TI TPS61087-Q1

TPS61087-Q1
Actual Size
3 mm x 3 mm
www.ti.com
SLVSB50 – DECEMBER 2011
650 kHz/1.2 MHz, 18.5 V STEP-UP DC-DC CONVERTER WITH 3.2 A SWITCH
Check for Samples: TPS61087-Q1
FEATURES
1
•
•
•
•
•
•
•
•
Qualified for Automotive Applications
2.5 V to 6 V Input Voltage Range
18.5 V Boost Converter With 3.2 A Switch Current
650 kHz/1.2 MHz Selectable Switching Frequency
Adjustable Soft-Start
Thermal Shutdown
Undervoltage Lockout
10-Pin QFN Package
DESCRIPTION
The TPS61087-Q1 is a high frequency, high efficiency DC to DC converter with an integrated 3.2 A, 0.13 Ω
power switch capable of providing an output voltage up to 18.5 V. The selectable frequency of 650 kHz or 1.2
MHz allows the use of small external inductors and capacitors and provides fast transient response. The external
compensation allows optimizing the application for specific conditions. A capacitor connected to the soft-start pin
minimizes inrush current at startup.
L
3.3 mH
VIN
2.5 V to 6 V
Cin
2* 10 mF
16 V
8
Cby
1 mF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
TPS61087-Q1
D
SL22
6
VS
15 V/500 mA
R1
200 kW
7
Cout
4* 10 mF
25 V
2
R2
18 kW
1
Rcomp
100 kW
10
Css
100 nF
Ccomp
820 pF
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.
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
TPS61087-Q1
SLVSB50 – DECEMBER 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.
ORDERING INFORMATION (1)
TA
–40 to 125°C
(1)
(2)
PACKAGE
QFN-10 (DRC)
Reel of 3000
(2)
ORDERABLE PART
NUMBER
TPS61087QDRCRQ1
TOP-SIDE MARKING
PMOQ
The DRC package is available taped and reeled.
For the most current package and ordering information, see the Package Option Addendum at the end
of this document, or see the TI website at www.ti.com.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
(2)
VALUE
UNIT
–0.3 to 7.0
V
Voltage range on pins EN, FB, SS, FREQ, COMP
–0.3 to 7.0
V
Voltage on pin SW
–0.3 to 20
V
ESD rating HBM
2
kV
ESD rating MM
200
V
ESD rating CDM
1000
V
Input voltage range IN
Continuous power dissipation
See Dissipation Rating Table
Operating junction temperature range
–40 to 150
°C
Storage temperature range
–65 to 150
°C
(1)
(2)
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability
All voltage values are with respect to network ground terminal.
DISSIPATION RATINGS (1)
(1)
(2)
(2)
PACKAGE
TA ≤ 25°C
POWER RATING
TA = 70°C
POWER RATING
TA = 125°C
POWER RATING
QFN
1.74 W
0.96 W
0.70 W
PD = (TJ – TA)/RθJA.
The exposed thermal die is soldered to the PCB using thermal vias. For more information, see the
Texas Instruments Application report SLMA002 regarding thermal characteristics of the PowerPAD
package.
