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 = 16.4mm 2 LED1 LED2 11018-002 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 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. Rev. 0 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. Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 ©2012 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com ADP1660 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Fixed 5 V Output Mode............................................................. 13 Applications ....................................................................................... 1 Frequency Foldback ................................................................... 13 Functional Block Diagram .............................................................. 1 Low Battery LED Current Foldback ........................................ 13 General Description ......................................................................... 1 Battery Input DC Current Limit .............................................. 14 Revision History ............................................................................... 2 Fixed 5 V Output Mode with Torch ........................................ 15 Specifications..................................................................................... 3 Safety Features................................................................................. 16 Recommended Specifications: Input and Output Capacitance and Inductance ............................................................................. 4 Short-Circuit Fault ..................................................................... 16 I2C-Compatible Interface Timing Specifications ..................... 5 Dynamic Overvoltage Protection Mode ................................. 16 Absolute Maximum Ratings............................................................ 6 Timeout Fault.............................................................................. 16 Thermal Data ................................................................................ 6 Overtemperature Fault .............................................................. 16 Thermal Resistance ...................................................................... 6 Current Limit .............................................................................. 16 ESD Caution .................................................................................. 6 Input Undervoltage .................................................................... 16 Pin Configuration and Function Descriptions ............................. 7 Soft Start ...................................................................................... 16 Typical Performance Characteristics ............................................. 8 Reset Using the Enable (EN) Pin ............................................. 16 Overvoltage Fault ....................................................................... 16 Theory of Operation ...................................................................... 10 Clearing Faults ............................................................................ 16 White LED Driver ...................................................................... 10 I C Interface .................................................................................... 17 Modes of Operation ................................................................... 10 Register Map ................................................................................... 18 Assist Light Mode ....................................................................... 11 Register Details ........................................................................... 