DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs General Description Features The AAT1270 is a high-efficiency, high-current boost converter capable of 1A maximum output current. It is an ideal power solution for LED photo flash applications in all singlecell Lithium-ion / polymer battery operated products. • Input Voltage Range: 2.7V to 5.5V • Dual Channel Output ▪ Up to 1A Regulated Output Current (0.5A per Channel) • Up to 85% Efficiency with Small Magnetics • 2 MHz Switching Frequency • Separate Flash Enable Input • Separate Flash Inhibit Input • Single Resistor Sets Flash and Movie Mode Current ▪ Fixed Flash-to-Movie Mode Current Ratio • 16-Level Movie Mode Current via S2Cwire™ • User-Programmable Safety Timer • True Load Disconnect • Input Current Limit • Over-Voltage (Open LED, Open Circuit), Short-Circuit, and Over-Temperature Protection • Shutdown Current: < 1.0µA • Small Inductor Solution: 1µH (0.9mm in height) • 14-pin STDFN 3x3 Package • -40 to +85°C Temperature Range The AAT1270 maintains output current regulation by switching the internal high-side and low-side switch transistors. The transistor switches are pulse-width modulated at a fixed frequency of 2MHz. The high switching frequency allows the use of a small inductor and output capacitor, making the AAT1270 ideally suited for small battery-powered applications. Skyworks’ proprietary S2Cwire™ (Simple Serial Control) serial digital interface is used to enable, disable and set the movie mode current level for the flash LEDs to one of 16 levels. The AAT1270 also includes a separate Flash Enable input to initiate both flash/strobe operation and the default timer, which can be used to terminate a flash event after a user-programmed delay or as a safety feature. A Flash Inhibit pin is also included which reduces flash current to movie mode level during high battery demand. The maximum flash and movie mode current is set by one external resistor; the ratio between flash and movie mode current is set at approximately 7.3:1. One or two LEDs can be connected to the AAT1270; when two LEDs are used, the output current is matched between each diode. The AAT1270 contains over-voltage protection and a thermal management system to protect the device in the event of an output open-circuit and short-circuit condition respectively. Built-in circuitry prevents excessive inrush current during start-up. The shutdown feature reduces quiescent current to less than 1.0µA. Applications • • • • • • • Camcorder Video Light (Torch Light) Cellphones / Smartphones Digital Still Cameras (DSC) LED Photo Flash Light (Strobe Light) Mobile Handsets MP3 Players PDAs and Notebook PCs The AAT1270 is available in a Pb-free, thermally-enhanced 14-pin 3x3mm STDFN package. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 1 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Typical Application L1 1µH IN Flash LEDs Lumiled LXCL-PWF1 or equivalent SW OUT CIN 2.2µF VBATTERY Movie Mode Enable and Set COUT 2.2µF EN/SET Flash Enable FLEN Flash Inhibit FLINH FLOUTB RSET CT RSET 162kΩ 2 AAT1270 FLOUTA GND AGND PGND FLGND CT 47nF Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Pin Descriptions Pin # Symbol 1 CT 2 EN/SET 3 4 FLEN AGND 5 IN 6 7 SW PGND 8 OUT 9 GND 10 FLINH 11 FLOUTB 12 FLGND 13 FLOUTA 14 RSET EP Function Flash timer control input. Connect a capacitor between CT and AGND to set maximum duration for the flash pulse. A 47nF ceramic capacitor sets the flash timer to 1s. To disable the flash timer, connect CT to AGND. Enable and movie mode serial control input. EN/SET is the S2Cwire programming input to adjust the movie mode current level to one of 16 different levels based on the maximum current/7.3 set via the RSET pin. Flash enable pin. A low-to-high transition on the FLEN pin initiates a flash pulse and starts the flash timer. Analog ground pin. Connect AGND to PGND, GND, and FLGND at a single point as close to the AAT1270 as possible. Power input. Connect IN to the input power supply voltage. Connect a 2.2µF or larger ceramic capacitor from IN to PGND as close