TPS61054DRC_技术文档

CSP-12

QFN-10

TPS61054, TPS61055

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SLUS760–SEPTEMBER 2007

HIGH POWER WHITE LED DRIVER

2-MHz SYNCHRONOUS BOOST CONVERTER WITH STANDARD LOGIC INTERFACE

1

FEATURES

DESCRIPTION

2

•

Four Operational Modes

–

Torch and Flash up to I_LED= 700 mA

Voltage-Regulated Boost Converter: 5.0 V

Shutdown: 0.3 μA (typ)

The TPS6105x device uses

a

high-frequency

synchronous-boost topology with constant current

sink to drive single white LEDs. The device uses an

inductive fixed-frequency PWM control scheme using

small external components, minimizing input ripple

current.

•

Total Solution Circuit Area < 25 mm²

Up to 96% Efficiency

Integrated LED Turn-On Safety Timer

Zero Latency TX-Masking Input

Integrated Low Light Dimming Mode

LED Disconnect During Shutdown

Open/Shorted LED Protection

Over-Temperature Protection

The 2-MHz switching frequency allows the use of

small and low-profile 2.2-μH inductors. To optimize

overall efficiency, the device operates with only a

250-mV LED feedback voltage.

The TPS6105x device not only operates as a

regulated current source, but also as a standard

voltage-boost regulator. This additional operating

mode can be useful to supply other high-power

devices in the system, such as a hands-free audio

power amplifier, or any other component requiring a

supply voltage higher than the battery voltage.

Available in a 12-Pin NanoFree™ (CSP) and

10-Pin QFN Packaging

APPLICATIONS

•

The LED current or the desired output voltage can be

programmed via two logic signals (MODE0/1). To

simplify flash synchronization with the camera

Camera White LED Torch/Flash for Cell

Phones, Smart-Phones and PDAs

General Lighting Applications

Audio Amplifier Power Supply

•

module, the device offers

a

trigger pin

(FLASH_SYNC) for fast LED turn-on time.

When the TPS6105x is not in use, it can be put into

shutdown mode, reducing the input current to 0.3 μA

(typ). During shutdown, the LED pin is high

impedance to avoid leakage current through the LED.

TPS61054

4.7 mm

L

+ BATTERY

SW

VOUT

INDUCTOR

2.2 mH

C1

C_OUT

AVIN

10 mF

L1

P

C_IN

LED

SENSE

P

PGND

LED

MODE1

MODE0

Tx-TOFF

PGND

FLASH_SYNC

PGND

P

C2

AGND

LED ANODE

Figure 1. Typical Application

Figure 2. Typical PC-Board Layout

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.

2

NanoFree, PowerPAD are trademarks of Texas Instruments.

PRODUCT PREVIEW information concerns products in the

formative or design phase of development. Characteristic data and

other specifications are design goals. Texas Instruments reserves

the right to change or discontinue these products without notice.

TPS61054, TPS61055

www.ti.com

SLUS760–SEPTEMBER 2007

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 OPTIONS

SAFETY TIMER

MAXIMUM

DURATION

PART

TORCH

FLASH

PACKAGE

MARKING

CURRENT LIMIT

PACKAGE

NUMBER⁽¹⁾⁽²⁾

CURRENT⁽³⁾

TPS61054YZG

TPS61054DRC

TPS61055YZG

TPS61055DRC

75 mA

700 mA

500 mA

820 ms

1500 mA (ILIM = 01)

1000 mA (ILIM = 00)

61054

61055

CSP-12

QFN-10

CSP-12

QFN-10

(1) All devices are specified for operation in the commercial temperature range, –40°C to 85°C.

(2) The YZG package is available in tape and reel. Add R suffix (TPS6105xYZGR, TPS6105xDRCR) to order quantities of 3000 parts. Add

T suffix (TPS6105xYZGT, TPS6105xDRCT) to order quantities of 250 parts.

(3) For customized current settings, please contact the factory.

ABSOLUTE MAXIMUM RATINGS

over operating free-air temperature range (unless otherwise noted)⁽¹⁾

TPS6105X

–0.3 to 7

–40 to 85

150

UNIT

V

(2)

Voltage range on AVIN, VOUT, SW, LED

(2)

Voltage range on MODE0, MODE1, FLASH_SYNC, Tx-TOFF

V

(3)

T_A

Operating ambient temperature range

°C

kV

V

T_{J (MAX)}

T_stg

Maximum operating junction temperature

Storage temperature range

Human body model

–65 to 150

2

ESD

Charge device model

1

rating⁽⁴⁾

Machine model

200

(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.