RECOMMENDED OPERATING CONDITIONS
MIN
VIN
Input voltage range
VS
Boost output voltage range
TA
Operating free-air temperature
2
TYP
MAX
UNIT
2.5
6
V
VIN + 0.5
18.5
V
–40
125
°C
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
ELECTRICAL CHARACTERISTICS
VIN = 5 V, EN = VIN, VS = 15 V, TA = –40°C to 125°C, typical values are at TA = 25°C (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
6
V
75
100
μA
4
μA
V
SUPPLY
VIN
Input voltage range
IQ
Operating quiescent current into IN
Device not switching, VFB = 1.3 V
ISDVIN
Shutdown current into IN
EN = GND
VUVLO
Under-voltage lockout threshold
VIN falling
2.4
VIN rising
2.5
TSD
Thermal shutdown
TSDHYS
Thermal shutdown hysteresis
2.5
Temperature rising
V
150
°C
14
°C
LOGIC SIGNALS EN, FREQ
VIH
High level input voltage
VIN = 2.5 V to 6.0 V
2
V
VIL
Low level input voltage
VIN = 2.5 V to 6.0 V
0.5
V
IINLEAK
Input leakage current
EN = FREQ = GND
0.1
μA
18.5
V
BOOST CONVERTER
VS
Boost output voltage
VIN +
0.5
VFB
Feedback regulation voltage
1.230
gm
Transconductance error amplifier
IFB
Feedback input bias current
VFB = 1.238 V
0.1
μA
rDS(on)
N-channel MOSFET on-resistance
VIN = VGS = 5 V, ISW = current limit
0.13
0.18
Ω
VIN = VGS = 3V, ISW = current limit
0.16
0.23
1.250
SW leakage current
EN = GND, VSW = VIN = 6.0V
ILIM
N-Channel MOSFET current limit
ISS
Soft-start current
VSS = 1.238 V
fS
Oscillator frequency
V
μA/V
107
ISWLEAK
2
μA
3.2
4.0
4.8
A
7
10
13
μA
FREQ = VIN
0.9
1.2
1.5
MHz
FREQ = GND
480
650
820
Line regulation
VIN = 2.5 V to 6.0 V, IOUT = 10 mA
Load regulation
VIN = 5.0 V, IOUT = 1 mA to 1 A
Copyright © 2011, Texas Instruments Incorporated
1.238
kHz
0.0002
%/V
0.11
%/A
3
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
PIN ASSIGNMENT
DRC PACKAGE
(TOP VIEW)
COMP
SS
FB
EN
FREQ
Thermal
Pad
IN
AGND
SW
PGND
SW
10-PIN 3mm x 3mm x 1mm QFN
PIN FUNCTIONS
PIN
NAME
NO.
I/O
DESCRIPTION
COMP
1
I/O
FB
2
I
Feedback pin
3
I
Shutdown control input. Connect this pin to logic high level to enable the device
EN
AGND
PGND
SW
Compensation pin
4,
Thermal
Pad
Analog ground
5
Power ground
6, 7
IN
8
FREQ
9
SS
10
Switch pin
Input supply pin
I
Frequency select pin. The power switch operates at 650 kHz if FREQ is connected to GND and at 1.2 MHz
if FREQ is connected to IN
Soft-start control pin. Connect a capacitor to this pin if soft-start needed. Open = no soft-start
TYPICAL CHARACTERISTICS
TABLE OF GRAPHS
FIGURE
IOUT(max)
Maximum load current
vs. Input voltage at High frequency (1.2 MHz)
Figure 1
IOUT(max)
Maximum load current
vs. Input voltage at Low frequency (650 kHz)
Figure 2
η
Efficiency
vs. Load current, VS = 15 V, VIN = 5 V
Figure 3
η
Efficiency
vs. Load current, VS = 9 V, VIN = 3.3 V
Figure 4
PWM switching - discontinuous conduction
Figure 5
PWM switching - continuous conduction
Figure 6
Load transient response
at High frequency (1.2 MHz)
Figure 7
Load transient response
at Low frequency (650 kHz)
Figure 8
Supply current
vs. Supply voltage
Figure 10
Oscillator frequency
vs. Load current
Figure 11
Oscillator frequency
vs. Supply voltage
Figure 12
Soft-start
Figure 9
The typical characteristics are measured with the inductors 7447789003 3.3 µH (high frequency) or 74454068
6.8 µH (low frequency) from Wurth and the rectifier diode SL22.
4
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
MAXIMUM LOAD CURRENT
vs
INPUT VOLTAGE
MAXIMUM LOAD CURRENT
vs
INPUT VOLTAGE
3.0
3.0
fS = 1.2 Mhz
2.5
VOUT = 9 V
2.0
VOUT = 12 V
1.5
VOUT = 15 V
1.0
VOUT = 18.5 V
0.5
IOUT - Maximum Load Current - A
IOUT - Maximum Load Current - A
fS = 650 kHz
2.5
2.0
VOUT = 9 V
VOUT = 12 V
1.5
1.0
VOUT = 18.5 V
0.5
VOUT = 15 V
0.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
0.0
2.5
6.0
4.0
4.5
Figure 2.
EFFICIENCY
vs
LOAD CURRENT
EFFICIENCY
vs
LOAD CURRENT
100
90
90
80
fS = 1.2 Mhz
70
L = 3.3 mH
5.0
5.5
6.0
fS = 650 kHz
L = 6.8 mH
80
fS = 650 kHz
70
Efficiency - %
L = 6.8 mH
Efficiency - %
3.5
Figure 1.