18 Flash Mode .................................................................................. 11 Applications Information .............................................................. 24 Assist to Flash Mode .................................................................. 12 External Component Selection ................................................ 24 Torch Mode ................................................................................. 12 PCB Layout...................................................................................... 25 Torch to Flash Mode .................................................................. 12 Outline Dimensions ....................................................................... 26 TxMASK Operation ................................................................... 12 Ordering Guide .......................................................................... 26 2 Independent Trigger Modes...................................................... 13 REVISION HISTORY 10/12—Revision 0: Initial Version Rev. 0 | Page 2 of 28 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 = 1.8 V Operating Quiescent Current SW Switch Leakage Current LED DRIVER LED Current Assist Light, Torch Mode Current Flash Mode Current LED Current Error per Channel LED Channel Mismatch LED Current Source Headroom LED1/LED2 Ramp-Up Time LED1/LED2 Ramp-Down Time SWITCHING REGULATOR Switching Frequency Minimum Duty Cycle N-FET Resistance P-FET Resistance Voltage Output Mode VOUT Voltage Output Current Line Regulation Load Regulation Pass-Through Mode Transition Flash Mode VIN to LED1/LED2, Entry VIN to LED1/LED2, Exit Torch Mode VIN to LED1/LED2, Entry VIN to LED1/LED2, Exit Test Conditions/Comments Min VIN falling 2.7 2.3 50 TJ = −40°C to +85°C, current into VIN pin, VIN = 2.7 V to 4.5 V TJ = −40°C to +85°C, current into VIN pin, VIN = 2.7 V to 4.5 V Torch mode, ILED = 100 mA TJ = −40°C to +85°C, VSW 3 = 5 V TJ = 25°C, VSW3 = 5 V Assist light value setting = 0 (0 0000 binary) Assist light value setting = 16 (1 0000 binary) Flash value setting = 0 (00 0000 binary) Flash value setting = 60 (11 1100 binary) ILED = 200 mA to 750 mA ILED = 100 mA to 187.5 mA ILED = 50 mA to 87.5 mA ILED = 25 mA to 37.5 mA ILED = 12.5 mA ILED = 275 mA to 750 mA ILED = 137.5 mA to 262.5 mA ILED = 25 mA to 125 mA ILED = 12.5 mA Flash mode, ILED = 750 mA Torch mode, ILED = 200 mA Typ Max Unit 2.4 100 0.2 5.0 2.5 150 1 V V mV µA 3 10 µA 2 0.5 mA µA µA 5.3 −5 −7 0 200 0 750 ±1 ±1 ±3 ±6 ±10 0.5 1 2 4 290 190 +5 +7 3 4 0.6 0.1 Switching frequency = 3 MHz Switching frequency = 1.5 MHz Switching frequency = 3 MHz Switching frequency = 1.5 MHz mA mA mA mA % % % % % % % % % mV mV ms ms 2.8 1.4 3.0 1.5 14 7 60 50 3.2 1.6 MHz MHz % % mΩ mΩ 4.575 5 5.425 500 ILOAD at VOUT pin = 300 mA 0.3 −0.7 V mA %/V %/A ILED1 = ILED2 = 750 mA ILED1 = ILED2 = 750 mA 580 435 mV mV ILED = 200 mA ILED = 200 mA 380 285 mV mV Rev. 0 | Page 3 of 28 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 7.4 DC current value setting = 0 (000 binary) DC current value setting = 1 (001 binary) DC current value setting = 2 (010 binary) DC current value setting = 3 (011 binary) DC current value setting = 4 (100 binary) DC current value setting = 5 (101 binary) DC current value setting = 6 (110 binary) DC current value setting = 7 (111 binary) −7.0 0.9 1.1 1.35 1.55 1.8 2.0 2.25 2.45 390 8.0 1600 1.0 1.25 1.5 1.75 2.0 2.25 2.5 2.75 3.2 Peak current value setting = 0 (00 binary) Peak current value setting = 1 (01 binary) Peak current value setting = 2 (10 binary) Peak current value setting = 3 (11 binary) Overvoltage Detection Threshold LED1/LED2 Short-Circuit Detection Comparator Reference Voltage Thermal Shutdown Threshold TJ Rising TJ Falling 2.02 2.47 2.9 3.15 5.15 50 2.25 2.75 3.25 3.5 5.5 1.0 2.5 3.0 3.5 3.85 5.9 1.3 150 140 % mV A A A A V V °C °C VIN is the input voltage to the circuit. 