(3) In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may

have to be derated. Maximum ambient temperature (T_A(max)) is dependent on the maximum operating junction temperature (T_J(max)), the

maximum power dissipation of the device in the application (P_D(max)), and the junction-to-ambient thermal resistance of the part/package

in the application (θ_JA), as given by the following equation: T_A(max)= T_J(max)–(θ_JAX P_D(max)).

(4) The human body model is a 100-pF capacitor discharged through a 1.5-kΩ resistor into each pin. The machine model is a 200-pF

capacitor discharged directly into each pin.

DISSIPATION RATINGS

POWER RATING

DERATING FACTOR

PACKAGE

THERMAL RESISTANCE^{(1) (2)}

T_A= 25°C

ABOVE^{(1) (2)}T_A= 25°C

YZG

DRC

θ_JA= 89°C/W

θ_JA= 49°C/W

θ_JB= 35°C/W

θ_JC= 3.2°C/W

1.1 W

2.4 W

12 mW/°C

20 mW/°C

(1) Measured with high-K board.

(2) Maximum power dissipation is a function of T_J(max), θ_JAand T_A. The maximum allowable power dissipation at any allowable ambient

temperature is P_D= (T_J(max)–T_A)/ θ_JA

.

2

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ELECTRICAL CHARACTERISTICS

Unless otherwise noted the specification applies for V_IN= 3.6 V over an operating junction temp. of –40°C ≤ T_J≤ 125°C.

Typical values are for T_A= 25°C.

PARAMETER

TEST CONDITIONS

MIN

TYP

MAX

UNIT

SUPPLY CURRENT

Input voltage range

2.5

6.0

2.5

V

V_IN

Minimum input voltage for start-up

Operating quiescent current into AVIN

Shutdown current into AVIN

MODE0 = 1, MODE1 = 1, R_L= 10 Ω

MODE0 = 1, MODE1 = 1

I_Q

8.5

0.3

2.3

mA

μA

V

I_SD

MODE0 = 0, MODE1 = 0, –40°C ≤ T_J≤ 85°C

V_INfalling

3.0

2.4

V_UVLO

OUTPUT

Undervoltage lockout threshold

Current regulator mode

Voltage regulator mode

V_OUTrising

V_IN

5.7

5.5

V_OUT

Output voltage range

V

5.0

6.0

OVP Output overvoltage protection

Output overvoltage protection hysterisis

Minimum duty cycle

6.25

V

OVP

D

0.15

7.5%

0.25 V ≤ V_LED≤ 2.0 V, I_LED= I_TORCH, T_J= 50°C

0.25 V ≤ V_LED≤ 2.0 V, I_LED= I_FLASH, T_J= 50°C

–15%

–12%

15%

12%

LED current accuracy⁽¹⁾

LED current temperature coefficient

DC output voltage accuracy

LED sense voltage

0.08

%/°C

2.5 V ≤ V_IN≤ 0.9 V_OUT, PWM operation

Boost Mode

–3%

3%

1

V_LED

250

0.1

mV

LED input leakage current

V_LED= V_OUT= 5 V, –40°C ≤ T_J≤ 85°C

μA

POWER SWITCH

Switch MOSFET on-resistance

80

r_DS(on)

I_lkg(SW)

I_lim

V_OUT= V_GS= 3.6 V

mΩ

μA

Rectifier MOSFET on-resistance

Switch MOSFET leakage

0.1

1

V_DS= 6.0 V, –40°C ≤ T_J≤ 85°C

Rectifier MOSFET leakage

0.1

2.5 V ≤ V_IN≤ 6.0 V, ILIM = 00

2.5 V ≤ V_IN≤ 6.0 V, ILIM = 01 ⁽¹⁾

850

1275

140

1000

1500

160

20

1150

1725

Switch current limit

mA

Thermal shutdown ⁽¹⁾

°C

Thermal shutdown hysteresis ⁽¹⁾

OSCILLATOR

f_SW

Oscillator frequency

1.8

1.2

2.0

2.2

MHz

MODE0, MODE1, Tx-TOFF, FLASH_SYNC

V_(IH)

V_(IL)

High-level input voltage

V

Low-level input voltage

0.4

0.1

V

I_(LKG)

Logic input leakage current

Tx-TOFF pull-down resistance

FLASH_SYNC pull-down resistance

Input connected to V_INor GND, –40°C ≤ T_J≤ 85°C

Tx-TOFF ≤ 0.4 V

0.01

400

μA

kΩ

FLASH_SYNC ≤ 0.4 V

TIMING

From shutdown into flash mode I_LED= 700 mA

1.2

ms

Start-up time

From shutdown into voltage mode

MODE0 = 1, MODE1 = 1, I_OUT= 0 mA

650

μs

LED current settling time⁽²⁾triggered by

rising edge on FLASH_SYNC

LED current settling time⁽²⁾triggered by

rising edge on Tx-TOFF

MODE0 = 0, MODE1 = 1,

I_LED= from 75mA to 700 mA

160

20

μs

MODE0 = 0, MODE1 = 1,

I_LED= 700 mA to 75 mA

(1) Assured by design. Not tested in production.

