AAT3123

AAT3123_08 ANALOGICTECH | Alldatasheet

Document overview

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• PDF pages: 19

Technical content

Features

• V IN Range: 2.7V to 5.5V
• Dual Mode 1X and 1.5X Charge Pump for Maximum Efficiency
• Drives Low-V F and High-VF Type LEDs
• Up to Six 20mA Outputs (AAT3124)
• Up to Four 20mA Outputs (AAT3123/23A)
• 32-Position Logarithmic Scale with Digital Control
• Simple Serial Control (S 2Cwire) Interface
• Low Noise Constant Frequency Operation
• 1MHz Switching Frequency
• Small Application Circuit
• Regulated Output Current
• Automatic Soft Start
• No Inductors
• I Q <1μA in Shutdown
• Temperature Range: -40°C to +85°C
• 12-Pin TSOPJW Package (AAT3123/23A)
• 16-Pin 4x4mm QFN and 14-Pin TSOPJW Packages (AAT3124)

Applications

• Color (RGB) Lighting
• Programmable Current Source
• White LED Backlighting
• White Photo Flash for DSCs Typical Application CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF D6 D5 D4 D3 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3124 D2 D1

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Pin Descriptions Pin # Symbol Function AAT3123/23A (TSOPJW-12) AAT3124 (QFN44-16) AAT3124 (TSOPJW-14) 1 10 8 C2+ Flying capacitor 2 positive terminal. Connect a 1μF capacitor be- tween C2+ and C2-. 2 9 9 OUT Charge pump output. Requires 1μF capacitor connected between this pin and ground. 3 7 10 C1- Flying capacitor 1 negative terminal. 4 6 11 C1+ Flying capacitor 1 positive terminal. Connect a 1μF capacitor be- tween C1+ and C1-. 5 5 12 D4 Current source output #4. 6 4 13 D3 Current source output #3. 7 1 2 D2 Current source output #2. 8 16 3 D1 Current source output #1. 9 15 4 EN/SET Control pin using S 2Cwire serial interface. 10 14 5 IN Input power supply. Requires 1μF capacitor connected between this pin and ground. 11 12 6 GND Ground. 12 11 7 C2- Flying capacitor 2 negative terminal. 2 1 D5 Current source output #5. 3 14 D6 Current source output #6. 8, 13 N/C No connection. EP Exposed paddle (bottom); connect to GND directly beneath package. Pin Configuration TSOPJW-12 QFN44-16 TSOPJW-14 (Top View) (Top View) (Top View) C2+ AAT3123 AAT3123A OUT C1- C1+ C2- GND IN EN/SET C1+ C1- N/C OUT C2+ C2- GND AAT3124 N/C IN EN/SET EN/SET IN GND C1+ C1- OUT 7 8C2- C2+ AAT3124

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET 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 0.3 V IOUT2 Maximum DC Output Current 150 mA TJ Operating Junction Temperature Range -40 to 150 °C Thermal Information3 Symbol Description Value Units θJA Thermal Resistance QFN44-16 50 °C/WTSOPJW-12 160 PD Maximum Power Dissipation QFN44-164 2.0 WTSOPJW-125 0.625 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at co nditions 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 20mW/°C above 25°C. 5. Derate 6.25mW/°C above 25°C.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Electrical Characteristics1 CIN = COUT = C1 = C2 = 1.0μF; TA = -40°C to +85°C, unless otherwise noted. Typical values are T A = 25°C, VIN = 3.5V. 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(MAX) Shutdown Current EN = 0 1 μA IDX Output Current V IN = 3.5V, Code = 32, TA = 25°C 18 20 22 mA ηCP Charge Pump Section Effi ciency VIN = 3.5V, IOUT(TOTAL) = 120mA, 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 V IN = 2.7V to 5.5V 0.5 V VEN(H) Enable Threshold High V IN = 2.7V to 5.5V 1.4 V TEN/SET LO EN/SET Low Time 0.3 75 μs TEN/SET HI Minimum EN/SET High Time 50 ns TOFF EN/SET Off Timeout 500 μs Input Current EN/SET Input Leakage -1 1 μA 1. The AAT3123/4 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is as sured by design, characterization, and cor- relation with statistical process controls.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Typical Characteristics Unless otherwise noted, VIN = 3.5V, CIN = COUT = C1 = C2 = 1μF, TA = 25°C. Efficiency vs. Input Voltage (4x20mA) Input Voltage (V) Efficiency (%) 100 VDIODE = 3.0V VDIODE = 3.2V VDIODE = 3.4V Efficiency vs. Input Voltage (4x10mA) Input Voltage (V) Efficiency (%) 100 VDIODE = 3.2V VDIODE = 3.4V VDIODE = 3.0V IDIODE vs. Input Voltage (4x20mA) Input Voltage (V) IDIODE (mA) VDIODE = 3.0V VDIODE = 3.2V VDIODE = 3.4V IDIODE vs. Input Voltage (4x10mA) Input Voltage (V) IDIODE (mA) VDIODE = 3.0V VDIODE = 3.2V VDIODE = 3.4V Quiescent Current vs. Input Voltage Input Voltage (V) Quiescent Current (mA)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 2.6 VDIODE = 3.0V VDIODE = 3.2V VDIODE = 3.4V 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 Input Voltage (V) VIH VIL