100
60
50
40
fS = 1.2 Mhz
L = 3.3 mH
60
50
40
30
30
20
VIN = 5 V
VS = 15 V
10
0
0.0 0.1
3.0
VIN - Input Voltage - V
VIN - Input Voltage - V
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
IOUT - Load Current - A
Figure 3.
Copyright © 2011, Texas Instruments Incorporated
20
VIN = 3.3 V
VS = 9 V
10
0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
IOUT - Load Current - A
Figure 4.
5
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
PWM SWITCHING
DISCONTINUOUS CONDUCTION MODE
PWM SWITCHING
CONTINUOUS CONDUCTION MODE
VSW
10 V/div
VSW
10 V/div
VS_AC
50 mV/div
VS_AC
50 mV/div
VIN = 5 V
VS = 15 V/2 mA
FREQ = VIN
Il
1 A/div
VIN = 5 V
VS = 15 V/500 mA
FREQ = VIN
IL
500 mA/div
200 ns/div
200 ns/div
Figure 5.
Figure 6.
LOAD TRANSIENT RESPONSE
HIGH FREQUENCY (1.2 MHz)
LOAD TRANSIENT RESPONSE
LOW FREQUENCY (650 kHz)
VIN = 5 V
VS = 15 V
VIN = 5 V
VS = 15 V
COUT = 40 mF
L = 6.8 mH
Rcomp = 110 kW
Ccomp = 1 nF
VS_AC
100 mV/div
COUT = 40 mF
IOUT = 100 mA - 500 mA
L = 3.3 mH
Rcomp = 150 kW
Ccomp = 820 pF
VS_AC
100 mV/div
IOUT = 100 mA - 500 mA
IOUT
200 mA/div
IOUT
200 mA/div
200 ms/div
Figure 7.
6
200 ms/div
Figure 8.
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
SOFT-START
2.0
ICC - Supply Current - mA
EN
5 V/div
VIN = 5 V
VS = 15 V/500 mA
VS
5 V/div
CSS = 100 nF
IL
1 A/div
1.8
SWITCHING
fS = 1.2 Mhz
1.6
L = 3.3 mH
1.4
SWITCHING
fS = 650 kHz
1.2
L = 6.8 mH
1.0
0.8
0.6
0.4
0.2
2 ms/div
0
2.5
NOT SWITCHING
3.0
3.5
4.0
4.5
5.0
VCC - Supply Voltage - V
Figure 9.
Figure 10.
OSCILLATOR FREQUENCY
vs
LOAD CURRENT
OSCILLATOR FREQUENCY
vs
SUPPLY VOLTAGE
1600
5.5
6.0
1400
VS = 15 V / 200 mA
FREQ = VIN
1200
L = 3.3 mH
fS - Oscillator Frequency - kHz
fS - Oscillator Frequency - kHz
1400
1200
1000
800
FREQ = GND
L = 6.8 mH
600
400
VIN = 5 V
VS = 15 V
200
0
0.0 0.1
0.2
0.3
0.4 0.5 0.6
0.7 0.8 0.9
IOUT - Load Current - mA
Figure 11.
Copyright © 2011, Texas Instruments Incorporated
FREQ = VIN
L = 3.3 mH
1000
800
600
FREQ = GND
L = 6.8 mH
400
200
1.0
0
2.5
3
3.5
4
4.5
5
VCC - Supply Voltage - V
5.5
6
Figure 12.
7
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
DETAILED DESCRIPTION
VIN
VS
EN
SS
IN
SW
FREQ
SW
Current limit
and
Soft Start
tOFF Generator
AGND
Bias Vref = 1.238V
UVLO
Thermal Shutdown
tON
PWM
Generator
Gate Driver of
Power
Transistor
COMP
GM Amplifier
FB
Vref
PGND
Figure 13. Block Diagram
The boost converter is designed for output voltages up to 18.5 V with a switch peak current limit of 3.2 A
minimum. The device, which operates in a current mode scheme with quasi-constant frequency, is externally
compensated for maximum flexibility and stability. The switching frequency is selectable between 650 kHz and
1.2 MHz and the minimum input voltage is 2.5 V. To limit the inrush current at start-up a soft-start pin is
available.