as possible to the AAT1270 Boost converter switching node. Connect a 1µH inductor between SW and IN. Power ground pin. Connect PGND to AGND, GND, and FLGND at a single point as close to the AAT1270 as possible. Power output of the boost converter. Connect a 2.2µF or larger ceramic capacitor from OUT to PGND as close as possible to the AAT1270. Connect OUT to the anode(s) of the flash LED(s). Ground pin. Connect GND to PGND, AGND, and FLGND at a single point as close to the AAT1270 as possible. Flash inhibit pin. FLINH is an active HIGH control input with an internal 200kΩ resistor to AGND. A low-to-high transition on the FLINH pin reduces FLOUTA and FLOUTB output currents to the maximum (default) movie-mode current level for the duration of FLINH. Strobing the FLINH pin low to high does not reset the flash timer. Flash output B. Connect cathode of Flash LEDB to FLOUT B. For a single flash LED, connect FLOUTB and FLOUTA together. For two flash LEDs, each output will conduct 50% of the total flash output current. Flash ground pin. Connect FLGND to PGND, GND, and AGND at a single point as close to the AAT1270 as possible Flash output A. Connect cathode of Flash LED A to FLOUTA. For a single flash LED, connect FLOUTA and FLOUTB together. For two flash LEDs, each output will conduct 50% of the total flash output current. Flash current setting input. A 162kΩ resistor from RSET to AGND sets the maximum flash current available at FLOUTA or FLOUTB to 500mA. Each FLOUTA and FLOUTB channel will conduct 50% of the maximum programmed current. The AAT1270’s flash-to-movie-mode ratio is fixed at 7.3. Exposed paddle (bottom); Connect EP to PGND as close as possible to the AAT1270. Pin Configuration STDFN33-14 (Top View) CT EN/SET FLEN AGND IN SW PGND 1 14 2 13 3 12 4 11 5 10 6 9 7 8 RSET FLOUTA FLGND FLOUTB FLINH GND OUT Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 3 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Absolute Maximum Ratings1 TA = 25°C unless otherwise noted. Symbol IN, SW, OUT RSET, EN/SET, FLEN, FLINH, CT, FLOUTA, FLOUTB TJ TS TLEAD Description Value Units Maximum Rating -0.3 to 6.0 V Maximum Rating VIN + 0.3 V -40 to 150 -65 to 150 300 °C °C °C Value Units 50 2 °C/W W Operating Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Recommended Operating Conditions Symbol θJA PD Description Thermal Resistance Maximum Power Dissipation 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Electrical Characteristics1 VIN = 3.6V; CIN = 2.2µF; COUT = 2.2µF; L = 1µH; RSET = 162kΩ; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions Power Supply VIN Input Voltage Range VOUT(MAX) Maximum Output Voltage IIN(Q) VIN Supply Current ISHDN(MAX) IFL(TOTAL) IFL(MATCH) VIN Shutdown Current Total Output Current, Flash Mode FLOUTA and FLOUTB Current Matching IMM(TOTAL) Total Output Current, Movie Mode fOSC Switching Frequency tDEFAULT Default ON time TSD Thermal Shutdown Threshold TSD(HYS) Thermal Shutdown Hysteresis EN/SET/ FLEN/ FLINH Logic Control VEN/SET(L), EN/SET, FLEN Input Low Threshold VFLEN(L) VEN/SET(H), EN/SET, FLEN Input High Threshold VFLEN(H) IEN/SET EN/SET Input Leakage Current IFLEN FLEN Input Leakage Current VT(FLINH) RIN(FLINH) tEN/SET(LOW) tEN/SET(HI_MIN) tEN/SET(HI_MAX) tEN/SET(OFF) tEN/SET(LAT) tFLEN_ON tFLEN_OFF tFLINH_ON tFLINH_OFF Min Max Units 5.5 5.5 1 V V 2.7 FLEN = IN, Set FL Load = 1A EN/SET = IN, Set FL Load = 0A, RSET = 162kW EN/SET = FLEN = FLINH = GND RSET = 162kW; FLOUTA + FLOUTB RSET = 162kW; Movie Mode Current Set = 100%; FLOUTA + FLOUTB TA = 25°C CT = 47nF 0.57 0.23 800 1000 10 1 1200 137 1.5 VEN/SET = VIN = 5V VFLEN = VIN = 5V 2.0 1 140 15 µA mA % 2.5 MHz s °C °C 0.4 V V -1 -1 1 1 ½ VIN 200 µA µA V 0.3 75 50 75 500 500 EN/SET = GND EN/SET = GND mA mA 1.4 FLINH Input Threshold Voltage FLINH Input Resistance to AGND EN/SET Serial Interface Low Time Minimum EN/SET High Time Maximum EN/SET High Time EN/SET Off Timeout EN/SET Latch Timeout FLEN ON Delay Time FLEN OFF Delay Time FLINH ON Delay Time FLINH OFF Delay Time Typ 100 20 100 5 kΩ µs ns µs µs µs µs µs µs µs 1. The AAT1270 