1.0 A LED Flash Driver with
I
2
C-Compatible Interface
Data Sheet
ADP1649
Rev. 0
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FEATURES
Ultracompact solution
Small, 2 mm × 1.5 mm, 12-ball WLCSP package
Smallest footprint, 1 mm height, 1 μH power inductor
LED current source for local LED grounding
Simplified routing to and from the LED
Improved LED thermals
Synchronous 3 MHz PWM boost converter, no external diode
High efficiency: 90% peak
Reduces high levels of input battery current during flash
Limits battery current drain in torch mode
I2C programmable
Currents of up to 1000 mA in flash mode for 1 LED with
±7% accuracy over all conditions
Currents of up to 200 mA in torch mode
Programmable dc battery current limit (4 settings)
Programmable flash timer up to 1600 ms
Low VBAT mode to reduce LED current automatically
4-bit ADC for LED VF, die/LED temperature readback
Control
I2C-compatible control registers
External strobe and torch input pins
2 transmitter mask (TxMASK) inputs
Safety
Thermal overload protection
Inductor fault detection
LED short-circuit and open-circuit protection
APPLICATIONS
Camera enabled cellular phones and smart phones
Digital still cameras, camcorders, and PDAs
FUNCTIONAL BLOCK DIAGRAM
Figure 1.
Figure 2. PCB Layout (WLCSP)
GENERAL DESCRIPTION
The ADP1649 is a very compact, highly efficient, single white
LED flash driver for high resolution camera phones that improves
picture and video quality in low light environments. The device
integrates a programmable 1.5 MHz or 3 MHz synchronous
inductive boost converter, an I2C-compatible interface, and a
1000 mA current source. The high switching frequency enables
the use of a tiny, 1 mm high, low cost, 1 µH power inductor, and
the current source permits LED cathode grounding for thermally
enhanced, low EMI, and compact layouts.
The LED driver maximizes efficiency over the entire battery
voltage range to maximize the input power-to-LED power
conversion and to minimize battery current draw during flash
events. A programmable dc battery current limit safely maximizes
LED current for all LED VF and battery voltage conditions.
Two independent TxMASK inputs permit the flash LED current
and battery current to reduce quickly during a power amplifier
current burst. The I2C-compatible interface enables the pro-
grammability of timers, currents, and status bit readback for
monitoring the operation and for safety control.
The ADP1649 is available in a compact 12-ball, 0.5 mm pitch
WLCSP package, and operates within specification over the full
−40°C to +125°C junction temperature range.
ADP1649
10µF
1.0µH
INPUT VOLTAGE = 2.7V TO 5.0V
VOUT
PGND
SW
STROBE
10µF
LED_OUT
EN SGND
SCL
SDA
TxMASK1/TORCH
TxMASK2/ILED/ADC
GPIO1
GPIO2
MAX 1.0A
VIN
10779-001
DIGITAL
INPUT/
OUTPUT
Li-ION +
Li-ION +
PGND
C1
L1
INDUCTOR
LED
ANODE
C2
AREA = 16. 4mm2
10779-002
ADP1649 Data Sheet
Rev. 0 | Page 2 of 28
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Recommended Specifications: Input and Output Capacitance
and Inductance ............................................................................. 5
I2C-Compatible Interface Timing Specifications ..................... 5
Absolute Maximum Ratings ....................................................... 6
Thermal Data ................................................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution .................................................................................. 6
Pin Configuration and Function Descriptions ............................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 11
White LED Driver ...................................................................... 11
Modes of Operation ................................................................... 11
Assist Light .................................................................................. 12
Flash Mode .................................................................................. 12
Assist to Flash Operation .......................................................... 12
Torch Mode ................................................................................. 12
Torch to Flash Mode .................................................................. 13
TxMASK Operation ................................................................... 13
Frequency Foldback ................................................................... 13
Indicator LED Driver ................................................................. 13
Low Battery LED Current Foldback ........................................ 13
Programmable Battery DC Current Limit .............................. 14
Analog-to-Digital Converter Operation ................................. 15
5 V Output Operation ............................................................... 15
Safety Features................................................................................. 17
Short-Circuit Fault ..................................................................... 17
Overvoltage Fault ....................................................................... 17
Dynamic Overvoltage Mode (DOVP) .................................... 17
Timeout Fault .............................................................................. 17
Overtemperature Fault .............................................................. 17
Indicator LED Fault ................................................................... 17
Current Limit .............................................................................. 17
Input Undervoltage .................................................................... 17
Soft Start ...................................................................................... 17
Reset Using the Enable (EN) Pin ............................................. 17
Clearing Faults ............................................................................ 17
I²C Interface ................................................................................ 18
I²C Register Map............................................................................. 19
Applications Information .............................................................. 25
External Component Selection ................................................ 25
PCB Layout ...................................................................................... 27
Packaging and Ordering Information ......................................... 28
Outline Dimensions ................................................................... 28
Ordering Guide .......................................................................... 28
REVISION HISTORY
7/12—Revision 0: Initial Version
Data Sheet ADP1649
Rev. 0 | Page 3 of 28
SPECIFICATIONS
VIN
1 = 3.6 V, TJ = −40°C to +125°C for minimum/maximum specifications, and TA = 25°C for typical specifications, unless otherwise noted.
Table 1.
Parameter
2
Test Conditions/Comments Min Typ Max Unit
SUPPLY
Input Voltage Range 2.7 5.0 V
Undervoltage Lockout
Threshold V
IN
falling 2.3 2.4 2.5 V
Hysteresis 50 100 150 mV
Shutdown Current (I
Q
), EN = 0 V T
J
= −40°C to +85°C, current into VIN pin, V
IN
= 2.7 V to 4.5 V 0.2 1 µA
Standby Current (ISTBY), EN = 1.8 V
TJ = −40°C to +85°C, current into VIN pin, VIN = 2.7 V to 4.5 V
3
10
µA
Operating Quiescent Current Torch mode, LED current = 100 mA 5.3 mA
Switch Leakage, SW T
J
= −40°C to +85°C, V
SW3
= 4.5 V 2 µA
T
J
= 25°C, V
SW
3 = 4.5 V 0.5 µA
LED DRIVER
LED Current
Assist Light, Torch Assist light value setting = 0 (000 binary) 25 mA
Assist light value setting = 7 (111 binary) 200 mA
Flash Flash value setting = 0 (00000 binary) 300 mA
Flash value setting = 14 (01110 binary) 1000 mA
LED Current Error I
LED
= 700 mA to 1000 mA −6 +6 %
I
LED
= 300 mA to 650 mA −7 +7 %
I
LED
= 75 mA to 200 mA −10 +10 %
I
LED
= 25 mA to 50 mA −15 +15 %
LED Current Source Headroom
Flash, 1000 mA LED current
265
mV
Torch, 200 mA LED current 190 mV
LED_OUT Ramp-Up Time 0.6 ms
LED_OUT Ramp-Down Time 0.1 ms
SWITCHING REGULATOR
Switching Frequency Switching frequency = 3 MHz 2.8 3 3.2 MHz
Switching frequency = 1.5 MHz 1.4 1.5 1.6 MHz
Minimum Duty Cycle Switching frequency = 3 MHz 14 %
Switching frequency = 1.5 MHz 7 %
NFET Resistance 60 mΩ
PFET Resistance 50 mΩ
Voltage Output Mode
VOUT Voltage 4.575 5.000 5.425 V
Output Current 500 mA
Line Regulation
ILOAD at VOUT = 300 mA
0.3
%/V
Load Regulation −0.7 %/A
Pass Through Mode Transition, Flash
VIN to LED_OUT
Entry 1000 mA LED current 530 mV
Exit 1000 mA LED current 400 mV
Pass Through Mode Transition, Torch
VIN to LED_OUT
Entry 200 mA LED current 380 mV
Exit 200 mA LED current 285 mV
ADP1649 Data Sheet
Rev. 0 | Page 4 of 28
Parameter2 Test Conditions/Comments Min Typ Max Unit
DIGITAL INPUTS/GPIOx
Input Logic
Low Voltage 0.54 V
High Voltage 1.26 V
GPIO1, GPIO2, STROBE Pull-Down
390
kΩ
Torch Glitch Filtering Delay From torch rising edge to device start 5.5 7 7.5 ms
INDICATOR LED
LED Current Accuracy −22 +22 %
Short-Circuit Detection Threshold 1.2 V
Open-Circuit Detection Threshold 2.45 V
ADC
Resolution 4 Bits
Error External voltage mode 0 ±1 LSB
V
F
mode, T
J
= 25°C ±1 LSB
V
F
mode, T
J
= −40°C to +125°C ±1.5 LSB
Input Voltage Range, GPIO2
External voltage mode
0
0. 5
V
SAFETY FEATURES
Maximum Timeout For Flash 1600 ms
Timer Accuracy −7.0 +7.0 %
DC Current Limit DC current value setting = 0 (00 binary) 1.35 1.5 1.65 A
DC current value setting = 1 (01 binary) 1.55 1.75 1.95 A
DC current value setting = 2 (10 binary) 1.8 2.0 2.2 A
Low VBAT Mode Transition Voltage
Error 3.2 %
Hysteresis
50
mV
Coil Peak Current Limit Peak current value setting = 0 (00 binary) 1.55 1.75 1.95 A
