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Dual 750 mA LED Flash Driver

with I

C-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

C 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

C-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 I

C-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 I

C-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.

Summary of content (28 pages)

PAGE 1
Dual 750 mA LED Flash Driver with I2C-Compatible Interface ADP1660 Data Sheet FEATURES FUNCTIONAL BLOCK DIAGRAM INPUT VOLTAGE = 2.7V TO 5.0V 10µF 1.0µH VIN TORCH/ TxMASK GPIO SW VOUT 10µF ADP1660 LED1 STROBE UP TO 750mA SCL LED2 SGND UP TO 750mA PGND 11018-001 SDA EN Figure 1. C1 Li-ION+ L1 PGND C2 INDUCTOR DIGITAL INPUT/ OUTPUT APPLICATIONS Camera-enabled cellular phones and smartphones Digital still cameras, camcorders, and PDAs AREA = 16.
PAGE 2
ADP1660 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Fixed 5 V Output Mode............................................................. 13 Applications ....................................................................................... 1 Frequency Foldback ................................................................... 13 Functional Block Diagram ...........................................................
PAGE 3
Data Sheet ADP1660 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 SUPPLY Input Voltage Range Undervoltage Lockout Threshold Undervoltage Lockout Hysteresis Shutdown Current, EN = 0 V Standby Current, EN = 1.
PAGE 4
ADP1660 Parameter 2 DIGITAL INPUTS/GPIO PIN Input Logic Low Voltage Input Logic High Voltage GPIO, STROBE Pull-Down Resistance Torch Glitch Filtering Delay 4 SAFETY FEATURES Maximum Timeout for Flash Timer Accuracy DC Current Limit 5 Low Battery Mode Transition Voltage Error Hysteresis Coil Peak Current Limit 6 Data Sheet Test Conditions/Comments Min Typ Max Unit 0.54 8.6 V V kΩ ms +7.0 1.1 1.4 1.65 1.95 2.2 2.5 2.75 3.1 ms % A A A A A A A A 1.26 From GPIO (torch) rising edge to device start 7.
PAGE 5
Data Sheet ADP1660 I2C-COMPATIBLE INTERFACE TIMING SPECIFICATIONS Table 3. Parameter1 fSCL tHIGH tLOW tSU, DAT tHD, DAT tSU, STA tHD, STA tBUF tSU, STO tR tF tSP CB 2 1 2 Min Max 1000 0.26 0.5 50 0 0.26 0.26 0.5 0.26 20 + 0.1 CB2 20 + 0.1 CB2 0 Unit kHz μs μs ns μs μs μs μs μs ns ns ns pF 0.
PAGE 6
ADP1660 Data Sheet ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 4. Parameter VIN, SDA, SCL, EN, GPIO, STROBE, LED1, LED2, SW, VOUT to PGND PGND to SGND Ambient Temperature Range (TA) Junction Temperature Range (TJ) Storage Temperature ESD Human Body Model Charged Device Model Machine Model 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.
PAGE 7
Data Sheet ADP1660 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS BALL A1 INDICATOR 1 2 3 PGND SGND VIN SW GPIO EN VOUT STROBE SDA LED1 LED2 SCL A B C TOP VIEW (BALL SIDE DOWN) Not to Scale 11018-004 D Figure 4. Pin Configuration Table 6. Pin Function Descriptions Pin No. A1 A2 A3 B1 B2 Mnemonic PGND SGND VIN SW GPIO B3 EN C1 VOUT C2 STROBE C3 D1 D2 D3 SDA LED1 LED2 SCL Description Power Ground. Signal Ground. Input Voltage for the Device.
PAGE 8
ADP1660 Data Sheet TYPICAL PERFORMANCE CHARACTERISTICS ILED = LED current, VLED = LED output voltage, IBAT = battery current. VLED1 2 INDUCTOR CURRENT ILED1 4 3 ILED1 INDUCTOR CURRENT 3 SW 2 STROBE CH1 5.00V CH2 1.00A CH3 500mA CH4 2.00V M800µs T 200µs CH1 2.00V CH2 100mA CH3 50.0mA Figure 5. Startup, Flash Mode, VIN = 3.6 V, ILED1 = ILED2 = 750 mA 11018-008 1 11018-005 1 M800µs T 100µs Figure 8.
PAGE 9
Data Sheet ADP1660 6 100 90 5 STANDBY CURRENT (µA) 80 60 50 VIN = 2.7V VIN = 3.0V VIN = 3.6V VIN = 4.2V 40 30 20 4 3 VIN = 4.5V 2 1 0.1 1 OUTPUT CURRENT (A) 0 –40 11018-100 0 0.01 20 40 60 80 100 120 Figure 14. Standby Current vs. Temperature 3.0 3 100mA PER CHANNEL 200mA PER CHANNEL 500mA PER CHANNEL 750mA PER CHANNEL 2.5 LED MATCHING (%) 2 LED CURRENT ERROR (%) 0 TEMPERATURE (ºC) Figure 11. Efficiency vs.
