DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs General Description Features The AAT1290 is a high-efficiency, high-current boost converter capable of 1.5A typical output current. It is an ideal power solution for LED photo flash applications in all single cell Li-ion powered products. •VIN Range: 2.7V to 5.5V • Single Channel Flash Output • Up to 1.5A Regulated Output Current • Up to 85% Efficiency with Small Inductor (1µH) • 2 MHz Switching Frequency • Separate Flash Enable • User-Programmable Safety Timer • Single Resistor Sets Flash and Movie Mode Current •AS2Cwire Single Wire Programming: ▪ Movie Mode Current ▪ Movie Mode Enable ▪ Flash/Movie Mode Current Ratio ▪ Flash Safety Timer • True Load Disconnect • Soft-Start and Input Current Limit • Over-Voltage (Open LED, Open Circuit), Short Circuit, and Over-Temperature Protection • Shutdown Current < 1.0µA • 14-pin TDFN 3x3 mm Package • -40°C to +85°C Temperature Range The AAT1290 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 AAT1290 ideally suited for small battery-powered applications. Skyworks' proprietary AS2Cwire™ (Advanced Simple Serial Control™) serial digital interface is used to enable, disable, configure, and program the operation of the AAT1290. Using the AS2Cwire interface, the movie-mode current level for the LED, the safety timer delay, and the flash-to-movie-mode current ratio can be programmed to one of 16 levels. In addition, the single-wire serial protocol sets output channel control. The AAT1290 also includes a separate Flash Enable input to initiate both the flash operation and the default timer which can be used either to terminate a flash event at the end of a userprogrammed delay or as a safety feature. Also included is a Flash Inhibit pin which reduces the flash current to movie-mode levels during high battery demand. The maximum flash and movie-mode current is set by one external resistor where the ratio of Flash to Moviemode current is set at approximately 7.3:1. The AAT1290 can drive one high current LED. Applications • Camera Enabled Mobile devices •Cellphones/Smartphones • Digital Still Cameras (DSCs) • LED Photo Flash/Torch • Multimedia Mobile Phone The AAT1290 contains a thermal management system to protect the device in the event of an output short-circuit condition. Built-in circuitry prevents excessive inrush current during start-up. The shutdown feature reduces quiescent current to less than 1.0µA. The AAT1290 is available in a Pb-free, thermallyenhanced 14-pin 3x3mm TDFN package. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 1 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Typical Application L1 1µH VBATT = 2.7V to 5.5V CIN 2.2µF SW IN OUT COUT 2.2µF AAT 1290 Enable /Set Input Flash Enable EN/SET FLEN Flash LED FL RSET RSET Flash Inhibit FLINH CT CT PGND AGND FLGND Pin Descriptions Pin # Symbol 1 CT 2 EN/SET 3 FLEN 4, 9 AGND 5 IN 6 7 SW PGND 8 OUT 10 FLINH 11 12 13 NC FLGND FL 14 RSET EP 2 Function Flash timer control input. Connect a capacitor between CT and AGND to set maximum duration of the flash pulse. To disable the flash timer, connect CT to AGND. Enable and Serial Control input. EN/SET is the AS2Cwire addressing and programming input to: a) adjust the movie-mode current level; b) program the flash timer based on CT; c) select the Flash-to-Movie-mode ratio; and d) enable/disable movie mode operation. Flash enable pin. A low-to-high transition on the FLEN pin initiates a flash pulse and a high-to-low transition on the FLEN pin terminates a flash pulse. Analog ground pin. Connect AGND to PGND and FLGND at a single point as close to the AAT1290 as possible. Flash output boost converter power input. Connect IN to the input power