Peak current value setting = 1 (01 binary) 2.02 2.25 2.5 A
Peak current value setting = 2 (10 binary) 2.47 2.75 3.0 A
Overvoltage Detection Threshold 5.15 5.5 5.9 V
LED_OUT Short-Circuit Detection
Comparator Reference Voltage
1.2
1.3
V
Thermal Shutdown Threshold
T
J
Rising 150 °C
T
J
Falling 140 °C
1 VIN is the input voltage to the circuit.
2 All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC).
3 VSW is the voltage on the SW switch pin.
Data Sheet ADP1649
Rev. 0 | Page 5 of 28
RECOMMENDED SPECIFICATIONS: INPUT AND OUTPUT CAPACITANCE AND INDUCTANCE
Table 2.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
CAPACITANCE
CMIN
Input T
A
= −40°C to +125°C 4.0 10 µF
Output T
A
= −40°C to +125°C 3.0 10 20 µF
MINIMUM AND MAXIMUM INDUCTANCE
L
TA = −40°C to +125°C
0.6
1.0
1.5
µH
I2C-COMPATIBLE INTERFACE TIMING SPECIFICATIONS
Table 3.
Parameter
1
Min Max Unit Description
f
SCL
400 kHz SCL clock frequency
t
HIGH
0.6 µs SCL high time
t
LOW
1.3 µs SCL low time
t
SU, DAT
100 ns Data setup time
t
HD, DAT
0 0.9 µs Data hold time
t
SU, STA
0.6 µs Setup time for repeated start
tHD, STA
0.6
µs
Hold time for start/repeated start
t
BUF
1.3 µs Bus free time between a stop and a start condition
t
SU, STO
0.6 µs Setup time for a stop condition
t
R
20 + 0.1 C
B
2 300 ns Rise time of SCL and SDA
t
F
20 + 0.1 C
B
2 300 ns Fall time of SCL and SDA
t
SP
0 50 ns Pulse width of suppressed spike
C
B2
400 pF Capacitive load for each bus line
1 Guaranteed by design.
2 CB is the total capacitance of one bus line in picofarads.
Timing Diagram
Figure 3. I2C-Compatible Interface Timing Diagram
SDA
SCL
S
S = START CONDITION
Sr = REP E ATED S TART CO NDIT IO N
P = STOP CONDITION
Sr P S
t
LOW
t
R
t
HD, DAT
t
HIGH
t
SU, DAT
t
F
t
F
t
SU, STA
t
HD, ST A
t
SP
t
SU, STO
t
BUF
t
R
10779-003
ADP1649 Data Sheet
Rev. 0 | Page 6 of 28
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter Rating
VIN, SDA, SCL, EN, GPIO1, GPIO2, STROBE,
LED_OUT, SW, VOUT to Power Ground
−0.3 V to +6 V
PGND to SGND −0.3 V to +0.3 V
Ambient Temperature Range (T
A
) −40°C to +85°C
Junction Temperature Range (T
J
) −40°C to +125°C
Storage Temperature JEDEC J-STD-020
ESD Models
Human Body ±2000 V
Charged Device
±500 V
Machine ±150 V
THERMAL DATA
Exceeding the junction temperature limits may damage the
ADP1649. Monitoring TA does not guarantee that TJ is within
the specified temperature limits. In applications with high power
dissipation and poor thermal resistance, the maximum TA may
need to be derated. In applications with moderate power dissipa-
tion and low printed circuit board (PCB) thermal resistance, the
maximum TA can exceed the maximum limit as long as the TJ is
within specification limits. TJ of the device is dependent on the
TA, the power dissipation (PD) of the device, and the junction-
to-ambient thermal resistance (θJA) of the package. Maximum TJ
is calculated from TA and PD using the following formula:
TJ = TA + (PD × θJA)
THERMAL RESISTANCE
θJA of the package is based on modeling and calculation using
a 4-layer board. θJA is highly dependent on the application and
board layout. In applications where high maximum power dissi-
pation exists, attention to thermal board design is required. The
value of θJA may vary, depending on PCB material, layout, and
environmental conditions. The specified value of θJA is based
on a 4-layer, 4 in × 3 in, 2½ oz copper board, per JEDEC
standards. For more information, see the AN-617 Application
Note, MicroCSP™ Wafer Level Chip Scale Package.
θJA is specified for a device mounted on a JEDEC 2s2p PCB.
Table 5. Thermal Resistance
Package Type θ
JA
Unit
12-Ball WLCSP
75
°C/W
ESD CAUTION
Stresses a bove those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Data Sheet ADP1649
Rev. 0 | Page 7 of 28
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 4. Pin Configuration
Table 6. Pin Function Descriptions
Pin No. Mnemonic Description
A1 PGND Power Ground.
A2 SGND Signal Ground.
A3 VIN Input Voltage for the Device. Connect an input bypass capacitor close to this pin.
B1
SW
Boost Switch. Connect the power inductor between SW and the input capacitor.
B2 GPIO2 General-Purpose Input/Output for the ILED/TxMASK2/ADC Modes. These modes are register selectable. This is
a multifunction pin for the red indicator LED current source, TxMASK2, or ADC input.
ILED Mode. For the ILED mode, connect this pin to the red LED anode. Connect the LED cathode to power
ground.
TxMASK2 Mode. TheTxMASK2 function of this pin reduces the current to the programmable TxMASK2 current.
ADC Mode. The ADC function of this pin is used as the input pin for the ADC.
B3 GPIO1 General-Purpose Input/Output for the Torch/TxMASK1 Modes. These modes are register selectable. This is a
multifunction pin for the external torch mode or TxMASK1 input.
Torch Mode. Enables the integrated circuit (IC) in direct torch mode.
TxMASK1 Mode. Reduces the flash current to the programmable TxMASK1 current.
C1 VOUT Boost Output. Connect an output bypass capacitor very close to this pin. VOUT is the output for the 5 V
external voltage mode.
C2 STROBE Strobe Signal Input. STROBE synchronizes the flash pulse to the image capture. In most cases, this signal
comes directly from the image sensor.
C3 EN Enable. Set EN low to bring the quiescent current (IQ) to <1 µA. Registers are set to their defaults when EN is
brought from low to high.
D1
LED_OUT
LED Current Source. Connect the LED_OUT pin to the anode of the flash LED.
D2
SDA
I2C Data Signal in I2C Mode.
D3 SCL I
2
C Clock Signal in I
2
C Mode.
