TI TPS61055DRC

CSP-12
QFN-10
TPS61054, TPS61055
www.ti.com
SLUS760 – SEPTEMBER 2007
HIGH POWER WHITE LED DRIVER
2-MHz SYNCHRONOUS BOOST CONVERTER WITH STANDARD LOGIC INTERFACE
FEATURES
1
APPLICATIONS
•
•
•
Camera White LED Torch/Flash for Cell
Phones, Smart-Phones and PDAs
General Lighting Applications
Audio Amplifier Power Supply
DESCRIPTION
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.
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.
The LED current or the desired output voltage can be
programmed via two logic signals (MODE0/1). To
simplify flash synchronization with the camera
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
VOUT
CIN
P
LED
MODE1
MODE0
L1
LED
SENSE
4.7 mm
P
INDUCTOR
C1
COUT
10 mF
P
AVIN
AGND
SW
SW
INPUT
CAP
2.2 mH
4.7 mm
+ BATTERY
PGND
DIGITAL I/O
L
Tx-TOFF
AGND
PGND
PGND
P
PGND
OUTPUT
CAP
FLASH_SYNC
C2
LED ANODE
Figure 1. Typical Application
Figure 2. Typical PC-Board Layout
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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.
Copyright © 2007, Texas Instruments Incorporated
PRODUCT PREVIEW
• Four Operational Modes
– Torch and Flash up to ILED = 700 mA
– Voltage-Regulated Boost Converter: 5.0 V
– Shutdown: 0.3 μA (typ)
• 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
• Available in a 12-Pin NanoFree™ (CSP) and
10-Pin QFN Packaging
2
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
PART
NUMBER (1) (2)
TORCH
CURRENT (3)
FLASH
CURRENT (3)
SAFETY TIMER
MAXIMUM
DURATION
CURRENT LIMIT
PACKAGE
MARKING
PACKAGE
TPS61054YZG
75 mA
700 mA
820 ms
1500 mA (ILIM = 01)
61054
CSP-12
TPS61054DRC
75 mA
700 mA
820 ms
1500 mA (ILIM = 01)
TPS61055YZG
75 mA
500 mA
820 ms
1000 mA (ILIM = 00)
TPS61055DRC
75 mA
500 mA
820 ms
1000 mA (ILIM = 00)
(1)
(2)
QFN-10
61055
CSP-12
QFN-10
All devices are specified for operation in the commercial temperature range, –40°C to 85°C.
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.
For customized current settings, please contact the factory.
(3)
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted) (1)
PRODUCT PREVIEW
Voltage range on AVIN, VOUT, SW, LED
(2)
Voltage range on MODE0, MODE1, FLASH_SYNC, Tx-TOFF
TA
TJ
Operating ambient temperature range
(2)
(3)
Maximum operating junction temperature
(MAX)
Tstg
Storage temperature range
Human body model
ESD
rating (4)
Charge device model
Machine model
(1)
(2)
(3)
(4)
TPS6105X
UNIT
–0.3 to 7
V
–0.3 to 7
V
–40 to 85
°C
150
°C
–65 to 150
°C
2
kV
1
kV
200
V
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.
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 (TA(max)) is dependent on the maximum operating junction temperature (TJ(max)), the
maximum power dissipation of the device in the application (PD(max)), and the junction-to-ambient thermal resistance of the part/package
in the application (θJA), as given by the following equation: TA(max)= TJ(max)–(θJA X PD(max)).
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
PACKAGE
(1)
(2)
2
THERMAL RESISTANCE (1)
(2)
POWER RATING
TA = 25°C
DERATING FACTOR
ABOVE (1) (2) TA = 25°C
YZG
θJA= 89°C/W
θJB= 35°C/W
1.1 W
12 mW/°C
DRC
θJA= 49°C/W
θJC= 3.2°C/W
2.4 W
20 mW/°C
Measured with high-K board.
Maximum power dissipation is a function of TJ(max), θJA and TA. The maximum allowable power dissipation at any allowable ambient
temperature is PD = (TJ(max)–TA)/ θJA.