(2) Settling time to ±15% of the target value

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SLUS760–SEPTEMBER 2007

DEVICE INFORMATION

PIN ASSIGMENTS

TERMINAL FUNCTIONS

TERMINAL

I/O

DESCRIPTION

NO.

(CSP)

NAME

(QFN)

AVIN

VOUT

LED

5

9

6

D3

A2

D2

I

O

I

This is the input voltage pin of the device. Connect directly to the input bypass capacitor.

Boost converter output.

LED return input. This feedback pin regulates the LED current through the internal sense

resistor by regulating the voltage across it. The regulation operates with typically 250 mV

dropout voltage. Connect to the cathode of the LED.

FLASH_SYNC

10

A1

I

Flash strobe pulse synchronization input.

FLASH_SYNC = LOW (GND): The device is operating and regulating the LED current to

the torch current level (TC).

FLASH_SYNC = HIGH (VIN): The device is operating and regulating the LED current to the

flash current level (FC).

MODE0

MODE1

2

1

B3

A3

I

Mode selection inputs. These pins must not be left floating and must be terminated.

MODE0 = 0, MODE1 = 0: Device in shutdown mode

MODE0 = 1, MODE1 = 0: Device in torch only mode

MODE0 = 0, MODE1 = 1: Device in torch and flash mode

MODE0 = 1, MODE1 = 1: Device in constant voltage regulation mode

RF PA synchronization input.

Tx-TOFF

SW

3

8

C3

I

Tx-TOFF = LOW : The device is operating normally.

Tx-TOFF = HIGH : The device is forced into torch mode.

B1, B2

I/O Inductor connection. Drain of the internal power MOSFET. Connect to the switched side of

the inductor. SW is high impedance during shutdown.

PGND

7

4

C1, C2

D1

Power ground. Connect to AGND underneath IC.

Analog ground.

AGND

PowerPAD™

N/A

Internally connected to PGND.

4

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SLUS760–SEPTEMBER 2007

FUNCTIONAL BLOCK DIAGRAM

AVIN

SW

Undervoltage

Lockout

Bias Supply

V_REF= 1.22 V

Bandgap

Ramp

Compensation

REF

OVP

COMPARATOR

VOUT

S

ERROR

AMPLIFIER

Control

Logic

V_REF

P

COMPARATOR

2 MHz

Oscillator

VOLTAGE

REGULATION

CURRENT

REGULATION

SENSE FB

LED

ON/OFF

Max t_ONTimer

MODE0

MODE1

CURRENT

CONTROL

Control

Logic

DAC

P

LED Current Regulator

FLASH_SYNC

Tx-TOFF

P

PGND

AGND

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SLUS760–SEPTEMBER 2007

TIMER BLOCK DIAGRAM

LED CURRENT CONTROL

Tx-TOFF

ILED

0

1

0

1

0

1

Torch Current

Flash Current

Torch Current

Tx-TOFF

MODE0

MODE1

400 kW

FLASH_SYNC

400 kW

Edge Detect

LED CURRENT CONTROL

0: TORCH CURRENT LEVEL

1: FLASH CURRENT LEVEL

Start

16-bit Prescaler

t

STIM

30.5 Hz

2 MHz CLOCK

Safety Timer

LED ON/OFF CONTROL

122 Hz

Duty-Cycle Generator (6.3%)

0: LED OFF

1: TORCH CURRENT LEVEL

PARAMETER MEASUREMENT INFORMATION

TPS6105x

L

SW

VOUT

2.2µH

VIN

C

OUT

10µF

AVIN

C

IN

P

LED

MODE1

MODE0

Tx-TOFF

FLASH_SYNC

P

PGND

AGND

List Of Components:

- L = Wuerth Elektronik WE-PD S Series

- C_IN= C_OUT= TDK C1605X5R0J106MT

6

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SLUS760–SEPTEMBER 2007

TYPICAL CHARACTERISTICS

Table 1. Table of Graphs

FIGURE

LED Power Efficiency

DC Input Current

vs. Input Voltage

Figure 3, Figure 4

vs. Input Voltage

Figure 5

LED Current

vs. LED Pin Headroom Voltage

vs. Output Current

vs. Load Current

Figure 6

Voltage Mode Efficiency

DC Output Voltage

Figure 7

Figure 8

DC Output Voltage

vs. Input Voltage

Figure 9

Quiescent Current

vs. Input Voltage

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Shutdown Current

vs. Input Voltage

Junction Temperature

PWM Operation

vs. GPIO Voltage

Down-Mode Operation

Voltage Mode Load Transient Response

Down-Mode Line Transient Response

Duty Cycle Jitter

Input Ripple Voltage

Low-Light Dimming Mode Operation

Torch/Flash Sequence

TX-Masking Operation

Start-up Into Flash Operation

Figure 21, Figure 22, Figure 23

Figure 24

LED POWER EFFICIENCY

vs

INPUT VOLTAGE

100

90

100

90

80

70

60

50

40

30

20

80

70

60

50

40

30

20

I

= 75mA

LED

I

= 500 mA

LED

I

= 700 mA

LED

I

= 1500 mA

I_LIM=1500 mA

LIM

10

0

10

0

2.5

2.9

3.3

3.7

4.1

4.5

4.9

5.3 5.5

2.5

2.9

3.3

3.7

4.1

4.5

4.9

5.3 5.5

V - Input Voltage - V

I

V - Input Voltage - V

I

Figure 3.

Figure 4.

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DC INPUT CURRENT

LED CURRENT

vs

LED PIN HEADROOM VOLTAGE

vs

INPUT VOLTAGE

2500

2250

1400

I

= 1500 mA

I

= 1500 mA

LIM

1200

1000

2000

1750

1500

1250

I

= 700 mA

LED

I

= 700 mA

LED

800

600

I

= 500 mA

LED

1000

750

500

250

400

200

0

I

= 500 mA

3.3

I = 75 mA

LED

0

2.5

550 650

950

250

350 450

750 850

1050

2.9

3.7

4.1

4.5

4.9

5.3 5.5

V - Input Voltage - V

I

LED Pin Headroom Voltage - mV

Figure 5.

Figure 6.

VOLTAGE MODE EFFICIENCY

DC OUTPUT VOLTAGE

vs

OUTPUT CURRENT

vs

LOAD CURRENT

100

90

5.15

5.10

5.05

5

V

IN

= 4.2 V

V

= 5 V,

OUT

I

= 1500 mA

LIM

80

70

60

V_IN= 3.6 V

V_IN= 3 V

V_IN= 2.5 V

V

= 4.2 V

IN

50

40

V

= 3.6 V

= 3 V

IN

4.95

4.90

4.85

V

IN

30

20

= 2.5 V

IN

V

I

= 5 V,

OUT

= 1500 mA

10

0

LIM

0

1

10

100

1000

10000

0.1

1

10

100

- Output Current - mA

1000

10000

I

- Output Current - mA

O

Figure 7.

Figure 8.

8

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DC OUTPUT VOLTAGE

vs

QUIESCENT CURRENT

vs

INPUT VOLTAGE

5.60

V

15

14

13

12

11

I

= 0 mA

OUT

= 5.0 V,

Voltage Mode Regulation,

= 5 V

OUT

V

5.50

I

= 1500 mA

O

LIM

I

= 100 mA

OUT

5.40

10

9

5.30

5.20

8

7

6

5.10

5

4

3

2

1

0

4.90

4.80

I

= 1000 mA

OUT

2.5

2.9

3.3

3.7

4.1

4.5

4.9

5.3 5.5

2.9

3.3

3.7

4.1

5.3 5.5

2.5

4.9

4.5

V - Input Voltage - V

I

V - Input Voltage - V

I

Figure 9.

Figure 10.

SHUTDOWN CURRENT

vs

JUNCTION TEMPERATURE

vs

INPUT VOLTAGE

GPIO VOLTAGE

200

175

150

125

1.40

1.20

1

GPIO = Input,

= -100 mA

I

T

= 85°C

GPIO

A

100

75

0.80

0.60

0.40

50

T

= 25°C

A

25

GPIO

Input Buffer

0

-25

-50

T

= -40°C

4.5

A

0.20

0

100 mA

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

2.5

2.9

3.3

3.7

4.1

4.9

5.3 5.5

V - Input Voltage - V

I

GPIO Voltage - V

Figure 11.

Figure 12.

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SLUS760–SEPTEMBER 2007

PWM OPERATION

DOWN-MODE OPERATION

I

LED

SW

(2V/div)

(50mA/div)

V

OUT

(500 mV/div - 3.5 V Offset)

LED Headroom Voltage

(1V/div)

I

L

(200mA/div - 0.6 A Offset)

I

L

(50mA/div)

V = 4.2 V,

I

V_I= 3.6 V, V_O= 5 V,

V

I

= 75 mA

OUT

(50mV/div - 5 V Offset)

I_O= 500 mA, I_LIM= 1500 mA

LED

t - Time = 250 ns/div

t - Time = 125 ns/div

Figure 13.