TPS61087-Q1 boost converter’s novel topology using adaptive off-time provides superior load and line transient
responses and operates also over a wider range of applications than conventional converters.
The selectable switching frequency offers the possibility to optimize the design either for the use of small sized
components (1.2 MHz) or for higher system efficiency (650 kHz). However, the frequency changes slightly
because the voltage drop across the rDS(on) has some influence on the current and voltage measurement and
thus on the on-time (the off-time remains constant).
The converter operates in continuous conduction mode (CCM) as soon as the input current increases above half
the ripple current in the inductor, for lower load currents it switches into discontinuous conduction mode (DCM). If
the load is further reduced, the part starts to skip pulses to maintain the output voltage.
8
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
Design Procedure
The first step in the design procedure is to verify that the maximum possible output current of the boost converter
supports the specific application requirements. A simple approach is to estimate the converter efficiency, by
taking the efficiency numbers from the provided efficiency curves or to use a worst case assumption for the
expected efficiency, e.g. 90%.
1. Duty cycle, D:
D = 1-
VIN ×h
VS
(1)
2. Maximum output current, Iout(max)
DI
æ
I out (max) = ç I LIM (min) - L
2
è
ö
÷ × (1 - D )
ø
3. Peak switch current in application, Iswpeak
I swpeak =
:
(2)
:
I
DI L
+ out
2 1- D
(3)
with the inductor peak-to-peak ripple current, ΔIL
DI L =
VIN × D
fS × L
(4)
and
VIN
Minimum input voltage
VS
Output voltage
ILIM(min)
Converter switch current limit (minimum switch current limit = 3.2 A)
fS
Converter switching frequency (typically 1.2 MHz or 650 kHz)
L
Selected inductor value
η
Estimated converter efficiency (please use the number from the efficiency plots or 90% as an estimation)
The peak switch current is the steady state peak switch current that the integrated switch, inductor and external
Schottky diode has to be able to handle. The calculation must be done for the minimum input voltage where the
peak switch current is the highest.
Soft-start
The boost converter has an adjustable soft-start to prevent high inrush current during start-up. To minimize the
inrush current during start-up an external capacitor, connected to the soft-start pin SS and charged with a
constant current, is used to slowly ramp up the internal current limit of the boost converter. When the EN pin is
pulled high, the soft-start capacitor CSS is immediately charged to 0.3 V. The capacitor is then charged at a
constant current of 10 μA typically until the output of the boost converter VS has reached its Power Good
threshold (roughly 98% of VS nominal value). During this time, the SS voltage directly controls the peak inductor
current, starting with 0 A at VSS = 0.3 V up to the full current limit at VSS = 800 mV. The maximum load current is
available after the soft-start is completed. The larger the capacitor the slower the ramp of the current limit and the
longer the soft-start time. A 100 nF capacitor is usually sufficient for most of the applications. When the EN pin is
pulled low, the soft-start capacitor is discharged to ground.
Copyright © 2011, Texas Instruments Incorporated
9
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
Inductor Selection
The TPS61087-Q1 is designed to work with a wide range of inductors. The main parameter for the inductor
selection is the saturation current of the inductor which should be higher than the peak switch current as
calculated in the Design Procedure section with additional margin to cover for heavy load transients. An
alternative, more conservative, is to choose an inductor with a saturation current at least as high as the
maximum switch current limit of 4.8 A. The other important parameter is the inductor DC resistance. Usually the
lower the DC resistance the higher the efficiency. It is important to note that the inductor DC resistance is not the
only parameter determining the efficiency. Especially for a boost converter where the inductor is the energy
storage element, the type and core material of the inductor influences the efficiency as well. At high switching
frequencies of 1.2 MHz inductor core losses, proximity effects and skin effects become more important. Usually
an inductor with a larger form factor gives higher efficiency. The efficiency difference between different inductors
can vary between 2% to 10%. For the TPS61087-Q1, inductor values between 3 μH and 6 μH are a good choice
with a switching frequency of 1.2 MHz, typically 3.3 μH. At 650 kHz we recommend inductors between 6 μH and
13 μH, typically 6.8 μH. Possible inductors are shown in Table 1.
Typically, it is recommended that the inductor current ripple is below 35% of the average inductor current.
