TEXAS INSTRUMENTS TPS61160A, TPS61161A Technical data

C1

D1

VIN SW

FB

GND

CTRL

COMP

C2

20mA

TPS61161A

ON/OFF

DIMMING

CONTROL

V 3Vto18V

I

L1

22 Hm

1 Fm

C3

220nF

R

10

set

W

1 Fm

L1: TDKVLCF5020T-220MR75-1 C1:MurataGRM188R61E105K C2: MurataGRM21BR71H105K D1:ONsemiMBR0540T1

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................................................................................................................................................................................................... SLVS937 – MARCH 2009

White LED Driver With PWM Brightness Control in 2mm x 2mm

QFN Package for up to 10 LEDs in Series

1

FEATURES

• 2.7V to 18V Input Voltage Range

• 26V Open LED Protection for 6 LEDs

(TPS61160A) 38V Open LED Protection for 10 LEDs

(TPS61161A)

• 200mV Reference Voltage With ± 2% Accuracy

• PWM Interface for Brightness Control

• Built-in Soft Start

• Up to 90% Efficiency

• 2mm × 2mm × 0.8mm 6-pin QFN Package With

Thermal Pad

APPLICATIONS

• Cellular Phones

• Portable Media Players

• Ultra Mobile Devices

• GPS Receivers

• White LED Backlighting for Media Form Factor

Display

TPS61160A TPS61161A

DESCRIPTION

With a 40-V rated integrated switch FET, the TPS61160A/61A is a boost converter that drives up to 10 LEDs in series. The boost converter runs at 600kHz fixed switching frequency to reduce output ripple, improve conversion efficiency, and allows for the use of small external components.

The default white LED current is set with the external sensor resistor Rset, and the feedback voltage is regulated to 200mV, as shown in the typical application. During the operation, the LED current can be controlled by a pulse width modulation (PWM) signal applied to the CTRL pin through which the duty cycle determines the feedback reference voltage. In PWM dimming mode, the TPS61160A/61A does not burst the LED current; therefore, it does not generate audible noises on the output capacitor. For maximum protection, the device features integrated open LED protection that disables the TPS61160A/61A to prevent the output from exceeding the absolute maximum ratings during open LED conditions.

The TPS61160A/61A is available in a space-saving, 2mm × 2mm QFN package with thermal pad.

1

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.

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.

Figure 1. Typical Application of TPS61161A

TPS61160A TPS61161A

SLVS937 – MARCH 2009 ...................................................................................................................................................................................................

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.

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(1)

(2)

PACKAGE MARKING

T

A

– 40 ° C to 85 ° C

ORDERING INFORMATION

OPEN LED PROTECTION PACKAGE

26V (typical) TPS61160ADRV OBV 38V (typical) TPS61161ADRV OBT

(1) For the most current package and ordering information, see the TI Web site at www.ti.com . (2) The DRV package is available in tape and reel. Add R suffix (TPS61160ADRVR) to order quantities of 3000 parts per reel or add T

suffix (TPS61160ADRVT) to order 250 parts per reel.

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range (unless otherwise noted)

Supply Voltages on VIN

V

I

P

D

T

J

T

STG

Voltages on CTRL Voltage on FB and COMP Voltage on SW

(2)

Continuous Power Dissipation See Dissipation Rating Table Operating Junction Temperature Range – 40 to 150 ° C Storage Temperature Range – 65 to 150 ° C

(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings

only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) All voltage values are with respect to network ground terminal.

(2)

(1)

VALUE UNIT

– 0.3 to 20 V – 0.3 to 20 V

– 0.3 to 3 V

– 0.3 to 40 V

DISSIPATION RATINGS

BOARD PACKAGE R

(1)

Low-K

High-K

DRV 20 ° C/W 140 ° C/W 7.1 mW/ ° C 715 mW 395 mW 285 mW

(2)

DRV 20 ° C/W 65 ° C/W 15.4 mW/ ° C 1540 mW 845 mW 615 mW

θ JC

R

θ JA

(1) The JEDEC low-K (1s) board used to derive this data was a 3in × 3in, two-layer board with 2-ounce copper traces on top of the board. (2) The JEDEC high-K (2s2p) board used to derive this data was a 3in × 3in, multilayer board with 1-ounce internal power and ground planes

and 2-ounce copper traces on top and bottom of the board.

