ADP1660CB-EVALZ - Analog Devices

Dual 750 mA LED Flash Driver

with I2C-Compatible Interface

Data Sheet ADP1660

Rev. 0 Document Feedback

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FEATURES

Ultracompact solution

Small, 2 mm × 1.7 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 LEDs

Improved LED thermal dissipation

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 up to 750 mA in flash mode per LED

with ±7% accuracy for currents above 100 mA

Torch mode

Programmable dc battery current limit

Programmable flash timer up to 1600 ms

Low battery mode to reduce LED current automatically

Device control

I2C-compatible control registers

External STROBE and torch input pins

Transmitter mask (TxMASK) input

Safety features

Thermal overload protection

Inductor fault detection

LED short-circuit/open-circuit protection

APPLICATIONS

Camera-enabled cellular phones and smartphones

Digital still cameras, camcorders, and PDAs

FUNCTIONAL BLOCK DIAGRAM

ADP1660

10µF

1.0µH

INPUT VOLTAGE = 2.7V TO 5.0

VOUT

PGND

STROBE

10µF

LED1

LED2

EN SGND

SCL

SDA

TORCH/

TxMASK GPIO

UP TO

750mA

UP TO

750mA

VIN

11018-001

Figure 1.

LED2

DIGITAL

INPUT/

OUTPUT

Li-ION+

PGND

INDUCTOR

LED1

AREA = 16.4mm

11018-002

Figure 2. PCB Layout

GENERAL DESCRIPTION

The ADP1660 is a very compact, highly efficient, dual 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 3.0 MHz synchronous

inductive boost converter, an I2C-compatible interface, and two

750 mA current sources. The high switching frequency enables

the use of a tiny, 1 mm high, low cost, 1 μH power inductor, and

the parallel current sources permit 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 minimize battery current draw during flash events.

A programmable dc battery current limit safely maximizes

LED current for all LED forward voltage and battery voltage

conditions.

A TxMASK input enables fast reduction of the flash LED

currents and battery current during a power amplifier current

burst. The I2C-compatible interface can be used to program

timers and currents and to read back status bits for operation

monitoring and safety control.

The ADP1660 comes 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.

ADP1660 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 ............................................................................. 4

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 ...................................................................... 10

White LED Driver ...................................................................... 10

Modes of Operation ................................................................... 10

Assist Light Mode ....................................................................... 11

Flash Mode .................................................................................. 11

Assist to Flash Mode .................................................................. 12

Torch Mode ................................................................................. 12

Torch to Flash Mode .................................................................. 12

TxMASK Operation ................................................................... 12

Independent Trigger Modes ...................................................... 13

Fixed 5 V Output Mode ............................................................. 13

Frequency Foldback ................................................................... 13

Low Battery LED Current Foldback ........................................ 13

Battery Input DC Current Limit .............................................. 14

Fixed 5 V Output Mode with Torch ........................................ 15

Safety Features ................................................................................. 16

Short-Circuit Fault ..................................................................... 16

Overvoltage Fault ....................................................................... 16

Dynamic Overvoltage Protection Mode ................................. 16

Timeout Fault .............................................................................. 16

Overtemperature Fault .............................................................. 16

Current Limit .............................................................................. 16

Input Undervoltage .................................................................... 16

Soft Start ...................................................................................... 16

Reset Using the Enable (EN) Pin ............................................. 16

Clearing Faults ............................................................................ 16

I2C Interface .................................................................................... 17

Applications Information .............................................................. 24

External Component Selection ................................................ 24

PCB Layout ...................................................................................... 25

Outline Dimensions ....................................................................... 26

Ordering Guide .......................................................................... 26

REVISION HISTORY

10/12—Revision 0: Initial Version

Data Sheet ADP1660

Rev. 0 | Page 3 of 28

SPECIFICATIONS

VIN1 = 3 . 6 V, T J = −40°C to +125°C for minimum/maximum specifications, and TA = 25°C for typical specifications, unless otherwise noted.

Table 1.

Parameter2 Test Conditions/Comments Min Typ Max Unit

SUPPLY

Input Voltage Range 2.7 5.0 V

Undervoltage Lockout Threshold VIN falling 2.3 2.4 2.5 V

Undervoltage Lockout Hysteresis 50 100 150 mV

Shutdown Current, EN = 0 V TJ = −40°C to +85°C, current into VIN pin,

VIN = 2.7 V to 4.5 V

0.2 1 µA

Standby Current, 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, ILED = 100 mA 5.3 mA

SW Switch Leakage Current TJ = −40°C to +85°C, VSW3 = 5 V 2 µA

TJ = 25°C, VSW3 = 5 V 0.5 µA

LED DRIVER

LED Current

Assist Light, Torch Mode Current Assist light value setting = 0 (0 0000 binary) 0 mA

Assist light value setting = 16 (1 0000 binary) 200 mA

Flash Mode Current

Flash value setting = 0 (00 0000 binary)

Flash value setting = 60 (11 1100 binary) 750 mA

LED Current Error per Channel ILED = 200 mA to 750 mA −5 ±1 +5 %

ILED = 100 mA to 187.5 mA −7 ±1 +7 %

ILED = 50 mA to 87.5 mA ±3 %

LED

= 25 mA to 37.5 mA

±6

ILED = 12.5 mA ±10 %

LED Channel Mismatch ILED = 275 mA to 750 mA 0.5 3 %

ILED = 137.5 mA to 262.5 mA 1 4 %

ILED = 25 mA to 125 mA 2 %

ILED = 12.5 mA 4 %

LED Current Source Headroom

Flash mode, I

LED

= 750 mA

290

Torch mode, ILED = 200 mA 190 mV

LED1/LED2 Ramp-Up Time 0.6 ms

LED1/LED2 Ramp-Down Time 0.1 ms

SWITCHING REGULATOR

Switching Frequency Switching frequency = 3 MHz 2.8 3.0 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

N-FET Resistance 60 mΩ

P-FET Resistance 50 mΩ

Voltage Output Mode

VOUT Voltage 4.575 5 5.425 V

Output Current 500 mA

Line Regulation

LOAD

at VOUT pin = 300 mA

0.3

%/V

Load Regulation −0.7 %/A

Pass-Through Mode Transition

Flash Mode

VIN to LED1/LED2, Entry ILED1 = ILED2 = 750 mA 580 mV

VIN to LED1/LED2, Exit ILED1 = ILED2 = 750 mA 435 mV

Torch Mode

VIN to LED1/LED2, Entry ILED = 200 mA 380 mV

VIN to LED1/LED2, Exit ILED = 200 mA 285 mV

ADP1660 Data Sheet

Rev. 0 | Page 4 of 28

Parameter2 Test Conditions/Comments Min Typ Max Unit

DIGITAL INPUTS/GPIO PIN

Input Logic Low Voltage 0.54 V

Input Logic High Voltage 1.26 V

GPIO, STROBE Pull-Down Resistance 390 kΩ

Torch Glitch Filtering Delay4

From GPIO (torch) rising edge to device start

7.4

8.0

8.6

SAFETY FEATURES

Maximum Timeout for Flash 1600 ms

Timer Accuracy

−7.0

+7.0

DC Current Limit5 DC current value setting = 0 (000 binary) 0.9 1.0 1.1 A

DC current value setting = 1 (001 binary) 1.1 1.25 1.4 A

DC current value setting = 2 (010 binary) 1.35 1.5 1.65 A

DC current value setting = 3 (011 binary) 1.55 1.75 1.95 A

DC current value setting = 4 (100 binary) 1.8 2.0 2.2 A

DC current value setting = 5 (101 binary)

2.0

2.25

2.5

DC current value setting = 6 (110 binary) 2.25 2.5 2.75 A

DC current value setting = 7 (111 binary) 2.45 2.75 3.1 A

Low Battery Mode Transition Voltage

Error 3.2 %

Hysteresis

Coil Peak Current Limit6 Peak current value setting = 0 (00 binary) 2.02 2.25 2.5 A

Peak current value setting = 1 (01 binary) 2.47 2.75 3.0 A

Peak current value setting = 2 (10 binary) 2.9 3.25 3.5 A

Peak current value setting = 3 (11 binary) 3.15 3.5 3.85 A

Overvoltage Detection Threshold 5.15 5.5 5.9 V

LED1/LED2 Short-Circuit Detection

Comparator Reference Voltage

1.0

1.3

Thermal Shutdown Threshold

TJ Rising 150 °C

TJ 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.