Therefore, the following equation can be used to calculate the inductor value, L:
2
æ V ö æ V -V
L = ç IN ÷ × ç S IN
è VS ø è I out × f S
ö æ h ö
÷×ç
÷
ø è 0.35 ø
(5)
with
VIN
Minimum input voltage
VS
Output voltage
Iout
Maximum output current in the application
fS
Converter switching frequency (typically 1.2 MHz or 650 kHz)
η
Estimated converter efficiency (please use the number from the efficiency plots or 90% as an estimation)
Table 1. Inductor Selection
L
(μH)
SUPPLIER
COMPONENT
CODE
SIZE
(L×W×H mm)
DCR TYP
(mΩ)
Isat (A)
4.2
Sumida
CDRH5D28
4.7
5.7 × 5.7 × 3
23
2.2
Wurth Elektronik
7447785004
5.9 × 6.2 × 3.3
60
2.5
5
Coilcraft
MSS7341
7.3 × 7.3 × 4.1
24
2.9
1.2 MHz
5
Sumida
CDRH6D28
7×7×3
23
2.4
4.6
Sumida
CDR7D28
7.6 × 7.6 × 3
38
3.15
4.7
Wurth Elektronik
7447789004
7.3 × 7.3 × 3.2
33
3.9
3.3
Wurth Elektronik
7447789003
7.3 × 7.3 × 3.2
30
4.2
744778910
7.3 × 7.3 × 3.2
51
2.2
650 kHz
10
10
Wurth Elektronik
10
Sumida
CDRH8D28
8.3 × 8.3 × 3
36
2.7
6.8
Sumida
CDRH6D26HPNP
7 × 7 × 2.8
52
2.9
6.2
Sumida
CDRH8D58
8.3 × 8.3 × 6
25
3.3
10
Coilcraft
DS3316P
12.95 × 9.40 ×
5.08
80
3.5
10
Sumida
CDRH8D43
8.3 × 8.3 × 4.5
29
4
6.8
Wurth Elektronik
74454068
12.7 × 10 × 4.9
55
4.1
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
Rectifier Diode Selection
To achieve high efficiency a Schottky type should be used for the rectifier diode. The reverse voltage rating
should be higher than the maximum output voltage of the converter. The averaged rectified forward current
Iavg
, the Schottky diode needs to be rated for, is equal to the output current Iout
:
I avg = I out
(6)
Usually a Schottky diode with 2 A maximum average rectified forward current rating is sufficient for most
applications. The Schottky rectifier can be selected with lower forward current capability depending on the output
current Iout but has to be able to dissipate the power. The dissipated power, PD
, is the average
rectified forward current times the diode forward voltage, Vforward
.
PD = I avg × V forward
(7)
Typically the diode should be able to dissipate around 500mW depending on the load current and forward
voltage.
Table 2. Rectifier Diode Selection
CURRENT
RATING Iavg
Vr
Vforward/Iavg
SUPPLIER
COMPONENT CODE
2A
20 V
0.44 V / 2 A
Vishay Semiconductor
SL22
2A
20 V
0.5 V / 2 A
Fairchild Semiconductor
SS22
Setting the Output Voltage
The output voltage is set by an external resistor divider. Typically, a minimum current of 50 μA flowing through
the feedback divider gives good accuracy and noise covering. A standard low side resistor of 18 kΩ is typically
selected. The resistors are then calculated as:
VS
R2 =
VFB
» 18k W
70 m A
æ V
ö
R1 = R 2 × ç S - 1÷
è VFB
ø
R1
VFB
R2
VFB = 1.238V
(8)
Compensation (COMP)
The regulator loop can be compensated by adjusting the external components connected to the COMP pin. The
COMP pin is the output of the internal transconductance error amplifier.
Standard values of RCOMP = 16 kΩ and CCOMP = 2.7 nF will work for the majority of the applications.
See Table 3 for dedicated compensation networks giving an improved load transient response. The following
equations can be used to calculate RCOMP and CCOMP
:
RCOMP =
110 × VIN × VS × Cout
L × I out
CCOMP =
Vs × Cout
7.5 × I out × RCOMP
(9)
with
VIN
Minimum input voltage
VS
Output voltage
Cout
Output capacitance
L
Inductor value, e.g. 3.3 μH or 6.8 μH
Iout
Maximum output current in the application
Make sure that RCOMP < 120 kΩ and CCOMP> 820 pF, independent of the results of the above formulas.