TOP VI EW
(BAL L SIDE DOW N)
Not t o Scale
PGND SGND VIN
SW GPIO2 GPIO1
VOUT STROBE EN
LED_OUT SDA SCL
1
A
B
C
D
2 3
BALLA1
INDICATOR
10779-004
ADP1649 Data Sheet
Rev. 0 | Page 8 of 28
TYPICAL PERFORMANCE CHARACTERISTICS
Figure 5. Start-Up Flash Mode, VIN = 3.6 V, ILED = 1000 mA
Figure 6. Start-Up Torch Mode, VIN = 3.6 V, ILED = 100 mA
Figure 7. 100 mA Torch to 1000 mA Flash Transition
Figure 8. Switching Waveforms, Flash Mode, ILED = 1000 mA
Figure 9. Pass Through to Boost Mode Transition, ILED = 100 mA
Figure 10. Entry into TxMASK1 Mode
CH1 5.00V CH2 1.00A
CH4 1.00VCH3 500mAM100.0µs A CH1 1.00V
3
4
2
1
T 400µs
LED_OUT
I
LED
I
L
STROBE
10779-005
CH1 5.00V CH2 100mA
CH4 2.00VCH3 100mAM1.00ms A CH1 1.00V
3
4
2
1
T 4.00ms
LED_OUT
I
LED
I
L
GPIO (TORCH)
10779-006
CH1 5.00V CH2 1.00A
CH4 1.00VCH3 500mAM100.0µs A CH1 1.00V
3
4
2
1
T 400µs
LED_OUT
I
LED
I
L
STROBE
10779-007
CH1 2.00V CH2 500mA
CH3 500mAM100.0ns A CH1 2.40V
3
2
1
T 4.00ms
I
LED
I
L
SWITCH
10779-008
CH1 2.00V CH2 100mA
CH4 2.00VCH3 100mAM500.0µs A CH1 1.00V
3
4
2
1
T 1.5ms
VIN
I
LED
I
L
10779-009
LED_OUT
CH1 2.00V CH2 500mA
CH4 2.00VCH3 500mAM10.00µs A CH1 1.00V
3
4
2
1
T 20.00µs
LED_OUT
IBAT
ILED
GP IO ( TxMAS K1)
10779-010
Data Sheet ADP1649
Rev. 0 | Page 9 of 28
Figure 11. Exit from TxMASK1 Mode
Figure 12. Switching Frequency vs. Supply Voltage (3 MHz Mode)
Figure 13. Standby Current vs. Temperature
Figure 14. Flash Mode Efficiency vs. LED Current
Figure 15. Voltage Regulation Mode Efficiency vs. Load Current
Figure 16. ADC External Voltage Mode Transfer Characteristic
CH1 2.00V CH2 500mA
CH4 2.00VCH3 500mAM20.00µs A CH1 1.20V
3
4
2
1
T 80.00µs
LED_OUT
IBAT
ILED
GP IO ( TxMAS K1)
10779-011
2.94
2.95
2.96
2.97
2.98
2.99
3.00
3.01
3.02
3.03
3.04
2.7 3.0 3.3 3.6 3.9 4.2 4.5 4.8 5.1 5.4
f
SW (MHz)
INP UT VOLTAGE (V)
–40°C
+25°C
+85°C
+125°C
10779-012
0
1
2
3
4
5
6
–40 –20 020 40 60 80 100 120
STANDBY CURRENT (µA)
TEMPERAT URE ( °C)
VIN = 2.7V
VIN = 3.6V
VIN = 4.5V
10779-013
0
10
20
30
40
50
60
70
80
90
100
0.3 0.5 0.7 0.9 1.0
EFFICIENCY ( %)
LE D CURRE NT (A)
VIN = 4.2V
VIN = 3.6V
VIN = 3.4V
VIN = 3.2V
10779-014
40
50
60
70
80
90
100
0.01 0.1 1
EFFICIENCY ( %)
OUTPUT CURRENT (A)
V
IN
= 2.7V
V
IN
= 3.0V
V
IN
= 3.3V
V
IN
= 3.6V
V
IN
= 4.2V
10779-015
050 100 150 200 250 300 350 400 450 500 550
ADC RESULT ( Binary)
ADC INP UT VOLTAGE (mV)
0010
0000
0100
0110
1000
1010
1100
1110
1111
10779-016
ADP1649 Data Sheet
Rev. 0 | Page 10 of 28
Figure 17. ADC Die Temperature Mode Transfer Characteristic
Figure 18. ADC LED VF Mode Transfer Characteristic
Figure 19. ADC LED VF Mode, Code 1000, Midpoint vs. Temperature
Figure 20. ADC External Voltage Mode, Code 1000, Midpoint vs. Temperature
Figure 21. LED Current Error vs. Temperature, ILED = 800 mA
Figure 22. LED Current Error vs. Temperature, ILED = 1000 mA
025 50 75 100 125 150
ADC RESULT ( Bin ary)
DIE TEMPERATURE ( °C)
0010
0000
0100
0110
1000
1010
1100
1110
1111
10779-017
08837-061
2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4
ADC RESULT ( Binary)
LE D_OUT V OLTAGE (V)
0010
0000
0100
0110
1000
1010
1100
1110
1111
3.710
3.715
3.720
3.725
3.730
3.735
3.740
3.745
3.750
3.755
3.760
–40 10 60 110
CODE 1000 M IDPOI NT (V )
V
IN
= 2.7V
V
IN
= 3.6V
V
IN
= 5.0V
TEMPERAT URE ( °C)
10779-019
286
287
288
289
290
291
292
293
294
295
–40 10 60 110
CODE 1000 M IDPOI NT (mV )
TEMPERAT URE ( °C)
VIN = 2.7V
VIN = 3.6V
VIN = 5V
10779-020
–3.0
–2.5
–2.0
–1.5
–1.0
–0.5
0
0.5
–40 10 60 110
LE D CURRE NT ERROR (%)
TEMPERAT URE ( °C)
VIN = 3.2V
VIN = 3.6V
VIN = 4.2V
10779-021
LE D CURRE NT ERROR (%)
–2.5
–2.0
–1.5
–1.0
–0.5
0
0.5
1.0
–40 10 60 110
LE D CURRE NT ERROR (%)
TEMPERAT URE ( °C)
VIN = 3.2V
VIN = 3.6V
VIN = 4.2V
10779-022
Data Sheet ADP1649
Rev. 0 | Page 11 of 28
THEORY OF OPERATION
The ADP1649 is a high power, I2C programmable, white LED
driver ideal for driving white LEDs for use as a camera flash.
The ADP1649 includes a boost converter and a current regu-
lator suitable for powering one high power white LED.
WHITE LED DRIVER
The ADP1649 drives a synchronous 3 MHz boost converter as
required to power the high power LED. If the sum of the LED
forward voltage and current regulator voltage is higher than
the battery voltage, the boost turns on. If the battery voltage is
higher than the sum of the LED VF and current regulator voltage,
the boost is disabled and the part operates in pass through mode.
The ADP1649 uses an integrated PFET high-side current regu-
lator for accurate brightness control.
MODES OF OPERATION
After the enable pin is high, the device can be set into the four
modes of operation using the LED_MOD bits in Register 0x04,
via the I2C-compatible interface.
Table 7. LED_MOD Bit Settings, I2C-Compatible Interface
LED_MOD
Setting Description
00 Sets the device to standby mode, consuming 3 μA
typical.
01 Sets the device to fixed VOUT = 5 V output mode.
10 Sets the device to assist light mode with continuous
LED current.
11 Sets the device to flash mode with an available
current of up to 1 A for 1.6 sec.
Figure 23. Detailed Block Diagram
LED_OUT PIN
PWM
CONTROLLER
PGND
PGND
VOUT
SW
PGNDSGND
VIN
UVLO
OVP
FAULT
REGISTER
IC THERMAL
SENSING
HPLED
SHORT
HPLED
DRIVER
CURRENT
SENSE
CURRENT
SENSE
SCL
STROBE
PGND
PGNDAGND
C
OUT
10µF
L1
1µF
INPUT VOLTAGE =
2.7V TO 5.0
V
C
IN
10µF
GPIO1 GPIO2
SDA
TORCH
EN
5.5V
HIGH POWER LE D
CURRENT CO NTROL
LED_OUT
25mA TO 1 .0A
INTERFACE
AND
CONTROL
TxMASK1 TxMASK2
4-BIT
ADC
VIN
ILED
IO2_CFG[7:6]
IO1_CFG[5:4]
2.4V
10779-023
ADP1649 Data Sheet
Rev. 0 | Page 12 of 28
ASSIST LIGHT
The assist light mode provides a continuous current that is
programmable from 25 mA to 200 mA. Set the assist light
current using the I_TOR bits (in Register 0x03).