DERATING FACTOR

ABOVE TA= 25 ° C

TA< 25 ° C TA= 70 ° C TA= 85 ° C

RECOMMENDED OPERATING CONDITIONS

MIN TYP MAX UNIT

V V L Inductor f Duty PWM duty cycle resolution at 10kHz 0.5 %

C C T T

(1) These values are recommended values that have been successfully tested in several applications. Other values may be acceptable in (2) The device can support the frequency range from 1kHz to 5kHz based on the specification, t

Input voltage range, VIN 2.7 18 V

I

Output voltage range VIN 38 V

O

dim

PWM dimming frequency

(1)

(2)

10 22 µ H

5 100 kHz

at 30kHz 1.5 Input capacitor 1 µ F

IN

Output capacitor

O

Operating ambient temperature – 40 85 ° C

A

Operating junction temperature – 40 125 ° C

J

(1)

0.47 10 µ F

other applications but should be fully tested by the user.

. The output ripple needs to be

considered in the range of 1kHz to 5kHz.

off

Product Folder Link(s): TPS61160A TPS61161A

TPS61160A TPS61161A

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ELECTRICAL CHARACTERISTICS

VIN = 3.6 V, CTRL = VIN, TA= – 40 ° C to 85 ° C, typical values are at TA= 25 ° C (unless otherwise noted)

SUPPLY CURRENT

V

I

Q

I

SD

UVLO Undervoltage lockout threshold VIN falling 2.2 2.5 V V

hys

ENABLE AND REFERENCE CONTROL

V

(CTRLh)

V

(CTRLl)

R

(CTRL)

t

off

VOLTAGE AND CURRENT CONTROL

V

REF

V

(REF_PWM)

I

FB

f

S

D

max

t

min_on

I

sink

I

source

G

ea

R

ea

f

ea

POWER SWITCH

R

DS(on)

I

LN_NFET

OC and OLP

I

LIM

I

LIM_Start

t

Half_LIM

V

ovp

V

(FB_OVP)

t

REF

t

step

THERMAL SHUTDOWN

T

shutdown

T

hysteresis

................................................................................................................................................................................................... SLVS937 – MARCH 2009

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Input voltage range, VIN 2.7 18 V Operating quiescent current into VIN Device PWM switching no load 1.8 mA Shutdown current CRTL=GND, VIN = 4.2 V 1 µ A

Undervoltage lockout hysterisis 70 mV

CTRL logic high voltage VIN = 2.7 V to 18 V 1.2 V CTRL logic low voltage VIN = 2.7 V to 18 V 0.4 V CTRL pull down resistor 400 800 1600 k Ω CTRL pulse width to shutdown CTRL high to low 2.5 ms

Voltage feedback regulation voltage 196 200 204 mV Voltage feedback regulation voltage under V

brightness control Voltage feedback input bias current V

= 50 mV 47 50 53 mV

FB

V

= 20 mV 17 20 23

FB

= 200 mV 2 µ A

FB

Oscillator frequency 500 600 700 kHz Maximum duty cycle V

= 100 mV 90 93 %

FB

Minimum on pulse width 40 ns Comp pin sink current 100 µ A Comp pin source current 100 µ A Error amplifier transconductance 240 320 400 µ mho Error amplifier output resistance 6 M Ω Error amplifier crossover frequency 5 pF connected to COMP 500 kHz

N-channel MOSFET on-resistance VIN = 3.6 V 0.3 0.6

VIN = 3.0 V 0.7

N-channel leakage current V

N-Channel MOSFET current limit D = D Start up current limit D = D

= 35 V, TA= 25 ° C 1 µ A

SW

max max

0.56 0.7 0.84 A

0.4 A Time step for half current limit 5 ms Open LED protection threshold Measured on the SW pin, TPS61160A 25 26 27 V

TPS61161A 37 38 39

Open LED protection threshold on FB Measured on the FB pin, percentage

of Vref, Vref = 200 mV and 20 mV

V

filter time constant 180 µ s

REF

V

ramp up time 213 µ s

REF

50%

Thermal shutdown threshold 160 ° C Thermal shutdown threshold hysteresis 15 ° C

Ω

Product Folder Link(s): TPS61160A TPS61161A

VIN

CTRL

SW

FB

COMP

GND

TOP VIEW

Thermal

Pad

6-PIN2mmx2mmx0.8mmQFN

TPS61160A TPS61161A

SLVS937 – MARCH 2009 ...................................................................................................................................................................................................

