AAT3131 SKYWORKS
Document overview
- Manufacturer or author: Provided By www.digicamel.com(free datasheet download site)
- PDF pages: 13
Technical content
Features
- VIN Range: 2.7V to 5.5V
- <1.0µA of Shutdown Current
- 1MHz Switching Frequency
- White LED Backlighting
- Fully Independent Display Lighting
- Dual Mode 1X and 1.5X Charge Pump for Maximum Efficiency
- Drives Low-VF and High-VF Type LEDs
- Up to Three 20mA Outputs
- Single 30mA Output
- Multi-Position Logarithmic Scale with Digital Control
- Low Noise Constant Frequency Operation
- Regulated Output Current
- Automatic Soft Start
- No Inductors
- Temperature Range: -40°C to +85°C
- 12-Pin TSOPJW Package
Applications
- Color (RGB) Lighting
- Programmable Current Source
- White LED Backlighting
- White Photo Flash for Digital Still Cameras
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 Pin Descriptions Pin # Symbol Function 1 C2+ Flying capacitor 2 positive terminal. Connect a 1µF capacitor between C2+ and C2-. 2 OUT Charge pump output. Requires 1µF capacitor connected between this pin and ground. 3 C1- Flying capacitor 1 negative terminal. 4 C1+ Flying capacitor 1 positive terminal. Connect a 1µF capacitor between C1+ and C1-. 5 D3 Current source output #3. 6 D2 Current source output #2. 7 D4 Current source output #4. 8 D1 Current source output #1. 9 EN/SET Control pin. 10 IN Input power supply. Requires 1µF capacitor connected between this pin and ground. 11 GND Ground. 12 C2- Flying capacitor 2 negative terminal. Pin Configuration TSOPJW-12 (Top View) C2+ OUT C1- C1+ C2- GND IN EN/SET
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 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. 2. Based on long-term current density limitation. 3. Mounted on an FR4 board. 4. Derate 6.25mW/°C above 25°C. Absolute Maximum Ratings1 Symbol Description Value Units VIN Input Voltage -0.3 to 6 V VOUT Charge Pump Output -0.3 to 6 V FB, VEN/SET FB or EN/SET to GND Voltage -0.3 to 6 V VEN/SET(MAX) Maximum EN/SET to Input Voltage VIN - 0.3 V IOUT2 Maximum DC Output Current 150 mA TJ Operating Junction Temperature Range -40 to 150 °C TLEAD Maximum Soldering Temperature (at leads, 10 sec.) 300 °C Thermal Information3 Symbol Description Value Units qJA Thermal Resistance 160 °C/W PD Maximum Power Dissipation4 (TA = 25°C) 625 mW
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 1. The AAT3131 is guaranteed to meet performance specifications over the -40 to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. Electrical Characteristics1 VIN = 3.5V, CIN = COUT = C1 = C2 = 1.0µF; TA = -40 to +85°C, unless otherwise noted. Typical values are T A = 25°C. Symbol Description Conditions Min Typ Max Units Input Power Supply VIN Operation Range 2.7 5.5 V ICC Operating Current 3.0 ≤ VIN ≤ 5.5, Active, No Load Current 1.8 3.5 mA ISHDN Shutdown Current EN = 0 1.0 µA IDX Maximum Output Current D1 to D3 3.0 ≤ VIN ≤ 5.5 18 20 22 mA IDX Maximum Output Current D4 3.0 ≤ VIN ≤ 5.5 27 30 33 mA I(D-Match) Current Matching Between Any Two Outputs VD1:D3 = 3.6, VIN = 3.3V 0.5 % hCP Charge Pump Section Efficiency VIN = 3.5V, IOUT(TOTAL) = 90mA, Measured from IN to OUT 93 % Charge Pump Section TSS Soft-Start Time 200 µs FCLK Clock Frequency 1000 kHz EN/SET VEN(L) Enable Threshold Low 0.5 V VEN(H) Enable Threshold High 1.4 V TEN/SET LO EN/SET Low Time VEN/SET < 0.5 0.3 75 µs TEN/SET HI Minimum EN/SET High Time VEN/SET > 1.4 50 ns TOFF EN/SET Off Timeout VEN/SET < 0.5 500 µs Input Current EN/SET Input Leakage -1 1 µA
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 Typical Characteristics Unless otherwise noted, VIN = 3.5V, CIN = COUT = C1 = C2 = 1µF, TA = 25°C. Efficiency vs. Input Voltage (4x20mA) 100 Input Voltage (V) Efficiency (%) VDIODE = 3.3V VDIODE = 3.4V VDIODE = 3.5V VDIODE = 3.6V IDIODE vs. Input Voltage (4x20mA) Input Voltage (V) IDIODE (mA) VDIODE = 3.3V VDIODE = 3.4V VDIODE = 3.5V VDIODE = 3.6V Quiescent Current vs. Input Voltage 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 Input Voltage (V) Quiescent Current (mA) VDIODE = 3.3V VDIODE = 3.4V VDIODE = 3.5V VDIODE = 3.6V VIH and VIL vs. VIN 0.600 0.625 0.650 0.675 0.700 0.725 0.750 0.775 0.800 0.825 0.850 VIN (V) VIH VIL Turn-On to Full-Scale Charge Pump Time (50µs/div) ENSET (1V/div) OUT (2V/div) VDIODE (1V/div) IIN (200mA/div) Turn-On to Full-Scale Load Switch Time (50µs/div) ENSET (1V/div) OUT (2V/div) VDIODE (2V/div) IIN (100mA/div)