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Typical Characteristics Unless otherwise noted, VIN = 3.5V, CIN = COUT = C1 = C2 = 1μF, TA = 25°C. Turn-On to Full-Scale Charge Pump Time (50µs/div) EN/SET (1V/div) OUT (2V/div) VDIODE (1V/div) IIN (200mA/div) Turn-On to Full-Scale Load Switch Time (50µs/div) EN/SET (1V/div) OUT (2V/div) VDIODE (2V/div) IIN (100mA/div) 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) EN/SET (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 ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Functional Description The AAT3123/23A/24 is a dual mode load switch (1X) and high efficiency (1.5X) fractional charge pump device intended for white LED backlight applications. The frac- tional charge pump consists of a low dropout linear volt- age regulator followed by a 1.5X charge pump with multiple current-source outputs. To maximize power conversion efficiency, an internal feedback control sens- ing 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 need- ed. This function significantly enhances overall device efficiency when the input voltage level is greater than the voltage required at the constant current source out- puts. For the AAT3123/23A, the 1X load switch/1.5X charge pump mode is decided on the voltage sensed on the output D1. The AAT3124 bases the 1X load switch/1.5X charge pump mode decision on the voltage levels sensed on either the D1-D4 output group or the D5-D6 output group, 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 intervention to maintain maximum efficiency. The AAT3123/23A/24 requires only four external compo- nents: two 1 μF ceramic capacitors for the charge pump flying capacitors (C 1 and C 2), one 1 μF ceramic input capacitor (C IN), and one 0.33 μF to 1 μF ceramic output capacitor (C OUT). The LDO/1.5X charge pump output is converted into four (D1 to D4) or six (D1 to D4 and D5 to D6) constant current outputs to drive four or six individ- ual LEDs with a maximum current of 20mA each. The current source output magnitude is controlled by the EN/ SET serial data S 2Cwire interface. The interface records rising edges of the EN/SET pin and decodes them into 32 individual current level settings each 1dB apart (see Table 1, Current Level Settings). Code 32 is full scale, and Code 1 is full scale attenuated by 31dB. The modulo 32 inter- face wraps states back to State 1 after the 32nd clock. With each EN/SET pulse, the output current increases by 1dB. To decrease the output current by 1dB, 31 EN/SET clock pulses are required. The counter can be clocked at speeds up to 1MHz, so intermediate states are not visi- ble. The first rising edge of EN/SET enables the IC and initially sets the output LED current to -31dB, the lowest setting equal to 525μA. 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 pro- grammed level. The device is disabled 500 μs after the EN/SET pin transitions to a logic low state. Functional Block Diagram 1x/1.5x Charge Pump Soft-Start Control 1MHz Oscillator Voltage Reference Quad Output DAC Dual Output DAC Current S2Cwire Interface 32 x 8 bit ROM Current Reference C1+ C1- C2+ C2- OUT D5* D6* GND EN/SET VIN *AAT3124 only

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Applications Information Constant Current Output Level Settings The constant current source output amplitude for out- puts D1 to D6 are set via the serial interface according to a logarithmic scale where each code is 1dB greater than the previous code. In this manner, LED brightness appears linear with each increasing code count. Because the outputs D1 to D6 are true independent constant cur- rent sources, the voltage observed on any single given output will be determined by the actual forward voltage F) for the LED being driven. Since the output current of the AAT3123/23A/24 is pro- grammable through its single-wire serial interface, no PWM (pulse width modulation) or additional control cir- cuitry is needed to control LED brightness. This feature greatly reduces the burden on a microcontroller or sys- tem 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 AAT3123/23A/24 can changed succes- sively 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. Code IOUT (mA) Code IOUT (mA) 1 0.549 17 3.529 2 0.627 18 4.000 3 0.706 19 4.471 4 0.784 20 5.020 5 0.863 21 5.647 6 1.020 22 6.353 7 1.098 23 7.059 8 1.255 24 7.922 9 1.412 25 8.941 10 1.569 26 10.039 11 1.804 27 11.216 12 1.961 28 12.627 13 2.275 29 14.118 14 2.510 30 15.843 15 2.824 31 17.804 16 3.137 32 20.000 Table 1: Constant Current Source Output Programming Levels (mA). Normalized Output Current Settings 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1 2 3 4 5 6 7 8 9 1 01 11 21 31 41 51 61 71 81 92 02 12 22 32 42 52 62 72 82 93 03 13 2 Code Normalized IOUT (D1 to D6)