4 Guaranteed by design. Torch glitch filtering depends directly on internal oscillator tolerances.

5 All dc current limit values are guaranteed by design except for the 1.25 A setting, which is tested in production.

6 All coil peak current limit values are guaranteed by design except for the 2.25 A setting, which is tested in production.

RECOMMENDED SPECIFICATIONS: INPUT AND OUTPUT CAPACITANCE AND INDUCTANCE

Table 2.

Parameter Symbol Test Conditions/Comments Min Typ Max Unit

CAPACITANCE CMIN TA = −40°C to +125°C

Input 4.0 10 µF

Output 3.0 10 20 µF

MINIMUM AND MAXIMUM INDUCTANCE L TA = −40°C to +125°C 0.6 1.0 1.5 µH

Data Sheet ADP1660

Rev. 0 | Page 5 of 28

I2C-COMPATIBLE INTERFACE TIMING SPECIFICATIONS

Table 3.

Parameter1 Min Max Unit Description

fSCL 1000 kHz SCL clock frequency

tHIGH 0.26 μs SCL high time

tLOW 0.5 μs SCL low time

tSU, DAT 50 ns Data setup time

tHD, DAT 0 0.9 μs Data hold time

tSU, STA 0.26 μs Setup time for repeated start

tHD, STA 0.26 μs Hold time for start/repeated start

tBUF 0.5 μs Bus free time between a stop and a start condition

tSU, STO 0.26 μs Setup time for stop condition

tR 20 + 0.1 CB2 120 ns Rise time of SCL and SDA

tF 20 + 0.1 CB2 120 ns Fall time of SCL and SDA

tSP 0 50 ns Pulse width of suppressed spike

CB2 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

SCL

S = S TART CONDI TI ON

Sr = REPEATED START CONDITIO N

P = S TO P CONDITI ON

Sr P S

tLOW tR

tHD, DAT tHIGH

tSU, DAT tFtF

tSU, STA

tHD, STA tSP

tSU, STO

tBUF

11018-003

Figure 3. I2C-Compatible Interface Timing Diagram

ADP1660 Data Sheet

Rev. 0 | Page 6 of 28

ABSOLUTE MAXIMUM RATINGS

Table 4.

Parameter Rating

VIN, SDA, SCL, EN, GPIO, STROBE,

LED1, LED2, SW, VOUT to PGND

−0.3 V to +6 V

PGND to SGND −0.3 V to +0.3 V

Ambient Temperature Range (TA) −40°C to +85°C

Junction Temperature Range (TJ) −40°C to +125°C

Storage Temperature JEDEC J-STD-020

ESD

Human Body Model

±1000 V

Charged Device Model ±500 V

Machine Model ±150 V

Stresses above 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.

THERMAL DATA

The ADP1660 may be damaged if the junction temperature

(TJ) limits are exceeded. Monitoring ambient temperature (TA)

does not guarantee that TJ is within the specified temperature

limits. In applications with high power dissipation and poor PCB

thermal resistance, the maximum TA may need to be derated.

In applications with moderate power dissipation and low PCB

thermal resistance, the maximum TA can exceed the maximum

limit as long as TJ is within the specification limits.

The junction temperature (TJ) of the device is dependent on

the ambient temperature (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

The junction-to-ambient 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 dissipation exists,

close 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 inch × 3 inch, 2½ oz copper board, per JEDEC

standards. For more information, see the AN-617 Application

Note, Wafer Level Chip Scale Package.

In Table 5, θJA is specified for a device mounted on a JEDEC

2S2P PCB.

Table 5. Thermal Resistance

Package Type θJA Unit

12-Ball WLCSP

°C/W

ESD CAUTION

Data Sheet ADP1660

Rev. 0 | Page 7 of 28

PIN CONFIGURATION AND FUNCTION DESCRIPTIONS

TOP VI EW

(BAL L SI DE DOW N)

Not t o Scal e

PGND SGND VIN

SW GPIO EN

VOUT STROBE SDA

LED1 LED2 SCL

2 3

BALLA1

INDICATOR

11018-004

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 very close to this pin.

B1 SW Boost Switch. Connect the power inductor between SW and the input capacitor.

B2 GPIO This pin enables the part to function in torch mode or functions as a TxMASK input, depending on the value set

using Bits[5:4] in Register 0x02 (see Table 14). When this pin is configured as a TxMASK input, the flash current is

reduced to the TxMASK current programmed in Register 0x07 (for LED1) and Register 0x0A (for LED2).

B3 EN Enable. Set EN low to bring the quiescent current (IQ) to <1 µA. Registers are set to their default values when EN

is brought from low to high.

C1 VOUT Boost Output. Connect an output bypass capacitor very close to this pin. This pin is the output for the 5 V

external voltage mode.

C2 STROBE Strobe Signal Input. This pin synchronizes the flash pulse to the image capture. In most cases, this signal comes

directly from the image sensor.

C3 SDA I2C Data Signal.

D1 LED1 Current Source for LED1. Connect this pin to the anode of flash LED1.

D2 LED2 Current Source for LED2. Connect this pin to the anode of flash LED2.

D3 SCL I2C Clock Signal.

ADP1660 Data Sheet

Rev. 0 | Page 8 of 28

TYPICAL PERFORMANCE CHARACTERISTICS

ILED = LED current, VLED = LED output voltage, IBAT = battery current.

CH1 5.00V CH2 1.00A

CH4 2.00VCH3 500mAM800µs

T200µs

LED1

STROBE

INDUCTOR CURRE NT

11018-005

Figure 5. Startup, Flash Mode, VIN = 3.6 V, ILED1 = ILED2 = 750 mA

CH1 5.00V CH2 100mA

CH4 2.00VCH3 100mAM8.00ms

T2.00ms

LED1

LED2

GPIO (TORCH)

11018-006

Figure 6. Startup, Torch Mode, VIN = 3.6 V, ILED1 = ILED2 = 150 mA

CH1 5.00V CH2 1.00A

CH4 5.00VCH3 500mAM400µs

T100µs

LED1

STROBE

INDUCTOR CURRE NT

11018-007

Figure 7. Torch Current to 750 mA Flash Transition, ILED1 = ILED2 = 50 mA

CH1 2.00V CH2 100mA

CH3 50.0mAM800µs

T100µs

LED1

INDUCTOR CURRE NT

11018-008

Figure 8. Switching Waveforms, Flash Mode, ILED1 = ILED2 = 750 mA

CH1 1.00V CH2 200mA

CH4 100mACH3 1.00V M20.0µs

T0.00000s

LED1

11018-009

LED1

INDUCTOR CURRE NT

A CH2 196mA

Figure 9. Pass-Through to Boost Mode Transition, Single LED, ILED1 = 50 mA

CH1 5.00V CH2 1.00A

CH4 500mVCH3 200mAM20µs

T10µs

LED1

BAT

GPIO (T xMASK)

11018-010

Figure 10. Entry into TxMASK Mode, ILED1 = ILED2 = 750 mA to 250 mA

Data Sheet ADP1660

Rev. 0 | Page 9 of 28

100

0.01 0.1 1

EFFICIENCY (%)