source. Connect a 2.2μF or larger ceramic capacitor from IN to PGND and locate as close as possible to the IC package for optimum performance. Boost converter switching node. Connect a 1µH inductor between SW and IN. Power ground. Connect PGND to the same single point as AGND located as close to the IC 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 AAT1290. Connect OUT to the anode of the Flash LED. Flash inhibit pin. FLINH is an active HIGH control input with an internal 200kΩ resistor to AGND. A low-tohigh transition on the FLINH pin reduces FL sink current 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. No connect. Flash ground pin. Connect FLGND to PGND and AGND at a single point as close to the AAT1290 as possible. LED Flash current sink pin. Connect the cathode of Flash LED to FL. Flash current setting input. Connect a resistor from RSET to AGND to program the desired flash current for the current sink FL. Exposed paddle (bottom); Connect EP to PGND as close as possible to the AAT1290. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Pin Configuration TDFN33-14 (Top View) TDFN 3x3mm (Top View) CT 1 14 RSET EN/SET 2 13 FL FLEN 3 12 FLGND AGND 4 11 NC IN 5 10 FLINH SW 6 9 AGND PGND 7 8 OUT Absolute Maximum Ratings1 Symbol Description Value IN, SW, OUT Maximum Rating -0.3 to 6.0 RSET, EN/SET, FLEN, FLINH, CT, FL Maximum Rating VIN + 0.3 TJ Ts TLEAD Operating Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Units -40 to 150 -65 to 150 300 °C Value Units 50 2 °C/W W 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. The AAT1290 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 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 3 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Electrical Characteristics1 VIN = 3.6V; CIN = 2.2µF; COUT = 2.2µF; L = 1µH; RSET = 107kΩ; 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) Supply Current ISHDN(MAX) IFL VIN Shutdown Current Output Current, Flash Mode IMM(LOAD) Output Current, Movie Mode IFL(ACC) Flash Current Accuracy fOSC Switching Frequency tDEFAULT Default Flash Timer 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, IFLEN EN/SET or FLEN Input Leakage Current VT(FLINH) FLINH Input Threshold Voltage RIN(FLINH) FLINH Input Resistance to AGND tEN/SET(LOW) EN/SET Serial Interface Low Time tEN/SET(HI_ MIN) Minimum EN/SET High Time tEN/SET(HI_ MAX) Maximum EN/SET High Time tEN/SET(OFF) EN/SET Off Timeout tEN/SET(LAT) EN/SET Latch Timeout tFLEN_ON FLEN ON Delay Time tFLEN_OFF FLEN OFF Delay Time tFLINH_ON FLINH ON Delay Time Min Typ 2.7 EN/SET = FLEN = IN, IFL = 1.5A EN/SET = IN, FLEN = AGND EN/SET = FLEN = FLINH = AGND RSET = 107kΩ RSET = 107kΩ , Movie Mode Current Set = 100% IFL = 1.2A TA = 25˚C CT = 68nF Max Units 5.5 5.5 V 1.4 0.23 mA 1 1.2 -10 1.5 1.5 µA A 206 mA 2.0 600 140 15 10 2.5 0.4 1.4 VEN/SET,VFLEN = VIN -1 1 ½VIN 200 0.3 75 50 75 500 500 EN/SET = AGND EN/SET = AGND 25 10 15 % MHz ms °C °C V µA V kΩ µs ns µs 1. The AAT1290 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. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Typical Characteristics Movie Mode Efficiency vs Input Voltage Flash Mode Efficiency vs Input Current 90 90 206mA 80 104mA 52mA 80 Efficiency (%) Efficiency (%) 85 75 70 65 60 60 50 320mA, Vf = 2.91V 40 540mA, Vf = 3.00V 30 900mA, Vf = 3.08V 1.2A, Vf = 3.15V 20 50 10 2.7 2.7 3.1 3.5 3.9 4.3 4.7 5.5 5.1 3 Current Accuracy (%) 3 2 1 0 -1 -2 -3 35 60 5.1 -1 -2 -3 -40 -15 10 35 60 85 Temperature (°C) Flash On Time Delay vs Input Voltage (IFL = 206mA; L = 1µH) (IFL = 1.5A; COUT = 2.2µF; L = 1µH) 40 3 35 2 30 TFLEN_OND (µs) 4 1 0 -1 -2 -3 25 20 15 10 85°C 25°C -40°C 5 2.7 3.1 3.5 3.9 4.3 Input Voltage (V) 4.7 5.1 5.5 0 Movie Mode Current Accuracy