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SLUS760 – SEPTEMBER 2007
ELECTRICAL CHARACTERISTICS
Unless otherwise noted the specification applies for VIN = 3.6 V over an operating junction temp. of –40°C ≤ TJ ≤ 125°C.
Typical values are for TA = 25°C.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY CURRENT
Input voltage range
VIN
2.5
6.0
V
2.5
V
Minimum input voltage for start-up
MODE0 = 1, MODE1 = 1, RL = 10 Ω
IQ
Operating quiescent current into AVIN
MODE0 = 1, MODE1 = 1
8.5
ISD
Shutdown current into AVIN
MODE0 = 0, MODE1 = 0, –40°C ≤ TJ ≤ 85°C
0.3
3.0
μA
VUVLO
Undervoltage lockout threshold
VIN falling
2.3
2.4
V
mA
OUTPUT
Current regulator mode
Output voltage range
OVP Output overvoltage protection
OVP
VIN
Voltage regulator mode
VOUT rising
5.7
Output overvoltage protection hysterisis
D
6.0
6.25
0.15
Minimum duty cycle
V
V
V
7.5%
LED current accuracy (1)
0.25 V ≤ VLED ≤ 2.0 V, ILED = ITORCH, TJ = 50°C
–15%
0.25 V ≤ VLED ≤ 2.0 V, ILED = IFLASH, TJ = 50°C
–12%
LED current temperature coefficient
VLED
5.5
5.0
15%
12%
0.08
DC output voltage accuracy
2.5 V ≤ VIN ≤ 0.9 VOUT, PWM operation
LED sense voltage
Boost Mode
250
LED input leakage current
VLED = VOUT = 5 V, –40°C ≤ TJ ≤ 85°C
0.1
–3%
%/°C
PRODUCT PREVIEW
VOUT
3%
mV
1
μA
POWER SWITCH
rDS(on)
Ilkg(SW)
Ilim
Switch MOSFET on-resistance
80
VOUT = VGS = 3.6 V
Rectifier MOSFET on-resistance
Switch MOSFET leakage
VDS = 6.0 V, –40°C ≤ TJ ≤ 85°C
Rectifier MOSFET leakage
2.5 V ≤ VIN ≤ 6.0 V, ILIM = 00
Switch current limit
mΩ
80
2.5 V ≤ VIN ≤ 6.0 V, ILIM = 01 (1)
Thermal shutdown (1)
0.1
1
0.1
1
μA
850
1000
1150
1275
1500
1725
140
160
°C
20
°C
Thermal shutdown hysteresis (1)
mA
OSCILLATOR
fSW
Oscillator frequency
1.8
2.0
2.2
MHz
MODE0, MODE1, Tx-TOFF, FLASH_SYNC
V(IH)
High-level input voltage
V(IL)
Low-level input voltage
1.2
V
I(LKG)
Logic input leakage current
Input connected to VIN or GND, –40°C ≤ TJ ≤ 85°C
0.01
Tx-TOFF pull-down resistance
Tx-TOFF ≤ 0.4 V
400
kΩ
FLASH_SYNC pull-down resistance
FLASH_SYNC ≤ 0.4 V
400
kΩ
From shutdown into flash mode ILED = 700 mA
1.2
ms
From shutdown into voltage mode
MODE0 = 1, MODE1 = 1, IOUT = 0 mA
650
μs
MODE0 = 0, MODE1 = 1,
ILED = from 75mA to 700 mA
160
μs
20
μs
0.4
V
0.1
μA
TIMING
Start-up time
(2)
LED current settling time triggered by
rising edge on FLASH_SYNC
LED current settling time
rising edge on Tx-TOFF
(1)
(2)
(2)
triggered by
MODE0 = 0, MODE1 = 1,
ILED = 700 mA to 75 mA
Assured by design. Not tested in production.
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.
(QFN)
NO.
(CSP)
AVIN
5
D3
I
This is the input voltage pin of the device. Connect directly to the input bypass capacitor.
VOUT
9
A2
O
Boost converter output.
LED
6
D2
I
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.
NAME
PRODUCT PREVIEW
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
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
Tx-TOFF
3
C3
I
RF PA synchronization input.
Tx-TOFF = LOW : The device is operating normally.