OUTPUT CURRE NT (A)

VIN = 2.7V

VIN = 3.0V

VIN = 3.6V

VIN = 4.2V

11018-100

Figure 11. Efficiency vs. Output Current, Fixed 5 V Output Mode

–3

–2

–1

–40 –20 020 40 60 80 100 120

LE D CURRE NT ERRO R ( %)

TEMPERATURE ( º C)

100mA PER CHANNEL

200mA PER CHANNEL

500mA PER CHANNEL

750mA PER CHANNEL

11018-102

Figure 12. LED Current Error vs. Temperature

100

100 300 500 700 900 1100 1300 1500

EFFICIENCY (%)

OUTPUT CURRE NT (mA)

= 3.6V

= 2.7V

11018-104

Figure 13. Efficiency (PLED/PIN) vs. LED Output Current

–40 –20 020 40 60 80 100 120

STANDBY CURRENT (µA)

TEMPERATURE ( º C)

= 4.5V

= 2.7V

11018-101

Figure 14. Standby Current vs. Temperature

–0.5

0.5

1.0

1.5

2.0

2.5

3.0

–40 –20 020 40 60 80 100 120

LE D MAT CHING ( %)

TEMPERATURE ( º C)

100mA PER CHANNEL

200mA PER CHANNEL

500mA PER CHANNEL

750mA PER CHANNEL

11018-103

Figure 15. LED Matching vs. Temperature

ADP1660 Data Sheet

Rev. 0 | Page 10 of 28

THEORY OF OPERATION

The ADP1660 is a high power, I2C programmable, dual white

LED driver ideal for driving white LEDs for use as a camera

flash. The ADP1660 includes a boost converter and two current

regulators suitable for powering two high power white LEDs.

WHITE LED DRIVER

The ADP1660 drives a synchronous 3 MHz boost converter as

required to power the high power LEDs.

• If the sum of the LED forward voltage plus the current

source headroom voltage is higher than the battery voltage,

the boost converter is turned on.

• If the battery voltage is higher than the sum of the LED

forward voltage plus 2× the current source headroom

voltage, the boost converter is disabled and the part

operates in pass-through mode.

The ADP1660 uses an integrated P-FET high-side current

regulator for accurate brightness control.

The ADP1660 supports the setting of different currents for each

LED, although this configuration is not recommended. Any mis-

match in the forward voltage of the two LEDs translates directly

to lower efficiency, as well as lower accuracy of the current for the

lower voltage LED. It is recommended that the voltages on the two

LEDs be kept within 1 V of one another during operation. The

user can disable one LED and use the other LED only, if desired.

MODES OF OPERATION

When the enable pin is high, the I2C-compatible interface can

be used to set the ADP1660 to one of seven modes of operation.

These modes are configured using the LED_MOD bits (Bits[2:0])

in Register 0x01 (see Table 7).

Table 7. Modes of Operation Set by the LED_MOD Bits

LED_MOD Bits Operating Mode

000 Standby mode, consuming 3 µA typical

(default)

001 Fixed 5 V output mode

010 Assist light mode with continuous LED current

011 Flash mode with LED currents up to 750 mA

available for up to 1.6 sec

100

Independent trigger mode with timeout

enabled (LED outputs are disabled if they are

on longer than the timer value configured by

the FL_TIM bits)

101 Independent trigger mode with timeout

disabled (FL_TIM value is ignored)

110

Fixed 5 V output mode with torch mode (total

output current must be below 500 mA)

111 Reserved

PWM

CONTROLLER

PGND

VOUT

PGNDSGND

VIN

UVLO

OVP

FAULT

IC THERMAL

SENSING

HP LED

SHORT

HP LED

DRIVER

CURRENT

SENSE

CURRENT

SENSE

SCL

STROBE

PGND

PGNDAGND

OUT

10µF

1µF

INP UT VOLTAGE =

2.7V TO 5.0V

10µF

GPIO

SDA

TORCH

5.5V

CURRENT

SENSE

HP LED

DRIVER

HIGH POWER LED

CURRENT CONTROL

LED2

UP T O

750mA

PGND

UP T O

750mA

INTERFACE

AND

CONTROL

TORCH TxMASK

IO_CFG

2.4V

11018-011

LED1

Figure 16. Detailed Block Diagram

Data Sheet ADP1660

Rev. 0 | Page 11 of 28

ASSIST LIGHT MODE

Assist light mode provides continuous LED current that is

programmable from 0 mA to 200 mA. Set the assist light

current using the I_TOR1 bits in Register 0x08 (for LED1)

and the I_TOR2 bits in Register 0x0B (for LED2).

To enable assist light mode, set the LED_MOD bits to 010

in Register 0x01, and set the LED1_EN and/or LED2_EN

bits to 1 in Register 0x0F. To disable assist light mode, set the

LED_MOD bits to 000 (standby mode), or set the LED1_EN

and LED2_EN bits to 0.

LE D2 CURRE NT

REG 0x08, I_TO R1 = X X X X X mA

REG 0x0B, I_TO R2 = X X X X X mA

REG 0x01, LE D_M OD = 010

REG 0x0F, LED1_E N = 1

LE D2_E N = 1

C DATA BUS

REG 0x0F, LED1_E N = 0

I_TOR2

LE D1 CURRE NT

I_TOR1

REG 0x0F, LED2_E N = 0

11018-012

Figure 17. Enabling Assist Light Mode

FLASH MODE

Flash mode provides up to 750 mA per LED for a program-

mable time of up to 1.6 seconds. Set the flash current using

the I_FL1 bits in Register 0x06 (for LED1) and the I_FL2 bits

in Register 0x09 (for LED2). Set the maximum flash duration

using the FL_TIM bits (Bits[3:0]) in Register 0x02.

To enable flash mode, set the LED_MOD bits to 011 in

to 1 in Register 0x0F. If the LED1_EN or LED2_EN bit is set

to 0, the corresponding LED will not output current during

the flash, regardless of the flash current level setting.

To enable flash mode without using the STROBE pin, set the

STR_MOD bit to 0 in Register 0x01 (software strobe mode).

When the STR_MOD bit is set to 1 (hardware strobe mode),

setting the STROBE pin high enables flash and synchronizes

it to the image sensor. Hardware strobe mode has two timeout

modes: level sensitive and edge sensitive.

Level-Sensitive STROBE Mode

In level-sensitive mode, the duration of STROBE high sets the

duration of the flash up to the maximum time set by the FL_TIM

timeout bits in Register 0x02 (see Figure 18). If STROBE is kept

high longer than the duration set by the FL_TIM bits, a timeout

fault disables the flash. The timeout fault flag (Bit 4) is set in the

fault information register (Register 0x0C).

LE D2 CURRE NT

REG 0x0F, LED1_E N = 1

LE D2_E N = 1

REG 0x01, ST R_M OD = 1

ST R_LV = 1

LE D_M OD = 011

C DATA BUS

I_FL2

STROBE

REG 0x02, FL_T IM = X X X X ms

REG 0x06, I_FL 1 = X X X X X X mA

REG 0x09, I_FL 2 = X X X X X X mA

ADP1660 SE TS L E D1_E N TO 0.

ADP1660 SE TS L E D2_E N TO 0.

ADP1660 SE TS L E D_M OD T O 000.

LE D1 CURRE NT

I_FL1

11018-013

Figure 18. Flash Operation: Level-Sensitive Mode

Edge-Sensitive STROBE Mode

In edge-sensitive mode, a rising edge on the STROBE pin

enables the flash, and the FL_TIM bits set the flash duration

(see Figure 19).