vs. Input Voltage -4 4.7 1 85 Temperature (°C) 4.3 2 -4 10 3.9 (IFL = 206mA; VIN = 3.6V; L = 1µH) 4 -15 3.5 Movie Mode Current Accuracy vs Temperature 4 -40 3.1 Input Voltage (V) (IFL= 1.5A; VIN= 3.6V; L = 1µH) -4 1.5A, Vf = 3.3V Flash Mode Current Accuracy vs Temperature Current Accuracy (%) 700mA, Vf = 3.04V 55 Input Voltage (V) Current Accuracy (%) 70 0 5.5 2.7 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 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 5 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Typical Characteristics Flash Timeout Delay vs CT Capacitor Flash Timeout vs Temperature (IFL = 1.5A; VIN = 3.6V; CT = 68nF) (IFL = 1.5A; VIN = 3.6V) 1200 700 1000 660 Flash Timeout (ms) Flash Timeout (ms) 680 640 620 600 580 560 540 520 500 -40 -15 10 35 60 800 600 400 200 0 85 60 80 100 120 140 EN/SET Latch Timeout vs Input Voltage 400 400 350 350 300 300 TEN/SET(LAT) (µs) TEN/SET(OFF) (µs) 40 CT Capacitor (nF) EN/SET Off Timeout vs Input Voltage 250 200 150 250 200 150 100 85°C 100 85°C 50 25°C 50 25°C 0 -40°C 2.7 3.1 3.5 3.9 4.3 4.7 5.1 0 5.5 1.3 1.2 1.2 1.1 1.1 VEN/SET, VFLEN (V) 1.3 1 0.9 0.8 85°C 25°C 0.6 0.5 2.7 3.5 3.9 4.3 Input Voltage (V) 4.7 3.5 5.1 3.9 4.3 4.7 5.1 1 0.9 0.8 85°C 0.7 0.5 5.5 5.5 EN/SET, FLEN Low Threshold Voltage vs Input Voltage 25°C 0.6 -40°C 3.1 3.1 Input Voltage (V) EN/SET, FLEN High Threshold Voltage vs Input Voltage 0.7 -40°C 2.7 Input Voltage (V) VEN/SET, VFLEN (V) 20 Temperature (°C) 6 0 -40°C 2.7 3.1 3.5 3.9 4.3 4.7 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 5.1 5.5 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Typical Characteristics Boost Switching Frequency vs Input Voltage Supply Current vs Input Voltage (VEN/SET = VFLEN = VIN; IFL = 0mA; Non-Switching) 4 400 3.5 350 Supply Current (µA) Switching Frequency (MHz) (TA = 25°C; L = 1µH) 3 2.5 2 1.5 1 0.5 0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 Input Voltage (V) 300 250 200 150 100 50 0 5.5 2.7 4.7 5.1 5.5 Flash Mode Ripple V OUT 150mV/div AC Coupling V SW 2V/div V SW 2V/div 0V 0V ISW 50mA/div ISW 100mA/div 100mA 1.65A 500ns/div Flash Turn On Characteristic 200ns/div Movie Mode to Flash Turn On Characteristic (IFL= 206mA to 1.5A; COUT = 2.2µF, VIN = 3.6V, L = 1µH) (IFL = 1.5A; COUT = 2.2µF; VIN = 3.6V; L = 1µH) IFL 1A/div 4.3 (IFL = 1.5A; COUT = 2.2µF; VIN = 3.6V; L = 1µH) V OUT 50mV/div AC Coupling V SINK 2V/div 3.9 Input Voltage (V) Movie Mode Ripple V OUT 2V/div 3.5 (IFL = 206mA; COUT = 2.2µF; VIN=3.3V; L =1µH) V FLEN 5V/div 3.1 V FLEN 5V/div 0V V OUT 2V/div 0V V SINK 2V/div 0V IFL 1A/div 0V 50ns/div 0V 2V 0V 0A 50ns/div Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 7 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Typical Characteristics Movie Mode Turn On Characteristic Movie Mode Transistion Characteristic (IFL= 206mA to 376mA/ch; COUT = 2.2µF, VIN = 3.6V, L = 1µH) (IFL= 206mA; COUT = 2.2µF, VIN = 3.6V, L = 1µH) V EN/SET 5V/div V EN/SET 2V/div 0V V OUT 2V/div V OUT 2V/div V SINK 2V/div V SINK 500mV/div 0V 0V 0V 0V 0V IFL 100mA/div IFL 100mA/div 0A 0A 100µs/div 100µs/div 8 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Functional Block Diagram FL EN/SET FLEN System Control Enable and AS2C Interface FLINH FLGND RSET CT AGND PGND Functional Description The AAT1290 is a boost converter with a current regulated output designed to drive high current white LEDs used in camera flash applications. The AAT1290 has a constant current sink channel to accurately regulate the current flow through a high current, high intensity white Flash LED. There are two basic modes of operation in the AAT1290; a Flash mode controlled by the FLEN pin and the movie mode controlled through the AS2Cwire interface. Flash