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 5 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Typical Characteristics Efficiency vs. Input Voltage Shutdown Current vs. Input Voltage (Movie and Flash Mode) (EN/SET = FLEN = 0V) 90 0.12 Efficiency (%) 80 500mA (Flash) Shutdown Current (µA) 68.5mA (Movie) 85 75 70 65 34.25mA (Movie) 60 55 13.7mA (Movie) 50 45 0.1 0.08 0.06 0.04 0.02 40 2.7 3.1 3.5 3.9 4.3 4.7 5.1 0 2.7 5.5 Input Voltage (V) 2.0 25°C 1.5 85°C 0.5 0.0 3.5 3.9 4.3 4.7 5.1 5.5 FLOUTB 5 0 FLOUTA -5 -10 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Movie Mode Current Matching vs. Temperature Flash Mode Current Matching vs. Temperature (68.5mA/ch) (500mA/ch) 515 70.5 70.0 FLOUTA LED Current (mA) LED Current (mA) 5.1 10 2.7 5.5 Input Voltage (V) 4.7 Input Voltage (V) LED Current Accuracy (%) Switching Frequency (MHz) -40°C 3.1 4.3 (68.5mA/Ch) 3.0 2.7 3.9 Movie Mode LED Current Accuracy vs. Input Voltage (EN/SET = FLEN = 0V) 1.0 3.5 Switching Frequency vs. Input Voltage 2.5 3.1 69.5 69.0 68.5 68.0 FLOUTB 67.5 67.0 66.5 510 505 FLOUTB 500 FLOUTA 495 490 66.0 485 -40 65.5 -40 -15 10 35 Temperature (°C) 6 60 85 -15 10 35 Temperature (°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 60 85 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Flash Mode Output Ripple 3.22 3.18 0V 1.4 1.2 1.0 Time (200ns/div) Movie Mode Output Ripple (68.5mA/channel; VIN = 3.0V) 3.18 3.16 3.14 0V 0.2 0.0 Time (500ns/div) EN/SET, FLEN Input High Threshold vs. Input Voltage EN/SET, FLEN Input Low Threshold vs. Input Voltage 1.2 1.2 -40°C -40°C 1.0 VEN/SET(L) (V) VEN/SET(H) (V) 1.0 0.8 25°C 85°C 0.6 0.8 0.6 25°C 85°C 0.4 0.4 0.2 0.2 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) EN/SET Latch Timeout vs. Input Voltage EN/SET Off Timeout vs. Input Voltage 550 450 TEN/SET(OFF) (µs) 350 85°C 25°C 300 -40°C 500 -40°C 400 TEN/SET(LAT) (µs) Inductor Current (bottom) (A) 3.26 Output Voltage (top) (V) Switching Voltage (2V/div) (middle) (V) (500mA/channel; VIN = 3.1V) Inductor Current (bottom) (A) Output Voltage (top) (V) Switching Voltage (2V/div) (middle) (V) Typical Characteristics 450 400 25°C 350 300 85°C 250 250 200 200 2.7 3.1 3.5 3.9 4.3 Input Voltage (V) 4.7 5.1 2.7 5.5 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 7 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Typical Characteristics FLEN ON Delay Time vs. Input Voltage Flash Inhibit On Delay Time (EN/SET = 0V; FLEN = 3.3V; 500mA/ch) 200 FLINH (2V/div) 180 -40°C 140 VOUT (2V/div) 120 100 VSINK (2V/div) 80 60 25°C 85°C 40 0V 4 2 0 1A ILED (500mA/div) 20 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Time (100µs/div) Movie Mode Turn On Movie Mode Turn On (13.7mA/ch) (68.5mA/ch) EN/SET (2V/div) 0V EN/SET (2V/div) VOUT (2V/div) 0V VOUT (2V/div) VSINK (2V/div) ILED (100mA/div) VSINK (2V/div) 0V ILED (100mA/div) 0A Time (200µs/div) 0V 0V 0V 0A Time (100µs/div) Movie Mode to Flash Mode Turn On Flash Mode Turn On (68.5mA/ch to 500mA/ch) VOUT (2V/div) FLEN (2V/div) 0V 4 2 VSINK (2V/div) 0 1A Voltage (V) FLEN (2V/div) (500mA/ch) ILED (1A/div) Time (100µs/div) 8 0V VOUT (2V/div) 0V VSINK (2V/div) 0V IIN (1A/div) 0A Time (100µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 Voltage (V) TFLEN_ON (µs) 160 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Typical Characteristics Movie Mode Line Transient Movie Mode Current Transition (68.5mA/ch; VIN = 4.2V to 3.6V) (68.5mA/ch to 13.7mA/ch) EN/SET (2V/div) 4.2V VIN (500mV/div) VOUT (AC coupled) (100mV/div) 3.6V VSINK (AC coupled) (200mV/div) ILED (AC coupled) (50mA/div) ILED (100mA/div) Time (50µs/div) 3.3V 0A Time (200µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 9 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Functional Block Diagram IN SW OUT FLOUTA FLOUTB EN/SET FLEN FLINH Control 200kΩ RSET CT Functional Description The AAT1270 is a boost converter with a current regulated output designed to drive high current white LEDs used in flash/movie light applications. The maximum flash current is set by an external resistor, RSET, which not only sets the flash current