LE D2 CURRE NT

REG 0x0F, LED1_E N = 1

LE D2_E N = 1

I_FL2

STROBE

REG 0x02, FL_T IM = X X X X ms

REG 0x06, I_FL 1 = X X X X X X mA

REG 0x09, I_FL 2 = X X X X X X mA

LE D1 CURRE NT

I_FL1

FL_TIM

C DATA BUS

ADP1660 SE TS L E D1_E N TO 0.

ADP1660 SE TS L E D2_E N TO 0.

ADP1660 SE TS L E D_M OD T O 000.

11018-014

REG 0x01, ST R_M OD = 1

ST R_LV = 0

LE D_M OD = 011

Figure 19. Flash Operation: Edge-Sensitive Mode

ADP1660 Data Sheet

Rev. 0 | Page 12 of 28

ASSIST TO FLASH MODE

The STR_POL bit in Register 0x01 can be used to change the

default polarity of the STROBE pin from active high to active low.

Additional image sensor-specific assist to flash enable modes are

included in the device. Information about these modes is avail-

able on request from the Analog Devices, Inc., sales team.

LED2 CURRE NT

STROBE

I_TOR2

REG 0x0F, LED1_E N = 1

LED2_E N = 1

REG 0x01, STR_L V = 1

LED_M OD = 010

I_FL1

LED1 CURRE NT

I_TOR1

I_FL2

REG 0x02, F L_T IM = X X X X ms

REG 0x06, I _FL 1 = X X X X X X mA

REG 0x08, I _TO R1 = X X X X X mA

REG 0x09, I _FL 2 = X X X X X X mA

REG 0x0B, I _TO R2 = X X X X X mA

C DATA BUS

ADP1660 SETS LED1_E N TO 0.

ADP1660 SETS LED2_E N TO 0.

ADP1660 SETS LED_M OD TO 000.

11018-015

Figure 20. Enabling Assist to Flash (Level-Sensitive) Mode

TORCH MODE

Set the assist/torch light current using the I_TORx bits. To enable

torch mode, set the LED_MOD bits to 000 (standby mode), and set

the LED1_EN and LED2_EN bits to 1 in Register 0x0F; then bring

GPIO high. Disable the LED current by bringing GPIO low or by

setting the LED1_EN and LED2_EN bits to 0. Bringing GPIO low

during torch mode automatically sets LED1_EN and LED2_EN =

0. To reenable torch mode, set LED1_EN and LED2_EN = 1 and

bring GPIO high again.

LED2 CURRE NT

C DATA BUS

GPIO (TORCH)

I_TOR2

LED1 CURRE NT

I_TOR1

REG 0x08, I _TO R1 = X X X X X mA

REG 0x0B, I _TO R2 = X X X X X mA

REG 0x0F, LED1_E N = 1

LED_M OD = 000

LED2_E N = 1

ADP1660 SETS LED1_E N TO 0.

ADP1660 SETS LED2_E N TO 0.

11018-016

Figure 21. Enabling External Torch Mode Using the GPIO Pin

TORCH TO FLASH MODE

The driver can move directly from external torch mode (using

the GPIO pin) to flash mode by bringing the STROBE pin high

before GPIO is brought low. Bringing the GPIO (torch) pin low

before STROBE goes high prevents the flash from firing.

The ADP1660 returns to standby mode after a successful flash

and sets the LED1_EN and LED2_EN bits to 0 in Register 0x0F.

LE D2 CURRE NT

STROBE

GPIO (TORCH)

I_TOR2

REG 0x0F, LED1_E N = 1

LE D2_E N = 1

REG 0x01, ST R_LV = 1

LE D_M OD = 000

I_FL1

LE D1 CURRE NT

I_TOR1

I_FL2

REG 0x02, IO_CF G = 01

FL_TI M = XXXXms

REG 0x06, I _FL 1 = X X X X X X mA

REG 0x08, I_TO R1 = X X X X X mA

REG 0x09, I_FL 2 = X X X X X X mA

REG 0x0B, I_TO R2 = X X X X X mA

C DATA BUS

ADP1660 SE TS L E D1_E N TO 0.

ADP1660 SE TS L E D2_E N TO 0.

11018-017

Figure 22. Enabling Flash Mode from External Torch Mode

TxMASK OPERATION

When the ADP1660 is in flash mode, the TxMASK function can

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 is reduced to the programmed TxMASK current

level in less than 21 µs. The TxMASK current level is programmed

in Register 0x07 (for LED1) and in Register 0x0A (for LED2).

GPIO (T xMASK)

FL_TX = 1

LED2 CURRE NT

STROBE

I_TX2

REG 0x0F, LED1_E N = 1

LED2_E N = 1

REG 0x01, STR_L V = 1

LED_M OD = 011

I_FL1

LED1 CURRE NT

I_TX1

I_FL2

REG 0x02, I O_CF G = 10

FL_TIM = XXXXms

REG 0x06, I _FL 1 = X X X X X X mA

REG 0x08, I _TO R1 = X X X X X mA

REG 0x09, I _FL 2 = X X X X X X mA

REG 0x0B, I _TO R2 = X X X X X mA

C DATA BUS

ADP1660 SETS LED1_E N TO 0.

ADP1660 SETS LED2_E N TO 0.

ADP1660 SETS LED_M OD TO 000.

11018-018

Figure 23. TxMASK Operation During Flash (Level-Sensitive) Mode

After a TxMASK event occurs, a flag is set in the fault informa-

tion register (Register 0x0C, Bit 3). When the TxMASK signal

goes low again, the LED current reverts to the full flash level in

a controlled manner to avoid overshoots on the battery current.

Data Sheet ADP1660

Rev. 0 | Page 13 of 28

INDEPENDENT TRIGGER MODES

When the LED_MOD bits are set to 100 or 101, the ADP1660

allows for independent triggering of each LED at a current level

between the configured flash currents and TxMASK currents.

In independent trigger mode, the STROBE pin controls LED1,

and the GPIO pin controls LED2 (see Figure 24).

• When the STROBE or GPIO pin goes high, the current

produced at the LED1 or LED2 pin is at the level specified

by the I_FL1 bits (Register 0x06) or the I_FL2 bits

(Register 0x09), respectively.

• When the STROBE or GPIO pin goes low, the current

produced at the LED1 or LED2 pin is at the level specified

by the I_TX1 bits (Register 0x07) or the I_TX2 bits

(Register 0x0A), respectively.

LE D1 CURRE NT

I_TX1

I_FL1

STROBE

LE D2 CURRE NT

I_TX2

I_FL2

GPIO

11018-019

Figure 24. Independent Trigger Mode

When the LED_MOD bits are set to 100, the flash timer is used.

If both LEDs are on for a combined time that is equal to the value

specified by the FL_TIM bits (both outputs OR’ed), the ADP1660

sets both LED_ENx bits to 0 and sets LED_MOD to 000.

The independent trigger modes (LED_MOD bits set to 100 or

101) present a possible overtemperature risk; careful evaluation

of their implementation must be performed. Before enabling either

independent trigger mode, contact your local Analog Devices

Field Applications Engineer for assistance.

FIXED 5 V OUTPUT MODE

When the LED_MOD bits are set to 001, the ADP1660 allows

VOUT to be regulated to 5 V. In this mode, the total output current

must be kept below 500 mA. Enabling one or both LEDs allows

low levels of current to the LEDs.

In fixed 5 V output mode, the VOUT pin is connected to the SW

node when the ADP1660 is not enabled. Do not connect VOUT

directly to a positive external voltage source; doing so causes

current to flow from VOUT to the battery. Changing the mode

to standby (LED_MOD = 000) ends voltage regulation; VOUT

returns to a value that is approximately the same as VIN.