Mode A flash pulse is initiated by strobing the FLEN input pin low-to-high. This also starts an internal flash timer. The maximum flash current in the AAT1290 is set by an external resistor, RSET, which programs the maximum flash current and the maximum movie-mode current. The AAT1290’s flash timer will terminate the flash current regardless of the status of the FLEN pin. This can be used either for a simple flash pulse timing or a safety timer in the event of a control logic malfunction to prevent the LED from over-heating. The maximum flash time is determined by an external timing capacitor connected to the CT pin. The flash duration can be set from 50ms up to a maximum of 1s. The AS2Cwire interface allows flexible adjustment of the flash timer duration. This allows the flash timer duration to be reduced in 16 linear steps from the maximum time set by the timing capacitor. If the safety timer is not needed in the application, it can be disabled by connecting the CT pin directly to AGND. 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 both the camera flash and PA transmission pulses from occurring simultaneously. This avoids potential dips to the Li-ion battery voltage below the system’s undervoltage lockout threshold (UVLO). During a flash event, strobing the FLINH pin low-to-high reduces the LED current to the default movie-mode current level for the duration of FLINH. Strobing FLINH high-to-low instructs the AAT1290 to revert to the maximum flash LED current level, assuming that the FLEN pin is still active (HIGH) and the flash timer has not expired. Movie Mode The movie / torch mode current level, and the flash to maximum movie mode current ratio are programmed by the AAT1290 AS2Cwire interface. The movie-mode current level can be adjusted to one of 16 steps using a logarithmic scale where each code level is 1dB below the previous code. The maximum movie to flash mode current ratio can be set from 1:2 to OFF with respect to the maximum programmed flash current as set by the RSET resistor. The manual FLEN signal has priority over moviemode operation. Movie mode operation is controlled entirely by the AS2Cwire interface via the EN/SET pin. The FLEN signal will override movie-mode AAT1290 operation when toggled to a logic high level. The part will not reenter movie mode when FLEN is brought low. To reenter movie mode after a flash event the part must be cycled off and back on to reset the movie mode and reprogrammed via the AS2Cwire interface to the desired movie mode operation. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 9 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Over-Temperature Protection The AAT1290 has internal thermal protection circuitry to disable the device if the power dissipation exceeds a preset thermal limit. The junction over-temperature threshold is 140°C with 15°C of temperature hysteresis. During Flash or movie-mode operation, should an environmental condition, flash current sink or the boost converter cause the internal die temperature to rise above 140°C, the boost converter will be shut down. The boost converter output operation will automatically recover when the over-temperature fault condition is removed. Over-Voltage Protection (Open LED, Open Circuit) The AAT1290’s output voltage is limited by internal overvoltage protection circuitry, which prevents damage to the AAT1290 from open LED or open circuit conditions. During an open circuit event, the boost converter output will rise to the over-voltage protection (OVP) threshold at 5.5V (typical). Upon sensing the OVP event, the boost converter will be disabled to prevent damage to the device. Once the open circuit fault condition is removed, boost converter