DEVICE INFORMATION

TERMINAL FUNCTIONS

TERMINAL

NAME NO.

VIN 6 I The input supply pin for the IC. Connect VIN to a supply voltage between 2.7V and 18V. SW 4 I GND 3 O Ground

FB 1 I Feedback pin for current. Connect the sense resistor from FB to GND. COMP 2 O

CTRL 5 I

Thermal Pad

I/O DESCRIPTION

This is the switching node of the IC. Connect the inductor between the VIN and SW pin. This pin is also used to sense the output voltage for open LED protection

Output of the transconductance error amplifier. Connect an external capacitor to this pin to compensate the regulator.

Control pin of the boost regulator. Enable and disable IC. PWM signal can be applied to the pin for LED brightness dimming as well.

The thermal pad should be soldered to the analog ground plane. If possible, use thermal via to connect to ground plane for ideal power dissipation.

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Product Folder Link(s): TPS61160A TPS61161A

SW

Ramp

Generator

Oscillator

Current Sensor

OLP

CTRL

GND

C3

L1

+

FB

Reference

Control

D1

Error

Amplifer

2

1

Rset

C2

Vin

C1

PWMControl

4

6

Soft

Start-up

5

3

COMP

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................................................................................................................................................................................................... SLVS937 – MARCH 2009

FUNCTIONAL BLOCK DIAGRAM

TPS61160A TPS61161A

TYPICAL CHARACTERISTICS

TABLE OF GRAPHS

FIGURE

Efficiency TPS61160A/61A VIN = 3.6 V; 4, 6, 8, 10 LEDs; L = 22 µ H Figure 2 Efficiency TPS61160A Figure 3 Efficiency TPS61161A Figure 4

Product Folder Link(s): TPS61160A TPS61161A

= 20 mA; PWM Freq = 10 kHz Figure 8

LOAD

= 20 mA; L = 22 µ H Figure 9

LOAD

= 20 mA; L =22 µ H Figure 10

LOAD

= 20 mA; L = 22 µ H Figure 11

LOAD

Current limit TA= 25 ° C Figure 5 Current limit Figure 6 PWM dimming linearity VIN = 3.6 V; PWM Freq = 10 kHz and 40 kHz Figure 7 Output ripple at PWM dimming 8 LEDs; VIN = 3.6 V; I Switching waveform 8 LEDs; VIN = 3.6 V; I Start-up 8 LEDs; VIN = 3.6 V; I Open LED protection 8 LEDs; VIN = 3.6 V; I

40

50

60

70

80

90

100

0 10 20 30 40 50

6LEDs- TPS61160A

V =3.6V

I

V =3V

I

V =4.2V

I

OutputCurrent-mA

Efficiency-%

40

50

60

70

80

90

100

0 10 20 30 40 50

OutputCurrent-mA

4(12.8V),6(19.2V)LEDs 8(25.6V),10(32V)LEDs

6LEDs

V =3.6V

I

4LEDs

8LEDs

10LEDs

Efficiency-%

300

400

500

600

700

800

900

1000

20 30 40 50 60 70 80 90

DutyCycle-%

SwitchCurrentLimit-mA

40

50

60

70

80

90

100

0 10 20 30 40 50

10LEDs- TPS61161A

V =5V

I

V =3.6V

I

V =12V

I

OutputCurrent-mA

Efficiency-%

300

400

500

600

700

800

900

1000

-40 -20 0 20 40 60 80 100 120 140

Temperature- C°

SwitchCurrentLimit-mA

0

40

80

120

160

200

0 20 40 60 80 100

PWMDutyCycle-%

10kHz,40kHz

FBVoltage-mV

TPS61160A TPS61161A

SLVS937 – MARCH 2009 ...................................................................................................................................................................................................