FREQUENCY FOLDBACK

The optional frequency foldback feature optimizes efficiency

by reducing the switching frequency to 1.5 MHz when the value

of VIN is slightly less than the value of VOUT. To enable frequency

foldback, set the FREQ_FB bit to 1 in Register 0x03.

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 other devices on the battery. The ADP1660

includes an optional low battery detection feature, which reduces

the flash current to a value from 0 mA to 750 mA when the battery

voltage falls below a programmable level. The low battery current

level can be set from 0 mA to 750 mA using the I_VB_LO bits

(Bits[5:0]) in Register 0x05.

To enable low battery detection and to specify the voltage at

which this detection becomes active, set the V_VB_LO bits

(Bits[2:0]) in Register 0x04 (see Tabl e 8).

Table 8. VDD Level for Low Battery Detection

V_VB_LO Bit Value VDD Level for Low Battery Detection (V)

000 Low battery detection disabled (default)

001 3.3

010 3.35

011 3.4

100 3.45

101 3.5

110 3.55

111 3.6

If a low battery fault is detected within a programmed window of

detection, the lower current is latched for the remainder of the

flash. The window size is specified by the V_BATT_WINDOW

bits (Bits[4:3]) in Register 0x04 (see Table 9).

Table 9. Low Battery Detection Window Size

V_BATT_WINDOW

Bit Value Window Size (ms)

00 Window disabled; low battery detection

is enabled for the entire flash period

01 1

10 2

11 5 (default)

By reducing the window size to the beginning of the flash only,

the user can reduce the chance of partial exposure of the picture

in the case that the image sensor is using a rolling scan. If a global

scan is used, it is recommended that the low battery detection

window be disabled, thereby providing low voltage protection

throughout the flash time.

ADP1660 Data Sheet

Rev. 0 | Page 14 of 28

BATTERY INPUT DC CURRENT LIMIT

The ADP1660 has an optional programmable input dc current

limit that limits the maximum battery current used over all con-

ditions. This feature allows higher LED currents to be used in a

system with significant variation in LED forward voltage (VF) and

supply battery voltage without the risk of exceeding the current

allocated to the flash. To enable the input dc current limit, set

the IL_DC_EN bit (Bit 0) in Register 0x03. To set the input dc

current limit, use the IL_DC bits (Bits[3:1]) in Register 0x03

(see Table 10).

Table 10. Input DC Current Limit

IL_DC Bit Value DC Current Limit (A)

000 1.0

001 1.25

010 1.5

011 1.75

100 2.0 (default)

101 2.25

110 2.5

111 2.75

During startup of the flash, if the battery current does not

exceed the dc current limit, the LED1 and LED2 currents are

set to the values of the I_FL1 and I_FL2 bits in Register 0x06

and Register 0x09, respectively.

If the battery current exceeds 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 (Bit 0

of Register 0x0C). The FL_I_FL1 bits in Register 0x0D and the

FL_I_FL2 bits in Register 0x0E are set to the actual LED current

values and are available for readback.

REG 0x02, FL _T I M = XXXX ms

REG 0x06, I _F L1 = XX XXXXmA

REG 0x09, I _F L2 = XX XXXXmA

REG 0x03, IL _DC_EN = 1

IL_DC = XX A

C DATA BU S

STROBE

PROGRAMME D L ED CURRENT

ACTUAL LED CURRENT

ADP1660 SETS FL _IDC (RE G 0x0C) T O 1.

ADP1660 SETS FL _I_FL1 (RE G 0x0D)

TO ACT U AL L E D CUR RE N T.

ADP1660 SETS LED1_E N TO 0.

ADP1660 SETS LED2_E N TO 0.

ADP1660 SETS L ED_MO D T O 000.

REG 0x0F, L E D1_E N = 1

LED2_EN = 1

REG 0x01, STR_LV = 1

LE D_M OD = 011

ADP1660 SETS FL_I_FL2 (RE G 0x0E)

TO ACT U AL L E D CUR RE N T.

11018-020

Figure 25. DC Current Limit Operation in a Low Battery, High LED VF Case

The camera system shown in Figure 26 can adjust the image

sensor settings based on the known reduced LED current for

a low battery and a high VF LED.

SELECT F LASH CURR E NT

SELECT MAX BA TT E RY CURR ENT

PREFLASH STROBE

DC LIMIT

EXCEEDED?

LE D CURREN T =

PROGRAMMED LED

CURRENT

LE D CUR RE NT LO CKE D

AT C URRE NT V ALUE

YES

BATTERY C URRE NT =

PRO GRAM M ED DC L IMIT

READ L E D CURR ENT

(RE G 0x0D AND REG 0x0E)

ADJUST IM AGE S E N SOR

STROBE

11018-021

Figure 26. Use of the DC Current Limit in an Optimized Camera System

Data Sheet ADP1660

Rev. 0 | Page 15 of 28

FIXED 5 V OUTPUT MODE WITH TORCH

The ADP1660 can be used as a 5 V boost converter for a key-

pad LED driver voltage or an audio voltage rail (see Figure 27

and Figure 28). In this mode, the device supplies up to 500 mA

with torch currents available on the LED outputs.

To enable 5 V output voltage mode with torch currents,

1. Set the LED1_EN and LED2_EN bits in Register 0x0F to 0.

2. Enable the 5 V output by setting the LED_MOD bits (Bits[2:0]

in Register 0x01) to 110.

3. Enable the LED outputs by setting the LED1_EN and

LED2_EN bits to 1.

4. If desired, set the torch/assist currents for the LEDs using

These currents can be toggled with the GPIO (torch) pin.

If the LED is enabled and the GPIO (torch) pin is low, the

LED outputs low levels of current.

The VOUT pin is connected to the SW node when the

ADP1660 is not enabled. Do not connect VOUT directly to

a positive external voltage source; doing so causes current to

flow from VOUT to the battery.

ADP1660

10µF

1.0µH

INPUT VOLTAGE =

2.7V TO 5.0V

PGND

STROBE

10µF

LED1

SGND

SCL

SDA

GPIO

OFF ON

I2C BUS

SDA, S CL

APPLICATIONS PROCESSOR

3.2 MEGAPIXEL

TO 5.0 MEGAPIXEL

CMOS IMAGE SENSOR

POWER-ON RESET

VO UT = 5. 0V

KEYPAD

LE D DRIVER

VDD

GND

VOUT*

VIN

LED2

*THE V OUT P IN I S CONNECT E D TO THE S W NODE WHEN THE ADP1660 IS NOT E NABLED. V OUT S HOUL D NOT BE CONNECTED DI RE CTL Y TO A P OSI TI V E

EXTERNAL VOLTAGE SOURCE BECAUSE THIS WILL CAUSE CURRENT TO FLOW FROM VOUT TO THE BATTERY.

11018-022

Figure 27. ADP1660 Voltage Regulation Mode: Keypad LED Driver Application

VO UT = 5. 0V ± 8.5%, IMAX = 500mA

SHUTDOWN

VDD

OUT+

OUT–

IN+

GND

AUDIO IN–

AUDIO IN+

SSM2315

80kΩ

160kΩ

BIAS

0.1µF

ADP1660

10µF

1.0µH

INPUT VOLTAGE =

2.7V TO 5.0V

PGND

SWSTROBE

10µF

SGND

SCL

SDA

GPIO

OFFON

I2C BUS

SDA, S CL

APPLICATIONS

PROCESSOR

3.2 MEGAPIXEL

TO 5.0 MEGAPIXEL

CMOS IMAGE SENSOR

POWER-ON

RESET

VOUT*

VIN

IN–

47nF

FET

DRIVER

POP/CLICK

SUPPRESSION

INTERNAL

OSCILLATOR

MODULATOR

(Σ-Δ)

LED1

LED2

11018-023

*THE V OUT P IN I S CONNECT E D TO THE S W NODE WHEN THE ADP1660 IS NOT E NABLED. V OUT S HOUL D NOT BE CONNECTED DI RE CTL Y TO A P OSI TI V E

EXTERNAL VOLTAGE SOURCE BECAUSE THIS WILL CAUSE CURRENT TO FLOW FROM VOUT TO THE BATTERY.