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. 1 2 RECOMMENDED SPECIFICATIONS: INPUT AND OUTPUT CAPACITANCE AND INDUCTANCE Table 2. Parameter CAPACITANCE Input Output MINIMUM AND MAXIMUM INDUCTANCE Symbol CMIN L Test Conditions/Comments TA = −40°C to +125°C TA = −40°C to +125°C Rev. 0 | Page 4 of 28 Min Typ Max Unit 4.0 3.0 0.6 10 10 1.0 20 1.5 µF µF µH 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 0.9 120 120 50 400 Description SCL clock frequency SCL high time SCL low time Data setup time Data hold time Setup time for repeated start Hold time for start/repeated start Bus free time between a stop and a start condition Setup time for stop condition Rise time of SCL and SDA Fall time of SCL and SDA Pulse width of suppressed spike Capacitive load for each bus line Guaranteed by design. CB is the total capacitance of one bus line in picofarads. Timing Diagram SDA tLOW tR tF tSU, DAT tF tHD, STA tSP tBUF tR SCL tHD, DAT tHIGH tSU, STA Sr tSU, STO P S 11018-003 S S = START CONDITION Sr = REPEATED START CONDITION P = STOP CONDITION Figure 3. I2C-Compatible Interface Timing Diagram Rev. 0 | Page 5 of 28 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. In applications where high maximum power dissipation exists, close attention to thermal board design is required. Rating −0.3 V to +6 V −0.3 V to +0.3 V −40°C to +85°C −40°C to +125°C JEDEC J-STD-020 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. ±1000 V ±500 V ±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. In Table 5, θJA is specified for a device mounted on a JEDEC 2S2P PCB. Table 5. Thermal Resistance Package Type 12-Ball WLCSP ESD CAUTION 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) Rev. 0 | Page 6 of 28 θJA 75 Unit °C/W 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. Connect an input bypass capacitor very close to this pin. Boost Switch. Connect the power inductor between SW and the input capacitor. 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). 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. Boost Output. Connect an output bypass capacitor very close to this pin. This pin is the output for the 5 V external voltage mode. Strobe Signal Input. This pin synchronizes the flash pulse to the image capture. In most cases, this signal comes directly from the image sensor. I2C Data Signal. Current Source for LED1. Connect this pin to the anode of flash LED1. Current Source for LED2. Connect this pin to the anode of flash LED2. I2C Clock Signal. Rev. 0 | Page 7 of 28 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. Switching Waveforms, Flash Mode, ILED1 = ILED2 = 750 mA VIN VLED1 VLED1 4 3 ILED1 3 1 INDUCTOR CURRENT ILED2 2 ILED1 2 GPIO (TORCH) M8.00ms T 2.00ms CH1 1.00V CH3 1.00V Figure 6. Startup, Torch Mode, VIN = 3.6 V, ILED1 = ILED2 = 150 mA CH2 200mA CH4 100mA M20.0µs T 0.00000s A CH2 196mA 11018-009 CH1 5.00V CH2 100mA CH3 100mA CH4 2.00V 4 11018-006 1 Figure 9. Pass-Through to Boost Mode Transition, Single LED, ILED1 = 50 mA VLED1 VLED1 4 INDUCTOR CURRENT IBAT 2 2 ILED1 ILED1 3 3 CH1 5.00V CH2 1.00A CH3 500mA CH4 5.00V M400µs T 100µs 1 4 GPIO (TxMASK) CH1 5.00V CH2 1.00A CH3 200mA CH4 500mV Figure 7. Torch Current to 750 mA Flash Transition, ILED1 = ILED2 = 50 mA Rev. 0 | Page 8 of 28 M20µs T 10µs 11018-010 STROBE 11018-007 1 Figure 10. Entry into TxMASK Mode, ILED1 = ILED2 = 750 mA to 250 mA 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. Output Current, Fixed 5 V Output Mode 1 0 –1 100mA PER CHANNEL 200mA PER CHANNEL 500mA PER CHANNEL 750mA PER