EFFICIENCY EFFICIENCY

vs vs

OUTPUT CURRENT OUTPUT CURRENT

Figure 2. Figure 3.

EFFICIENCY SWITCH CURRENT LIMIT

vs vs

OUTPUT CURRENT DUTY CYCLE

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Figure 4. Figure 5.

SWITCH CURRENT LIMIT FB VOLTAGE

vs vs

TEMPERATURE PWM DUTY CYCLE

Figure 6. Figure 7.

Product Folder Link(s): TPS61160A TPS61161A

t-1 s/divm

SW 20V/div

VOUT 20mV/div AC

I 200mA/div

L

t-100 s/divm

PWM2V/div

VOUT 20mV/div AC

I 10mA/div

LED

t-2ms/div

CTRL 5V/div

VOUT

10V/div

COMP 500mV/div

I 200mA/div

L

t-100 s/divm

OPENLED 5V/div

FB 200mV/div

VOUT

10V/div

I 200mA/div

L

TPS61160A TPS61161A

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................................................................................................................................................................................................... SLVS937 – MARCH 2009

OUTPUT RIPPLE at PWM DIMMING SWITCHING WAVEFORM

Figure 8. Figure 9.

START-UP OPEN LED PROTECTION

Figure 10. Figure 11.

Product Folder Link(s): TPS61160A TPS61161A

I

LED

+

V

FB

R

SET

TPS61160A TPS61161A

SLVS937 – MARCH 2009 ...................................................................................................................................................................................................

DETAILED DESCRIPTION

OPERATION

The TPS61160A/61A is a high efficiency, high output voltage boost converter in small package size that is ideal for driving up to 10 white LED in series. The serial LED connection provides even illumination by sourcing the same output current through all LEDs, eliminating the need for expensive factory calibration. The device integrates 40V/0.7A switch FET and operates in pulse width modulation (PWM) with 600kHz fixed switching frequency. For operation see the block diagram. The duty cycle of the converter is set by the error amplifier output and the current signal applied to the PWM control comparator. The control architecture is based on traditional current-mode control; therefore, a slope compensation is added to the current signal to allow stable operation for duty cycles larger than 50%. The feedback loop regulates the FB pin to a low reference voltage (200mV typical), reducing the power dissipation in the current sense resistor.

SOFT START-UP

Soft-start circuitry is integrated into the IC to avoid a high inrush current during start-up. After the device is enabled, the voltage at FB pin ramps up to the reference voltage in 32 steps, each step takes 213 µ s. This ensures that the output voltage rises slowly to reduce the input current. Additionally, for the first 5msec after the COMP voltage ramps, the current limit of the switch is set to half of the normal current limit spec. During this period, the input current is kept below 400mA (typical). See the start-up waveform of a typical example,

Figure 10 .

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OPEN LED PROTECTION

Open LED protection circuitry prevents IC damage as the result of white LED disconnection. The TPS61160A/61A monitors the voltage at the SW pin and FB pin during each switching cycle. The circuitry turns off the switch FET and shuts down the IC as soon as the SW voltage exceeds the Vovp threshold and the FB voltage is less than half of regulation voltage for 8 clock cycles. As a result, the output voltage falls to the level of the input supply. The device remains in shutdown mode until it is enabled by toggling the CTRL pin logic. To allow the use of inexpensive low-voltage output capacitor, the TPS61160A/61A has different open lamp protection thresholds to prevent the internal 40V FET from breaking down. The threshold is set at 26V for the TPS61160A and 38V for the TPS61161A. The devices can be selected according to the number of external LEDs and their maximum forward voltage.

SHUTDOWN

The TPS61160A/61A enters shutdown mode when the CTRL voltage is logic low for more than 2.5ms. During shutdown, the input supply current for the device is less than 1 µ A (max). Although the internal FET does not switch in shutdown, there is still a DC current path between the input and the LEDs through the inductor and Schottky diode. The minimum forward voltage of the LED array must exceed the maximum input voltage to ensure that the LEDs remain off in shutdown; however, in the typical application with two or more LEDs, the forward voltage is large enough to reverse bias the Schottky and keep leakage current low.