PAGE 10
ADP1660 Data Sheet THEORY OF OPERATION MODES 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. When the enable pin is high, the I2C-compatible interface can be used to set the ADP1660 to one of seven modes of operation.
PAGE 11
Data Sheet ADP1660 Level-Sensitive STROBE Mode ASSIST LIGHT 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).
PAGE 12
ADP1660 Data Sheet 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 available on request from the Analog Devices, Inc., sales team. The ADP1660 returns to standby mode after a successful flash and sets the LED1_EN and LED2_EN bits to 0 in Register 0x0F.
PAGE 13
Data Sheet ADP1660 INDEPENDENT TRIGGER MODES FREQUENCY FOLDBACK 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). The optional frequency foldback feature optimizes efficiency by reducing the switching frequency to 1.
PAGE 14
ADP1660 Data Sheet The ADP1660 has an optional programmable input dc current limit that limits the maximum battery current used over all conditions. 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.
PAGE 15
Data Sheet ADP1660 FIXED 5 V OUTPUT MODE WITH TORCH 4. The ADP1660 can be used as a 5 V boost converter for a keypad 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. 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.
PAGE 16
ADP1660 Data Sheet SAFETY FEATURES For critical fault conditions—such as output overvoltage, flash timeout, LED output short circuit, and overtemperature conditions—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).
PAGE 17
Data Sheet ADP1660 I2C INTERFACE 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. The ADP1660 includes an I2C-compatible serial interface for control of the LED currents, as well as for readback of system status registers.
PAGE 18
ADP1660 Data Sheet REGISTER MAP The highest bit number (7) represents the most significant bit; the lowest bit number (0) represents the least significant bit. Table 11.
PAGE 19
Data Sheet ADP1660 Table 14. GPIO and Timer Register (Register 0x02) Bits 7 Bit Name LED_SD Access R/W 6 [5:4] TEST_SR IO_CFG R/W R/W [3:0] FL_TIM R/W Description 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. Test mode only. This bit must be set to its default value, 1. Do not set this bit to 0. These bits configure the GPIO pin.
PAGE 20
ADP1660 Data Sheet Table 16. Low Battery Mode Enable Register (Register 0x04) Bits [7:5] [4:3] Bit Name Reserved V_BATT_WINDOW Access R/W R/W [2:0] V_VB_LO R/W Description Reserved. 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).
PAGE 21
Data Sheet ADP1660 Table 19. LED1 TxMASK Current Register (Register 0x07) Bits [7:6] [5:0] Bit Name Reserved I_TX1 Access R/W R/W Description Reserved. 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.
PAGE 22
ADP1660 Data Sheet Table 22. LED2 TxMASK Current Register (Register 0x0A) Bits [7:6] [5:0] Bit Name Reserved I_TX2 Access R/W R/W Description Reserved. 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.
PAGE 23
Data Sheet ADP1660 Table 25. LED1 Flash Current Fault Readback Register (Register 0x0D) Bits [7:6] [5:0] Bit Name Reserved FL_I_FL1 Access R R Description Reserved. 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.
PAGE 24
ADP1660 Data Sheet APPLICATIONS INFORMATION 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.
PAGE 25
Data Sheet ADP1660 PCB LAYOUT • • • • • 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.
PAGE 26
ADP1660 Data Sheet OUTLINE DIMENSIONS 1.695 1.655 1.615 BOTTOM VIEW (BALL SIDE UP) 3 2 1 A BALL A1 IDENTIFIER 2.060 2.020 1.980 1.50 REF B C D 0.50 REF TOP VIEW (BALL SIDE DOWN) 1.00 REF END VIEW COPLANARITY 0.05 SEATING PLANE 0.360 0.320 0.280 0.270 0.240 0.210 09-07-2012-A 0.660 0.600 0.540 Figure 33.
PAGE 27
Data Sheet ADP1660 NOTES Rev.
PAGE 28
ADP1660 Data Sheet NOTES I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors). ©2012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D11018-0-10/12(0) Rev.