CHANNEL 2.0 1.5 1.0 0.5 –2 0 –20 0 20 40 60 80 100 120 TEMPERATURE (ºC) –0.5 –40 11018-102 –3 –40 VIN = 2.7V 80 70 VIN = 3.6V 60 50 40 30 20 300 500 700 900 1100 1300 OUTPUT CURRENT (mA) 1500 11018-104 10 0 100 0 20 40 60 80 Figure 15. LED Matching vs. Temperature 100 90 –20 TEMPERATURE (ºC) Figure 12. LED Current Error vs. Temperature EFFICIENCY (%) –20 11018-101 VIN = 2.7V 10 Figure 13. Efficiency (PLED/PIN) vs. LED Output Current Rev. 0 | Page 9 of 28 100 120 11018-103 EFFICIENCY (%) 70 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. These modes are configured using the LED_MOD bits (Bits[2:0]) in Register 0x01 (see Table 7). WHITE LED DRIVER The ADP1660 drives a synchronous 3 MHz boost converter as required to power the high power LEDs. • LED_MOD Bits 000 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. 001 010 011 100 The ADP1660 uses an integrated P-FET high-side current regulator for accurate brightness control. 101 The ADP1660 supports the setting of different currents for each LED, although this configuration is not recommended. Any mismatch 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. 110 111 Operating Mode Standby mode, consuming 3 µA typical (default) Fixed 5 V output mode Assist light mode with continuous LED current Flash mode with LED currents up to 750 mA available for up to 1.6 sec 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) Independent trigger mode with timeout disabled (FL_TIM value is ignored) Fixed 5 V output mode with torch mode (total output current must be below 500 mA) Reserved INPUT VOLTAGE = 2.7V TO 5.0V CIN 10µF L1 1µF COUT 10µF PGND PGND VIN VOUT SW CURRENT SENSE UVLO HP LED DRIVER HP LED DRIVER 5.5V 2.4V CURRENT SENSE LED1 OVP PWM CONTROLLER CURRENT SENSE EN FAULT REGISTER SCL SDA STROBE INTERFACE AND CONTROL TORCH TxMASK LED2 HP LED SHORT UP TO 750mA IC THERMAL SENSING HIGH POWER LED CURRENT CONTROL PGND UP TO 750mA PGND TORCH IO_CFG GPIO SGND AGND PGND PGND Figure 16. Detailed Block Diagram Rev. 0 | Page 10 of 28 11018-011 • Table 7. Modes of Operation Set by the LED_MOD Bits 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). 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. I_FL1 LED1 CURRENT 0A I_TOR1 I_FL2 LED1 CURRENT 0A LED2 CURRENT I_TOR2 0A LED2 CURRENT STROBE 0A I2C DATA BUS I2C DATA BUS REG 0x02, FL_TIM = XXXXms REG 0x06, I_FL1 = XX XXXXmA REG 0x09, I_FL2 = XX XXXXmA REG 0x0F, LED1_EN = 0 ADP1660 SETS LED1_EN TO 0. ADP1660 SETS LED2_EN TO 0. ADP1660 SETS LED_MOD TO 000. REG 0x0F, LED2_EN = 0 REG 0x01, LED_MOD = 010 REG 0x0F, LED1_EN = 1 LED2_EN = 1 Figure 17. Enabling Assist Light Mode 11018-013 REG 0x0F, LED1_EN = 1 LED2_EN = 1 REG 0x01, STR_MOD = 1 STR_LV = 1 LED_MOD = 011 11018-012 Figure 18. Flash Operation: Level-Sensitive Mode FLASH MODE Flash mode provides up to 750 mA per LED for a programmable 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 Register 0x01, and set the LED1_EN and/or LED2_EN bits 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. 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). I_FL1 LED1 CURRENT 0A I_FL2 LED2 CURRENT 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. 0A FL_TIM STROBE I2C DATA BUS REG 0x02, FL_TIM = XXXXms REG 0x06, I_FL1 = XX XXXXmA REG 0x09, I_FL2 = XX XXXXmA ADP1660 SETS LED1_EN TO 0. ADP1660 SETS LED2_EN TO 0. ADP1660 SETS LED_MOD TO 000. REG 0x0F, LED1_EN = 1 LED2_EN = 1 REG 0x01, STR_MOD = 1 STR_LV = 0 LED_MOD = 011 Figure 19. Flash Operation: Edge-Sensitive Mode Rev. 0 | Page 11 of 28 11018-014 REG 0x08, I_TOR1 = X XXXXmA REG 0x0B, I_TOR2 = X XXXXmA 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. I_FL1 LED1 CURRENT I_TOR1 0A I_FL1 I_FL2 LED1 CURRENT I_TOR1 LED2 CURRENT I_TOR2 0A 0A STROBE I_FL2 GPIO (TORCH) LED2 CURRENT I_TOR2 0A I2C DATA BUS STROBE I2C DATA BUS REG 0x0F, LED1_EN = 1 LED2_EN = 1 REG 0x01, STR_LV = 1 LED_MOD = 000 Figure 22. Enabling Flash Mode from External Torch Mode REG 0x0F, LED1_EN = 1 LED2_EN = 1 REG 0x01, STR_LV = 1 LED_MOD = 010 11018-015 REG 0x02, FL_TIM = XXXXms REG 0x06, I _FL1 = XX XXXXmA REG 0x08, I_TOR1 = X XXXXmA REG 0x09, I_FL2 = XX XXXXmA REG 0x0B, I_TOR2 = X XXXXmA ADP1660 SETS LED1_EN TO 0. ADP1660 SETS LED2_EN TO 0. ADP1660 SETS LED_MOD TO 000. ADP1660 SETS LED1_EN TO 0. ADP1660 SETS LED2_EN TO 0. 