Copyright © 2011, Texas Instruments Incorporated
11
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
Table 3. Recommended Compensation Network Values at High/Low Frequency
FREQUENCY
L
VS
15 V
3.3 μH
High (1.2 MHz)
12 V
9V
15 V
6.8 μH
Low (650 kHz)
12 V
9V
VIN ± 20%
RCOMP
CCOMP
5V
100 kΩ
820 pF
3.3 V
91 kΩ
1.2 nF
5V
68 kΩ
820 pF
3.3 V
68 kΩ
1.2 nF
5V
39 kΩ
820 pF
3.3 V
39 kΩ
1.2 nF
5V
51 kΩ
1.5 nF
3.3 V
47 kΩ
2.7 nF
5V
33 kΩ
1.5 nF
3.3 V
33 kΩ
2.7 nF
5V
18 kΩ
1.5 nF
3.3 V
18 kΩ
2.7 nF
Table 3 gives conservative RCOMP and CCOMP values for certain inductors, input and output voltages providing a
very stable system. For a faster response time, a higher RCOMP value can be used to enlarge the bandwidth, as
well as a slightly lower value of CCOMP to keep enough phase margin. These adjustments should be performed in
parallel with the load transient response monitoring of TPS61087-Q1.
Input Capacitor Selection
For good input voltage filtering low ESR ceramic capacitors are recommended. TPS61087-Q1 has an analog
input IN. Therefore, a 1 μF bypass is highly recommended as close as possible to the IC from IN to GND.
Two 10 μF (or one 22 μF) ceramic input capacitors are sufficient for most of the applications. For better input
voltage filtering this value can be increased. See Table 4 and typical applications for input capacitor
recommendation.
Output Capacitor Selection
For best output voltage filtering a low ESR output capacitor like ceramic capcaitor is recommended. Four 10 μF
ceramic output capacitors (or two 22 μF) work for most of the applications. Higher capacitor values can be used
to improve the load transient response. See Table 4 for the selection of the output capacitor.
Table 4. Rectifier Input and Output Capacitor Selection
CAPACITOR/SIZE
VOLTAGE RATING
SUPPLIER
COMPONENT CODE
CIN
22 μF/1206
16 V
Taiyo Yuden
EMK316 BJ 226ML
IN bypass
1 μF/0603
16 V
Taiyo Yuden
EMK107 BJ 105KA
COUT
10 μF/1206
25 V
Taiyo Yuden
TMK316 BJ 106KL
To calculate the output voltage ripple, the following equation can be used:
DVC =
VS - VIN I out
×
VS × f S Cout
DVC _ ESR = I L ( peak ) × RC _ ESR
(10)
with
ΔVC
Output voltage ripple dependent on output capacitance,output current and switching frequency
VS
Output voltage
VIN
Minimum input voltage of boost converter
fS
Converter switching frequency (typically 1.2 MHz or 650 kHz)
Iout
Output capacitance
ΔVC_ESR
Output voltage ripple due to output capacitors ESR (equivalent series resistance)
ISWPEAK
Inductor peak switch current in the application
RC_ESR
Output capacitors equivalent series resistance (ESR)
12
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
www.ti.com
SLVSB50 – DECEMBER 2011
ΔVC_ESR can be neglected in many cases since ceramic capacitors provide low ESR.
Frequency Select Pin (FREQ)
The frequency select pin FREQ allows to set the switching frequency of the device to 650 kHz (FREQ = low) or
1.2 MHz (FREQ = high). Higher switching frequency improves load transient response but reduces slightly the
efficiency. The other benefits of higher switching frequency are a lower output ripple voltage. The use of a 1.2
MHz switching frequency is recommended unless light load efficiency is a major concern.
Undervoltage Lockout (UVLO)
To avoid mis-operation of the device at low input voltages an undervoltage lockout is included that disables the
device, if the input voltage falls below 2.4 V.
Thermal Shutdown
A thermal shutdown is implemented to prevent damages due to excessive heat and power dissipation. Typically
the thermal shutdown happens at a junction temperature of 150°C. When the thermal shutdown is triggered the
device stops switching until the junction temperature falls below typically 136°C. Then the device starts switching
again.
Overvoltage Prevention
If overvoltage is detected on the FB pin (typically 3 % above the nominal value of 1.238 V) the part stops
switching immediately until the voltage on this pin drops to its nominal value. This prevents overvoltage on the
output and secures the circuits connected to the output from excessive overvoltage.