CURRENT PROGRAM

The FB voltage is regulated by a low 0.2V reference voltage. The LED current is programmed externally using a current-sense resistor in series with the LED string. The value of the RSET is calculated using Equation 1 :

Where

I

= output current of LEDs

LED

V

= regulated voltage of FB

FB

R

= current sense resistor

SET

The output current tolerance depends on the FB accuracy and the current sensor resistor accuracy.

(1)

Product Folder Link(s): TPS61160A TPS61161A

VFB+ Duty 200 mV

VBG

200mV

Error

Amplifier

FB

CTRL

TPS61160A TPS61161A

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PWM BRIGHTNESS DIMMING

When the CTRL pin is constantly high, the FB voltage is regulated to 200mV typically. However, the CTRL pin allows a PWM signal to reduce this regulation voltage; therefore, it achieves LED brightness dimming. The relationship between the duty cycle and FB voltage is given by Equation 2 .

Where

As shown in Figure 12 , the IC chops up the internal 200mV reference voltage at the duty cycle of the PWM signal. The pulse signal is then filtered by an internal low pass filter. The output of the filter is connected to the error amplifier as the reference voltage for the FB pin regulation. Therefore, although a PWM signal is used for brightness dimming, only the WLED DC current is modulated, which is often referred as analog dimming. This eliminates the audible noise which often occurs when the LED current is pulsed in replica of the frequency and duty cycle of PWM control. Unlike other scheme which filters the PWM signal for analog dimming, TPS61160A/61A regulation voltage is independent of the PWM logic voltage level which often has large variations.

For optimum performance, use the PWM dimming frequency in the range of 5kHz to 100kHz. The requirement of minimum dimming frequency comes from the output ripple. Low frequency causes high output ripple. Since the CTRL pin is logic only pin, applying an external RC filter to the pin does not work.

................................................................................................................................................................................................... SLVS937 – MARCH 2009

Duty = duty cycle of the PWM signal 200 mV = internal reference voltage

(2)

Figure 12. Block Diagram of Programmable FB Voltage Using PWM Signal

To use lower PWM dimming, add an external RC network connected to the FB pin as shown in the additional typical application (Figure 15 ).

UNDERVOLTAGE LOCKOUT

An undervoltage lockout prevents operation of the device at input voltages below typical 2.2V. When the input voltage is below the undervoltage threshold, the device is shutdown and the internal switch FET is turned off. If the input voltage rises by undervoltage lockout hysteresis, the IC restarts.

THERMAL SHUTDOWN

An internal thermal shutdown turns off the device when the typical junction temperature of 160 ° C is exceeded. The device is released from shutdown automatically when the junction temperature decreases by 15 ° C.

Product Folder Link(s): TPS61160A TPS61161A

ú û

ù

ê ë

é

+

-+

´´

=

)

V

1

VVV

1

(FL

1

I

ininfout

s

P

I

out_max

+

Vin ǒI

lim

* IPń2

Ǔ

h

Vout

I

in_DC

+

Vout Iout

Vin h

TPS61160A TPS61161A

SLVS937 – MARCH 2009 ...................................................................................................................................................................................................

APPLICATION INFORMATION

MAXIMUM OUTPUT CURRENT

The overcurrent limit in a boost converter limits the maximum input current and thus maximum input power for a given input voltage. Maximum output power is less than maximum input power due to power conversion losses. Therefore, the current limit setting, input voltage, output voltage and efficiency can all change maximum current output. The current limit clamps the peak inductor current; therefore, the ripple has to be subtracted to derive maximum DC current. The ripple current is a function of switching frequency, inductor value and duty cycle. The following equations take into account of all the above factors for maximum output current calculation.

Where:

Ip= inductor peak to peak ripple L = inductor value Vf= Schottky diode forward voltage Fs = switching frequency V

= output voltage of the boost converter. It is equal to the sum of VFB and the voltage drop across LEDs.

out

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(3)

Where:

I I

= maximum output current of the boost converter

out_max

= over current limit

lim

η = efficiency

For instance, when VIN is 3.0V, 8 LEDs output equivalent to VOUT of 26V, the inductor is 22 µ H, the Schottky forward voltage is 0.2V; and then the maximum output current is 65mA in typical condition. When VIN is 5V, 10 LEDs output equivalent to VOUT of 32V, the inductor is 22 µ H, the Schottky forward voltage is 0.2V; and then the maximum output current is 85mA in typical condition.