11018-017 REG REG REG REG REG 0x02, IO_CFG = 01 FL_TIM = XXXXms 0x06, I _FL1 = XX XXXXmA 0x08, I_TOR1 = X XXXXmA 0x09, I_FL2 = XX XXXXmA 0x0B, I_TOR2 = X XXXXmA 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. 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). I_FL1 LED1 CURRENT I_TX1 0A I_FL2 I_TOR1 LED2 CURRENT I_TX2 LED1 CURRENT 0A 0A GPIO (TxMASK) I_TOR2 LED2 CURRENT STROBE GPIO (TORCH) I2C DATA BUS ADP1660 SETS LED1_EN TO 0. REG 0x08, I_TOR1 = X XXXXmA ADP1660 SETS LED2_EN TO 0. REG 0x0B, I_TOR2 = X XXXXmA REG 0x0F, LED1_EN = 1 LED2_EN = 1 LED_MOD = 000 11018-016 I2C DATA BUS REG 0x02, IO_CFG = 10 FL_TIM = XXXXms REG 0x06, I _FL1 = XX XXXXmA REG 0x08, I_TOR1 = X XXXXmA REG 0x09, I_FL2 = XX XXXXmA REG 0x0B, I_TOR2 = X XXXXmA FL_TX = 1 ADP1660 SETS LED1_EN TO 0. ADP1660 SETS LED2_EN TO 0. ADP1660 SETS LED_MOD TO 000. REG 0x0F, LED1_EN = 1 LED2_EN = 1 REG 0x01, STR_LV = 1 LED_MOD = 011 Figure 21. Enabling External Torch Mode Using the GPIO Pin TORCH TO FLASH MODE 11018-018 0A Figure 23. TxMASK Operation During Flash (Level-Sensitive) 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. After a TxMASK event occurs, a flag is set in the fault information 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. Rev. 0 | Page 12 of 28 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 1.5 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. • 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. • 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. LOW BATTERY LED CURRENT FOLDBACK 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 Table 8). I_FL1 LED1 CURRENT I_TX1 Table 8. VDD Level for Low Battery Detection STROBE I_FL2 LED2 CURRENT 11018-019 I_TX2 GPIO 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. V_VB_LO Bit Value 000 001 010 011 100 101 110 111 VDD Level for Low Battery Detection (V) Low battery detection disabled (default) 3.3 3.35 3.4 3.45 3.5 3.55 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 00 01 10 11 Window Size (ms) Window disabled; low battery detection is enabled for the entire flash period 1 2 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. Rev. 0 | Page 13 of 28 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. To set the input dc current limit, use the IL_DC bits (Bits[3:1]) in Register 0x03 (see Table 10). 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. PROGRAMMED LED CURRENT ACTUAL LED CURRENT STROBE Table 10. Input DC Current Limit DC Current Limit (A) 1.0 1.25 1.5 1.75 2.0 (default) 2.25 2.5 2.75 REG 0x02, FL_TIM = XXXXms REG 0x06, I_FL1 = XX XXXXmA REG 0x09, I_FL2 = XX XXXXmA REG 0x03, IL_DC_EN = 1 IL_DC = XX A ADP1660 SETS FL_IDC (REG 0x0C) TO 1. ADP1660 SETS FL_I_FL1 (REG 0x0D) TO ACTUAL LED CURRENT. ADP1660 SETS FL_I_FL2 (REG 0x0E) TO ACTUAL LED CURRENT. REG 0x0F, LED1_EN = 1 LED2_EN = 1 REG 0x01, STR_LV = 1 LED_MOD = 011 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. 