Tx-TOFF = HIGH : The device is forced into torch mode.
SW
8
B1, B2
PGND
7
C1, C2
AGND
4
PowerPAD™
4
I/O
Inductor connection. Drain of the internal power MOSFET. Connect to the switched side of
the inductor. SW is high impedance during shutdown.
Power ground. Connect to AGND underneath IC.
D1
Analog ground.
N/A
Internally connected to PGND.
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SLUS760 – SEPTEMBER 2007
FUNCTIONAL BLOCK DIAGRAM
AVIN
SW
Undervoltage
Lockout
Bias Supply
VREF = 1.22 V
Ramp
Compensation
Bandgap
REF
OVP
COMPARATOR
VOUT
S
ERROR
AMPLIFIER
Control
Logic
P
COMPARATOR
CURRENT
REGULATION
VOLTAGE
REGULATION
2 MHz
Oscillator
SENSE FB
MODE0
MODE1
FLASH_SYNC
LED
ON/OFF
Max tON Timer
Control
Logic
PRODUCT PREVIEW
VREF
DAC
CURRENT
CONTROL
P
LED Current Regulator
Tx-TOFF
P
AGND
PGND
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SLUS760 – SEPTEMBER 2007
TIMER BLOCK DIAGRAM
LED CURRENT CONTROL
Tx-TOFF
ILED
0
0
Torch Current
0
1
Torch Current
1
0
Flash Current
1
1
Torch Current
Tx-TOFF
MODE0
400 kW
MODE1
FLASH_SYNC
400 kW
Edge Detect
LED CURRENT CONTROL
0: TORCH CURRENT LEVEL
1: FLASH CURRENT LEVEL
PRODUCT PREVIEW
Start
tSTIM
30.5 Hz
2 MHz CLOCK
16-bit Prescaler
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
2.2µH
VIN
SW
SW
VOUT
C OUT
10 µF
P
AVIN
CIN
P
P
LED
MODE1
MODE0
Tx-TOFF
FLASH_SYNC
AGND
PGND
PGND
P
List Of Components:
- L = Wuerth Elektronik WE-PD S Series
- CIN = COUT = TDK C1605X5R0J106MT
6
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SLUS760 – SEPTEMBER 2007
TYPICAL CHARACTERISTICS
Table 1. Table of Graphs
vs. Input Voltage
Figure 3, Figure 4
DC Input Current
vs. Input Voltage
Figure 5
LED Current
vs. LED Pin Headroom Voltage
Figure 6
Voltage Mode Efficiency
vs. Output Current
Figure 7
DC Output Voltage
vs. Load Current
Figure 8
DC Output Voltage
vs. Input Voltage
Figure 9
Quiescent Current
vs. Input Voltage
Figure 10
Shutdown Current
vs. Input Voltage
Figure 11
Junction Temperature
vs. GPIO Voltage
Figure 12
PWM Operation
Figure 13
Down-Mode Operation
Figure 14
Voltage Mode Load Transient Response
Figure 15
Down-Mode Line Transient Response
Figure 16
Duty Cycle Jitter
Figure 17
Input Ripple Voltage
Figure 18
Low-Light Dimming Mode Operation
Figure 19
Torch/Flash Sequence
Figure 20
TX-Masking Operation
Figure 21, Figure 22, Figure 23
Start-up Into Flash Operation
Figure 24
LED POWER EFFICIENCY
vs
INPUT VOLTAGE
100
100
90
90
80
ILED = 75mA
70
60
50
40
30
20
ILIM = 1500 mA
10
0
2.5
2.9
3.3
3.7
4.1
4.5
VI - Input Voltage - V
4.9
LED Power Efficiency (PLED/PIN) - %
LED Power Efficiency (PLED/PIN) - %
LED POWER EFFICIENCY
vs
INPUT VOLTAGE
PRODUCT PREVIEW
FIGURE
LED Power Efficiency
80
70
ILED = 500 mA
60
ILED = 700 mA
50
40
30
20
ILIM =1500 mA
10
5.3 5.5
0
2.5
2.9
Figure 3.