To enable assist, set LED_MOD to assist light mode and set
OUTPUT_EN = 1 (in Register 0x04). Disable assist light mode by
setting LED_MOD to standby mode or setting OUTPUT_EN = 0.
Figure 24. Enabling and Disabling Assist Light Mode
FLASH MODE
Flash mode provides 300 mA to 1 A for a programmable time of
up to 1.6 seconds. Set the flash current using the I_FL bits (in
Register 0x03) and the maximum flash duration with the FL_TIM
bits (in Register 0x02). To enable flash mode, set LED_MOD
to flash mode and set OUTPUT_EN = 1. Enable flash without
the STROBE pin by setting STR_MODE (in Register 0x04) to 0
(software strobe).
When STR_MODE is in hardware strobe mode, setting the
STROBE pin high enables flash and synchronizes it to the image
sensor. Hardware strobe mode has two modes for timeout: level
sensitive (STR_LV = 1, Register 0x04) and edge sensitive
(STR_LV = 0, Register 0x04).
Figure 25. Flash Operation: Level Sensitive Mode
In level sensitive mode, the duration of the STROBE pin set to
high sets the duration of the flash up to the maximum time
indicated by the FL_TIM timeout. If STROBE remains high
longer than the duration set by FL_TIM, a timeout fault
disables the flash.
Figure 26. Flash Operation: Edge Sensitive Mode
In edge sensitive mode, a positive edge on the STROBE pin
enables the flash, and the FL_TIM bits set the flash duration.
ASSIST TO FLASH OPERATION
Figure 27. Enabling Assist to Flash (Level Sensitive) Mode
The STR_POL bit in Register 0x07 changes the default enable of
the STROBE pin from low to high and from high to low. Additional
image sensor specific assist/flash enable modes are included in
the device, and information on these modes is available by request
from the Analog Devices, Inc., sales team.
TORCH MODE
Set the assist/torch light current modes using the I_TOR bits.
To enable torch mode using a logic signal, set LED_MOD to
standby mode, set OUTPUT_EN = 1, and bring GPIO1 high.
Disable the external torch mode by setting GPIO1 low or pro-
gramming OUTPUT_EN = 0. Bringing GPIO1 low during torch
mode automatically sets OUTPUT_EN = 0. To reenable torch
mode, program OUTPUT_EN = 1 and bring GPIO high again.
Figure 28. Enabling External Torch Mode Using GPIO1
LE D C URRENT
REG 0x03, I_T OR = XX X mA
REG 0x04, OUT PUT_EN = 1
LED_MOD = 10
I2C DATA BUS
REG 0x04, OUTP UT_E N = 0
0A
IASSIST
10779-024
LE D C URRE N T
REG 0x04, OUT PUT _EN = 1
STR_LV = 1
LE D_MO D = 11
I2C DAT A BU S
0A
IFLASH
STROBE
REG 0x02, F L _TI M = XXXX ms
REG 0x03, I_FL = XXXXX mA ADP1649 SETS OUTPUT _E N TO 0.
ADP1649 SETS LED_MOD TO 00.
10779-025
I2C DAT A BUS
LED CURRENT
REG 0x02, FL_TI M = XXXX ms
REG 0x03, I_FL = XXXXX mA
REG 0x04, OUTPU T_E N = 1
STR_LV = 0
LE D_M OD = 11
0A
I
FLASH
STROBE
ADP1649 SETS OUTPUT_EN TO 0.
ADP1649 SETS LED_MOD TO 00 .
FL_TIM
10779-026
LED CURRENT
REG 0x02, FL_TI M = XXXX ms
REG 0x03, I_TOR = XXX mA
REG 0x03, I_FL = XXXXX mA
REG 0x04, OUTP UT_EN = 1
STR_LV = 1
LE D_M O D = 10
I
2
CDATABUS
0A
I
FLASH
STROBE
ADP1649 SETS OUTP UT_EN TO 0.
ADP1649 SETS LED_MOD TO 00.
I
ASSIST
10779-027
LED CURRENT
REG 0x03, I_T OR = XXX m A
REG 0x04, OUT PUT_ E N = 1
LED_MOD = 00
I
2
C DATA BUS
0A
I
ASSIST
ADP1649 SETS OUT P UT_E N T O 0
GPIO1 (TORCH)
10779-028
Data Sheet ADP1649
Rev. 0 | Page 13 of 28
TORCH TO FLASH MODE
The driver can move directly from external torch mode (using
GPIO1) to flash mode by bringing the STROBE pin high before
bringing the GPIO1 pin (set for the torch mode) low. Bringing
torch low before the STROBE pin goes high prevents the flash
from firing when the STROBE pin goes high.
The ADP1649 returns to standby mode after a successful flash
and sets OUTPUT_EN = 0.
Figure 29. Enabling Flash Mode from External Torch Mode
TxMASK OPERATION
When the ADP1649 is in flash mode, the TxMASK1 and the
TxMASK2 functions reduce the battery load in response to the
system enabling a power amplifier. The device remains in flash
mode, but the LED driver output current reduces to the pro-
grammed TxMASK light level in less than 21 µs.
Figure 30. TxMASK1 Operation During Flash (Level Sensitive) Mode
The device selects the TxMASK1 or TxMASK2 current level
based on whether the TxMASK1 or TxMASK2 input is used.
Anytime TxMASK1 or TxMASK2 is brought high during a
flash event, a flag is set in the fault information register. To avoid
overshoots on the battery current, when the TxMASK signal goes
low again, the LED current returns to the full flash level in a
controlled manner. If both TxMASK inputs are set high
simultaneously, the TxMASK1 current level is used.
FREQUENCY FOLDBACK
Frequency foldback is an optional mode that optimizes efficiency
by reducing the switching frequency to 1.5 MHz when VIN is
slightly less than VOUT. Enable frequency foldback by setting
FREQ_FB = 1 in Register 0x04.
INDICATOR LED DRIVER
The indicator LED driver on GPIO2 provides a programmable
current source of between 2.75 mA and 11 mA for driving a red
privacy LED; the I_ILED bits in Register 0x07 program the current
level. The circuit consists of a programmable current source and
a monitoring circuit that uses comparators to determine whether
the indicator LED is short circuit or open circuit. The threshold
for detection of a short circuit is 1.2 V (maximum), and for an
open circuit, the threshold is 2.45 V (minimum). The indicator
LED must not be used at the same time as a flash or an assist/
torch event.
LOW BATTERY LED CURRENT FOLDBACK
As the battery discharges, the lower battery voltage results in
higher peak currents through the battery ESR, which may cause
early shutdown of the phone. The ADP1649 features an optional
low battery detection option that reduces the flash current (to a
programmable level) when the battery voltage falls below a
programmable level. Set V_VB_LO = 000 to disable the low
battery current foldback (see Table 8 for details).
Figure 31. Register 0x09 Sets the Battery Voltage Threshold Level and the
Reduced LED Current Level
LED CURRENT
REG 0x02, F L_T IM = X X X X ms
IO1_CF G = 01, T ORCH
REG 0x03, I _TO R = X X X mA
REG 0x03, I _FL = X X X X X mA
REG 0x04, O UTPUT_EN = 1
ST R_LV = 1
LE D_M OD = 00
I2C DATA BUS
0A
IFLASH
STROBE
ADP1649 SETS OUTPUT_EN T O 0
IASSIST
TORCH
10779-029
LE D CURRE NT
REG 0x02, I O1_CF G = 10
FL_TI M = XXXX ms
REG 0x03, I _FL = X X X X X mA
REG 0x06, I _TX1 = X X X X mA
REG 0x04, O UTPUT_EN = 1
ST R_LV = 1
LE D_M OD = 11
I2C DATA BUS
0A
I
FLASH
STROBE
ADP1649 SE TS OUT P UT_EN TO 0.