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. SELECT FLASH CURRENT SELECT MAX BATTERY CURRENT PREFLASH STROBE NO DC LIMIT EXCEEDED? YES LED CURRENT LOCKED AT CURRENT VALUE LED CURRENT = PROGRAMMED LED CURRENT BATTERY CURRENT = PROGRAMMED DC LIMIT STROBE READ LED CURRENT (REG 0x0D AND REG 0x0E) ADJUST IMAGE SENSOR STROBE Figure 26. Use of the DC Current Limit in an Optimized Camera System Rev. 0 | Page 14 of 28 11018-021 IL_DC Bit Value 000 001 010 011 100 101 110 111 ADP1660 SETS LED1_EN TO 0. ADP1660 SETS LED2_EN TO 0. ADP1660 SETS LED_MOD TO 000. I2C DATA BUS 11018-020 BATTERY INPUT DC CURRENT LIMIT 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. To enable 5 V output voltage mode with torch currents, INPUT VOLTAGE = 2.7V TO 5.0V ON OFF 3.2 MEGAPIXEL TO 5.0 MEGAPIXEL CMOS IMAGE SENSOR 10µF 1.0µH STROBE VIN SW VOUT = 5.0V VOUT* GPIO 10µF APPLICATIONS PROCESSOR SCL ADP1660 KEYPAD LED DRIVER I2C BUS SDA, SCL VDD SDA LED1 POWER-ON RESET EN LED2 EN GND SGND PGND *THE VOUT PIN IS CONNECTED TO THE SW NODE WHEN THE ADP1660 IS NOT ENABLED. VOUT SHOULD NOT BE CONNECTED DIRECTLY TO A POSITIVE EXTERNAL VOLTAGE SOURCE BECAUSE THIS WILL CAUSE CURRENT TO FLOW FROM VOUT TO THE BATTERY. 11018-022 3. Set the LED1_EN and LED2_EN bits in Register 0x0F to 0. Enable the 5 V output by setting the LED_MOD bits (Bits[2:0] in Register 0x01) to 110. Enable the LED outputs by setting the LED1_EN and LED2_EN bits to 1. Figure 27. ADP1660 Voltage Regulation Mode: Keypad LED Driver Application INPUT VOLTAGE = 2.7V TO 5.0V ON 3.2 MEGAPIXEL TO 5.0 MEGAPIXEL CMOS IMAGE SENSOR OFF 10µF 1.0µH STROBE VIN SW VOUT = 5.0V ±8.5%, IMAX = 500mA VOUT* GPIO 10µF APPLICATIONS PROCESSOR SCL SDA, SCL 47nF AUDIO IN+ SDA LED1 EN 160kΩ VDD ADP1660 I2C BUS POWER-ON RESET 0.1µF IN– 80kΩ AUDIO IN– SSM2315 IN+ 80kΩ OUT+ MODULATOR FET (Σ-Δ) DRIVER OUT– 47nF LED2 EN SGND 160kΩ PGND SHUTDOWN SD BIAS INTERNAL OSCILLATOR POP/CLICK SUPPRESSION GND *THE VOUT PIN IS CONNECTED TO THE SW NODE WHEN THE ADP1660 IS NOT ENABLED. VOUT SHOULD NOT BE CONNECTED DIRECTLY TO A POSITIVE 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 Rev. 0 | Page 15 of 28 11018-023 1. 2. If desired, set the torch/assist currents for the LEDs using Register 0x08 (for LED1) and Register 0x0B (for LED2). 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. 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). 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 fault bit is cleared. 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. If a noncritical event occurs, the LED driver continues to operate. 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. CURRENT LIMIT SHORT-CIRCUIT FAULT 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. 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 information register (Register 0x0C) is set high. The ADP1660 shuts down and remains disabled until the processor clears the fault register. When the flash driver is disabled, the high-side current regulator 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. 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. OVERVOLTAGE FAULT INPUT UNDERVOLTAGE 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. 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. 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 temperature, 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 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). If hardware strobe mode is enabled and strobe is set to levelsensitive 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. Rev. 0 | Page 16 of 28 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. The I2C chip address is 0x30 (0x60 in write mode and 0x61 in read mode). Additional I2C addresses are available on request. For information about the registers and descriptions of all register bits, see the Register Map section. MASTER STOP 1 0 0 0 0 CHIP ADDRESS 0 0 0 0 SUBADDRESS ADP1660 RECEIVES DATA S P ADP1660 ACK 1 ADP1660 ACK 0 ADP1660 ACK S T 11018-024 0 = WRITE Figure 29. I2C Write Sequence