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 Typical Characteristics Unless otherwise noted, VIN = 3.5V, CIN = COUT = C1 = C2 = 1µF, TA = 25°C. Charge Pump to Load Switch (80mA) Time (50µs/div) VIN (10mV/div) OUT (2V/div) VDIODE (2V/div) IIN (100mA/div) Load Switch to Charge Pump (80mA) Time (50µs/div) VIN (20mV/div) OUT (1V/div) VDIODE (1V/div) IIN (200mV/div) Turn-Off Time (200µs/div) ENSET (1V/div) VDIODE (2V/div) IIN (100mA/div) 80mA Load Characteristics Time (1µs/div) 20mV/div VIN OUT VDIODE
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 Functional Description The AAT3131 is a dual mode load switch (1X) and high efficiency (1.5X) fractional charge pump device intended for white LED backlight applications. The fractional charge pump consists of a low dropout linear voltage regulator followed by a 1.5X charge pump with multiple current-source outputs. To maximize power conversion efficiency, an internal feedback control sensing circuit monitors the voltage required on the constant current source outputs. This control circuit then sets the load switch and charge pump functions based upon the input voltage level versus the output voltage level needed. This function significantly enhances overall device efficiency when the input voltage level is greater than the voltage required at the constant current source outputs. The 1X load switch/1.5X charge pump mode decision is based on the voltage levels sensed on either the D1 output or the D4 output, whichever is greater. Switchover between the 1.5X (charge pump) operating mode and the 1X (load switch) mode occurs automatically (as a function of input and output voltages) and does not require user interven- tion to maintain maximum efficiency. The AAT3131 requires only four external components: two 1µF ceramic capacitors for the charge pump flying capacitors (C1 and C2), one 1µF ceramic input capacitor (CIN), and one 0.33µF to 1µF ceramic output capacitor (COUT). The LDO/1.5X charge pump output is converted into three (D1 to D3) constant current outputs to drive three individual LEDs with a maximum current of 20mA each, and one (D4) constant current output with a Functional Block Diagram 1X/1.5X Charge Pump Soft-Start Control 1MHz Oscillator Voltage Reference Quad Output DAC Single Output DAC Current Reference S2Cwire Interface 32x16 bit ROM C1+ C1- C2+ C2- OUT GND EN/SET VIN 32x16 bit ROM
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 Output Current Level Settings Address Code Current (mA) Figure 1: Output Level Current Settings. maximum current of 30mA. The current source output magnitude is controlled by the EN/SET serial data inter - face. The interface records rising edges of the EN/SET pin and decodes them into 32 addresses corresponding to individual current level settings. The 32 addresses are divided such that outputs D1 to D3 can be controlled independently of output D4. For Addresses 1 to 8, 9 to 16, 17 to 24, and 25 to 32, outputs D1 to D3 start at 0mA and increase from 0.5mA to 20mA in three 8dB steps and three 2.5dB steps. Output D4 remains con - stant over these address ranges, which provides orthog- onal control of the two channels. For Addresses 1 to 8, D4 is set to 0mA; for Addresses 9 to 16, D4 is set to 1mA; for Addresses 17 to 24, D4 is set to 15mA; and for Addresses 25 to 32, D4 is set to 30mA. This is summa - rized in Table 1 and Figure 1. The modulo 32 interface wraps states back to State 1 after the 32nd clock. With each EN/SET pulse, the output current changes to the next setting in the address decoding. To change settings to the previous address decoding, 31 EN/SET clock pulses are required. The counter can be clocked at speeds up to 1MHz, so that intermediate states are not visible. The first rising edge of EN/SET enables the IC and initially sets the output LED currents to 0mA. Additional clocks are required to set the desired current level. Once the final clock cycle is input for the desired brightness level, the EN/SET pin is held high to maintain the device output current at the programmed level. The device is disabled 500µs after the EN/SET pin transitions to a logic low state. Address Current Level Settings (mA) D1-3 D4 1 0.0 0.0 2 0.5 0.0 3 1.3 0.0 4 3.3 0.0 5 8.3 0.0 6 11.1 0.0 7 15.0 0.0 8 20.0 0.0 9 0.0 1.0 10 0.5 1.0 11 1.3 1.0 12 3.3 1.0 13 8.3 1.0 14 11.1 1.0 15 15.0 1.0 16 20.0 1.0 17 0.0 15.0 18 0.5 15.0 19 1.3 15.0 20 3.3 15.0 21 8.3 15.0 22 11.1 15.0 23 15.0 15.0 24 20.0 15.0 25 0.0 30.0 26 0.5 30.0 27 1.3 30.0 28 3.3 30.0 29 8.3 30.0 30 11.1 30.0 31 15.0 30.0 32 20.0 30.0 Table 1: Constant Current Source Output Programming Levels.