ADP1649 SE TS LED_M OD T O 00.
ITxMASK1
TxMASK1
(GPIO1)
FL_TX1 = 1
10779-030
LE D CURRE NT
REG 0x09, I _V B_LO = X X X X mA
V_VB_LO = XXX V
I
2
C DATA BUS
0
A
I
FLASH
STROBE
ADP1649 SE TS OUT P UT_EN TO 0.
ADP1649 SE TS LED_M OD T O 00.
I
I_VB_LO
VIN
V
V_VB_LO
REG 0x04, O UTPUT_EN = 1
LE D_M OD = 10
FL_VB_LO = 1
50mV HYS
GLI TCH < 50µ s IG NORED
10779-031
ADP1649 Data Sheet
Rev. 0 | Page 14 of 28
Table 8. VDD Level at Which the VBAT Low Function Is Enabled
Bit Name V
DD
Level
V_VB_LO 000 = disabled (default)
001 = 3.3 V
010 = 3.35 V
011 = 3.4 V
100 = 3.45 V
101 = 3.5 V
110 = 3.55 V
111 = 3.6 V
PROGRAMMABLE BATTERY DC CURRENT LIMIT
The ADP1649 has four optional programmable input dc current
limits that limit the maximum input battery current over all con-
ditions. This allows use of higher LED currents in a system with
significant variation in LED forward voltage (VF) and supply
battery voltage without risk of exceeding the current allocated
to the flash.
Table 9. Input DC CurrentLimit Setting the LED Current
Bit Name Current Limit
IL_DC 00 = 1.5 A
01 = 1.75 A
10 = 2.0 A (default)
11 = reserved
During startup of the flash, if the battery current does not reach
the dc current limit, the LED current is set to the current value
of the I_FL bits. If the battery current reaches the programmed
dc current limit on startup, the LED current does not increase
further. The dc current limit flag is set in the fault information
register. The I_FL bits in Register 0x03 are set to the automatically
reduced current-limit LED current and are available for readback.
Figure 32. DC Current-Limit Operation in a Low Battery, High LED VF Case
The camera system shown in Figure 33 can adjust the image
sensor settings based on the known reduced LED current for a
low battery and a high VF LED.
Figure 33. Use of the DC Current Limit in an Optimized Camera System
REG 0x 02 , FL_T I M = XXXX m s
REG 0x 03 , I _ FL = XXXXX m A
REG 0x07 IL_DC_EN = 1
REG 0x07 IL_DC = XX A
I
2
C DATA BUS
STROBE
ADP1649 SETS OUTPUT_EN TO 0.
ADP1649 SETS LED_MOD TO 00.
NO L IM IT L ED CURRENT
ACTUAL LED CURRENT
ADP1649 SETS FL_IDC (REG 0x05) TO 1.
ADP164 9 S ETS I_F L T O ACTUAL L ED CURRENT .
REG 0x04, O UTPUT_EN = 1
STR_LV = 1
LED_M OD = 11
10779-032
SELECT F LASH CURRE NT
SELECT MAX BATT E RY CURRE NT
PREFLASH STROBE
DCLIMIT HIT?
LE D CURRE NT =
PROGAMMED LED
CURRENT
NO
LE D CURRE NT =
REDUCED LED CURRE NT
YES
BATTERY CURRE NT =
PRO GRAMM E D DC LI M IT
I2C READ L E D CURRE NT
ADJUST IMAGE S E NS OR
STROBE
STROBE
10779-033
Data Sheet ADP1649
Rev. 0 | Page 15 of 28
ANALOG-TO-DIGITAL CONVERTER OPERATION
The internal 4-bit analog-to-digital converter (ADC) is config-
urable to measure the LED VF, the integrated circuit (IC) die
temperature, or to measure an external voltage using the GPIO2
pin. Read the 4-bit resolution output code from Register 0x08
using the I2C interface.
Figure 34. Available ADC Modes
The ADC can perform the conversion immediately on an I2C
command or it can delay the conversion until the next time the
ADP1649 exits an active mode. Delayed conversion can be
useful, for example, for measuring the IC temperature at the
end of a timed flash period.
To set up a delayed conversion, set ADC_EN to the required
mode while OUTPUT_EN = 0. Next, set the ADP1649 to the
desired output mode (torch, flash assist light, or 5 V output) and
set OUTPUT_EN = 1. The ADC conversion is performed when
the ADP1649 exits the chosen mode.
To perform an immediate conversion, set ADC_EN to the
required mode during ADP1649 operation (OUTPUT_EN = 1).
Note that an ADC conversion cannot be performed when the
ADP1649 is idle. This is interpreted as an attempt to set up a
delayed conversion.
LED VF Mode
The ADC can measure the LED VF in both flash and assist/torch
modes. In torch mode, set ADC_EN = 01 to begin a conversion.
The value can be read back from the ADC_VAL[5:2] bits 1 ms
after the conversion has started. Assist/torch mode, rather than
flash mode, is best in the handset production test to verify the
LED VF.
Figure 35. ADC Timing for All Modes Except VF Measurement in Flash Mode
In flash mode, set ADC_EN = 01. The conversion occurs imme-
diately before the timeout; therefore, the FL_TIM bits set when
the ADC sample occurs. This allows the VF to settle from the
initial peak as the junction temperature of the LED stabilizes.
An LED temperature vs. flash time profile for the handset PCB
design can be generated during the design phase by varying the
FL_TIM bits from the lowest to the highest setting and collecting a
VF sample on each flash.
Figure 36. ADC Timing for VF Measurement in Flash Mode
Die Temperature Mode
The ADC measures the IC die temperature and provides the result
to the I2C interface. This is useful during the design phase of the
flash system to optimize PCB layout for the best thermal design.
Write ADC_EN = 10 to begin a die temperature measurement.
The value can be read back from the ADC_VAL[5:2] bits 1 ms
after the conversion has started. The most stable and accurate value
of the die temperature is available at the end of the flash pulse.
External Voltage Mode
The ADC measures the voltage on the GPIO2 pin when the GPIO2
is configured as an ADC input by setting IO2_CFG = 11. One
example is using an external temperature dependent resistor to
create a voltage based on the temperature of the flash LED. The
EN line can be used for biasing to reduce leakage current when
the flash is not being used.
5 V OUTPUT OPERATION
The ADP1649 can be used as a 5 V boost to supply up to 500 mA
for an audio voltage rail or keypad LED driver voltage. To move
into voltage regulation mode, the OUTPUT_EN bit must be set
to 0. To enable the 5 V output, set LED_MOD[1:0] = 01, and set
OUTPUT_EN = 1. The ADP1649 sets the VOUT pin to 5 V
and disconnects VOUT from LED_OUT. The VOUT pin is
connected to the SW node when the ADP1649 is not enabled.
Do not connect VOUT directly to a positive external voltage
source because this causes current to flow from VOUT to the
battery.