INDUCTOR SELECTION

The selection of the inductor affects steady state operation as well as transient behavior and loop stability. These factors make it the most important component in power regulator design. There are three important inductor specifications, inductor value, DC resistance and saturation current. Considering inductor value alone is not enough.

The inductor value determines the inductor ripple current. Choose an inductor that can handle the necessary peak current without saturating, according to half of the peak-to-peak ripple current given by Equation 3 , pause the inductor DC current given by:

Inductor values can have ± 20% tolerance with no current bias. When the inductor current approaches saturation level, its inductance can decrease 20% to 35% from the 0A value depending on how the inductor vendor defines saturation current. Using an inductor with a smaller inductance value forces discontinuous PWM when the inductor current ramps down to zero before the end of each switching cycle. This reduces the boost converter ’ s maximum output current, causes large input voltage ripple and reduces efficiency. Large inductance value provides much more output current and higher conversion efficiency. For these reasons, a 10 µ H to 22 µ H inductor value range is recommended. A 22 µ H inductor optimized the efficiency for most application while maintaining low inductor peak to peak ripple. Table 1 lists the recommended inductor for the TPS61160A/61A. When recommending inductor value, the factory has considered – 40% and +20% tolerance from its nominal value.

(4)

(5)

Product Folder Link(s): TPS61160A TPS61161A

C

out

+

ǒ

V

out

* V

in

Ǔ

I

out

V

out

Fs V

ripple

V

ripple_ESR

+ I

out

R

ESR

TPS61160A TPS61161A

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TPS61160A/61A has built-in slope compensation to avoid sub-harmonic oscillation associated with current mode control. If the inductor value is lower than 10 µ H, the slope compensation may not be adequate, and the loop can be unstable. Therefore, customers need to verify the inductor in their application if it is different from the recommended values.

VLCF5020T-220MR75-1 22 0.4 750 5 × 5 × 2.0 TDK

SCHOTTKY DIODE SELECTION

The high switching frequency of the TPS61160A/61A demands a high-speed rectification for optimum efficiency. Ensure that the diode average and peak current rating exceeds the average output current and peak inductor current. In addition, the diode ’ s reverse breakdown voltage must exceed the open LED protection voltage. The ONSemi MBR0540 and the ZETEX ZHCS400 are recommended for TPS61160A/61A.

COMPENSATION CAPACITOR SELECTION

The compensation capacitor C3 (see the block diagram), connected from COMP pin to GND, is used to stabilize the feedback loop of the TPS61160A/61A. Use a 220nF ceramic capacitor for C3.

................................................................................................................................................................................................... SLVS937 – MARCH 2009

Table 1. Recommended Inductors for TPS61160A/61A

PART NUMBER VENDOR

LQH3NPN100NM0 10 0.3 750 3 × 3 × 1.5 Murata

CDH3809/SLD 10 0.3 570 4 × 4 × 1.0 Sumida

A997AS-220M 22 0.4 510 4 × 4 × 1.8 TOKO

L DCR MAX SATURATION CURRENT SIZE

( µ H) ( Ω ) (mA) (L × W × H mm)

INPUT AND OUTPUT CAPACITOR SELECTION

The output capacitor is mainly selected to meet the requirements for the output ripple and loop stability. This ripple voltage is related to the capacitor ’ s capacitance and its equivalent series resistance (ESR). Assuming a capacitor with zero ESR, the minimum capacitance needed for a given ripple can be calculated by

where, V using:

Due to its low ESR, Vripple_ESR can be neglected for ceramic capacitors, but must be considered if tantalum or electrolytic capacitors are used.

Care must be taken when evaluating a ceramic capacitor ’ s derating under dc bias, aging and AC signal. For example, larger form factor capacitors (in 1206 size) have a resonant frequencies in the range of the switching frequency. So the effective capacitance is significantly lower. The DC bias can also significantly reduce capacitance. Ceramic capacitors can loss as much as 50% of its capacitance at its rated voltage. Therefore, leave the margin on the voltage rating to ensure adequate capacitance at the required output voltage.