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 EN/SET Timing Diagram EN/SET Code 1 2 3 OFFOFF tHI tLO tOFF Applications Information Constant Current Output Level Settings The constant current source output amplitude for outputs D1 to D3 and D4 are set via the serial interface according to a logarithmic scale. Using a logarithmic scale, LED brightness appears linear with each increasing code count. Because the outputs D1 to D4 are true indepen - dent constant current sources, the voltage observed on any single given output will be determined by the actual forward voltage (VF) for the LED being driven. Since the output current of the AAT3131 is program - mable through its S 2Cwire interface, no PWM (pulse width modulation) or additional control circuitry are needed to control LED brightness. This feature greatly reduces the burden on a microcontroller or system IC to manage LED or display brightness, allowing the user to “set it and forget it.” Furthermore, with its high-speed serial interface (1MHz data rate), the output current of the AAT3131 can be changed successively to brighten or dim LEDs in smooth transitions (e.g., to fade out) or in abrupt steps, giving the user complete programmability and real-time control of LED brightness. EN/SET Serial Interface The current source output magnitude is controlled by the EN/SET serial data interface. The interface records rising edges of the EN/SET pin and decodes them into 32 indi- vidual current level settings. The modulo 32 interface wraps states back to State 1 after the 32nd clock, so that the previous state is achieved by clocking the EN/ SET pin 31 times. The counter can be clocked at speeds up to 1MHz, so that intermediate states are not visible. The first rising edge of EN/SET enables the IC and ini - tially sets the output LED current to 0dB. Once the final clock cycle is input for the desired brightness level, the EN/SET pin is held high to maintain the device output current at the programmed level. The device is disabled 500µs after the EN/SET pin transitions to a logic low state. The EN/SET timing is designed to accommodate a wide range of data rates. After the first rising edge of EN/SET, the charge pump is enabled and reaches full capacity after the soft-start time (T SS). During the soft- start time, multiple clock pulses may be entered on the EN/SET pin to set the final output current level with a single burst of clocks. Alternatively, the EN/SET clock pulses may be entered one at a time to gradually increase the LED brightness over any desired time peri - od. A constant current is sourced as long as EN/SET remains in a logic high state. The current source outputs are switched off after EN/SET has remained in a low state for at least the TOFF timeout period. LED Selection The AAT3131 is specifically intended for driving white LEDs. However, the device design will allow the AAT3131 to drive most types of LEDs with forward voltage speci - fications ranging from 2.0V to 4.3V. LED applications may include main and sub-LCD display backlighting, camera photo-flash applications, color (RGB) LEDs, infrared (IR) diodes for remotes, and other loads bene - fiting from a controlled output current generated from a varying input voltage. Since the D1 to D4 output current sources are matched with negligible voltage depen - dence, the LED brightness will be matched regardless of the specific LED forward voltage (VF) levels. In some instances (e.g., in high luminous output appli - cations such as photo flash), it may be necessary to drive high-VF type LEDs. The low dropout current sourc- es in the AAT3131 makes it capable of driving LEDs with forward voltages as high as 4.3V at full current from an input supply as low as 3.0V. Outputs can be paralleled to drive high-current LEDs without complication.