INTERFACE/
CONTROL LED_OUT
SDA
SCL
ADC_EN[1:0]
4-BIT ADC
IC TEM PERATURE
SENSOR
EN
GPIO2
ADC_VAL[5:2] PTC
10779-034
REG 0x08, ADC_E N = 01
START CONVERSION
(I NTE R NAL SIGNAL )
1
m
s
ADC_VAL[5:2]
AVAI LABL E F OR READ
I2
C DAT A BUS
10779-035
LE D CU RRENT
REG 0x 02, FL _TI M = XXXX m s
REG 0x03, I_FL = XXXXX mA
REG 0 x04, OUT P UT_E N = 1
STR_LV = 0
LE D_M OD = 1 1
I2C DATA BUS
0A
STROBE
FL_TIM
START CONVERSI O N
(I NTERNA L SIGNAL )
ADC_VAL[5:2]
AVAILABLE FOR READ
REG 0x0 8, ADC_E N = 01
t
S
= 1ms
10779-036
I
FLASH
ADP1649 Data Sheet
Rev. 0 | Page 16 of 28
Figure 37. Voltage Regulation Mode: LED Driver Application
Figure 38. Voltage Regulation Mode: Class-D Audio Application
ADP1649
10µF
1.0µH
INPUT VOLTAGE =
2.7V TO 5.0V
PGND
SWSTROBE
10µF
LED_OUT
EN
SGND
SCL
SDA
GPIO1
GPIO2
OFF
ON
I2C BUS
SDA, S CL
EN
APPLICATIONS PROCESSOR
3.2 MEGAPIXEL
TO 5.0 MEGAPIXEL
CMOS IMAGE SENSOR
POWER-ON RESET
VO UT = 5. 0V
KEYPAD
LE D DRIVE R
VDD
GND
VOUT*
VIN
*THE V OUT P IN I S CONNECTED TO THE S W NO DE WHEN THE ADP 1649 IS NOT E NABLED. VOUT S HOUL D NOT BE CONNECTED DIRECTL Y TO A P OSIT IVE
EXTERNAL VOL TAG E S OURCE BE CAUS E THI S CAUS E S CURRE NT T O F LO W F ROM V OUT TO THE BATT E RY .
10779-037
VO UT = 5. 0V ± 8.5%, IMAX = 500mA
SHUTDOWN
VDD
OUT+
OUT–
IN+
GND
SD
AUDIO I N–
AUDIO I N+
SSM2315
80kΩ
80kΩ
160kΩ
160kΩ
BIAS
0.1µF
ADP1649
10µF
1.0µH
INPUT VOLTAGE =
2.7V TO 5.0V
PGND
SWSTROBE
10µF
LED_OUT
EN
SGND
SCL
SDA
GPIO1
GPIO2
OFF
ON
I2C BUS
SDA, S CL
EN
APPLICATIONS
PROCESSOR
3.2 TO 5.0 MEGAPIXEL
CMOS IMAGE SENSOR
POWER-ON
RESET
VOUT
VIN
IN–
47nF
47nF
FET
DRIVER
POP/CLICK
SUPPRESSION
INTERNAL
OSCILLATOR
MODULATOR
(Σ-Δ)
10779-038
Data Sheet ADP1649
Rev. 0 | Page 17 of 28
SAFETY FEATURES
For critical fault conditions, such as output overvoltage, flash
timeout, LED output short-circuit, and overtemperature
conditions, the ADP1649 has built-in protection modes. If a
critical fault occurs, OUTPUT_EN (Register 0x04) is set to 0,
and the driver shuts down. The appropriate fault bit is set in the
fault information register (Register 0x05). The processor can
read the fault information register through the I2C interface to
determine the nature of the fault condition. When the fault
register is read, the corresponding fault bit is cleared.
If a noncritical event such as an indicator LED open-circuit,
short-circuit, TxMASK1, or TxMASK2 event occurs, or if the dc
or soft inductor current limit is reached, the LED driver continues
operating. The corresponding information bits are set in the
fault information register until the processor reads them.
SHORT-CIRCUIT FAULT
When the flash driver is disabled, the high-side current regulator
disconnects the dc path between the battery and the LED, pro-
tecting the system from an LED short circuit. The LED_OUT
pin features short-circuit protection that monitors the LED
voltage when the LED driver is enabled. If the LED_OUT pin
remains below the short-circuit detection threshold, a short
circuit is detected. Bit 6 of the fault information register is set
high. The ADP1649 remains disabled until the processor clears
the fault register.
OVERVOLTAGE FAULT
The ADP1649 contains a comparator at the VOUT pin that
monitors the voltage between VOUT and GND. If the voltage
exceeds 5.5 V (typical), the ADP1649 shuts down. Bit 7 in the
fault information register is read back as high. The ADP1649 is
disabled until the fault is cleared, ensuring protection against an
open circuit.
DYNAMIC OVERVOLTAGE MODE (DOVP)
Dynamic OVP mode is a programmable feature that limits the
VOUT voltage exceeding the OVP level while maintaining as
much current as possible through the LED. This mode prevents
an overvoltage fault in the case of a much higher than expected
LED forward voltage. If the LED forward voltage reduces due to
the LED temperature rising, the ADP1649 moves out of DOVP
mode and regulates the LED at the programmed current level.
Set Bit 7 of Register 0x07 high to enable the DOVP mode.
TIMEOUT FAULT
When the external strobe mode is enabled (Register 0x04, Bit 2)
and the strobe enable bit is set to the level sensitive mode
(Register 0x04, Bit 5), then, if the STROBE pin remains high for
longer than the programmed timeout period, the timeout fault
bit (Register 0x05, Bit 4) is read back as high. The ADP1649
remains disabled until the processor clears the fault register.
OVERTEMPERATURE FAULT
When the junction temperature of the ADP1649 rises above
150°C, a thermal protection circuit shuts down the device. Bit 5 of
the fault information register is set high. The ADP1649 remains
disabled until the processor clears the fault register.
INDICATOR LED FAULT
The GPIO2 pin features open-circuit and short-circuit protec-
tion in the indicator LED mode. If a short circuit or open circuit
occurs, Bit 2 of the fault information register is set high. The
indicator LED regulator ensures that no damage occurs to the
IC during a fault.
CURRENT LIMIT
The internal switch limits battery current by ensuring that the
peak inductor current does not exceed the programmed limit
(Bit 6 and Bit 7 in Register 0x04 set the current limit). The default
mode of the ADP1649 is soft current-limit mode. If the peak
inductor current limit is reached, Bit 1 of the fault information
register is set, and the inductor and LED current cannot increase
further although the ADP1649 continues to operate. If the
ADP1649 has soft current limit disabled and the peak inductor
current exceeds the limit, the device shuts down and Bit 1 of the
fault information register is set high. In this case, the ADP1649
remains disabled until the processor clears the fault register.
INPUT UNDERVOLTAGE
The ADP1649 includes a battery undervoltage lockout circuit.
During 5 V or LED operation, the battery voltage dropping
below the 2.4 V (typical) input UVLO threshold shuts down the
ADP1649. A power-on reset circuit resets the registers to their
default conditions when the voltage rises above the UVLO rising
threshold.
SOFT START
The ADP1649 has a soft start mode that controls the rate of
increase of battery current at startup by digitally controlling the
output current ramp. The maximum soft start time is 0.6 ms.
RESET USING THE ENABLE (EN) PIN
A low to high transition on the EN pin resets all registers to
their default values. Bringing EN low reduces the IQ to 0.2 µA
(typical).
CLEARING FAULTS
The information bits and faults in Register 0x05 automatically
clear when the processor reads the fault register.
ADP1649 Data Sheet
Rev. 0 | Page 18 of 28
I²C INTERFACE
The ADP1649 includes an I2C-compatible serial interface for
control of the LED current, as well as for readback of the system
status registers. The I2C chip address is 0x30 (0x60 in write
mode and 0x61 in read mode). Additional I2C addresses are
available on request.
Figure 39 illustrates the I2C write sequence to a single register.
The subaddress content selects which of the nine ADP1649
registers is written to. The ADP1649 sends an acknowledgment
to the master after the 8-bit data byte has been written. Figure 40
shows the I2C read sequence of a single register. See the I²C
Register Map section for a list of register definitions.
Figure 39. I2C Single Register Write Sequence
Figure 40. I2C Single Register Read Sequence
SUBADDRESS
CHIP ADDRE S S
0 1 1 0 0 0 0 0
0
0
0 = WRIT E
0
ADP1649 ACK
ADP1649 ACK
ADP1649 ACK
ADP1649 RECE IVE S
DATA
S
TS
P
MASTER
STOP
10779-039
ADP1649 ACK
ADP1649 ACK
ADP1649 ACK
CHIP ADDRE S S
0 1 1 0 0 0 0 0 010
MASTER
STOP
CHIP ADDRESS
S
T
S
T
0110000 010
0 = WRIT E 1 = READ
S
P
MASTER ACK
ADP1649 SENDS
DATA
SUBADDRESS
10779-040
Data Sheet ADP1649
Rev. 0 | Page 19 of 28
I²C REGISTER MAP
The lowest bit number (0) represents the least significant bit, the highest bit number (7) represents the most significant bit, and R/W indicates
whether the bit is read only (R), write only (W), or both read and write (R/W).
