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19-3783; Rev 1; 2/07 KIT ATION EVALU E AILABL AV 1MHz PWM Boost Converter for 1.5A White LED Camera Flash General Description Features Supports Lumileds and Other High-Power White LEDs Independently Set Flash/Movie Currents Flash-Mode Current Up to 1.5A Movie-Mode Current Up to 360mA Disco Mode with Fixed 5V (Up to 1A) and 80mA LED Current 84% Efficiency (PLED / PBATT) at 1.1A TA Derating Function for LED Thermal Protection Output Overvoltage Protection (OVP) Soft-Start Eliminates Inrush Current 1MHz PWM Operation at All Loads Small External Components 2.7V to 5.5V Input Voltage Range 0.1A Shutdown Mode 14-Pin, 3mm x 3mm TDFN Package MAX8607 The MAX8607 white LED boost converter is optimized for camera flash/strobe applications using high-current white LEDs. The MAX8607 integrates a 1MHz PWM boost converter, 1.5A low-dropout (LDO) current regulator, and logic control circuitry for a space-saving LED flash design. Two logic inputs control four modes of operation: shutdown mode reduces the quiescent current to 0.1A (typ), movie mode supplies up to 360mA of LED current for continuous lighting, flash mode supplies up to 1.5A of LED current for short-duration lighting during an exposure, and disco mode supplies +5V (at up to 1A) to external circuits while driving the LED with a fixed 80mA current. The internal 1MHz boost converter features an adaptive control scheme with an internal switching MOSFET and synchronous rectifier to improve efficiency and minimize external component count. The MAX8607 is available in a 14-pin, 3mm x 3mm TDFN package (0.8mm max height). Applications Camera Flashes/Strobes Cell Phones/Smartphones PDAs and Digital Cameras Ordering Information PART* MAX8607ETD+ PIN-PACKAGE 14 TDFN 3mm x 3mm (T1433-1) TOP MARK ABA +Indicates lead-free package. *The MAX8607ETD is characterized over the -40C to +85C temperature range. Pin Configuration TOP VIEW INPUT 2.7V TO 5.5V LED 2.2H Typical Operating Circuit OUTPUT LX 10F PGND COMP PGND PGND OUTS OUT LX LX MAX8607 OUT OUTS LGND GND 10F UP TO 1.5A FLASH UP TO 360mA MOVIE 14 13 12 11 10 9 8 MAX8607 + 1 COMP 2 EN1 3 EN2 4 MOV 5 FLSH 6 GND 7 LGND MODESELECT INPUTS EN1 EN2 FLSH LED MOV TDFN 3mm x 3mm ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1MHz PWM Boost Converter for 1.5A White LED Camera Flash MAX8607 ABSOLUTE MAXIMUM RATINGS OUT, OUTS, EN1, EN2 to GND ................................-0.3V to +6V FLSH, MOV, LED, COMP, LX to GND ....-0.3V to (VOUTS + 0.3V) LGND, PGND to GND. ..........................................-0.3V to +0.3V LX Current. ........................................................................2ARMS Continuous Power Dissipation (TA = +70C) 14-Pin TDFN 3mm x 3mm (derate 18.2mW/C above +70C)..............................................................1455mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VEN1 = VEN2 = 5V, VOUT = VOUTS = 4V, COUT = 10F, TA = -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1) PARAMETER Supply Voltage Undervoltage-Lockout Threshold OUT Quiescent Current, Flash or Movie Mode OUT Quiescent Current, Shutdown Mode CONDITIONS IC supplied from OUTS VOUTS rising, 100mV (typ) hysteresis LX switching, ILED = 0mA EN1 = EN2 = GND TA = +25C TA = +85C 5.3 3.65 4.8 TA = +25C TA = +85C Flash mode Movie mode Disco mode 1200 338 MIN 2.7 2.25 2.38 4 0.1 1 5.5 3.85 5.0 0.01 0.5 1500 360 80 1200 TA 0C (Note 2) TA = -40C -3 -6 62 0.5 0.5 48 80 5000 3 200 4.4 600 600 VCOMP = 1.5V 60 420 +3 +6 100 108 A/A % mV mA A/A % mV A mV mV S mA 5.7 3.95 5.2 1 A V 1 TYP MAX 5.5 2.65 UNITS V V mA A Overvoltage limit, ILED = 0mA, VLED = 0V OUT Regulation Voltage VLED = 0.5V Disco mode, ILED = 80mA LED Current, Shutdown Mode EN1 = EN2 = GND RMOV = 2k, RFLSH = 2k, VLED = 0.5V IMOV up to 300A RMOV = 2k, VLED = 0.5V RMOV = 2k VEN1 = 