Copyright © 2011, Texas Instruments Incorporated
13
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
APPLICATION INFORMATION
L
3.3 µH
VIN
5 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
VS
15 V/900 mA max.
D
SL22
6
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
100 kΩ
10
Css
100 nF
TPS61087-Q1
Ccomp
820 pF
Figure 14. Typical Application, 5 V to 15 V (fS = 1.2 MHz)
L
6.8 µH
VIN
5 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
TPS61087-Q1
VS
15 V/900 mA max.
D
SL22
6
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
51 kΩ
10
Css
100 nF
Ccomp
1.5 nF
Figure 15. Typical Application, 5 V to 15 V (fS = 650 kHz)
14
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
L
3.3 µH
VIN
3.3 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
D
SL22
6
VS
9 V/950 mA max.
R1
110 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
39 kΩ
10
Css
100 nF
TPS61087-Q1
Ccomp
1.2 nF
Figure 16. Typical Application, 3.3 V to 9 V (fS = 1.2 MHz)
L
6.8 µH
VIN
3.3 V ± 20%
Cin
2* 10 µF
16 V
8
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
AGND
COMP
PGND
SS
TPS61087-Q1
VS
9 V/950 mA max.
D
SL22
6
R1
110 kΩ
7
Cout
4* 10 µF
25 V
2
R2
18 kΩ
1
Rcomp
18 kΩ
10
Css
100 nF
Ccomp
2.7 nF
Figure 17. Typical Application, 3.3 V to 9 V (fS = 650 kHz)
Copyright © 2011, Texas Instruments Incorporated
15
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
Riso
10 kW
L
6.8 µH
VIN
5 V ± 20%
Cby
1 µF/16 V
8
Cin
2* 10 µF/
16 V
3
9
4
Enable
SW
IN
SW
EN
FREQ
FB
AGND
COMP
PGND
SS
5
VS
15 V/300 mA
BC857C
D
SL22
6
Ciso
1 µF/ 25 V
7
R1
200 kΩ
2
Cout
4*10 µF/
25 V
R2
18 kΩ
1
Rcomp
51 kΩ
10
TPS61087-Q1
Css
100 nF
Ccomp
1.5 nF
Figure 18. Typical Application with External Load Disconnect Switch
L
6.8 µH
D
SL22
VIN
5 V ± 20%
8
Cin
2* 10 µF
16 V
Cby
1 µF
16 V
3
9
4
5
IN
SW
EN
SW
FREQ
FB
COMP
AGND
PGND
SS
TPS61087-Q1
Overvoltage
Protection
VS
15 V/900 mA max.
6
Dz
BZX84C 18V
R1
200 kΩ
7
Cout
4* 10 µF
25 V
2
Rlimit
110 Ω
1
R2
18 kΩ
Rcomp
51 kΩ
10
Css
100 nF
Ccomp
1.5 nF
Figure 19. Typical Application, 5 V to 15 V (fS = 1.2 MHz) with Overvoltage Protection
16
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
TFT LCD APPLICATION
T2
BC850B
3·Vs
VGL
-7 V/20 mA
T1
BC857B
R8
6.8 kΩ
C13
1 µF/
35 V
C16
470 nF/
50 V
-Vs
C14
470 nF/
25 V
D4
BAV99
C15
470 nF/
50 V
D3
BAV99
C18
470 nF/
50 V
R10
13 kΩ
2·Vs
C17
470 nF/
50 V
D2
BAV99
D8
BZX84C7V5
Vgh
26.5 V/20 mA
C20
1 µF/
35 V
C19
470 nF/
50 V
D9
BZX84C27V
L
3.3 µH
VIN
5 V ± 20%
Cin
2*10 µF/
16 V
Cby
1 µF/
16 V
D
SL22
8
IN
SW
EN
SW
3
7
9
R1
200 kΩ
Cout
4*10µF/
25V
2
FREQ
FB
4
5
VS
15 V/500 mA
6
R2
18 kΩ
1
AGND
COMP
PGND
SS
TPS61087-Q1
Rcomp
100 kΩ
10
Css
100 nF
Ccomp
820 pF
Figure 20. Typical Application 5 V to 15 V (fS = 1.2 MHz) for TFT LCD with External Charge Pumps (VGH,
VGL)
Copyright © 2011, Texas Instruments Incorporated
17