Table 10. Design Information Register (Register 0x00)
Bit Bit Name R/W Reset State
[7:0]
Manufacturer Information
R
00100010
Table 11. VREF and Timer Register (Register 0x02)
Bit Bit Name R/W Description
[7:6] IO2_CFG R/W GPIO2 configuration
00 = high impedance (default)
01 = indicator LED
10 = TxMASK2 operation mode
11 = analog input (to ADC)
[5:4] IO1_CFG R/W GPIO1 configuration
00 = high impedance (default)
01 = torch
10 = TxMASK1 operation mode
11 = reserved
[3:0] FL_TIM R/W Flash timer value setting
0000 = 100 ms
0001 = 200 ms
0010 = 300 ms
0011 = 400 ms
0100 = 500 ms
0101 = 600 ms
0110 = 700 ms
0111 = 800 ms
1000 = 900 ms
1001 = 1000 ms
1010 = 1100 ms
1011 = 1200 ms
1100 = 1300 ms
1101 = 1400 ms
1110 = 1500 ms
1111 = 1600 ms (default)
ADP1649 Data Sheet
Rev. 0 | Page 20 of 28
Table 12. Current Set Register (Register 0x03)
Bit Bit Name R/W Description
[7:3] I_FL R/W Flash current value setting
00000 = 300 mA
00001 = 350 mA
00010 = 400 mA
00011 = 450 mA
00100 = 500 mA
00101 = 550 mA
00110 = 600 mA
00111 = 650 mA
01000 = 700 mA
01001 = 750 mA
01010 = 800 mA
01011 = 850 mA
01100 = 900 mA
01101 = 950 mA
01110 = 1000 mA (default)
Codes above 01110 are reserved
[2:0] I_TOR R/W Torch and assist light current value setting
000 = 25 mA
001 = 50 mA
010 = 75 mA
011 = 100 mA (default)
100 = 125 mA
101 = 150 mA
110 = 175 mA
111 = 200 mA
Data Sheet ADP1649
Rev. 0 | Page 21 of 28
Table 13. Output Mode Register (Register 0x04)
Bit Bit Name R/W Description
[7:6] IL_PEAK R/W Inductor peak current-limit setting
00 = 1.75 A
01 = 2.25 A
10 = 2.75 A (default)
11 = reserved
5 STR_LV R/W 0 = edge sensitive
1 = level sensitive (default)
4 FREQ_FB R/W 0 = frequency foldback to 1.5 MHz not allowed (default)
1 = frequency foldback to 1.5 MHz allowed
3 OUTPUT_EN R/W 0 = output off (default)
1 = output on
2
STR_MODE R/W
0 = software strobe mode (software flash occurs when output is enabled in flash mode)
1 = hardware strobe mode (the STROBE pin must go high for flash) (default)
[1:0] LED_MOD R/W Configures LED output mode
00 = standby mode (default)
01 = voltage output mode, VOUT = 5 V
10 = assist light mode
11 = flash mode
Table 14. Fault Information Register (Register 0x05)
Bit Bit Name R/W Description
7
FL_OVP
R
0 = no fault (default)
1 = overvoltage fault
6 FL_SC R 0 = no fault (default)
1 = short-circuit fault
5 FL_OT R 0 = no fault (default)
1 = overtemperature fault
4 FL_TO R 0 = no fault (default)
1 = timeout fault
3 FL_TX1 R 0 = no TxMASK1 operation mode during last flash (default)
1 = TxMASK1 operational mode occurred during last flash
2
FL_IO2 R
If GPIO2 is configured as TxMASK2
0 = no TxMASK2 operation mode during last flash (default)
1 = TxMASK2 operational mode occurred during last flash
If GPIO2 is configured as ILED
0 = no fault (default)
1 = indicator LED fault
1 FL_IL R 0 = no fault (default)
1 = inductor peak current-limit fault
0 FL_IDC R 0 = programmed dc current limit is not hit (default)
1 = programmed dc current limit is hit
ADP1649 Data Sheet
Rev. 0 | Page 22 of 28
Table 15. Input Control Register (Register 0x06)
Bit Bit Name R/W Description
[7:4] I_TX2 R/W TxMASK2 operational mode foldback current
0000 = 100 mA
0001 = 150 mA
0010 = 200 mA
0011 = 250 mA
0100 = 300 mA
0101 = 350 mA
0110 = 400 mA (default)
0111 = 450 mA
1000 = 500 mA
1001 = 550 mA
1010 = 600 mA
1011 = 650 mA
1100 = 700 mA
1101 = 750 mA
1110 = 800 mA
1111 = 850 mA
[3:0] I_TX1 R/W TxMASK1 operational mode foldback current
0000 = 100 mA
0001 = 150 mA
0010 = 200 mA
0011 = 250 mA
0100 = 300 mA
0101 = 350 mA
0110 = 400 mA (default)
0111 = 450 mA
1000 = 500 mA
1001 = 550 mA
1010 = 600 mA
1011 = 650 mA
1100 = 700 mA
1101 = 750 mA
1110 = 800 mA
1111 = 850 mA
Data Sheet ADP1649
Rev. 0 | Page 23 of 28
Table 16. Additional Mode Register, AD_MOD (Register 0x07)
Bit Bit Name R/W Description
7 DYN_OVP R/W Dynamic overvoltage protection (DOVP)
0 = DOVP off (default)
1 = DOVP on
6 SW_LO R/W Force 1.5 MHz switching frequency
0 = disabled (default)
1 = enabled
5 STR_POL R/W Strobe polarity
0 = active low
1 = active high (default)
[4:3] I_ILED R/W Indicator LED current
00 = 2.75 mA (default)
01 = 5.5 mA
10 = 8.25 mA
11 = 11 mA
[2:1] IL_DC R/W Input dc current limit setting the LED current
00 = 1.5 A
01 = 1.75 A
10 = 2.0 A (default)
11 = reserved
0 IL_DC_EN R/W Input dc current limit
0 = disabled (default)
1 = enabled
Table 17. Additional Mode Register, ADC (Register 0x08)
Bit Bit Name R/W Description
7 Reserved R/W Test mode
0 = disabled (default)
1 = enabled
6
FL_VB_LO R
Programmed VBAT low threshold status; low battery mode must be enabled in Register 0x09
0 = V
DD
is greater than the V
BAT
low threshold (default)
1 = V
DD
is less than the V
BAT
low threshold
[5:2] ADC_VAL R/W ADC readback value; four bits (see Figure 16, Figure 17, and Figure 18)
[1:0] ADC_EN R/W ADC enable mode
00 = disabled (default)
01 = LED V
F
measurement
10 = die temperature measurement
11 = external voltage mode
ADP1649 Data Sheet
Rev. 0 | Page 24 of 28
Table 18. Battery Low Mode Register (Register 0x09)
Bit Bit Name R/W Description
7 CL_SOFT R/W Soft inductor peak current limit
0 = disabled (ADP1649 is disabled when the inductor peak current limit is reached)
1 = enabled (default)
[6:3] I_VB_LO R Current setting for V
BAT
low mode
0000 = 300 mA
0001 = 350 mA
0010 = 400 mA
0011 = 450 mA
0100 = 500 mA
0101 = 550 mA
0110 = 600 mA
0111 = 650 mA
1000 = 700 mA
1001 = 750 mA
1010 = 800 mA (default)
1011 = 850 mA
1100 = 900 mA
1101 = 950 mA
1110 = 1000 mA
1111 = reserved
[2:0]
V_VB_LO
R/W
VDD level where VBAT low function is enabled
000 = disabled (default)
001 = 3.3 V
010 = 3.35 V
011 = 3.4 V
100 = 3.45 V
101 = 3.5 V
110 = 3.55 V
111 = 3.6 V
Data Sheet ADP1649
Rev. 0 | Page 25 of 28
APPLICATIONS INFORMATION
EXTERNAL COMPONENT SELECTION
Selecting the Inductor
The ADP1649 boost converter increases the battery voltage
to allow driving of one LED, whose voltage drop is higher than
the battery voltage plus the current source headroom voltage.