but also sets the maximum movie mode current reduced by a factor of 7.3. A flash pulse is initiated by switching the FLEN (flash enable) pin from low to high, which initiates the flash pulse and also starts the internal timer. The maximum flash time is determined by an external timing capacitor connected to the CT pin. The flash duration can be set from 50ms to a maximum of 1s. The flash timer will terminate the flash current regardless of the status of the FLEN pin. 10 AGND PGND FLGND GND This can be either used as a simple flash timing pulse or as a safety timer in the event of a control logic malfunction to prevent the LED from over-heating. If the safety timer is not needed in the application, it can be disabled by connecting the CT pin directly to AGND. For applications using two flash LEDs, each diode can be connected to its corresponding current sink (FLOUTA or FLOUTB) and the output current will be equally shared. In single flash LED applications, the two current sinks can be connected together to apply the full output current into the LED. If one sink pin (FLOUTA or FLOUTB) is not used, the unused current sink must be directly connected to OUT, which disables that channel. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs The movie-mode output current is controlled by the EN/ SET pin, which uses a single-wire S2Cwire interface to adjust the output current to one of 16 different levels. As shown in Table 1, the current settings are in logarithmic scale where each code is 1dB below the previous code. The FLEN signal takes priority over movie-mode operation. In mobile GSM systems where the phone remains in constant contact with the base station by regular communication, a FLINH pin is provided to prevent the camera flash and PA transmission pulses from occurring simultaneously, potentially causing the battery voltage to drop below the system’s undervoltage lockout threshold (UVLO) or creating unwanted EMI. During a flash event, strobing the FLINH pin low-to-high will reduce the LED current to the maximum movie mode current level for the duration of FLINH. Strobing FLINH high-to-low will instruct the AAT1270 to revert the flash LED current to its default (maximum) level assuming that the FLEN pin is still active (HIGH) and that the flash timer has not expired. Over-Temperature Protection Thermal protection disables the AAT1270 when internal power dissipation becomes excessive, as it disables both MOSFETs. The junction over-temperature threshold is 140°C with 15°C of temperature hysteresis. The output voltage automatically recovers when the over-temperature fault condition is removed. Over-Voltage Protection (Open LED, Open Circuit) The AAT1270’s output voltage is limited by internal overvoltage protection circuitry, which prevents damage to the AAT1270 from open LED or open circuit conditions. During an open circuit, the output voltage rises and reaches 5.5V (typical), and the OVP circuit disables the switching, preventing the output voltage from rising higher. Once the open circuit condition is removed, switching will resume. The controller will return to normal operation and maintain an average output voltage. Applications Information LED Selection The AAT1270 is specifically designed to drive white flash LEDs (typical forward voltage of 2.5V to 4.5V). Since the FLOUTA and FLOUTB input current sinks are matched with low voltage dependence; the LED-to-LED brightness will be matched regardless of the individual LED forward voltage (VF) levels. Flash Mode LED Current The LED current is controlled by the RSET resistor. For maximum accuracy, a 1% tolerance resistor is recommended. FLOUTA and FLOUTB can be programmed up to a maximum total flash current of 1A, or up to 500mA per channel. FLOUTA and FLOUTB output current is matched across the programming range. The maximum flash current in each FLOUTA and FLOUTB is set by the RSET resistor and can be calculated using the following equation: IFLOUTA = IFLOUTB = 81kΩ ⋅ A 81kΩ ⋅ A = = 500mA per channel RSET 162kΩ Movie Mode LED Current In the default movie