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
WHITE LED APPLICATIONS
L
6.8 µH
optional
VIN
5 V ± 20%
Cin
2* 10 µF/
16 V
Cby
1 µF/ 16 V
6
8
3
9
4
5
IN
SW
EN
SW
D
SL22
Dz
BZX84C 18 V
VS
500 mA
3S3P wLED
LW E67C
7
Cout
4* 10 µF/
25 V
2
FREQ
FB
AGND
COMP
PGND
SS
Rlimit
110 Ω
1
10
TPS61087-Q1
Rsense
15 Ω
Rcomp
51 kΩ
Css
100 nF
Ccomp
1.5 nF
Figure 21. Simple Application (5 V input voltage) (fS = 650 kHz) for wLED Supply (3S3P) (with optional
clamping Zener diode)
L
6.8 µH
optional
VIN
5 V ± 20%
Cin
2* 10 µF/
16 V
Cby
1 µF/ 16 V
3
9
4
PWM
100 Hz to 500 Hz
6
8
5
IN
SW
EN
SW
D
SL22
Dz
BZX84C 18 V
VS
500 mA
3S3P wLED
LW E67C
7
Cout
4* 10 µF/
25 V
2
FREQ
FB
AGND
COMP
PGND
TPS61087-Q1
SS
Rlimit
110 Ω
1
Rcomp
51 kΩ
10
Css
100 nF
Rsense
15 Ω
Ccomp
1.5 nF
Figure 22. Simple Application (5 V input voltage) (fS = 650 kHz) for wLED Supply (3S3P) with Adjustable
Brightness Control using a PWM Signal on the Enable Pin (with optional clamping Zener diode)
18
Copyright © 2011, Texas Instruments Incorporated
TPS61087-Q1
SLVSB50 – DECEMBER 2011
www.ti.com
L
6.8 µH
optional
VIN
5 V ± 20%
Cin
2* 10 µF/
16 V
Cby
1 µF/ 16 V
6
8
3
9
4
5
IN
SW
EN
SW
D
SL22
Dz
BZX84C 18 V
VS
500 mA
3S3P wLED
LW E67C
7
2
FREQ
FB
AGND
COMP
PGND
SS
TPS61087-Q1
R1
180 kΩ
Rlimit
110 Ω
1
10
Css
100 nF
Rcomp
51 kΩ
Ccomp
1.5 nF
Cout
4* 10 µF/
25 V
Rsense
15 Ω
R2
127 kΩ
Analog Brightness Control
3.3 V ~ wLED off
0 V ~ lLED = 30 mA (each string)
PWM Signal
Can be used swinging from 0 V to 3.3 V
Figure 23. Simple Application (5 V input voltage) (fS = 650 kHz) for wLED Supply (3S3P) with Adjustable
Brightness Control using an Analog Signal on the Feedback Pin (with optional clamping Zener diode)
Copyright © 2011, Texas Instruments Incorporated
19
PACKAGE OPTION ADDENDUM
www.ti.com
26-Dec-2011
PACKAGING INFORMATION
Orderable Device
TPS61087QDRCRQ1
Status
(1)
Package Type Package
Drawing
ACTIVE
SON
DRC
Pins
Package Qty
10
3000
Eco Plan
(2)
Green (RoHS
& no Sb/Br)
Lead/
Ball Finish
MSL Peak Temp
(3)
Samples
(Requires Login)
CU NIPDAU Level-3-260C-168 HR
(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.
OTHER QUALIFIED VERSIONS OF TPS61087-Q1 :
• Catalog: TPS61087
NOTE: Qualified Version Definitions:
• Catalog - TI's standard catalog product
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
14-Jul-2012
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
TPS61087QDRCRQ1
Package Package Pins
Type Drawing
SON
DRC
10
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
3000
330.0
12.4
Pack Materials-Page 1
3.3
B0
(mm)
K0
(mm)
P1
(mm)
3.3
1.1
8.0
W
Pin1
(mm) Quadrant
12.0
Q2
PACKAGE MATERIALS INFORMATION
www.ti.com
14-Jul-2012
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
TPS61087QDRCRQ1
SON
DRC
10
3000
367.0
367.0
35.0
Pack Materials-Page 2
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