This allows the converter to regulate the LED current over the
entire battery voltage range and with a wide variation of LED
forward voltage.
The inductor saturation current should be greater than the sum
of the dc input current and half of the inductor ripple current. A
reduction in the effective inductance due to saturation increases
the inductor current ripple. Table 19 provides a list of recom-
mended inductors.
Selecting the Input Capacitor
The ADP1649 requires an input bypass capacitor to supply
transient currents while maintaining constant input and output
voltages. The input capacitor carries the input ripple current,
allowing the input power source to supply only the dc current.
Increased input capacitance reduces the amplitude of the switching
frequency ripple on the battery. Due to the dc bias characteris-
tics of ceramic capacitors, the use of a 0603, 6.3 V, X5R/X7R,
10 µF ceramic capacitor is preferable. Higher value input
capacitors help to reduce the input voltage ripple and improve
transient response.
To minimize supply noise, place the input capacitor as close to
the VIN pin of the ADP1649 as possible. A low ESR capacitor is
required. Table 20 provides a list of suggested input capacitors.
Selecting the Output Capacitor
The output capacitor maintains the output voltage and supplies
the LED current during the period when the NFET power
switch is on. The output capacitor also stabilizes the loop. The
recommended output capacitor is a 10 µF, 6.3 V, X5R/X7R
ceramic capacitor with low ESR.
Note that dc bias characterization data is available from capa-
citor manufacturers and should be taken into account when
selecting input and output capacitors. The 6.3 V capacitors are
best for most designs. Table 21 provides a list of recommended
output capacitors.
Higher output capacitor values reduce the output voltage ripple
and improve load transient response. When choosing this value,
it is also important to account for the loss of capacitance caused
by output voltage dc bias.
Ceramic capacitors have a variety of dielectrics, each with different
behavior over temperature and applied voltage. Capacitors must
have a dielectric that ensures the minimum capacitance over the
necessary temperature range and dc bias conditions. X5R or X7R
dielectrics with a voltage rating of 6.3 V or 10 V are recommended
for best performance. Y5V and Z5U dielectrics are not recom-
mended for use with any dc-to-dc converter because of their
poor temperature and dc bias characteristics.
Table 19. Suggested Inductors
Vendor Value (µH) Part No. DCR (mΩ) I
SAT
(A) Dimensions L × W × H (mm)
Coilcraft 1.0 XFL3010 43 2.4 3.0 × 3.0 × 1.0
Murata
1.0
LQM32P_G0
60
3
3.2 × 2.5 × 1.0
Wurth 1.0 744028001 65 1.5 2.8 × 2.8 × 1.1
Taiyo Yuden 1.0 NR 3015T 1R0N 36 2.1 3.0 × 3.0 × 1.5
FDK 1.0 MIP3226D 40 3 2.5 × 2.0 × 1.2
Table 20. Suggested Input Capacitors
Vendor Value Part No. Dimensions L × W × H (mm)
Murata 10 µF, 6.3 V GRM188R60J106ME47 1.6 × 0.8 × 0.8
TDK 10 µF, 6.3 V C1608JB0J106K 1.6 × 0.8 × 0.8
Taiyo Yuden 10 µF, 6.3 V JMK107BJ106MA 1.6 × 0.8 × 0.8
Table 21. Suggested Output Capacitors
Vendor Value Part No. Dimensions L × W × H (mm)
Murata 10 µF, 6.3 V GRM188R60J106ME47 1.6 × 0.8 × 0.8
TDK 10 µF, 6.3 V C1608JB0J106K 1.6 × 0.8 × 0.8
Taiyo Yuden 10 µF, 6.3 V JMK107BJ106MA 1.6 × 0.8 × 0.8
ADP1649 Data Sheet
Rev. 0 | Page 26 of 28
The worst-case capacitance accounting for capacitor variation
over temperature, component tolerance, and voltage is calcu-
lated using the following equation:
CEFF = COUT × (1 − TEMPCO) × (1 − TOL)
where:
CEFF is the effective capacitance at the operating voltage.
TEMPCO is the worst-case capacitor temperature coefficient.
TOL is the worst-case component tolerance.
In this example, the 10 μF X5R capacitor has the following
characteristics:
• TEMPCO from −40°C to +85°C is 15%.
• TOL is 10%.
• COUT at VOUT (max) = 5 V, is 3 μF, as shown in Figure 41.
Figure 41. DC Bias Characteristic of a 6.3 V, 10 μF Ceramic Capacitor
Substituting these values in the equation yields
CEFF = 3 μF × (1 − 0.15) × (1 − 0.1) = 2.3 μF
The effective capacitance needed for stability, which includes
temperature and dc bias effects, is 3.0 μF.
10
0
–10
–20
–30
–40
–50
–60
–70
–80
–90 6.305.043.782.52
DC BIAS V OLTAGE (V)
CAPACITANCE CHANGE (%)
1.260
10779-041
Data Sheet ADP1649
Rev. 0 | Page 27 of 28
PCB LAYOUT
Poor layout can affect performance, causing electromagnetic
interference (EMI) and electromagnetic compatibility (EMC)
problems, ground bounce, and power losses. Poor layout can
also affect regulation and stability. Figure 42 shows an optimized
layout implemented using the following guidelines:
• Place the inductor, input capacitor, and output capacitor
close to the IC using short tracks. These components carry
high switching frequencies and large currents.
• Route the trace from the inductor to the SW pin, providing
as wide a trace as possible. The easiest path is through the
center of the output capacitor.
• Route the LED_OUT path away from the inductor and the
SW node to minimize noise and magnetic interference.
• Maximize the size of ground metal on the component side
to help with thermal dissipation.
• Use a ground plane with two to three vias connected to the
component side ground near the output capacitor to
reduce noise interference on sensitive circuit nodes.
Analog Devices applications engineers can be contacted
through the Analog Devices sales team to discuss different
layouts based on system design constraints.
Figure 42. Layout of the ADP1649 Driving a High Power White LED (WLCSP)
DIGITAL
INPUT/
OUTPUT
Li-ION +
Li-ION +
PGND
C1
L1
INDUCTOR
LED
ANODE
C2
AREA = 16. 4mm2
10779-042
ADP1649 Data Sheet
Rev. 0 | Page 28 of 28
PACKAGING AND ORDERING INFORMATION
OUTLINE DIMENSIONS
Figure 43. 12-Ball Wafer Level Chip Scale Package [WLCSP]
(CB-12-4)
Dimensions shown in millimeters
ORDERING GUIDE
Model1
Temperature Range
Package Description
Package Option2
ADP1649ACBZ-R7
−40°C to +125°C
12-Ball Wafer Level Chip Scale Package [WLCSP]
CB-12-4
ADP1649CB-EVALZ Evaluation Board WLCSP Package
1 Z = RoHS Compliant Part.
2 This package option is halide free.
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
020409-B
A
B
C
D
0.660
0.602
0.544
1.54
1.50
1.46
2.04
2.00
1.96
1
2
3
BOTTOM VIEW
(BALL SIDEUP)
TOP VIEW
(BALL SIDE DOWN)
0.330
0.310
0.290
1.50
REF
SEATING
PLANE
1.00
REF
0.50
REF
0.380
0.352
0.324 0.280
0.250
0.220
0.04 MAX
COPLANARITY
0.022
REF
BALL A1
IDENTIFIER
©2012 Analog Devices, Inc. All rights reserved. Trademarks and
registered
trademarks are the property of their
respective owners.
D10779-0-7/12(0)
www.analog.com/ADP1649