Figure 28. ADP1660 Voltage Regulation Mode: Class-D Audio Application

ADP1660 Data Sheet

Rev. 0 | Page 16 of 28

SAFETY FEATURES

For critical fault conditions—such as output overvoltage, flash

timeout, LED output short circuit, and overtemperature condi-

tions—the ADP1660 has built-in protection modes. If a critical

fault occurs, the LED1_EN and LED2_EN bits in Register 0x0F

are set to 0 and the driver shuts down. The appropriate fault bit

is set in the fault information register (Register 0x0C). The pro-

cessor 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 fault bit is cleared.

If a noncritical event occurs, the LED driver continues to oper-

ate. Noncritical events include TxMASK event, dc current limit

reached, or soft inductor current limit reached. The corresponding

information bits are set in the fault information register

(Register 0x0C) until the processor reads them.

SHORT-CIRCUIT FAULT

When the flash driver is disabled, the high-side current regu-

lator disconnects the dc path between the battery and the LED,

protecting the system from an LED short circuit. The LED1 and

LED2 pins feature short-circuit protection that monitors the LED

voltage when the LED driver is enabled. If the voltage on the LED1

or LED2 pin remains below the short-circuit detection threshold,

a short circuit is detected, and Bit 6 of the fault information register

(Register 0x0C) is set high. The ADP1660 remains disabled until

the processor clears the fault register.

OVERVOLTAGE FAULT

The ADP1660 contains a comparator at the VOUT pin that

monitors the voltage between VOUT and PGND. If the voltage

exceeds 5.5 V (typical), the ADP1660 shuts down. Bit 7 in the

fault information register (Register 0x0C) is read back as high.

The ADP1660 is disabled until the fault is cleared, ensuring

protection against an open circuit, which would cause an

overvoltage condition.

DYNAMIC OVERVOLTAGE PROTECTION MODE

Dynamic overvoltage protection (OVP) mode is a programmable

feature that prevents the VOUT voltage from exceeding the OVP

level while maintaining as much current as possible through the

LEDs. Dynamic OVP mode prevents an overvoltage fault in the

case of a much higher than expected LED forward voltage. If the

LED forward voltage is reduced due to a rise in LED tempera-

ture, the ADP1660 transitions out of dynamic OVP mode and

regulates the LED at the programmed current level. To enable

dynamic OVP mode, set Bit 6 of Register 0x03 high.

TIMEOUT FAULT

If hardware strobe mode is enabled and strobe is set to level-

sensitive mode (Register 0x01, Bits[5:4] = 11) and if the STROBE

pin remains high for longer than the programmed timeout period,

the timeout fault bit (Register 0x0C, Bit 4) is read back as high.

The ADP1660 remains disabled until the processor clears the

fault register. The timeout value is set using the FL_TIM bits

(Bits[3:0]) in Register 0x02.

OVERTEMPERATURE FAULT

If the junction temperature of the ADP1660 rises above 150°C,

a thermal protection circuit shuts down the device. Bit 5 of the

fault information register (Register 0x0C) is set high. The ADP1660

remains disabled until the processor clears the fault register.

CURRENT LIMIT

An internal switch limits battery current by ensuring that the

peak inductor current does not exceed the limit programmed

using Bits[7:6] in Register 0x01. By default, the soft inductor

peak current limit mode is disabled (Register 0x03, Bit 7 = 1).

When the soft inductor peak current limit is disabled and the

peak inductor current exceeds the limit, Bit 1 of the fault infor-

mation register (Register 0x0C) is set high. The ADP1660 shuts

down and remains disabled until the processor clears the fault

When the soft inductor peak current limit is enabled (Register

0x03, Bit 7 = 0) and the peak inductor current reaches the limit,

Bit 1 of the fault information register (Register 0x0C) is set high.

The inductor and LED current cannot increase further, but the

ADP1660 continues to operate.

INPUT UNDERVOLTAGE

The ADP1660 includes a battery undervoltage lockout circuit.

During fixed 5 V output or LED operation, if the battery voltage

falls below the input UVLO threshold (2.4 V typical), the ADP1660

shuts down. A power-on reset circuit resets the registers to their

default values when the voltage rises above the UVLO rising

threshold.

SOFT START

The ADP1660 uses a soft start 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 bits in the fault information register (Register 0x0C) are

cleared automatically when the processor reads the fault register

(provided that the faults no longer exist).

Data Sheet ADP1660

Rev. 0 | Page 17 of 28

I2C INTERFACE

The ADP1660 includes an I2C-compatible serial interface for

control of the LED currents, as well as for readback of 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 29 shows the I2C write sequence for a single register.

The subaddress byte selects the register that is written to. The

ADP1660 sends an acknowledgment to the master after the 8-bit

data byte is written. Figure 30 shows the I2C read sequence for a

single register.

For information about the registers and descriptions of all

SUBADDRESS

CHIP ADDRE S S

0 1 1 0 0 0 0 0

0 = WRIT E

ADP1660 ACK

ADP1660 RECE IVES

DATA

MASTER

STOP

11018-024

Figure 29. I2C Write Sequence for a Single Register

ADP1660 ACK

CHIP ADDRE S S

0 1 1 0 0 0 0 0 010

MASTER

STOP

CHIP ADDRESS

0110000 010

0 = WRIT E 1 = READ

MASTER ACK

ADP1660 SENDS

DATA

SUBADDRESS

11018-025

Figure 30. I2C Read Sequence for a Single Register

ADP1660 Data Sheet

Rev. 0 | Page 18 of 28

The highest bit number (7) represents the most significant bit; the lowest bit number (0) represents the least significant bit.

Table 11. Register Map

Address Register Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

0x00 Design information DEVICE_ID REV_ID

0x01 Output mode IL_PEAK STR_LV STR_MOD STR_POL LED_MOD

0x02 GPIO and timer LED_SD TEST_SR IO_CFG FL_TIM

0x03 Additional features CL_SOFT DYN_OVP SW_LO FREQ_FB IL_DC IL_DC_EN

0x04 Low battery mode enable Reserved V_BATT_WINDOW V_VB_LO

0x05 Low battery mode current Reserved I_VB_LO

0x06 LED1 flash current Reserved I_FL1

0x07 LED1 TxMASK current Reserved I_TX1

0x08 LED1 torch/assist current Reserved I_TOR1

0x09 LED2 flash current Reserved I_FL2

0x0A LED2 TxMASK current Reserved I_TX2

0x0B LED2 torch/assist current Reserved I_TOR2

0x0C Fault information FL_OVP FL_SC FL_OT FL_TO FL_TX FL_VB_LO FL_IL FL_IDC

0x0D LED1 flash current fault

readback

Reserved FL_I_FL1

0x0E LED2 flash current fault

readback

Reserved FL_I_FL2

0x0F LED enable mode Reserved LED2_EN LED1_EN

Table 12. Design Information Register (Register 0x00)

Bits Bit Name Access Description

[7:3] DEVICE_ID R Device ID for the ADP1660 (00011).

[2:0] REV_ID R Revision ID.

Table 13. Output Mode Register (Register 0x01)

Bits Bit Name Access Description

[7:6] IL_PEAK R/W These bits set the inductor peak current limit.

00 = 2.25 A.

01 = 2.75 A.

10 = 3.25 A (default).

11 = 3.5 A.

5 STR_LV R/W This bit sets the sensitivity for the STROBE pin.

0 = edge sensitive.