switching will resume. Short Circuit Protection The AAT1290 is equipped with an auto-disable feature for the flash LED current sink. After the IC is enabled and system start up commences, a test current of 2-3mA (typical) is forced through the current sink. The current sink will be disabled if the voltage of the SINK pin does not drop to a predetermined threshold. This feature is very convenient for disabling the current sink in the event of the flash LED short-circuit failure. This small test current is added to the set output current in both Flash and movie mode conditions. Timing Diagram FLASH FLASH FLASH FLASH FLASH FLASH TIMES OUT tDLY(CT) MOVIE MODE NO FLASH LED CURRENT t DLY(CT) NO FLASH FLASH TIMES OUT SET BY CT FLASH LOWERED TO DEFAULT MOVIE-MODE DURING FLINH DATA TO MOVIE-MODE LEVEL EN/SET FLASH ENABLE FLASH INHIBIT No AS2C address programming shown. 10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Applications Information Flash Mode LED Current The flash sink current can be programmed up to a maximum flash current level of 1.5A. The maximum flash current is set by the RSET resistor. For the desired flash current in output, the resistor value can be calculated using the following equation: RSET = 1A ∙ 162kΩ IFL(MAX) age of the maximum movie mode current level. Address 1 controls the safety timer duration as a percentage of the maximum value set by an external timing capacitor. Address 2 enables the LED channel during movie mode. Finally, Address 3 sets the maximum possible current for movie mode operation. The maximum movie mode current is set as a fraction of the flash current with a peak value of 1/2 and a default value of 1/7.3. The last column in Table 1 shows the default values for each of the address registers. AS2Cwire Serial Interface A flash event is initiated by asserting the FLEN pin. A flash event is automatically terminated when FLEN is deasserted or if the safety timer terminates before the FLEN pin is de-asserted. Any time that the FLINH pin is asserted, the default movie-mode current level will appear at FL. The default movie-mode current level will be maintained on FL as long as the FLINH and FLEN pins are asserted, and the safety timer continues to run. AS2Cwire Control of Movie Mode Operation and Flash Safety Timer In the AAT1290, control of the movie mode operation and flash timer is managed by the Advanced Simple Serial Control (AS2Cwire) interface. AS2Cwire relies on the number of rising edges of the EN/SET pin to address and load the AAT1290’s registers. As shown in Table 1, Address 0 controls the Movie Current level as a percent- AS2Cwire latches data or address after the EN/SET pin has been held high for longer than tLAT (500µs). Address or data is differentiated by the number of EN/SET rising edges. Since the data registers are 4 bits each, the differentiating number of pulses is 24 or 16, so that Address 0 is signified by 17 rising edges, Address 1 by 18 rising edges and Address 2 by 19 rising edges and Address 3 by 20 rising edges. Data is applied to any number of rising edges between 1 and 16, inclusive. A typical write protocol is a burst of EN/SET rising edges, signifying a particular address, followed by a pause with EN/SET held high for the prescribed tLAT timeout period, a burst of rising edges signifying data, and a tLAT timeout for the data registers. Once an address is set, then multiple writes to the corresponding data register are allowed. Address 0 is the default address on the first rising edge after the AAT1290 has been disabled. Address EN/SET Rising Edges Function Default (No programming) 0 1 2 3 17 18 19 20 Movie Mode Current Flash Safety Timer Movie Mode Output Configuration Flash/Movie Mode Current Ratio 100% 16/16 OFF 1/7.3 Table 1: AS2Cwire Serial Interface Addressing. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 11 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs When EN/SET is strobed low and held low longer than tOFF (500µs), the AAT1290 enters shutdown mode and draws less than 1µA from VIN. All data and address are cleared (reset to 0) during shutdown. IMOVIE MODE = Address 0 controls precise movie mode current levels. The FL movie-mode current can be adjusted in logarithmic fashion to one of 16 steps represented as a fraction of the maximum movie mode current in Table 2. To adjust the movie-mode current the user must first access Address 0 before writing the data to set the MM Current value. The AS2Cwire addressing allows the control of the moviemode output current, the safety timer delay, the FL current sink, and the ratio of movie-mode current to flash current. If there are no programmed write instructions applied to the EN/SET pin prior to the assertion of the FLEN pin and the device is enabled, then all registers will be loaded with their default values shown in Table 1. In the event that the number of rising edges applied at the EN/SET pin is less than 17, the AAT1290’s state machine will interpret instruction to program the output currents to the desired current level for movie-mode operation. Data Percentage of Maximum MM Current 1* 100% 2 89% 3 79% 4 71% 5 63% 6 56% 7 50% 8 45% 9 40% 10 36% 11 32% 12 28% 13 25% 14 22% 15 20% 16 0% Movie Mode Current – Address 0 The AAT1290 movie mode current settings are controlled using the AS2Cwire interface. Movie Mode current has a maximum value of 50% of the flash current with 240 possible current levels. The maximum movie mode current is set by Address register 3 (discussed below). The default ratio between the maximum movie mode current level and the flash current level is 1:7.3. The corresponding FL maximum movie mode current can be calculated: IMOVIE MODE = IFLMAX 1500mA = = 206mA 7.3 7.3 IFLMAX 7.3 Table 2: Address 0, Movie Mode Current Programming. For example, if an RSET value of 107kΩ is chosen, then the FL flash current is set to 1500mA. For movie mode operation, the maximum current available at FL is then: Address Data T HI T LO TLAT TLAT EN/SET 1 Address Data Reg 1 2 16 17 1 0 2... n ≤ 16 1 0 n Figure 1: AS2CwireTM Serial Interface Timing. * Denotes the default value. 12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Flash/Safety Timer – Address 1 A timer function that enables the flash current sinks for a programmed amount of time is incorporated in the AAT1290. The on-time is programmed by loading the Timing Register at Address 1 with a value from 1 to 16 and by choosing a value for the external timing capacitor, CT (see Table 3). When data is latched into Address 1, the data will be used at the next occurrence of an asserted FLEN, it will then revert to the default value of Data 1, or 16/16. This feature eliminates the need for an external, housekeeping baseband controller to contain a safety delay routine. The flash safety timer also serves as a protection feature to minimize thermal issues with the flash LEDs in the event the external controller’s flash routine experiences a software failure. If no write instruction is applied to Address 1, then the safety timer will default to the maximum delay programmed externally by CT. The Flash Time T can be calculated by the following equation: T= 8.82s × CT(µF) µF Ratio of MM Timeout 1* 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 16/16 15/16 14/16 13/16 12/16 11/16 10/16 9/16 8/16 7/16 6/16 5/16 4/16 3/16 2/16 1/16 Table 3: Address 1, Flash Safety Timer Programming; Maximum Value Programmed by