0V, VEN2 = 5V IFLSH up to 300A RFLSH = 2k, VLED = 0.5V, TA -40C (Note 2) RFLSH = 2k Current-Source Guaranteed Sink Current Current-Source Multiplier in MOV Mode (ILED / IMOV) Current-Source Accuracy in MOV Mode MOV Current-Source Dropout Voltage Disco Current-Source Current Setting Current-Source Multiplier in FLSH Mode (ILED / IFLSH) Current-Source Accuracy in FLSH Mode FLSH Current-Source Dropout Voltage LX n-Channel Current Limit MOV Regulation Voltage FLSH Regulation Voltage LED to COMP Transconductance 2 _______________________________________________________________________________________ 1MHz PWM Boost Converter for 1.5A White LED Camera Flash ELECTRICAL CHARACTERISTICS (continued) (VEN1 = VEN2 = 5V, VOUT = VOUTS = 4V, COUT = 10F, TA = -40C to +85C. Typical values are at TA = +25C, unless otherwise noted.) (Note 1) PARAMETER COMP Input Resistance to GND LED TA Derating Function Threshold LED TA Derating Function Slope EN1 and EN2 Logic-High Input Voltage EN1 and EN2 Logic-Low Input Voltage EN1 and EN2 Logic Input Bias Current LX n-Channel On-Resistance LX p-Channel On-Resistance LX Leakage Operating Frequency Maximum Duty Cycle Minimum Duty Cycle CONDITIONS During shutdown or UVLO Temperature when the LED current derating function begins TA = +40C to +85C VOUTS = 2.7V to 5.5V VOUTS = 2.7V to 5.5V VEN_ = 5.5V ILX = 200mA ILX = 200mA VLX = 5.5V TA = +25C TA = +85C 0.8 65 TA = +25C TA = +85C 0.01 0.03 50 100 0.01 0.03 1.0 75 4 8 1.2 100 200 1 1.4 0.4 1 MIN TYP 140 +40 -1.67 MAX 250 UNITS C %/C V V A m m A MHz % % MAX8607 Note 1: All devices are production tested at TA = +25C. Specifications over temperature are guaranteed by design and characterization and not production tested. Note 2: For temperatures below the thermal derating start point. Typical Operating Characteristics (Circuit of Figure 2, VIN = VEN1 = 3.6V, VEN2 = 0V, TA = +25C, unless otherwise noted.) FLASH-MODE BATTERY CURRENT vs. INPUT VOLTAGE MAX8607toc01 MOVIE-MODE BATTERY CURRENT vs. INPUT VOLTAGE MAX8607toc02 BOOST CONVERTER EFFICIENCY vs. LOAD CURRENT (DISCO MODE) 98 96 94 EFFICIENCY (%) 92 90 88 86 84 82 INCLUDES 83mA LED CURRENT MAX8607toc03 4000 3500 BATTERY CURRENT (mA) 3000 2500 2000 1500 1000 500 0 2.7 3.1 3.5 4.7 4.3 INPUT VOLTAGE (V) 3.9 5.1 RFLSH = 3.01k RFLSH = 4.02k RFLSH = 8.06k RFLSH = 2k 600 500 BATTERY CURRENT (mA) RMOV = 2.00k 400 300 200 RMOV = 6.49k 100 0 100 RMOV = 3.57k 80 2.7 3.1 3.5 4.7 4.3 INPUT VOLTAGE (V) 3.9 5.1 5.5 10 100 LOAD CURRENT (mA) 1000 5.5 _______________________________________________________________________________________ 3 1MHz PWM Boost Converter for 1.5A White LED Camera Flash MAX8607 Typical Operating Characteristics (continued) (Circuit of Figure 2, VIN = VEN1 = 3.6V, VEN2 = 0V, TA = +25C, unless otherwise noted.) LED CURRENT vs. AMBIENT TEMPERATURE MAX8607toc04 IC SUPPLY CURRENT vs. INPUT VOLTAGE DISCO MODE FLASH MODE 900 800 SUPPLY CURRENT (A) 700 600 500 400 300 200 100 0 MOVIE MODE MAX8607toc05 400 350 300 LED CURRENT (mA) 250 200 150 100 50 0 -40 -20 60 40 AMBIENT TEMPERATURE (C) 0 20 80 1000 2.7 3.1 3.5 3.9 4.3 4.7 INPUT VOLTAGE (V) 5.1 5.5 SWITCHING WAVEFORMS (MOVIE MODE) MAX8607toc06 SOFT-START RESPONSE (STANDBY TO MOVIE-MODE TRANSITION) MAX8607toc07 VIN 20mV/div VEN1 0V 5V/div 200mA/div VOUT 10mV/div ILED 0A IL 100mA/div IIN 0A 100mA/div VLX 5V/div VOUT 0V 2V/div 400ns/div 100s/div SOFT-START RESPONSE (MOVIE-MODE TO FLASH TRANSITION) MAX8607toc08 LOAD TRANSIENT (DISCO MODE) MAX8607toc09 VEN2 5V/div IL0AD 700mA 100mA ILED 200mA/div IIN 0A 500mA/div 0A 2V/div VOUT(RIPPLE) 500mV/div VOUT 0V 400s/div 2ms/div 4 _______________________________________________________________________________________ 1MHz PWM Boost Converter for 1.5A White LED Camera Flash MAX8607 Typical Operating Characteristics (continued) (Circuit of Figure 2, VIN = VEN1 = 3.6V, VEN2 = 0V, TA = +25C, unless otherwise noted.) MOVIE-MODE LED CURRENT vs. MOV RESISTANCE MAX8607toc10 FLASH-MODE LED CURRENT vs. FLSH RESISTANCE 1400 1200 LED CURRENT (mA) 1000 800 600 400 200 0 MAX8607toc11 400 350 300 LED CURRENT (mA) 250 200 150 100 50 0 1 10 RMOV (k) 1600 100 1 10 RFLSH (k) 100 Pin Description PIN 1 2 3 4 5 6 7 8 9, 10 11, 12 13 14 -- NAME COMP EN1 EN2 MOV FLSH GND LGND LED PGND LX OUT OUTS EP FUNCTION Compensation Input. Connect a 0.1F ceramic capacitor from COMP to GND for regulator stability. Enable Input 1. EN1 and EN2 set the operating mode (see Table 1). Enable Input 2. EN1 and EN2 set the operating mode (see Table 1). Movie Current Program Input. Connect a resistor from MOV to GND to set the LED current in movie mode. RMOV must be greater than 2k. Flash Current Program Input. Connect a resistor from FLSH to GND to set the LED current in flash mode. RFLSH must be greater than 2k. Analog Ground. Connect GND to the exposed paddle directly under the IC. LED Current Regulator Ground. Connect LGND to the ground plane on the PC board. LED Current Regulator. Connect LED to the cathode of the external LED. LED is high impedance during shutdown. Power Ground. Connect PGND to the input capacitor ground. Also, connect PGND to the PC board ground plane. Inductor Connection. Connect LX to the switched side of the inductor. LX is internally connected to the drains of the internal MOSFETs. Both MOSFETs are off during shutdown. Regulator Output. Connect OUT to the anode of the external LED. Bypass OUT to PGND with a 10F or larger ceramic capacitor. During shutdown, OUT is one body-diode drop below the input voltage. Output Sense and IC Supply Input. Connect OUTS to OUT at the output bypass capacitor. The IC's operating power is supplied from OUTS. Exposed Paddle. Connect the exposed paddle to GND directly under the IC and to a large PC board ground plane for increased thermal performance. _______________________________________________________________________________________ 5 1MHz PWM Boost Converter for 1.5A White LED Camera Flash MAX8607 LX OUT REF OUTS FORCED-PWM BOOST CONTROL PGND 1MHz CLOCK COMP 1.25V FEEDBACK SELECT EN1 EN2 SHUTDOWN AND MODE CONTROL LED FLSH MOV LDO REGULATOR GND MAX8607 LGND Figure 1. Functional Diagram Detailed Description Boost Converter The MAX8607 includes a fixed-frequency, PWM boost converter that supplies the LED current. The output voltage is adaptively controlled to provide adequate headroom with varying LED forward voltage. The boost converter switches an internal power MOSFET and synchronous rectifier at a constant 1MHz frequency with varying duty cycle up to 75% to maintain constant LED current over the 2.7V to 5.5V input range. Internal special circuits prevent any unwanted subharmonic switching in the critical buck/boost region. 6 LDO Current Regulator (LED) A low-dropout (LDO) linear current regulator from LED to LGND sinks current from the external LED's cathode terminal. The LED current is regulated to a user-programmable level. In movie mode, the current into LED is regulated to 1200 times the current set by the MOV resistor (RMOV). In flash mode, the current into LED is regulated to 5000 times the current set by the FLSH resistor (RFLSH). In disco mode, the current into LED is regulated to 80mA. _______________________________________________________________________________________ 1MHz PWM Boost Converter for 1.5A White LED Camera Flash Mode-Select Inputs (EN1, EN2) Drive EN1 high and EN2 low to enable movie mode. In this mode, the current regulator regulates the current through the LED to 1200 times the current set by the MOV resistor. See the Setting the Movie-Mode Current section for details on setting the movie-mode current. Drive EN1 and EN2 high to enable flash mode. In this mode, the current through the LED