for a Single Register SUBADDRESS CHIP ADDRESS Figure 30. I2C Read Sequence for a Single Register Rev. 0 | Page 17 of 28 ADP1660 SENDS DATA S P 11018-025 CHIP ADDRESS 1 0 1 1 0 0 0 0 1 0 0 ADP1660 ACK 0 S T 0 0 0 ADP1660 ACK 0 1 1 0 0 0 ADP1660 ACK S T MASTER STOP 1 = READ MASTER ACK 0 = WRITE 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. Register Map Address 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A 0x0B 0x0C 0x0D 0x0E 0x0F Register Name Design information Output mode GPIO and timer Additional features Low battery mode enable Low battery mode current LED1 flash current LED1 TxMASK current LED1 torch/assist current LED2 flash current LED2 TxMASK current LED2 torch/assist current Fault information LED1 flash current fault readback LED2 flash current fault readback LED enable mode Bit 7 Bit 6 IL_PEAK LED_SD TEST_SR CL_SOFT DYN_OVP Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved FL_OVP FL_SC Reserved Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 DEVICE_ID REV_ID STR_LV STR_MOD STR_POL LED_MOD IO_CFG FL_TIM SW_LO FREQ_FB IL_DC V_BATT_WINDOW V_VB_LO I_VB_LO I_FL1 I_TX1 I_TOR1 I_FL2 I_TX2 I_TOR2 FL_OT FL_TO FL_TX FL_VB_LO FL_IL FL_I_FL1 Reserved Bit 0 IL_DC_EN FL_IDC FL_I_FL2 Reserved LED2_EN LED1_EN REGISTER DETAILS Table 12. Design Information Register (Register 0x00) Bits [7:3] [2:0] Bit Name DEVICE_ID REV_ID Access R R Description Device ID for the ADP1660 (00011). Revision ID. Table 13. Output Mode Register (Register 0x01) Bits [7:6] Bit Name IL_PEAK Access R/W 5 STR_LV R/W 4 STR_MOD R/W 3 STR_POL R/W [2:0] LED_MOD R/W Description 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. This bit sets the sensitivity for the STROBE pin. 0 = edge sensitive. 1 = level sensitive (default). 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). This bit sets the polarity of the STROBE pin. 0 = active low. 1 = active high (default). 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. Rev. 0 | Page 18 of 28 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. 00 = high impedance (default). 01 = torch mode. 10 = TxMASK operation mode. 11 = torch mode without the 8 ms deglitch filter. 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 7 Bit Name CL_SOFT Access R/W 6 DYN_OVP R/W 5 SW_LO R/W 4 FREQ_FB R/W [3:1] IL_DC R/W 0 IL_DC_EN R/W Description 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. This bit enables or disables dynamic OVP. 0 = disable dynamic OVP (default). 1 = enable dynamic OVP. This bit sets the switching frequency. 0 = 3 MHz (default). 1 = 1.5 MHz. This bit enables or disables frequency foldback to 1.5 MHz. 0 = disable frequency foldback (default). 1 = enable frequency foldback. 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. This bit enables or disables the input dc current limit function. 0 = disable input dc current limit (default). 1 = enable input dc current limit. Rev. 0 | Page 19 of 28 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). 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 [7:6] [5:0] Bit Name Reserved I_VB_LO Access R/W R/W Description Reserved. 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 [7:6] [5:0] Bit Name Reserved I_FL1 Access R/W R/W Description Reserved. 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. Rev. 0 | Page 20 of 28 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. LED1 Torch/Assist Current Register (Register 0x08) Bits [7:5] [4:0] Bit Name Reserved I_TOR1 Access R/W R/W Description Reserved. 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 [7:6] [5:0] Bit Name Reserved I_FL2 Access R/W R/W Description Reserved. 