CT. Movie Mode Enable – Address 2 Where T is in seconds and CT is in µF. For example, using a 47nF capacitor at CT sets the flash timeout to: Flash Timeout = Data 8.82s × 68nF = 600ms µF The relationship between the flash safety timeout and the capacitance of the timer capacitor is illustrated in Figure 2. Flash Timeout Delay vs CT Capacitor To enable or disable the flash, a write instruction to Address 2 is applied to the AAT1290’s EN/SET pin. If no write instruction is applied, the default value for Address 2 is OFF. During a flash event, the LED will be enabled regardless of the movie-mode setting. Data Movie Mode Enable 1* 2 3 4 OFF1 OFF1 ON ON Table 4: Address 2, Movie Mode Output Configuration. (IFL = 1.5A; VIN = 3.6V) 1200 Flash Timeout (ms) 1000 800 600 400 200 0 0 20 40 60 80 100 120 140 CT Capacitor (nF) Figure 2: Flash Safety Timeout vs. Timer Capacitor. 1 A small current will flow due to the start-up test current. * Default value. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 13 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Maximum Movie to Flash Mode Current Ratio – Address 3 The maximum movie-mode current is a fixed ratio of the flash current controlled by Address 3. The ratio may be varied from 1:2 to OFF in 16 linear steps as shown in Table 5. The default value for Address 3 is Data=4 and represents a flash to maximum movie mode current level of 7.3 to 1. Data MM to FL Ratio 1 2 3 4* 5 6 7 8 9 10 11 12 13 14 15 16 1/1.92 1/3.7 1/5.5 1/7.3 1/9 1/10.7 1/12.4 1/14 1/15.9 1/17.5 1/19.1 1/20.8 1/22.4 1/24 1/25.6 OFF1 IMOVIE MODE = IFLMAX 1500mA = = 206mA 7.3 7.3 The maximum movie mode current level can be calculated using the following equation: IMOVIE MODE = 162kΩ × A 1 = = Max Movie Mode Current RSET FL to MM Ratio Shutdown Since the sink switches are the only power returns for all loads, there is no leakage current to the load when the sink switches are disabled. When EN/SET pin is held low for an amount of time greater than tOFF (500µs), the AAT1290 enters shutdown mode and draws less than 1µA from VIN. All data and address registers are cleared (reset to 0) during shutdown. Selecting the Boost Inductor Table 5: Address 3, Movie/Flash Mode Current Ratio. * Denotes the default value. The default maximum movie mode current can be calculated: IMOVIE MODE = For example, if an RSET value of 107kΩ is chosen, then the FL flash current is set to 1500mA. For movie mode operation, the maximum current available at FL is then: IFLMAX 7.3 The AAT1290 DC/DC boost controller utilizes PWM control with a fixed switching frequency. To maintain a 2MHz maximum switching frequency and stable operation, a 1μH inductor is recommended. Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and peak 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. Manufacturer Part Number Inductance (µH) Saturated Rated Current (A) DCR (mΩ) Size (mm) LxWxH Cooper Bussmann Cooper Bussmann Cooper Bussmann Sumida Coilcraft SD3812-1R0-R SDH3812-1R0-R SD10-1R0-R CDH38D11/S LPS4012-102NLC 1 1 1 1 1 2.69 3 2.25 2.8 2.5 48 45 44.8 48.8 60 4.0x4.0x1.2 3.8x3.8x1.2 5.2x5.2x1.0 4.0x4.0x1.2 4.1x4.1x1.2 Type Shielded Shielded Shielded Shielded Shielded Table 6: Typical Suggested Surface Mount Inductors. 1. A small current will flow due to the short circuit test current. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 Drum Drum Drum Drum Drum Core Core Core Core Core DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs The 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. 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: IRMS = IPEAK 3 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: PLOSS(INDUCTOR) = I2RMS · DCR Manufacturer Murata Selecting the Boost Capacitors 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. 