Figure 14.

VOLTAGE MODE LOAD TRANSIENT RESPONSE

DOWN-MODE LINE TRANSIENT RESPONSE

V

OUT

(200 mV/div - 4 V Offset)

V

= 3.6 V, V = 5 V,

O

= 1500 mA

I

LIM

V

OUT

(500 mV/div - 5 V Offset)

Battery Voltage

(200 mV/div - 4 V Offset)

I

LED

(100 mA/div - 0.3 A Offset)

I

L

(200 mA/div - 0.3 A Offset)

I

L

(500 mA/div)

V = 3.6 V to 3.9 V,

I

OUT

(500 mA/div)

I

= 500 mA, I

= 1500 mA

LIM

LED

t - Time = 20 ms/div

t - Time = 50 ms/div

Figure 15.

Figure 16.

10

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DUTY CYCLE JITTER

INPUT RIPPLE VOLTAGE

Battery Voltage

TRIGGERED ON RISING EDGE

(10 mV/div - 3.3 V Offset)

SW

(1 V/div)

V_OUT(20 mV/div - 4.2 V Offset)

I

L

V = 3.6 V,

I

(200 mA/div - 0.5 A Offset)

V

I

= 5 V,

O

= 500 mA,

= 1500 mA

O

I

LED

I

LIM

(200 mA/div - 0.3 A Offset)

Li-Polymer Battery at 3.3V, I

= 700 mA, I = 1500 mA

LIM

LED

t - Time = 50 ns/div

t - Time = 500 ns/div

Figure 17.

Figure 18.

LOW-LIGHT DIMMING MODE OPERATION

TORCH/FLASH SEQUENCE

FLASH_SYNC

(2 V/div)

SAFETY TIMER LIMITATION

Frequency = 121 Hz

Duty Cycle = 6.25%

I

LED

(500 mA/div)

I

LED

(20 mA/div)

V

OUT

(500 mV/div - 3.40 V Offset)

V

OUT

(200 mV/div - 3.5 V Offset)

LED Pin Headroom Voltage

(200 mV/div)

V

= 3.6 V, I

= 75 mA

TORCH

IN

V = 3.2 V, I

LIM

= 1500 mA

I

= 75 mA (Torch) to 700 mA (Flash)

LED

t - Time = 100 ms/div

t - Time = 2 ms/div

Figure 19.

Figure 20.

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TX-MASKING OPERATION

V = 3.6 V, I

= 1500 mA

FLASH_SYNC

(2 V/div)

I

LIM

I

= 75 mA, I

= 700 mA

TORCH

FLASH

Tx-TOFF

(2 V/div)

Tx-TOFF

(2 V/div)

I

LED

(200 mA/div)

I

L

(500 mA/div)

I

L

(500 mA/div)

V = 3.6 V, I

= 1500 mA

I

LIM

I

= 75 mA, I

= 700 mA

FLASH

TORCH

t - Time = 10 ms/div

t - Time = 200 ms/div

Figure 21.

Figure 22.

TX-MASKING OPERATION

START-UP IN FLASH OPERATION

Tx-TOFF

(2 V/div)

V = 3.6 V, I

LIM

= 1500 mA ,I = 700 mA

FLASH

I

MODE0 = GND, FLASH_SYNC = HIGH

MODE1

(2 V/div)

V

OUT

(2 V/div)

I

LED

I

(200 mA/div)

LED

(500 mA/div)

I

L

(500 mA/div)

I

L

(200 mA/div)

V = 3.6 V, I

= 1500 mA

I

LIM

I

= 75 mA, I = 700 mA

FLASH

TORCH

t - Time = 200 ms/div

t - Time = 50 ms/div

Figure 23.

Figure 24.

12

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DETAILED DESCRIPTION

OPERATION

The TPS6105x family employs a 2-MHz constant-frequency, current-mode PWM converter to generate the

output voltage required to drive high-power LEDs. The device integrates a power stage based on an NMOS

switch and a synchronous NMOS rectifier. The device also implements a linear low-side current regulator to

control the LED current when the battery voltage is higher than the diode forward voltage.

In boost mode, the duty cycle of the converter is set by the error amplifier and the saw-tooth ramp applied to the

comparator. Because the control architecture is based on a current-mode control, a compensation ramp is added

to allow stable operation at duty cycles larger than 50%. The converter is a fully-integrated synchronous-boost

converter, always operating in continuous-conduction mode. This allows low-noise operation, and avoids ringing

on the switch pin, which would be seen on a converter when entering discontinuous-conduction mode.