3.3
3.7
4.1
4.5
VI - Input Voltage - V
4.9
5.3 5.5
Figure 4.
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SLUS760 – SEPTEMBER 2007
DC INPUT CURRENT
vs
INPUT VOLTAGE
2500
LED CURRENT
vs
LED PIN HEADROOM VOLTAGE
1400
ILIM = 1500 mA
ILIM = 1500 mA
2250
1200
1000
1750
ILED = 700 mA
LED Current - mA
DC Input Current - mA
2000
1500
1250
1000
750
800
ILED = 700 mA
600
ILED = 500 mA
400
500
250
PRODUCT PREVIEW
0
2.5
200
ILED = 500 mA
2.9
3.3
3.7
4.1
4.5
VI - Input Voltage - V
4.9
0
250
5.3 5.5
350
450
650
750
850
950
1050
LED Pin Headroom Voltage - mV
Figure 6.
VOLTAGE MODE EFFICIENCY
vs
LOAD CURRENT
DC OUTPUT VOLTAGE
vs
OUTPUT CURRENT
5.15
VIN = 4.2 V
90
VOUT = 5 V,
ILIM = 1500 mA
5.10
80
VIN = 3.6 V
DC Output Voltage - V
VIN = 3 V
70
VIN = 2.5 V
60
50
40
30
5.05
VIN = 4.2 V
5
VIN = 3.6 V
4.95
VIN = 3 V
VIN = 2.5 V
20
4.90
VOUT = 5 V,
ILIM = 1500 mA
10
0
0
1
10
100
1000
IO - Output Current - mA
10000
4.85
0.1
1
Figure 7.
8
550
Figure 5.
100
Efficiency - %
ILED = 75 mA
10
100
1000
IO - Output Current - mA
10000
Figure 8.
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SLUS760 – SEPTEMBER 2007
DC OUTPUT VOLTAGE
vs
INPUT VOLTAGE
5.60
12
IOUT = 100 mA
5.40
Voltage Mode Regulation,
VO = 5 V
14
13
Quiescent Current - mA
DC Output Voltage - V
15
IOUT = 0 mA
VOUT = 5.0 V,
ILIM = 1500 mA
5.50
QUIESCENT CURRENT
vs
INPUT VOLTAGE
5.30
5.20
5.10
11
10
9
8
7
6
5
4
5
3
2
1
0
2.5
IOUT = 1000 mA
4.80
2.9
3.3
3.7
4.1
4.9
4.5
VI - Input Voltage - V
5.3 5.5
3.3
3.7
4.1
4.5
VI - Input Voltage - V
Figure 10.
SHUTDOWN CURRENT
vs
INPUT VOLTAGE
JUNCTION TEMPERATURE
vs
GPIO VOLTAGE
5.3 5.5
200
175
TJ - Junction Temperature - °C
TA = 85°C
1.20
1
0.80
0.60
TA = 25°C
0.40
TA = -40°C
0.20
GPIO = Input,
IGPIO = -100 mA
150
125
100
75
50
25
GPIO
Input Buffer
0
-25
0
2.5
4.9
Figure 9.
1.40
Shutdown Current - mA
2.9
VGPIO
2.5
PRODUCT PREVIEW
4.90
2.9
3.3
3.7
4.1
4.5
4.9
VI - Input Voltage - V
5.3 5.5
-50
-0.50
-0.45
Figure 11.
-0.40
-0.35
-0.30
100 mA
-0.25
-0.20
GPIO Voltage - V
Figure 12.
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SLUS760 – SEPTEMBER 2007
PWM OPERATION
DOWN-MODE OPERATION
ILED
SW
(2V/div)
(50mA/div)
VOUT
(500 mV/div - 3.5 V Offset)
LED Headroom Voltage
(1V/div)
IL
(200mA/div - 0.6 A Offset)
IL
(50mA/div)
VOUT
(50mV/div - 5 V Offset)
VI = 4.2 V,
ILED = 75 mA
VI = 3.6 V, VO = 5 V,
IO = 500 mA, ILIM = 1500 mA
t - Time = 250 ns/div
Figure 14.
PRODUCT PREVIEW
t - Time = 125 ns/div
Figure 13.