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 AAT1290 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 2.2μF ceramic output capacitor is recommended (see Table 7). 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. 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. Part Number Capacitance (μF) Voltage Rating (V) Temp Co. Case Size GRM185R60J225KE26 GRM188R71A225KE15 GRM21BR70J225KA01 GRM21BR71A225KA01 GRM219R61A475KE19 2.2 2.2 2.2 2.2 4.7 6.3 10 6.3 10 10 X5R X7R X7R X7R X5R 0603 0603 0805 0805 0805 GRM21BR71A106KE51 10 10 X7R 0805 Table 7: Typical Suggested Surface Mount Capacitors. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 15 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs 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 AAT1290 1.5A step-up regulator is shown in Figures 4 and 5. 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 under the inductor between 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 PGND. Connect AGND, FLGND to PGND as close as possible to the package. DC DC + JP 6 JP7 R10 0 10k MCU Safety Timer (S.T.) Movie Mode Enable Control (A/B) R6 R7 10K 10K 10K U2 1 SW1 0 2 4 Movie Mode Current Control (M.M.C.) R5 2 3 1 3 5 4 SW2 0 2 4 1 3 5 2 4 1 3 5 VSS GP 5 GP 0 GP 4 GP 1 GP 3 GP 2 PIC12F675 8 C4 1 µF FLEN 7 6 0 R8 5 R9 330 LED2 330 2 4 1 3 5 0 SW4 FLINH 2 4 JP3 LED1 RED GRN SW 0 VDD 1 3 5 R3 R4 100k 100k ( opt ) SW 5 JP4 JP1 0 D1 U1 1 2 3 JP 5 EN / SET R2 100K 4 5 6 L1 C1 2 .2 µF 1µH 7 C3 CT RSET FL ENSET FLEN FLGND NC AGND IN FLINH SW AGND PGND OUT 14 13 12 11 10 9 8 AAT1290TDFN33-14 74 nF C2 R1 107k Figure 3: AAT1290 Evaluation Board Schematic. 16 VOUT Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 2 .2 µF DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Figure 4: AAT1290 Evaluation Board Top Side Layout. Component Part Number U1 AAT1290IWO U2 SW1 – SW5 R1 R2, R3, R4 R5, R6, R7, R10 R8, R9 JP1, JP2(Not Mounted), JP7 C1, C2 C3 C4 L1 D1, D2(Not Mounted) LED1 LED2 JP3, JP4, JP5, JP6 Figure 5: AAT1290 Evaluation Board Bottom Side Layout. Description Manufacturer PIC12F675 PTS645TL50 Chip Resistor Chip Resistor Chip Resistor Chip Resistor 1.5A Step-Up Current Regulator for Flash LEDs; TDFN33-14 package 8-bit CMOS, FLASH-based μC; 8-pin PDIP package Switch, SPST, 5mm 107kΩ, 1%, 1/4W; 0402 100kΩ, 1%, 1/4W; 0603 10kΩ, 1%, 1/4W; 0603 330Ω, 1%, 1/4W; 0603 Microchip ITT Industries Vishay Vishay Vishay Vishay Chip Resistor 0Ω, 1% Vishay 2.2µF, 10V, X7R, 0603 Murata 74nF, 10V, X7R, 0402 Murata 1µF, 10V, X5R, 0805 Murata Drum Core, 1µH, 2.69A, 48mΩ White Flash LED Red LED; 1206 Green LED; 1206 Conn. Header, 2mm zip Cooper Bussmann Lumileds, Philips Chicago Miniature Lamp Chicago Miniature Lamp Sullins Electronics GRM188R71A225KE15 GRM155R71A743KA01 GRM216R61A105KA01 SD3812-1R0-R LXCL-PWF4 CMD15-21SRC/TR8 CMD15-21VGC/TR8 PRPN401PAEN Skyworks Table 8: AAT1290 Evaluation Board Bill of Materials. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 17 DATA SHEET AAT1290 1.5A Step-Up Current Regulator for Flash LEDs Ordering Information Package Marking1 Part Number (Tape and Reel)2 TDFN33-14 U6XYY AAT1290IWO-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 Information TDFN33-143 Detail "A" 3.000 ± 0.050 2.500 ± 0.050 Index Area 3.000 ± 0.050 1.650 ± 0.050 Top View Bottom View + 0.100 - 0.000 Pin 1 Indicator (Optional) 0.180 ± 0.050 Side View 0.400 BSC 0.000 0.203 REF 0.750 ± 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 202106A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 26, 2012 DATA SHEET AAT1290 1.5A 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. 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