The capacitor in the range of 1 µ F to 4.7 µ F is recommended for input side. The output requires a capacitor in the range of 0.47 µ F to 10 µ F. The output capacitor affects the loop stability of the boost regulator. If the output capacitor is below the range, the boost regulator can potentially become unstable. For example, if use the output capacitor of 0.1 µ F, a 470nF compensation capacitor has to be used for the loop stable.

The popular vendors for high value ceramic capacitors are:

TDK (http://www.component.tdk.com/components.php ) Murata (http://www.murata.com/cap/index.html )

= peak-to-peak output ripple. The additional output ripple component caused by ESR is calculated

ripple

(6)

Product Folder Link(s): TPS61160A TPS61161A

CTRL

GND

C3

L1

Rset

Vin

CTRL

SW

FB

COMP

GND

C1 Vin

C2

LEDsIN

LEDsOut

Minimizethe areaofthis trace

Placeenough VIAsaround thermalpadto enhancethermal performance

P

D(max)

+

125°C * T

A

RqJA

TPS61160A TPS61161A

SLVS937 – MARCH 2009 ...................................................................................................................................................................................................

LAYOUT CONSIDERATIONS

As for all switching power supplies, especially those high frequency and high current ones, layout is an important design step. If layout is not carefully done, the regulator could suffer from instability as well as noise problems. To reduce switching losses, the SW pin rise and fall times are made as short as possible. To prevent radiation of high frequency resonance problems, proper layout of the high frequency switching path is essential. Minimize the length and area of all traces connected to the SW pin and always use a ground plane under the switching regulator to minimize inter-plane coupling. The loop including the PWM switch, Schottky diode, and output capacitor, contains high current rising and falling in nanosecond and should be kept as short as possible. The input capacitor needs not only to be close to the VIN pin, but also to the GND pin in order to reduce the IC supply ripple. Figure 13 shows a sample layout.

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Figure 13. Sample Layout

THERMAL CONSIDERATIONS

The maximum IC junction temperature should be restricted to 125 ° C under normal operating conditions. This restriction limits the power dissipation of the TPS61160A/61A. Calculate the maximum allowable dissipation, P

, and keep the actual dissipation less than or equal to P

D(max)

determined using Equation 7 :

where, T junction-to-ambient given in Power Dissipation Table.

is the maximum ambient temperature for the application. R

A

The TPS61160A/61A comes in a thermally enhanced QFN package. This package includes a thermal pad that improves the thermal capabilities of the package. The R layout and thermal pad connection. The thermal pad must be soldered to the analog ground on the PCB. Using thermal vias underneath the thermal pad as illustrated in the layout example. Also see the QFN/SON PCB

of the QFN package greatly depends on the PCB

θ JA

Attachment application report (SLUA271 ).

Product Folder Link(s): TPS61160A TPS61161A

. The maximum-power-dissipation limit is

D(max)

is the thermal resistance

θ JA

(7)

Vin3Vto5V

L1

10 Hm

C1

1 Fm

D1

Rset

10 W

VIN SW

FB

GND

CTRL

COMP

C2

0.47 Fm

20 mA

C3

220 nF

TPS61160A

ON/ OFF

DIMMING

CONTROL

L1: C1:MurataGRM188R61A105K C2:MurataGRM188R61E474K D1:

MurataLQH3NPN100NM0

ONsemiMBR0540T1

L1

10 Hm

C1

D1

Rset 10 W

VIN SW

FB

GND

CTRL

COMP

C2

220 nF

TPS61160A

ON/OFF

DIMMING

CONTROL

80kW

10kW

100kW

C3

PWMSignal:1.8V;200Hz LEDCurrent=1.8Vx(1-d)/(8xRset)

L1: C1:MurataGRM188R61A105K C2:MurataGRM188R61E474K D1:

MurataLQH3NPN100NM0

ONsemiMBR0540T1

Vin3Vto5V

L1

22 Hm

D1

Rset 10 W

VIN SW

FB

GND

CTRL

COMP

C2

20mA

C3

220nF

TPS61161A

ON/OFF

DIMMING

CONTROL

C1

L1: TDKVLCF5020T-220MR75-1 C1:MurataGRM188R61A105K C2: MurataGRM21BR71H105K D1:ONsemiMBR0540T1

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ADDITIONAL TYPICAL APPLICATIONS

TPS61160A TPS61161A

................................................................................................................................................................................................... SLVS937 – MARCH 2009

Figure 14. Li-Ion Driver for 6 White LEDs

Figure 15. Li-Ion Driver for 6 White LEDs With External PWM Dimming Network

Figure 16. Li-Ion Driver for 8 White LEDs

Product Folder Link(s): TPS61160A TPS61161A

PACKAGE OPTION ADDENDUM

www.ti.com 14-May-2009

PACKAGING INFORMATION

Orderable Device Status

(1)

Package

Type

Package Drawing

Pins Package

Qty

Eco Plan

TPS61160ADRVR ACTIVE SON DRV 6 3000 Green (RoHS &

(2)

Lead/Ball Finish MSL Peak Temp

CU NIPDAU Level-2-260C-1 YEAR

(3)

no Sb/Br)

TPS61160ADRVT ACTIVE SON DRV 6 250 Green (RoHS &

CU NIPDAU Level-2-260C-1 YEAR

no Sb/Br)

TPS61161ADRVR ACTIVE SON DRV 6 3000 Green (RoHS &

CU NIPDAU Level-2-260C-1 YEAR

no Sb/Br)

TPS61161ADRVT ACTIVE SON DRV 6 250 Green (RoHS &

CU NIPDAU Level-2-260C-1 YEAR

no Sb/Br)

(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 isin 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 notbe 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.

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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 8-Jun-2009

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type

TPS61160ADRVR SON DRV 6 3000 330.0 12.4 2.2 2.2 1.1 8.0 12.0 Q2 TPS61160ADRVT SON DRV 6 250 180.0 12.4 2.2 2.2 1.1 8.0 12.0 Q2 TPS61161ADRVR SON DRV 6 3000 330.0 12.4 2.2 2.2 1.1 8.0 12.0 Q2 TPS61161ADRVT SON DRV 6 250 180.0 12.4 2.2 2.2 1.1 8.0 12.0 Q2

Package Drawing

Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

A0 (mm) B0 (mm) K0 (mm) P1

(mm)W(mm)

Pin1

Quadrant

Pack Materials-Page 1

PACKAGE MATERIALS INFORMATION

www.ti.com 8-Jun-2009

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

TPS61160ADRVR SON DRV 6 3000 346.0 346.0 29.0

TPS61160ADRVT SON DRV 6 250 190.5 212.7 31.8

TPS61161ADRVR SON DRV 6 3000 346.0 346.0 29.0

TPS61161ADRVT SON DRV 6 250 190.5 212.7 31.8

Pack Materials-Page 2

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TEXAS INSTRUMENTS TPS61160A, TPS61161A Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual

FEATURES

APPLICATIONS

DESCRIPTION

ABSOLUTE MAXIMUM RATINGS

DISSIPATION RATINGS

RECOMMENDED OPERATING CONDITIONS

ELECTRICAL CHARACTERISTICS

DEVICE INFORMATION

FUNCTIONAL BLOCK DIAGRAM

TYPICAL CHARACTERISTICS

TABLE OF GRAPHS

DETAILED DESCRIPTION

OPERATION

SOFT START-UP

OPEN LED PROTECTION

SHUTDOWN

CURRENT PROGRAM

PWM BRIGHTNESS DIMMING

UNDERVOLTAGE LOCKOUT

THERMAL SHUTDOWN

APPLICATION INFORMATION

MAXIMUM OUTPUT CURRENT

INDUCTOR SELECTION

SCHOTTKY DIODE SELECTION

COMPENSATION CAPACITOR SELECTION

INPUT AND OUTPUT CAPACITOR SELECTION

LAYOUT CONSIDERATIONS

THERMAL CONSIDERATIONS

ADDITIONAL TYPICAL APPLICATIONS