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 Device Switching Noise Performance The AAT3131 operates at a fixed frequency of approxi - mately 1MHz to control noise and limit harmonics that can interfere with the RF operation of cellular telephone handsets or other communication devices. Back-injected noise appearing on the input pin of the charge pump is 20mV peak-to-peak, typically ten times less than induc- tor-based DC/DC boost converter white LED backlight solutions. The AAT3131 soft-start feature prevents noise transient effects associated with inrush currents during start-up of the charge pump circuit. Power Efficiency and Device Evaluation The charge pump efficiency discussion in the following sections only accounts for efficiency of the charge pump section itself. Due to the unique circuit architecture and design of the AAT3131, it is very difficult to measure efficiency in terms of a percent value comparing input power over output power. Since the AAT3131 outputs are pure constant current sources and typically drive individual loads, it is difficult to measure the output voltage for a given output (D1 to D4) to derive an overall output power measurement. For any given application, white LED forward voltage levels can differ, yet the output drive current will be maintained as a constant. This makes quantifying output power a difficult task when taken in the context of comparing to other white LED driver circuit topologies. A better way to quantify total device efficiency is to observe the total input power to the device for a given LED current drive level. The best white LED driver for a given application should be based on trade-offs of size, external component count, reliability, operating range, and total energy usage...not just % efficiency. The AAT3131 efficiency may be quantified under very specific conditions and is dependent upon the input volt- age versus the output voltage seen across the loads applied to outputs D1 through D4 for a given constant current setting. Depending upon the case of V IN being greater than the specific voltage seen across the load on D1 (or D4), the device will operate in load switch mode. If VIN is less than the voltage required on the constant current source, the device will operate in 1.5X charge pump mode. Each of these two modes will yield different efficiency values. Refer to the following two sections for explanations for each operational mode. Load Switch Mode Efficiency The AAT3131 load switch mode is operational at all times and functions alone to enhance device power conversion efficiency when VIN is greater than voltage across the load connected to the constant current source outputs. When in load switch mode, the voltage conversion efficiency is defined as output power divided by input power: η = POUT PIN The expression to define the ideal efficiency ( h) can be rewritten as: η = POUT = VOUT /uni2219 IOUT = VOUT PIN VIN /uni2219 IOUT VIN -or- η(%) = 100 VOUT VIN Charge Pump Section Efficiency The AAT3131 contains a fractional charge pump which will boost the input supply voltage in the event that V IN is less than the voltage required on the constant current source outputs. The efficiency (h) can be simply defined as a linear voltage regulator with an effective output voltage that is equal to one and one half times the input voltage. Efficiency (h) for an ideal 1.5X charge pump can typically be expressed as the output power divided by the input power. η = POUT PIN In addition, with an ideal 1.5X charge pump, the output current may be expressed as 2/3 of the input current. The expression to define the ideal effi - ciency (h) can be rewritten as: η = POUT = VOUT /uni2219 IOUT = VOUT PIN VIN /uni2219 1.5IOUT 1.5VIN -or- η(%) = 100 VOUT 1.5VIN
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 For a charge pump with an output of 5V and a nominal input of 3.5V, the theoretical efficiency is 95%. Due to internal switching losses and IC quiescent current con - sumption, the actual efficiency can be measured at 93%. These figures are in close agreement for output load conditions from 1mA to 100mA. Efficiency will decrease as load current drops below 0.05mA, or when level of V IN approaches V OUT. Refer to the Typical Characteristics section of this datasheet for measured plots of efficiency versus input voltage and output load current for the given charge pump output voltage options. Capacitor Selection Careful selection of the four external capacitors C IN, C1, C2, C OUT is important because they will affect turn-on time, output ripple, and transient performance. Optimum performance will be obtained when low equivalent series resistance (ESR) ceramic capacitors are used; in gener - al, low ESR may be defined as less than 100mW. A value of 1µF for all four capacitors is a good starting point when choosing capacitors. If the LED current sources are only programmed for light current levels, then the capacitor size may be decreased. Capacitor Characteristics Ceramic composition capacitors are highly recommend - ed over all other types of capacitors for use with the AAT3131. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counter - parts. A ceramic capacitor typically has very low ESR, is lowest cost, has a smaller PCB footprint, and is non- polarized. Low ESR ceramic capacitors help maximize charge pump transient response. Since ceramic capaci - tors are non-polarized, they are not prone to incorrect connection damage. Equivalent Series Resistance ESR is an important characteristic to consider when selecting a capacitor. ESR is a resistance internal to a capacitor that is caused by the leads, internal connec - tions, size or area, material composition, and ambient temperature. Capacitor ESR is typically measured in mil- liohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. Ceramic Capacitor Materials Ceramic capacitors less than 0.1µF are typically made from NPO or C0G materials. NPO and C0G materials have tight tolerance and are stable over temperature. Large capacitor values are typically composed of X7R, X5R, Z5U, or Y5V dielectric materials. Large ceramic capacitors, greater than 2.2µF, are often available in low-cost Y5V and Z5U dielectrics, but capacitors greater than 1µF are usually not required for AAT3131 applica - tions. Capacitor area is another contributor to ESR. Capacitors that are physically large will have a lower ESR when compared to an equivalent material smaller capacitor. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size. Thermal Protection The AAT3131 has a thermal protection circuit that will shut down the internal LDO and charge pump if the die temperature rises above the thermal limit, as is the case during a short-circuit of the OUT pin. Driving Multiple LEDs, White LED Display Module Backlights, and Individual LEDs Connected in Parallel The AAT3131 D1 to D4 outputs are true constant current sources capable of driving up to 20mA (D1 to D3) or 30mA (D4) each over the operation input voltage range. Since these outputs are true constant current sources, they may be connected in parallel to drive a single power output. Any combination of outputs (D1 to D4) may be connected in parallel. The maximum total output current is a sum of how many current sources are parallel con - nected. This feature is particularly useful to power pre- manufactured display modules which are pre-wired with white LED backlights connected in a parallel circuit con - figuration. Any combination of outputs may be con - nected in parallel to drive groups of LEDs. The AAT3131 internal current source reference circuit bases feedback from current sensed on the D1 and D4 outputs. For best operation, the only requirement for this type of applica - tion is the outputs D1 and D4 should always be con - nected to the load circuit.
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 CIN 1µF VBATTERY COUT 1µF EN/SET 1µF 1µF VIN VOUT C1+ C1- C2+ C2- D4EN/SET GND AAT3131 D2 D3 D4D1 RB*R B*R B*R B* D5 D6 RB*R B* *In some applications, white LED forward voltages (VF) can vary significantly. Ballast resistors between the LED cathodes and ground are recommended for balancing the forward voltage differences. The ballast resistor value may be approximated by the following equation: RB = VSOURCE - VF IF Figure 2: AAT3131 Driving Two Groups of Paralleled White LEDs (e.g., main LCD and sub-LCD backlights). The AAT3131 may be used to drive multiple LEDs having differing forward voltages. Using feedback techniques, the current in D1 to D3 output currents sources are ref - erenced to the current in the LED connected to D1. Current source output D4 is its own reference. If all LEDs are of similar type, the diodes will be matched in current, maintaining uniform LED brightness despite variations in manufacturer, production, etc. However, if the diodes are dramatically different in type comprising a mix of high-V F type and low-VF-type LEDs, the AAT3131 has the capability to optimally and simulta- neously drive up to four LEDs of one type and up to two LEDs of another type. This feature can be useful for driv- ing different color LEDs; driving both display backlight and photo-flash LEDs; or for driving main-LCD and sub- LCD display LED backlights from a single charge pump IC. For example, when driving independent RGB LEDs, the green and blue type LEDs typically require a high V F to operate (e.g., 3.7V), while the red LED needs a low for - ward voltage (e.g., 2V). By connecting the green and blue diodes to outputs D1 to D3 and the red diodes to D4, good control and uniformity in brightness are maintained despite the 2V difference in the diode forward voltages. The AAT3131 determines if the 1.5X charge pump circuit is needed based on the voltage on D1 and D4, whichever is higher. If adequate voltage is available to drive the higher voltage LED (of output D1 or D4) without the charge pump running, the IC automatically switches into load switch (1X) mode to maximize efficiency. Similarly, if a 4V photo-flash LED array is connected to outputs D1 through D3 (with the outputs shorted togeth- er) and two 3.3V sub-LCD display backlight LEDs are connected to output D4, then the AAT3131 can opti - mally drive each set of LEDs at the programmed current level (see Figure 2).
High Efficiency 1X/1.5X Fractional Charge Pump for White LED Applications Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 13 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202136A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 5, 2012 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. Sky - works 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 here- under, 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, IN - CLUDING 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 en- vironmental 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 pub- lished 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. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.
Ordering Information
Package Marking1 Part Number (Tape and Reel)2 TSOPJW-12 KBXYY AAT3131ITP-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
0.20 + 0.10 - 0.05 0.055 ± 0.045 0.45 ± 0.15 7° NOM 4° ± 4° 3.00 ± 0.10 2.40 ± 0.10 2.85 ± 0.20 0.15 ± 0.05 0.9625 ± 0.0375 1.00 + 0.10 - 0.065
0.04 REF
0.010 2.75 ± 0.25 All dimensions in millimeters.