is regulated to 5000 times the current set by the FLSH resistor. See the Setting the Flash-Mode Current section for details on setting the flash-mode current. The time duration of the flash mode must be set using external circuitry or software. Drive EN1 low and EN2 high to enable disco mode. In this mode, the output of the boost converter provides a regulated +5V at up to 1A for external circuitry, while the LED current is regulated to 80mA. The LED current is not adjustable in this mode. Drive EN1 and EN2 low to place the IC into a lowpower shutdown mode. See the Shutdown section for more details. MAX8607 Table 1. EN1 and EN2 Mode Selection EN1 0 0 1 1 EN2 0 1 0 1 Shutdown Disco Mode Movie Mode Flash Mode MODE Shutdown Drive EN1 and EN2 low to place the MAX8607 into a low-power shutdown mode. In shutdown, supply current is reduced to 0.1A (typ). CCOMP is discharged during shutdown, allowing the device to reinitiate softstart when it is enabled. The internal MOSFET and synchronous rectifier are turned off during shutdown; however, OUT is one body-diode drop below the input. LED is high impedance so the external LED is off, but any external circuitry on OUT is not disconnected and, therefore, should include its own shutdown capability. Typical shutdown timing characteristics are shown in the Typical Operating Characteristics. Overvoltage Protection The output voltage of the MAX8607 is limited by internal overvoltage-protection (OVP) circuitry, which prevents the output from exceeding 5.7V under any conditions. In flash and movie modes, if the output voltage nears 5.5V, the LED current is smoothly reduced through proprietary means to prevent overvoltage without sudden termination of the output current. In case of an LED with very high forward voltage (V F), this circuit provides more reliable and repeatable flash than would a simple on/off comparator. In disco mode, the output is limited by the internal 5.0V regulation. Ambient Temperature Derating Function The MAX8607 limits the maximum LED current depending on its die temperature. Once the die temperature reaches +40C, the LED current decreases by 1.67% per C. This corresponds to approximately 0mA of LED current at +100C. Due to the package's exposed paddle, the die temperature is very close to the PC board temperature. The temperature derating function allows the LED current to be safely set higher at normal operating temperatures, thereby allowing either a brighter flash or movie light to be used for normal ambient temperatures. See the Typical Operating Characteristics for a graph of LED Current vs. Ambient Temperature. Undervoltage Lockout The MAX8607 contains undervoltage-lockout (UVLO) circuitry that disables the IC until VOUTS is greater than 2.38V. Prior to startup, VOUTS is one diode drop below the input voltage. This ensures a great enough input voltage for startup. Applications Information Setting the Movie-Mode Current To set the LED current during movie mode, connect a resistor from MOV to GND (RMOV). VMOV is regulated to 0.6V and the current through RMOV is mirrored to LED with a gain of 1200. RMOV is calculated as: RMOV = (0.6V x 1200) / ILED(MOV) Soft-Start The MAX8607 attains soft-start by charging C COMP with a 100A current source. During this time, the internal MOSFET is switching at the minimum duty cycle. Once VCOMP rises above 1V, the duty cycle increases until output reaches the desired regulation level. COMP is pulled to GND with a 140 internal resistor during UVLO, OVP, or shutdown. See the Typical Operating Characteristics for an example of soft-start operation. Setting the Flash-Mode Current To set the LED current during flash mode, connect a resistor from FLSH to GND (RFLSH). VFLSH is regulated to 0.6V and the current through RFLSH is mirrored to LED with a gain of 5000. RFLSH is calculated