mode, the corresponding FLOUTA/ FLOUTB movie mode current can be calculated: IMOVIE MODE[A/B] = IFLOUT[A/B]MAX 7.3 For example, if an RSET value of 162kΩ is chosen, then the FLOUTA/FLOUTB flash current is set to 500mA. For movie mode operation, the maximum current available at either FLOUTA or FLOUTB is then: IMOVIE MODE[A/B] = IFLOUT[A/B]MAX 500mA = = 68.5mA 7.3 7.3 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 11 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Alternatively, the AAT1270 S2Cwire interface programs the movie mode current at a reduced level. The FLOUTA/ FLOUTB movie-mode current can be adjusted in logarithmic fashion to one of 16 steps. Table 1 illustrates approximate movie mode levels to which the AAT1270 movie mode operation can be programmed. S2Cwire Data Percentage of Maximum Movie Mode Current (%) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 161 100 89 79 71 63 56 50 44.7 39.8 35.5 31.6 28.2 25.1 22.4 20 0 faster than 1MHz, or at much slower speeds, such as 15kHz. After data is applied, EN/SET is strobed high and held high to latch the data. Once the signal applied at the EN/SET pin has been held in the logic high state for time longer than tLAT (500µs), the programmed current becomes active and the internal data register is reset to zero. For subsequent current level programming, the number of rising edges corresponding to the desired code must be applied to the EN/SET pin. Flash Timer The AAT1270A includes a timer circuit that enables the flash current sinks for a programmed period of time. This feature eliminates the need for an external, housekeeping baseband controller to contain a safety delay routine. It also serves as a protection feature to minimize thermal issues with the flash LEDs in the event an external controller’s flash software routine experiences hang-up or freeze. The flash timeout T can be calculated by the following equation: T = 21.5s/µF · CT Table 1: Programming Movie Mode Current via S2Cwire (%). Where T is in seconds and CT is the capacitance of the timer capacitor in µF. S2Cwire Serial Interface For example, using a 47nF capacitor for CT sets the flash timeout to: The Simple Serial Control (S2Cwire) serial interface records rising edges at the EN/SET pin and decodes them into 16 different states. The S2Cwire serial interface has flexible timing. Data can be applied at speeds Flash Timeout = 21.5s/µF · 0.047µF = 1s THI TLO TOFF T LAT EN/SET 1 Data Reg 2 n-1 0 n ≤ 16 n 0 Figure 1: S2Cwire Serial Interface Timing. 1. When the device is in off state (EN/SET = 0V), programming S2Cwire data to DATA=16 for the first time will generate a small test current sourced through the two flash channels for a very short time. As a result, the two LEDs will blink. 12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs The relationship between capacitance of the timer capacTimer Capacitor vs. Flash Timeout itor and the flash timeout is illustrated in Figure 2. 50 Capacitance (nF) 45 40 35 inductor current rating, which is determined by the saturation characteristics. Measurements at full load and high ambient temperature should be performed to ensure that the inductor does not saturate or exhibit excessive temperature rise. The output inductor (L) is selected to avoid saturation at minimum input voltage and maximum output load conditions. Worst-case peak current occurs at minimum input voltage (maximum duty cycle) and maximum load. 30 25 20 15 10 5 0 0 100 200 300 400 500 600 700 800 900 1000 Flash Timeout (ms) Figure 2: Timer Capacitor vs. Flash Timeout. Selecting the Boost Inductor The AAT1270 controller utilizes PWM control and the switching frequency is fixed. To maintain 2MHz maximum switching frequency and stable operation, an 1µH output inductor is recommended. At high load the switching frequency is somewhat diminished, resulting in higher IPEAK. Bench measurements are recommended to confirm actual IPEAK and to ensure that the inductor does not saturate at maximum LED current and minimum input supply voltage. The RMS current flowing through the boost