VOLTAGE MODE LOAD TRANSIENT RESPONSE
VOUT
(200 mV/div - 4 V Offset)
VI = 3.6 V, VO = 5 V,
ILIM = 1500 mA
VOUT
(500 mV/div - 5 V Offset)
IL
(500 mA/div)
DOWN-MODE LINE TRANSIENT RESPONSE
Battery Voltage
(200 mV/div - 4 V Offset)
IL
(200 mA/div - 0.3 A Offset)
VI = 3.6 V to 3.9 V,
ILED = 500 mA, ILIM = 1500 mA
IOUT
(500 mA/div)
t - Time = 20 ms/div
t - Time = 50 ms/div
Figure 15.
10
ILED
(100 mA/div - 0.3 A Offset)
Figure 16.
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SLUS760 – SEPTEMBER 2007
DUTY CYCLE JITTER
INPUT RIPPLE VOLTAGE
Battery Voltage
(10 mV/div - 3.3 V Offset)
TRIGGERED ON RISING EDGE
SW
(1 V/div)
VOUT (20 mV/div - 4.2 V Offset)
IL
(200 mA/div - 0.5 A Offset)
VI = 3.6 V,
VO = 5 V,
IO = 500 mA,
ILIM = 1500 mA
ILED
(200 mA/div - 0.3 A Offset)
Li-Polymer Battery at 3.3V, ILED = 700 mA, ILIM = 1500 mA
t - Time = 50 ns/div
Figure 17.
t - Time = 500 ns/div
LOW-LIGHT DIMMING MODE OPERATION
PRODUCT PREVIEW
Figure 18.
TORCH/FLASH SEQUENCE
FLASH_SYNC
(2 V/div)
SAFETY TIMER LIMITATION
Frequency = 121 Hz
Duty Cycle = 6.25%
ILED
(500 mA/div)
ILED
(20 mA/div)
VOUT
(200 mV/div - 3.5 V Offset)
VIN = 3.6 V, ITORCH = 75 mA
VOUT
(500 mV/div - 3.40 V Offset)
LED Pin Headroom Voltage
(200 mV/div)
VI = 3.2 V, ILIM = 1500 mA
ILED = 75 mA (Torch) to 700 mA (Flash)
t - Time = 2 ms/div
Figure 19.
t - Time = 100 ms/div
Figure 20.
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SLUS760 – SEPTEMBER 2007
TX-MASKING OPERATION
TX-MASKING OPERATION
VI = 3.6 V, ILIM = 1500 mA
ITORCH = 75 mA, IFLASH = 700 mA
FLASH_SYNC
(2 V/div)
Tx-TOFF
(2 V/div)
Tx-TOFF
(2 V/div)
ILED
(200 mA/div)
ILED
(200 mA/div)
IL
(500 mA/div)
IL
(500 mA/div)
VI = 3.6 V, ILIM = 1500 mA
ITORCH = 75 mA, IFLASH = 700 mA
t - Time = 10 ms/div
t - Time = 200 ms/div
PRODUCT PREVIEW
Figure 21.
Figure 22.
TX-MASKING OPERATION
START-UP IN FLASH OPERATION
Tx-TOFF
(2 V/div)
VI = 3.6 V, ILIM = 1500 mA ,IFLASH = 700 mA
MODE0 = GND, FLASH_SYNC = HIGH
MODE1
(2 V/div)
VOUT
(2 V/div)
ILED
ILED
(200 mA/div)
(500 mA/div)
IL
(500 mA/div)
IL
(200 mA/div)
VI = 3.6 V, ILIM = 1500 mA
ITORCH = 75 mA, IFLASH = 700 mA
t - Time = 200 ms/div
t - Time = 50 ms/div
Figure 23.
12
Figure 24.
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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.
Table 2. TPS6105x Operating Modes
MODE1 MODE0
OPERATING MODES
0
0
Power stage is in shutdown. The output is either connected directly to the battery via the rectifer’s body diode.
0
1
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.