as: RFLSH = (0.6V x 5000) / ILED(FLSH) _______________________________________________________________________________________ 7 1MHz PWM Boost Converter for 1.5A White LED Camera Flash MAX8607 Capacitor Selection L1 INPUT 2.7V TO 5.5V 2.2H C1 10F 11, 12 13 14 C2 10F LX MAX8607 U1 OUT OUTS 9, 10 C3 0.1F 1 PGND D1 COMP LGND GND 7 6 MODESELECT INPUTS 2 3 EN1 EN2 FLSH 5 R1 Bypass the input to PGND using a ceramic capacitor. Place the capacitor as close to the IC as possible. The exact value of the input capacitor is not critical. The typical value for the input capacitor is 10F; however, larger value capacitors can be used to reduce input ripple at the expense of size and higher cost. The output capacitance required depends on the required LED current. A 10F ceramic capacitor works well in most situations, but a 4.7F capacitor is acceptable for load current below 300mA. MOV 4 LED EP R2 8 PC Board Layout Due to fast switching waveforms and high-current paths, careful PC board layout is required. Connect GND directly to the exposed paddle underneath the IC; connect the exposed paddle to the PC board ground plane. Connect LGND and PGND to the ground plane. The output bypass capacitor should be placed as close to the IC as possible. C COMP should be connected from COMP to GND as close to the IC as possible. Minimize trace lengths between the IC and the inductor, the input capacitor, and the output capacitor; keep these traces short, direct, and wide. The ground connections of CIN and COUT should be as close together as possible and connected to PGND. The traces from the input to the inductor and from the output capacitor to the LED may be longer. A sample layout is available in the MAX8607 evaluation kit (MAX8607EVKIT) to speed design. Figure 2. Typical Application Circuit Inductor Selection The MAX8607 is designed to use a 2.2H inductor. To prevent core saturation, ensure that the inductor-saturation current rating exceeds the peak inductor current for the application. Calculate the worst-case peak inductor current with the following formula: IPEAK = 5V x ILED(MAX) 0.9 x VIN(MIN) + VIN(MIN) x 0.5s 2 x 2.2H Chip Information PROCESS: BiCMOS Table 2 provides a list of suggested inductors. Table 2. Suggested Inductors MANUFACTURER Coilcraft Cooper (Coiltronics) FDK TOKO SERIES LPO3310 SD3114 MIPF2520 MIPW3226 DE2812C FDSE0312 INDUCTANCE (H) 2.2 2.2 2.2 2.2 2.2 2.2 DCR (m) 150 83 80 100 70 160 ISAT (A) 1.1 1.48 0.7 1.1 1.6 2.3 DIMENSIONS (LTYP x WTYP x HMAX = Volume) 3.3 x 3.3 x 1.0 = 11mm3 3.0 x 3.0 x 1.45 = 13mm3 2.5 x 2.0 x 1.0 = 5mm3 3.2 x 2.6 x 1.0 = 8mm3 3.0 x 2.8 x 1.2 = 10mm3 3.0 x 3.0 x 1.2 = 11mm3 8 _______________________________________________________________________________________ 1MHz PWM Boost Converter for 1.5A White LED Camera Flash Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 6, 8, &10L, DFN THIN.EPS MAX8607 MAX8607 _______________________________________________________________________________________ 9 1MHz PWM Boost Converter for 1.5A White LED Camera Flash MAX8607 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 0.20 MAX. 0.80 3.10 3.10 0.05 0.40 PACKAGE VARIATIONS PKG. CODE T633-2 T833-2 T833-3 T1033-1 T1033-2 T1433-1 T1433-2 N 6 8 8 10 10 14 14 D2 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.700.10 1.700.10 E2 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.65 BSC 0.65 BSC 0.50 BSC 0.50 BSC 0.40 BSC 0.40 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEC MO229 / WEEC MO229 / WEED-3 MO229 / WEED-3 ------b 0.400.05 0.300.05 0.300.05 0.250.05 0.250.05 0.200.05 0.200.05 [(N/2)-1] x e 1.90 REF 1.95 REF 1.95 REF 2.00 REF 2.00 REF 2.40 REF 2.40 REF 0.25 MIN. 0.20 REF. Revision History Pages changed at Rev 1: 1, 2, 9, 10 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. |
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