The TPS6105x device not only operates as a regulated current source but also as a standard voltage-boost

regulator. This additional operating mode can be useful to properly synchronize the converter when supplying

other high-power devices in the system, such as a hands-free audio power amplifier, or any other component

requiring a supply voltage higher than the battery voltage.

The mode of operation (shutdown, torch and flash modes, constant voltage regulation) selection is done via the

MODE0/1 control inputs.

Table 2. TPS6105x Operating Modes

MODE1 MODE0

OPERATING MODES

0

Power stage is in shutdown. The output is either connected directly to the battery via the rectifer’s body diode.

LED is turned-on for torch light operation. The converter is operating in the current regulation mode (CM).

The output voltage is controlled by the forward voltage characteristic of the LED.

0

1

LED is turned-on for flashlight operation. The converter is operating in the current regulation mode (CM).

The output voltage is controlled by the forward voltage characteristic of the LED.

1

0

1

LED is turned-off and the converter is operating in voltage regulation mode (VM).

The output voltage is regulated to 5.0V.

To simplify flash synchronization with the camera module, the device offers a FLASH_SYNC strobe input pin to

switch (with zero latency) the LED current from flash to torch light. The LED is driven at the flashlight current

level when a logic high signal is applied to the FLASH_SYNC pin.

The maximum duration of the flash pulse can be limited by means of an internal safety timer (820ms). The safety

timer starts on the rising edge of the FLASH_SYNC signal and stops either on its falling edge or after a timeout

whatever occurs first.

FLASH_SYNC

STIM

TIMER

TIME-OUT

TORCH

FLASH

TIME-OUT

TORCH

LED CONTROL

Figure 25. Level Sensitive Safety Timer (Timeout)

Figure 26. Level Sensitive Safety Timer

(Normal Operation + Timeout)

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EFFICIENCY

The sense voltage has a direct effect on the converter’s efficiency. Because the voltage across the low-side

current regulator does not contribute to the output power (LED brightness), the lower the sense voltage, the

higher the efficiency will be.

When running in boost mode (V_F(LED)> V_IN), the voltage present at the LED pin of the low-side current regulator

is typically 250 mV, which contributes to high power-conversion efficiency.

When running in the linear down-ocnverter mode (V_F(LED)< V_IN), the low-side current regulator drops the voltage

difference between the input voltage and the LED forward voltage. Depending on the input voltage and the LED

forward voltage characteristic, the converter displays efficiency of approximately 80% to 90%.

FLASH BLANKING

The TPS6105x device also integrates a Tx-TOFF input that can be used as flash masking input. This blanking

function turns the LED from flash to torch light, thereby reducing almost instantaneously the peak current loading

from the battery. This function has no influence on the safety timer duration.

I_FLASH

LED Current

I_TORCH

FLASH_SYNC

Tx-TOFF

Figure 27. Synchronized Flash With Blanking Periods (MODE0 = 0, MODE1 = 1)

LOW LIGHT DIMMING MODE

The TPS6105x device features white LED drive capability at very low light intensity. To generate a reduced LED

average current, the device employs a 122 Hz fixed frequency PWM modulation scheme. Operation is

understood best by referring to the timer block diagram.

The torch current is modulated with a 6.3% duty cycle. The low light dimming mode can only be activated in the

torch only mode (MODE1 = 0, MODE0 = 1) together with a logic level high applied to the FLASH_SYNC input.

I_TORCH

I_LED(DC)

=

0.063 x I_TORCH

0

Figure 28. PWM Dimming Principle

White-LED blinking can be achieved by turning on/off periodically the LED dimmer via the (DIM) bit, see

Figure 29.

LED OFF

LED ON with Reduced Current

I_TORCH

6.3% PWM Dimming Steps

MODE0

Figure 29. White LED Blinking Control (MODE1 = 0, FLASH_SYNC = 1)

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SOFT-START

Since the output capacitor always remains biased to the input voltage, the TPS6105x can immediately start

switching once it has been enabled. The device starts-up by smoothly ramping up it’s internal reference voltage,

thus limiting the inrush current.

SHUTDOWN

In shutdown mode, the regulator stops switching and the LED pin is high impedance thus eliminating any DC

conduction path. The internal switch and rectifier MOSFET are turned off. VOUT is one body-diode drop below

the input voltage and the device consumes only a shutdown current of 0.3 μA (typ). The output capacitor remains

biased to the input voltage.

LED FAILURE MODES

If the LED fails as a short circuit, the low-side current regulator limits the maximum output current.