1
0
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
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
FLASH_SYNC
STIM
TIMER
FLASH
LED CONTROL
STIM
TIMER
TIME-OUT
TORCH
Figure 25. Level Sensitive Safety Timer (Timeout)
FLASH
LED CONTROL
TIME-OUT
TORCH
Figure 26. Level Sensitive Safety Timer
(Normal Operation + Timeout)
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PRODUCT PREVIEW
The mode of operation (shutdown, torch and flash modes, constant voltage regulation) selection is done via the
MODE0/1 control inputs.
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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 (VF(LED) > VIN), 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 (VF(LED) < VIN), 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.
IFLASH
LED Current
PRODUCT PREVIEW
ITORCH
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
ITORCH
ITORCH
6.3% PWM Dimming Steps
MODE0
Figure 29. White LED Blinking Control (MODE1 = 0, FLASH_SYNC = 1)
14
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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.).
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, TJ, 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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PRODUCT PREVIEW
UNDERVOLTAGE LOCKOUT
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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 L [ I OUT +
h VIN
(1)
I L(PEAK) +
PRODUCT PREVIEW
I OUT
VIN D
)
2 f L (1 * D)
V
* V IN
with D + OUT
h
VOUT
(2)
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
16
MANUFACTURER
SERIES
DIMENSIONS
TDK
VLF3010AT
2,6 mm × 2,8 mm × 1,0 mm max. height
TAIYO YUDEN
NR3010
3,0 mm × 3,0 mm × 1,0 mm max. height
FDK
MIPSA2520
2,5 mm × 2,0 mm × 1,2 mm max. height
TDK
VLF3014AT
2,6 mm × 2,8 mm × 1,4 mm max. height
COILCRAFT
LPS3015
3,0 mm × 3,0 mm × 1,5 mm max. height
MURATA
LQH3NP
3,0 mm × 3,0 mm × 1,5 mm max. height
TOKO
FDSE0312
3,0 mm × 3,0 mm × 1,2 mm max. height
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ILIM SETTINGS
1000 mA (typ.)
1500 mA (typ.)
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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:
C min [
I OUT
f
ǒVOUT * VINǓ
DV
V OUT
(3)
Parameter f is the switching frequency and ΔV is the maximum allowed ripple.
ΔVESR = IOUT × RESR
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, IL
• Output ripple voltage, VOUT(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
rDS(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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PRODUCT PREVIEW
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:
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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.
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 (TJ) 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
Single Pulse Power Disipation - W
PRODUCT PREVIEW
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
3
2.5
2
1.5
tPCB = 85°C
1
0.5
0
0
Theta JB: 35°CW
100 200 300 400 500 600 700 800 900 1000
Pulse Width - ms
Figure 30. Single Pulse Power Capability (CSP Package)
18
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TYPICAL APPLICATIONS
TPS61054
L
VBAT
2.2 mH
SW
SW
VOUT
COUT
10 mF
P
AVIN
Li-Ion
CIN
P
WHITE LED
FLASH-LIGHT
P
LED
MODE1
MODE0
CAMERA ENGINE
Tx-TOFF
FLASH_SYNC
AGND
PGND
PGND
P
RF PA TX ACTIVE
PRODUCT PREVIEW
Figure 31. High Power White LED Solution Featuring No-Latency Turn-Down via PA TX Signal
TPS61054
L
SW
VBAT
2.2 mH
SW
VOUT
COUT
10 mF
AVIN
Li-Ion
C IN
LED 1
P
1 .5 R
P
LED 2
1 .5 R
P
LED
MODE1
LED 1, LED 2 VF variation
should be with 100 mV from each other
MODE0
Tx-TOFF
FLASH _SYNC
PGND
AGND
P
PGND
Figure 32. 2 × 350 mA Dual LED Camera Flash
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PACKAGE SUMMARY
CHIP SCALE PACKAGE
(BOTTOM VIEW)
A3
A2
A1
B3
B2
B1
C3
C2
C1
D3
D2
D1
CHIP SCALE PACKAGE
(TOP VIEW)
YMLLLLS
6105x
D
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.
PRODUCT PREVIEW
Table 4. YZG Package Dimensions
20
Packaged Devices
D
E
TPS6105xYZG
1.96 ±0.05 mm
1.46 ±0.05 mm
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