1 = level sensitive (default).

4 STR_MOD R/W This bit sets the strobe mode.

0 = software strobe mode; software flash occurs when the output is enabled in flash mode.

1 = hardware strobe mode; the STROBE pin must go high for flash (default).

3 STR_POL R/W This bit sets the polarity of the STROBE pin.

0 = active low.

1 = active high (default).

[2:0] LED_MOD R/W These bits set the LED output mode.

000 = standby mode (default).

001 = fixed 5 V output mode.

010 = assist light mode.

011 = flash mode.

100 = independent trigger mode with timeout enabled.

101 = independent trigger mode with timeout disabled.

110 = fixed 5 V output mode with torch mode (total output current must be below 500 mA).

111 = reserved.

Data Sheet ADP1660

Rev. 0 | Page 19 of 28

Table 14. GPIO and Timer Register (Register 0x02)

Bits Bit Name Access Description

7 LED_SD R/W This bit configures the shutdown function for LED1 and LED2.

0 = enter shutdown after LED1 or LED2 flash or torch ends (default).

1 = do not enter shutdown after LED1 or LED2 flash or torch ends.

6 TEST_SR R/W Test mode only. This bit must be set to its default value, 1. Do not set this bit to 0.

[5:4]

IO_CFG

R/W

These bits configure the GPIO pin.

00 = high impedance (default).

01 = torch mode.

10 = TxMASK operation mode.

11 = torch mode without the 8 ms deglitch filter.

[3:0] FL_TIM R/W These bits set the flash timer value.

0000 = 100 ms.

0001 = 200 ms.

…

0100 = 500 ms.

…

0110 = 700 ms.

…

1001 = 1000 ms.

…

1100 = 1300 ms.

…

1111 = 1600 ms (default).

Table 15. Additional Features Register (Register 0x03)

Bits Bit Name Access Description

7 CL_SOFT R/W This bit enables or disables the soft inductor peak current limit.

0 = enable soft inductor peak current limit.

1 = disable soft inductor peak current limit (default). The ADP1660 is disabled when the inductor

peak current limit is reached.

6 DYN_OVP R/W This bit enables or disables dynamic OVP.

0 = disable dynamic OVP (default).

1 = enable dynamic OVP.

5 SW_LO R/W This bit sets the switching frequency.

0 = 3 MHz (default).

1 = 1.5 MHz.

4 FREQ_FB R/W This bit enables or disables frequency foldback to 1.5 MHz.

0 = disable frequency foldback (default).

1 = enable frequency foldback.

[3:1] IL_DC R/W These bits set the input dc current limit. (Bit 0 must be set to 1.)

000 = 1.0 A.

001 = 1.25 A.

010 = 1.5 A.

011 = 1.75 A.

100 = 2.0 A (default).

101 = 2.25 A.

110 = 2.5 A.

111 = 2.75 A.

0 IL_DC_EN R/W This bit enables or disables the input dc current limit function.

0 = disable input dc current limit (default).

1 = enable input dc current limit.

ADP1660 Data Sheet

Rev. 0 | Page 20 of 28

Table 16. Low Battery Mode Enable Register (Register 0x04)

Bits Bit Name Access Description

[7:5] Reserved R/W Reserved.

[4:3]

V_BAT T_WINDOW

R/W

These bits set the window size for low battery detection mode.

00 = window disabled; low battery detection is enabled for the entire flash period.

01 = window enabled for 1 ms.

10 = window enabled for 2 ms.

11 = window enabled for 5 ms (default).

[2:0] V_VB_LO R/W These bits enable or disable low battery detection and set the battery voltage level at which

the low battery detection function is enabled.

000 = low battery detection disabled (default).

001 = low battery detection enabled at 3.3 V.

010 = low battery detection enabled at 3.35 V.

011 = low battery detection enabled at 3.4 V.

100 = low battery detection enabled at 3.45 V.

101 = low battery detection enabled at 3.5 V.

110 = low battery detection enabled at 3.55 V.

111 = low battery detection enabled at 3.6 V.

Table 17. Low Battery Mode Current Register (Register 0x05)

Bits Bit Name Access Description

[7:6] Reserved R/W Reserved.

[5:0]

I_VB_LO

R/W

These bits set the flash current value for the low battery voltage setting. The current setting

is equal to the value of these six bits multiplied by 12.5 mA (I_VB_LO × 12.5). The maximum

current value is 750 mA.

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA.

…

10 1000 = 500 mA (default).

…

11 1100 = 750 mA.

…

11 1111 = 750 mA.

Table 18. LED1 Flash Current Register (Register 0x06)

Bits

Bit Name

Access

Description

[7:6] Reserved R/W Reserved.

[5:0] I_FL1 R/W These bits set the flash current value for LED1. The current setting is equal to the value of these

six bits multiplied by 12.5 mA (I_FL1 × 12.5). The maximum current value is 750 mA.

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA.

…

10 1000 = 500 mA (default).

…

11 1100 = 750 mA.

…

11 1111 = 750 mA.

Data Sheet ADP1660

Rev. 0 | Page 21 of 28

Table 19. LED1 TxMASK Current Register (Register 0x07)

Bits Bit Name Access Description

[7:6] Reserved R/W Reserved.

[5:0]

I_TX1

R/W

These bits set the TxMASK current value for LED1. The current setting is equal to the value of these

six bits multiplied by 12.5 mA (I_TX1 × 12.5). The maximum TxMASK current value is 750 mA.

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA (default).

…

10 1000 = 500 mA.

…

11 1100 = 750 mA.

…

11 1111 = 750 mA.

Table 20. LED1 Torch/Assist Current Register (Register 0x08)

Bits Bit Name Access Description

[7:5] Reserved R/W Reserved.

[4:0] I_TOR1 R/W These bits set the torch/assist current value for LED1. The current setting is equal to the value of

these five bits multiplied by 12.5 mA (I_TOR1 × 12.5). The maximum current value is 200 mA.

0 0000 = 0 mA.

…

0 0100 = 50 mA (default).

…

0 1000 = 100 mA.

…

0 1100 = 150 mA.

…

1 0000 = 200 mA.

…

1 1111 = 200 mA.

Table 21. LED2 Flash Current Register (Register 0x09)

Bits

Bit Name

Access

Description

[7:6] Reserved R/W Reserved.

[5:0] I_FL2 R/W These bits set the flash current value for LED2. The current setting is equal to the value of these six

bits multiplied by 12.5 mA (I_FL2 × 12.5). The maximum current value is 750 mA.

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA.

…

10 1000 = 500 mA (default).

…

11 1100 = 750 mA.

…

11 1111 = 750 mA.

ADP1660 Data Sheet

Rev. 0 | Page 22 of 28

Table 22. LED2 TxMASK Current Register (Register 0x0A)

Bits Bit Name Access Description

[7:6] Reserved R/W Reserved.

[5:0]

I_TX2

R/W

These bits set the TxMASK current value for LED2. The current setting is equal to the value of these

six bits multiplied by 12.5 mA (I_TX2 × 12.5). The maximum TxMASK current value is 750 mA.

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA (default).

…

10 1000 = 500 mA.

…

11 1100 = 750 mA.

…

11 1111 = 750 mA.

Table 23. LED2 Torch/Assist Current Register (Register 0x0B)

Bits Bit Name Access Description

[7:5]

Reserved

R/W

Reserved.

[4:0] I_TOR2 R/W These bits set the torch/assist current value for LED2. The current setting is equal to the value of

these five bits multiplied by 12.5 mA (I_TOR2 × 12.5). The maximum current value is 200 mA.

0 0000 = 0 mA.

…

0 0100 = 50 mA (default).

…

0 1000 = 100 mA.

…

0 1100 = 150 mA.