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. Rev. 0 | Page 21 of 28 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. LED2 Torch/Assist Current Register (Register 0x0B) Bits [7:5] [4:0] Bit Name Reserved I_TOR2 Access R/W R/W Description Reserved. 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 7 Bit Name FL_OVP Access R 6 FL_SC R 5 FL_OT R 4 FL_TO R 3 FL_TX R 2 FL_VB_LO R 1 FL_IL R 0 FL_IDC R Description 0 = no overvoltage fault (default). 1 = overvoltage fault. 0 = no short-circuit fault (default). 1 = short-circuit fault. 0 = no overtemperature fault (default). 1 = overtemperature fault. 0 = no timeout fault (default). 1 = timeout fault. 0 = no TxMASK operation mode during last flash (default). 1 = TxMASK operation mode occurred during last flash. 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. 0 = no inductor peak current limit fault (default). 1 = inductor peak current limit fault. 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. Rev. 0 | Page 22 of 28 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. LED2 Flash Current Fault Readback Register (Register 0x0E) Bits [7:6] [5:0] Bit Name Reserved FL_I_FL2 Access R R Description Reserved. 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 [7:2] 1 Bit Name Reserved LED2_EN Access R/W R/W 0 LED1_EN R/W Description Reserved. 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. 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. Rev. 0 | Page 23 of 28 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. 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 Toko Toko Coilcraft Murata FDK Value (µH) 1.0 1.0 1.0 1.0 1.0 Part No. FDSD0312 DFE2520 XFL3010 LQM32P_G0 MIP3226D DCR (mΩ) 43 50 43 48 40 ISAT (A) 4.5 3.4 2.4 3 3 Dimensions L × W × H (mm) 3.0 × 3.0 × 1.2 2.5 × 2.0 × 1.0 3.0 × 3.0 × 1.0 3.2 × 2.5 × 1.0 3.2 × 2.6 × 1.0 Selecting the Input Capacitor The ADP1660 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 characteristics of ceramic capacitors, the recommended capacitor is a 10.0 µF, 6.3 V, X5R/X7R ceramic capacitor. 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 recommended 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 Higher input capacitor values help to reduce the input voltage ripple and improve transient response. Table 29. Suggested Input and Output Capacitors Vendor Murata TDK Taiyo Yuden Value 10 µF, 6.3 V 10 µF, 6.3 V 10 µF, 6.3 V Part No. GRM188R60J106ME47 C1608JB0J106K JMK107BJ106MA Dimensions L × W × H (mm) 1.6 × 0.8 × 0.8 1.6 × 0.8 × 0.8 1.6 × 0.8 × 0.8 CAPACITANCE CHANGE (%) 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. 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 0 1.26 2.52 3.78 5.04 DC BIAS VOLTAGE (V) 6.30 11018-026 EXTERNAL COMPONENT SELECTION Figure 31. DC Bias Characteristic of a 10 μF, 6.3 V Ceramic Capacitor 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 Table 29). 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. Rev. 0 | Page 24 of 28 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. 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. Rev. 0 | Page 25 of 28 C1 Li-ION+ L1 PGND C2 INDUCTOR DIGITAL INPUT/ OUTPUT AREA = 16.4mm 2 LED1 LED2 11018-027 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: Figure 32. Layout of the ADP1660 Driving a High Power White LED 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. 12-Ball Wafer Level Chip Scale Package [WLCSP] (CB-12-7) Dimensions shown in millimeters ORDERING GUIDE Model 1 ADP1660ACBZ-R7 ADP1660CB-EVALZ 1 2 Temperature Range −40°C to +125°C Package Description 12-Ball Wafer Level Chip Scale Package [WLCSP] Evaluation Board Z = RoHS Compliant Part. This package option is halide free. Rev. 0 | Page 26 of 28 Package Option 2 CB-12-7 Branding LM7 Data Sheet ADP1660 NOTES Rev. 0 | Page 27 of 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. 0 | Page 28 of 28