AG
CAPACITOR SELECTION
Input Capacitor
At least a 4.7 μF input capacitor is recommended to improve transient behavior of the regulator and EMI
behavior of the total power supply circuit. A ceramic capacitor placed as close as possible to the VIN and GND
pins of the IC is recommended.
Output Capacitor
For the output capacitor, use of a small ceramic capacitors placed as close as possible to the VOUT and GND
pins of the IC is recommended. If, for any reason, the application requires the use of large capacitors which can
not be placed close to the IC, use a smaller ceramic capacitor in parallel to the large capacitor. The small
capacitor should be placed as close as possible to the VOUT and GND pins of the IC.
The output capacitor should be at least 2.2 μF. There are no additional requirements regarding minimum ESR.
There is also no theoretical upper limit for the output capacitance value. The device has been tested with
capacitors up to 100 μF. In general larger capacitors will cause lower output voltage ripple as well as lower
output voltage drop during load transients. To improve control performance especially when using high output
capacitance values a feedforward capacitor in parallel to R1 is recommended. The value should be in the range
of the value calculated in Equation 4
C ff = 0.3 × Ω ×
C2
R2
(4)
LAYOUT CONSIDERATIONS
For all switching power supplies, the layout is an important step in the design, especially at high peak currents
and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as
well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground
tracks. The input capacitor, output capacitor, and the inductor should be placed as close as possible to the IC.
Use a common ground node for power ground and a different one for control ground to minimize the effects of
ground noise. Connect these ground nodes at any place close to the ground pin of the IC.
The feedback divider should be placed as close as possible to the control ground connection. To lay out the
control ground, short traces are recommended 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.
Copyright © 2011, Texas Instruments Incorporated
Submit Documentation Feedback
13
TPS61260, TPS61261
SLVSA99 – MAY 2011
www.ti.com
VIN
L1
VOUT
C2
C1
GND
R3
EN
GND
R2
R1
Figure 20. PCB Layout Suggestion
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 by soldering the PowerPAD™
• Introducing airflow in the system
For more details on how to use the thermal parameters in the dissipation ratings table please check the Thermal
Characteristics Application Note (SZZA017) and the IC Package Thermal Metrics Application Note (SPRA953).
14
Submit Documentation Feedback
Copyright © 2011, Texas Instruments Incorporated
PACKAGE OPTION ADDENDUM
www.ti.com
4-Jun-2011
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package
Drawing
Pins
Package Qty
Eco Plan
(2)
Lead/
Ball Finish
MSL Peak Temp
(3)
TPS61260DRVR
ACTIVE
SON
DRV
6
3000
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
TPS61260DRVT
ACTIVE
SON
DRV
6
250
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
TPS61261DRVR
ACTIVE
SON
DRV
6
3000
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
TPS61261DRVT
ACTIVE
SON
DRV
6
250
Green (RoHS
& no Sb/Br)
CU NIPDAU Level-2-260C-1 YEAR
Samples
(Requires Login)
(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.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
11-Jun-2011
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
TPS61260DRVR
SON
DRV
6
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
3000
330.0
12.4
2.2
2.2
1.1
8.0
12.0
Q2
TPS61260DRVT
SON
DRV
6
250
180.0
12.4
2.2
2.2
1.1
8.0
12.0
Q2
TPS61261DRVR
SON
DRV
6
3000
330.0
12.4
2.2
2.2
1.1
8.0
12.0
Q2
TPS61261DRVT
SON
DRV
6
250
180.0
12.4
2.2
2.2
1.1
8.0
12.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
11-Jun-2011
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
TPS61260DRVR
SON
DRV
6
3000
346.0
346.0
29.0
TPS61260DRVT
SON
DRV
6
250
190.5
212.7
31.8
TPS61261DRVR
SON
DRV
6
3000
346.0
346.0
29.0
TPS61261DRVT
SON
DRV
6
250
190.5
212.7
31.8
Pack Materials-Page 2
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