…

1 0000 = 200 mA.

…

1 1111 = 200 mA.

Table 24. Fault Information Register (Register 0x0C)

Bits Bit Name Access Description

7 FL_OVP R 0 = no overvoltage fault (default).

1 = overvoltage fault.

6 FL_SC R 0 = no short-circuit fault (default).

1 = short-circuit fault.

5 FL_OT R 0 = no overtemperature fault (default).

1 = overtemperature fault.

FL_TO

0 = no timeout fault (default).

1 = timeout fault.

3 FL_TX R 0 = no TxMASK operation mode during last flash (default).

1 = TxMASK operation mode occurred during last flash.

2 FL_VB_LO R Low battery detection threshold status; low battery detection must be enabled in Register 0x04.

0 = VDD is greater than the configured low battery threshold (default).

1 = VDD is less than the configured low battery threshold.

1 FL_IL R 0 = no inductor peak current limit fault (default).

1 = inductor peak current limit fault.

0 FL_IDC R DC current limit threshold status; dc current limit must be enabled in Register 0x03.

0 = dc current limit not reached (default).

1 = dc current limit reached.

Data Sheet ADP1660

Rev. 0 | Page 23 of 28

Table 25. LED1 Flash Current Fault Readback Register (Register 0x0D)

Bits Bit Name Access Description

[7:6] Reserved R Reserved.

[5:0]

FL_I_FL1

These bits contain the flash current value for LED1 when the dc current limit fault occurs. The

current setting is equal to the value of these six bits multiplied by 12.5 mA (FL_I_FL1 × 12.5).

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA.

…

10 1000 = 500 mA.

…

11 1100 = 750 mA.

Table 26. LED2 Flash Current Fault Readback Register (Register 0x0E)

Bits Bit Name Access Description

[7:6] Reserved R Reserved.

[5:0]

FL_I_FL2

These bits contain the flash current value for LED2 when the dc current limit fault occurs. The

current setting is equal to the value of these six bits multiplied by 12.5 mA (FL_I_FL2 × 12.5).

00 0000 = 0 mA.

00 0001 = 12.5 mA.

…

00 1000 = 100 mA.

…

01 0100 = 250 mA.

…

10 1000 = 500 mA.

…

11 1100 = 750 mA.

Table 27. LED Enable Mode Register (Register 0x0F)

Bits Bit Name Access Description

[7:2] Reserved R/W Reserved.

LED2_EN

R/W

This bit enables or disables the LED2 output.

0 = disable LED2 output (default).

1 = enable LED2 output.

To enable both channels at once, set both LED2_EN and LED1_EN to 0 and then set both bits to 1

in the same I2C write command. If LED1 is already enabled and the user tries to set the LED2_EN bit

to 1, this write is ignored.

0 LED1_EN R/W This bit enables or disables the LED1 output.

0 = disable LED1 output (default).

1 = enable LED1 output.

To enable both channels at once, set both LED1_EN and LED2_EN to 0 and then set both bits to 1

in the same I2C write command. If LED2 is already enabled and the user tries to set the LED1_EN bit

to 1, this write is ignored.

ADP1660 Data Sheet

Rev. 0 | Page 24 of 28

APPLICATIONS INFORMATION

EXTERNAL COMPONENT SELECTION

Selecting the Inductor

The ADP1660 boost converter increases the battery voltage to

allow driving of two LEDs when the forward voltage of the LEDs

is higher than the battery voltage minus 2× 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 voltages.

The inductor saturation current should be greater than the sum

of the dc input current and half the inductor ripple current. A

reduction in the effective inductance due to saturation increases

the inductor ripple current. Table 28 provides a list of suggested

inductors.

Table 28. Suggested Inductors

Vendor

Value

(µH) Part No.

DCR

(mΩ)

ISAT

(A)

Dimensions

L × W × H (mm)

Toko 1.0 FDSD0312 43 4.5 3.0 × 3.0 × 1.2

Toko

1.0

DFE2520

3.4

2.5 × 2.0 × 1.0

Coilcraft 1.0 XFL3010 43 2.4 3.0 × 3.0 × 1.0

Murata 1.0 LQM32P_G0 48 3 3.2 × 2.5 × 1.0

FDK 1.0 MIP3226D 40 3 3.2 × 2.6 × 1.0

Selecting the Input Capacitor

The ADP1660 requires an input bypass capacitor to supply tran-

sient 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 characteristics

of ceramic capacitors, the recommended capacitor is a 10.0 µF,

6.3 V, X5R/X7R ceramic capacitor.

Higher input capacitor values 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 ADP1660 as possible. A low ESR capacitor is

required. Table 29 provides a list of suggested input and output

capacitors.

Table 29. Suggested Input and 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

Selecting the Output Capacitor

The output capacitor maintains the output voltage and supplies

the LED current during the on period of the N-FET power

switch. It also stabilizes the loop. The recommended capacitor

is a 10.0 µF, 6.3 V, X5R/X7R ceramic capacitor (see Tabl e 29).

Note that dc bias characterization data is available from capacitor

manufacturers and should be taken into account when selecting

input and output capacitors. Capacitors of 6.3 V or 10 V are best

for most designs.

Higher output capacitor values reduce the output voltage ripple

and improve load transient response. When selecting an output

capacitor value, it is also important to account for the loss of

capacitance due to 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.

The worst-case capacitance accounting for capacitor variation

over temperature, component tolerance, and voltage is calculated

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.

For example, a 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 (see Figure 31).

–10

–20

–30

–40

–50

–60

–70

–80

–90 6.305.043.782.52

DC BIAS V OLTAGE (V)

CAPACITANCE CHANGE ( %)

1.260

11018-026

Figure 31. DC Bias Characteristic of a 10 μF, 6.3 V 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.

Data Sheet ADP1660

Rev. 0 | Page 25 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 32 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.

• Use as wide a trace as possible between the inductor and

the SW pin. The easiest path for this trace is through the

center of the output capacitor.

• Route the LED1/LED2 path away from the inductor and

SW node to minimize noise and magnetic interference.

• Maximize the size of ground metal on the component side

of the board to help with thermal dissipation.

• Use a ground plane with two or three vias connecting 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.

LED2

DIGITAL

INPUT/

OUTPUT

PGND

LED1

AREA = 16. 4mm

11018-027

Li-ION+

INDUCTOR

Figure 32. Layout of the ADP1660 Driving a High Power White LED

ADP1660 Data Sheet

Rev. 0 | Page 26 of 28

OUTLINE DIMENSIONS

0.660

0.600

0.540

1.695

1.655

1.615

2.060

2.020

1.980

BOTTOM VI EW

(BALL SIDE UP)

TOP VIEW

(BALL SI DE DOW N)

END VIEW

0.360

0.320

0.280

1.50

REF

1.00

REF

0.50

REF

BALLA1

IDENTIFIER

09-07-2012-A

SEATING

PLANE 0.270

0.240

0.210

COPLANARITY

0.05

Figure 33. 12-Ball Wafer Level Chip Scale Package [WLCSP]

(CB-12-7)

Dimensions shown in millimeters

ORDERING GUIDE

Model1 Temperature Range Package Description Package Option2 Branding

ADP1660ACBZ-R7 −40°C to +125°C 12-Ball Wafer Level Chip Scale Package [WLCSP] CB-12-7 LM7

ADP1660CB-EVALZ Evaluation Board

1 Z = RoHS Compliant Part.

2 This package option is halide free.

Data Sheet ADP1660

Rev. 0 | Page 27 of 28

NOTES

ADP1660 Data Sheet

Rev. 0 | Page 28 of 28

NOTES

I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).

registered trademarks are the property of their respective owners.

D11018-0-10/12(0)

Mouser Electronics

Authorized Distributor

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