If the LED fails as an open circuit, the control loop initially attempts to regulate off of its low-side current regulator

feedback signal. This drives VOUT higher. Because the open-circuited LED will never accept its programmed

current, VOUT must be voltage-limited by means of a secondary control loop. In this failure mode, the TPS6105x

limits VOUT to 6.0 V (typ.).

UNDERVOLTAGE LOCKOUT

The undervoltage lockout circuit prevents the device from misoperation at low input voltages. It prevents the

converter from turning on the switch or rectifier MOSFET under undefined conditions.

THERMAL SHUTDOWN

As soon as the junction temperature, T_J, exceeds 160°C typical, the device goes into thermal shutdown. In this

mode, the boost power stage and the low-side current regulator are turned off. To resume operation, the device

needs to be cycled through a shutdown phase (MODE0 = 0, MODE1 = 0).

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APPLICATION INFORMATION

INDUCTOR SELECTON

A boost converter requires two main passive components for storing energy during the conversion. A boost

inductor and a storage capacitor at the output are required. The TPS6105x device integrates a current limit

protection circuitry. The peak current of the NMOS switch is sensed to limit the maximum current flowing through

the switch and the inductor (e.g. 1000 mA or 1500 mA).

In order to optimize solution size the TPS6105x device has been designed to operate with inductance values

between a minimum of 1.3 μH and maximum of 2.9 μH. In typical high-current white LED applications a 2.2 μH

inductance is recommended.

To select the boost inductor, it is recommended to keep the possible peak inductor current below the current limit

threshold of the power switch in the chosen configuration. The highest peak current through the inductor and the

power switch depends on the output load, the input and output voltages. Estimation of the maximum average

inductor current and the maximum inductor peak current can be done using Equation 1 and Equation 2:

V

OUT

I [ I

+

L

OUT

h V

IN

(1)

(2)

I_OUT

2 f L (1 * D) h

V

_OUT* V_IN

V_OUT

V_IN D

I_L(PEAK)

+

)

with D +

with:

f = switching frequency (2 MHz)

L = inductance value (2.2 μH)

η = estimated efficiency (85%)

For example, for an output current of 500 mA at 5 V, the TPS6105x device needs to be set for a 1000 mA

current limit operation together with an inductor supporting this peak current.

The losses in the inductor caused by magnetic hysteresis losses and copper losses are a major parameter for

total circuit efficiency.

Table 3. List of Inductors

MANUFACTURER

TDK

SERIES

VLF3010AT

NR3010

DIMENSIONS

I_LIMSETTINGS

2,6 mm × 2,8 mm × 1,0 mm max. height

3,0 mm × 3,0 mm × 1,0 mm max. height

2,5 mm × 2,0 mm × 1,2 mm max. height

2,6 mm × 2,8 mm × 1,4 mm max. height

3,0 mm × 3,0 mm × 1,5 mm max. height

3,0 mm × 3,0 mm × 1,2 mm max. height

TAIYO YUDEN

FDK

1000 mA (typ.)

MIPSA2520

VLF3014AT

LPS3015

TDK

COILCRAFT

MURATA

TOKO

1500 mA (typ.)

LQH3NP

FDSE0312

16

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CAPACITOR SELECTION

Input Capacitor

For good input voltage filtering low ESR ceramic capacitors are recommended. A 10-μF input capacitor is

recommended to improve transient behavior of the regulator and EMI behavior of the total power supply circuit.

The input capacitor should be placed as close as possible to the input pin of the converter.

Output Capacitor

The primary parameter necessary to define the output capacitor is the maximum allowed output voltage ripple of

the converter. This ripple is determined by two parameters of the capacitor, the capacitance and the ESR. It is

possible to calculate the minimum capacitance needed for the defined ripple, supposing that the ESR is zero, by

using Equation 3:

ǒ_V

f DV V

_INǓ

I

* V

OUT

C

[

min

OUT

(3)

Parameter f is the switching frequency and ΔV is the maximum allowed ripple.

With a chosen ripple voltage of 10mV, a minimum capacitance of 10 μF is needed. The total ripple is larger due

to the ESR of the output capacitor. This additional component of the ripple can be calculated using Equation 4:

ΔV_ESR= I_OUT× R_ESR

The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of the

capacitor. Additional ripple is caused by load transients. This means that the output capacitor has to completely

supply the load during the charging phase of the inductor. A reasonable value of the output capacitance depends

on the speed of the load transients and the load current during the load change.

For the high current white LED application, a minimum of 3 μF effective output capacitance is usually required

when operating with 2.2 μH (typ) inductors. For solution size reasons, this is usually one or more X5R/X7R

ceramic capacitors. For stable operation of the internally compensated control loop, a maximum of 50 μF

effective output capacitance is tolerable.