inductor is equal to the DC plus AC ripple components. Under worst-case RMS conditions, the current waveform is critically continuous. The resulting RMS calculation yields worst-case inductor loss. The RMS current value should be compared against the inductor manufacturer’s temperature rise, or thermal derating, guidelines: Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and peak IRMS = IPEAK 3 Timing Diagram FLASH FLASH FLASH FLASH FLASH FLASH TIMES OUT tDLY(CT) MOVIE MODE LED CURRENT (0mA) FLASH LOWERED TO MOVIE-MODE DURING FLINH tDLY(CT) FLASH TIMES OUT SET BY CT FLASH LOWERED TO MOVIE-MODE DURING FLINH DATA TO MOVIE-MODE LEVEL EN/SET FLASH ENABLE FLASH INHIBIT Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 13 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Manufacturer Part Number Inductance (μH) Max DC ISAT Current (A) DCR (mΩ) Size (mm) (LxWxH) Type Murata Murata CoilCraft Cooper Bussmann Cooper Bussmann Sumida LQM2HPN1R0MG0 LQH3NPN1R0G0 LPS3010 SD3110 SD3812 CDH38D11/S 1.0 1.0 1.0 1.0 1.0 1.0 1.6 1.58 1.6 1.47 2.69 2.8 55 110 85 68.3 48 39 2.5x2.0x0.9 3.0X3.0x1.0 3.0x3.0x1.0 3.1x3.1x1.0 4.0x4.0x1.2 4.0x4.0x1.2 Multilayer Wirewound Wirewound Wirewound Wirewound Wirewound Table 2: Typical Suggested Surface Mount Inductors. For a given inductor type, smaller inductor size leads to an increase in DCR winding resistance and, in most cases, increased thermal impedance. Winding resistance degrades boost converter efficiency and increases the inductor’s operating temperature: boost regulator. MLC capacitors of type X7R or X5R are recommended to ensure good capacitance stability over the full operating temperature range. The output capacitor is selected to maintain the output load without significant voltage droop (∆VOUT) during the power switch ON interval. A ceramic output capacitor 2.2µF is recommended (see Table 3). PLOSS(INDUCTOR) = IRMS2 · DCR In general, it is good design practice to place a decoupling capacitor (input capacitor) between the IN and GND pins. An input capacitor in the range of 2.2µF to 10µF is recommended. A larger input capacitor in this application may be required for stability, transient response, and/or ripple performance. Typically, 6.3V or 10V rated capacitors are required for this flash LED boost output. Ceramic capacitors selected as small as 0603 are available which meet these requirements. MLC capacitors exhibit significant capacitance reduction with applied voltage. Output ripple measurements should confirm that output voltage droop and operating stability are within acceptable limits. Voltage derating can minimize this factor, but results may vary with package size and among specific manufacturers. The high output ripple inherent in the boost converter necessitates the use of low impedance output filtering. Multi-layer ceramic (MLC) capacitors provide small size and adequate capacitance, low parasitic equivalent series resistance (ESR) and equivalent series inductance (ESL), and are well suited for use with the AAT1270 To maintain stable operation at full load, the output capacitor should be selected to maintain ∆VOUT between 100mV and 200mV. The boost converter input current flows during both ON and OFF switching intervals. The input ripple current is less than the output ripple and, as a result, less input capacitance is required. Selecting the Boost Capacitors Manufacturer Part Number Capacitance (μF) Voltage Rating (V) Temp Co. Case Size Murata Murata Murata Murata Murata Murata GRM185R60J225KE26 GRM188R71A225KE15 GRM21BR70J225KA01 GRM21BR71A225KA01 GRM219R61A475KE19 GRM21BR71A106KE51 2.2 2.2 2.2 2.2 4.7 10 6.3 10 6.3 10 10 10 X5R X7R X7R X7R X5R X7R 0603 0603 0805 0805 0805 0805 Table 3: Typical Suggested Surface Mount Capacitors. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs DC- DC+ JP6 MCU R5 10K EN/SET 0 2 4 1 2 3 4 SW1 1 3 5 U2 VDD GP5 GP4 GP3 VSS GP0 GP1 GP2 PIC12F675 8 7 6 5 EN/SET R8 0 10k C4 1µF R7 330 LED2 GRN JP5 JP7 FLEN R6 330 0 LED1 RED 2 4 1 3 5 FLINH 0 SW2 JP3 2 4 R2 100K L1 C1 2.2µF 1µH C3 47nF SW3 JP4 U1 CT RSET EN/SET FLOUTA FLEN FLGND AGND FLOUTB IN FLINH SW GND PGND OUT AAT1270 STDFN33-14 VOUT JP1 0 R4 100k (opt) R3 100k 1 2 3 4 5 6 7 1 3 5 D1 14 13 12 11 10 9 8 R1 162k JP2 0 D2 C2 2.2µF L1 Murata LQM2HPN1R0MG0 1µH 1.6A 55mΩ C1, C2 Murata GRM188R71A225KE15 2.2µF 0603 X7R 10V C3 Murata GRM155R71A473KA01 47nH 0402 X7R 10V Figure 3: AAT1270 Evaluation Board Schematic. PCB Layout Guidelines Boost converter performance can be adversely affected by poor layout. Possible impact includes high input and output voltage ripple, poor EMI performance, and reduced operating efficiency. Every attempt should be made to optimize the layout in order to minimize parasitic PCB effects (stray resistance, capacitance, and inductance) and EMI coupling from the high frequency SW node. A suggested PCB layout for the AAT1270 1A step-up regulator is shown in Figures 4 through 7. The following PCB layout guidelines should be considered: 1. Minimize the distance from capacitor CIN and COUT’s negative terminals to the PGND pins. This is especially true with output capacitor COUT, which conducts high ripple current from the output to the PGND pins. 2. Minimize the distance between L1 to IN and switching pin SW; minimize the size of the PCB area connected to the SW pin. 3. Maintain a ground plane and connect to the IC PGND pin(s) as well as the PGND connections of CIN and COUT. 4. Consider additional PCB exposed area for the flash LEDs to maximize heatsinking capability. This may be necessary when using high current application and long flash duration application. 5. Connect the exposed paddle (bottom of the die) to either PGND or GND. Connect AGND, FLGND to GND as close as possible to the package. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 15 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Figure 4: AAT1270 Evaluation Board Top Side Layout. Figure 5: AAT1270 Evaluation Board Second Layer. Figure 6: AAT1270 Evaluation Board Third Layer. Figure 7: AAT1270 Evaluation Board Bottom Side Layout. Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 16 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Component Part Number U1 AAT1270IFO U2 SW1-SW3 R1 R2, R3, R4 R5, R8 R6, R7 JP1, JP2, JP7 C1, C2 C3 C4 L1 D1-D2 LED1 LED2 JP3, JP4, JP5, JP6 PIC12F675 PTS645TL50 Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor GRM188R71A225KE15 GRM155R71A473KA01 GRM216R61A105KA01 LQM2HPN1R0MG0 LXCL-PWF1 CMD15-21SRC/TR8 CMD15-21VGC/TR8 PRPN401PAEN Description 1A Step-Up Current Regulator for Flash LEDs; STDFN33-14 package 8-bit CMOS, FLASH-based μC; 8-pin PDIP package Switch Tact, SPST, 5mm 162kΩ, 1%, 1/4W; 0402 100kΩ, 1%, 1/4W; 0603 10kΩ, 5%, 1/4W; 0603 330Ω, 5%, 1/4W; 0603 0Ω, 5% 2.2µF, 10V, X7R, 0603 47nF, 10V, X7R, 0402 1µF, 10V, X5R, 0805 Multilayer, 1µH, 1.6A, 55mΩ White Flash LED Red LED; 1206 Green LED; 1206 Conn. Header, 2mm zip Manufacturer Skyworks Microchip ITT Industries Vishay Vishay Vishay Vishay Vishay Murata Murata Murata Murata Lumileds, Philips Chicago Miniature Lamp Chicago Miniature Lamp Sullins Electronics Table 4: AAT1270 Evaluation Board Bill of Materials. Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 17 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Ordering Information Package Marking1 Part Number (Tape and Reel)2 STDFN33-14 XXXYY AAT1270IFO-T1 Skyworks Green™ products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of Green™, document number SQ04-0074. Package Information3 STDFN33-14 Detail "A" 3.000 ± 0.050 2.570 ± 0.050 Index Area 3.000 ± 0.050 1.700 ± 0.050 Top View Bottom View Pin 1 Indicator (Optional) 0.210 ± 0.050 Side View R0.2 0.400 BSC 0.025 ± 0.025 0.152 REF 0.550 ± 0.050 0.425 ± 0.050 Detail "A" All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3.The leadless package family, which includes QFN, TQFN, DFN, TDFN, and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. 18 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 DATA SHEET AAT1270 1A Step-Up Current Regulator for Flash LEDs Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202083B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 21, 2012 19