Depending on the material, size and margin to the rated voltage of the used output capacitor, degradation on the

effective capacitance can be observed. This loss of capacitance is related to the DC bias voltage applied. It is

therefore always recommended to check that the selected capacitors are showing enough effective capacitance

under real operating conditions.

CHECKING LOOP STABILITY

The first step of circuit and stability evaluation is to look from a steady-state perspective at the following signals:

•

Switching node, SW

Inductor current, I_L

Output ripple voltage, V_OUT(AC)

These are the basic signals that need to be measured when evaluating a switching converter. When the

switching waveform shows large duty cycle jitter or the output voltage or inductor current shows oscillations the

regulation loop may be unstable. This is often a result of board layout and/or L-C combination.

The next step in regulation loop evaluation is to perform a load transient test. Output voltage settling time after

the load transient event is a good estimate of the control loop bandwidth. The amount of overshoot and

subsequent oscillations (ringing) indicates the stability of the control loop. Without any ringing, the loop has

usually more than 45° of phase margin.

Because the damping factor of the circuitry is directly related to several resistive parameters (e.g., MOSFET

r_DS(on)) that are temperature dependant, the loop stability analysis has to be done over the input voltage range,

output current range, and temperature range.

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LAYOUT CONSIDERATIONS

As for all switching power supplies, the layout is an important step in the design, especially at high peak currents

and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as

well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground

tracks.

The input 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 one of the ground pins of the IC.

To lay out the control ground, it is recommended to use short traces as well, separated from the power ground

traces. This avoids ground shift problems, which can occur due to superimposition of power ground current and

control ground current.

THERMAL INFORMATION

Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires

special attention to power dissipation. Many system-dependant issues such as thermal coupling, airflow, added

heat sinks and convection surfaces, and the presence of other heat-generating components affect the

power-dissipation limits of a given component.

Three basic approaches for enhancing thermal performance are listed below:

•

Improving the power dissipation capability of the PCB design

Improving the thermal coupling of the component to the PCB

Introducing airflow in the system

Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where

high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design.

The maximum junction temperature (T_J) of the TPS6105x is 150°C.

The maximum power dissipation gets especially critical when the device operates in the linear down mode at

high LED current. For single pulse power thermal analysis (e.g., flash strobe), the allowable power dissipation for

the device is given by Figure 30.

4

No Airflow

3.5

3

2.5

2

t

= 85°C

1.5

1

PCB

0.5

0

Theta JB: 35°CW

0

100 200 300 400 500 600 700 800 900 1000

Pulse Width - ms

Figure 30. Single Pulse Power Capability (CSP Package)

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TYPICAL APPLICATIONS

TPS61054

L

SW

VBAT

VOUT

2.2 mH

C

10 mF

P

OUT

AVIN

WHITE LED

FLASH-LIGHT

Li-Ion

C

IN

P

LED

MODE1

MODE0

CAMERA ENGINE

Tx-TOFF

FLASH_SYNC

PGND

P

AGND

RF PA TX ACTIVE

Figure 31. High Power White LED Solution Featuring No-Latency Turn-Down via PA TX Signal

TPS61054

L

SW

VBAT

VOUT

SW

2.2 mH

C

LED 1

1 .5 R

LED 2

OUT

10 mF

AVIN

Li-Ion

C

IN

P

1 .5 R

P

LED

MODE1

MODE0

LED 1, LED 2 VF variation

should be with 100 mV from each other

Tx-TOFF

FLASH _SYNC

AGND

PGND

P

Figure 32. 2 × 350 mA Dual LED Camera Flash

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PACKAGE SUMMARY

CHIP SCALE PACKAGE

(BOTTOM VIEW)

CHIP SCALE PACKAGE

(TOP VIEW)

A3

B3

A2

B2

A1

B1

YMLLLLS

6105x

D

C3

D3

C2

D2

C1

D1

A1

E

Code:

•

Y — 2 digit date code

LLLL - lot trace code

S - assembly site code

PACKAGE DIMENSIONS

The dimensions for the YZG package are shown in Table 4. See the package drawing at the end of this data

sheet.

Table 4. YZG Package Dimensions

Packaged Devices

D

E

TPS6105xYZG

1.96 ±0.05 mm

1.46 ±0.05 mm

20

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型号：	TPS61054DRC
厂家：	TEXAS INSTRUMENTS
描述：	HIGH POWER WHITE LED DRIVER 2-MHz SYNCHRONOUS BOOST CONVERTER WITH STANDARD LOGIC INTERFACE 大功率白光LED驱动器2 - MHz的同步升压型与标准的逻辑接口转换器驱动器转换器高功率电源
文件：	总24页 (文件大小：811K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

TPS61054DRC [TI]

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