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET EN/SET Serial Interface The current source output magnitude is controlled by the EN/SET pin, using AnalogicTech’s Simple Serial Control 2Cwire) interface. The interface records rising edges of the EN/SET pin, and decodes them into 32 individual cur- rent level settings each 1dB apart. Code 32 is full scale, and Code 1 is full scale attenuated by 31dB. The modulo 32 interface wraps states back to State 1 after the 32nd clock, so 1dB of attenuation is achieved by clocking the EN/SET pin 31 times. The counter can be clocked at speeds up to 1MHz, so intermediate states are not visible. The first rising edge of EN/SET enables the IC and ini- tially sets the output LED current to -31dB, the lowest setting equal to 525μA. 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 pro- grammed 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 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 LED brightness over any desired time period. 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 t OFF timeout period. LED Selection The AAT3123/23A/24 is specifically intended for driving white LEDs. However, the device design will allow the AAT3123/23A/24 to drive most types of LEDs with for- ward voltage specifications 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 benefiting from a controlled output current gener- ated from a varying input voltage. Since the D1 to D6 output current sources are matched with negligible volt- age dependence, LED brightness will be matched regard- less of the specific LED forward voltage (V F) levels. In some instances (e.g., in high luminous output applica- tions such as photo flash), it may be necessary to drive high-V F type LEDs. The low-dropout current sources in the AAT3123/23A/24 make 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. Device Switching Noise Performance The AAT3123/23A/24 operates at a fixed frequency of approximately 1MHz to control noise and limit harmonics that can interfere with the RF operation of cellular tele- phone 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 inductor-based DC/DC boost converter white LED back- light solutions. The AAT3123/23A/24 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 AAT3123/23A/24, it is very difficult to measure efficiency in terms of a percent value compar- ing input power over output power. EN/SET Timing EN/SET Code 1 2 3 OFFOFF tHI tLO tOFF

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Since the AAT3123/23A/24 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 D6) to derive an overall output power measure- ment. For any given application, white LED forward volt- age 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 AAT3123/23A/24 efficiency may be quantified under very specific conditions and is dependent upon the input voltage versus the output voltage seen across the loads applied to outputs D1 through D4 or D6 for a given con- stant current setting. Depending upon the case of V IN being greater than the specific voltage seen across the load on D1 (or D5 when the AAT3124 is used) the device will operate in load switch mode. If the voltage seen on the constant current source output is less than V IN, then 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 of each operational mode. Load Switch Mode Efficiency The AAT3123/23A/24 load switch mode is operational at all times and functions alone to enhance device power conversion efficiency when the condition exists where V IN 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 ( η) can be rewritten as: η = POUT = VOUT × IOUT = VOUT PIN VIN × IOUT VIN -or- η(%) = 100 VOUT VIN ⎛ ⎞ ⎝ ⎠ Charge Pump Section Efficiency The AAT3123/23A/24 contains a fractional charge pump which will boost the input supply voltage in the event where V IN is less than the voltage required on the con- stant current source outputs. The efficiency ( η) 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 ( η) 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 efficiency ( η) can be rewritten as: η = POUT = VOUT × IOUT = VOUT PIN VIN × 1.5IOUT 1.5VIN -or- η(%) = 100 VOUT 1.5VIN 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 con- ditions from 1mA to 100mA. Efficiency will decrease as load current drops below 0.05mA or when the level of V IN approaches VOUT. Refer to the Typical Character istics sec- tion 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, and COUT is important because they will affect turn-on time, output ripple, and transient performance. Optimum performance will be obtained when low equivalent series

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET resistance (ESR) ceramic capacitors are used. In gen- eral, low ESR may be defined as less than 100m Ω. A value of 1 μF 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 AAT3123/23A/24. Ceramic capacitors offer many advan- tages over their tantalum and aluminum electrolytic counterparts. 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 to max- imize charge pump transient response. Since ceramic capacitors 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 0.1 μF are typically made from NPO or C0G materials. NPO and C0G materials typically have tight tolerance and are stable over tem- perature. Large capacitor values are typically composed of X7R, X5R, Z5U, or Y5V dielectric materials. Large ceramic capacitors, typically greater than 2.2 μF, are often available in low-cost Y5V and Z5U dielectrics, but capacitors greater than 1μF are typically not required for AAT3123/23A/24 applications. 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. Test Current/Channel Disable Each channel of the output is equipped with test current function. A small amount of current (~2 μA) is injected into each output current source to detect the presence of load (LED). Unused channels that are tied to ground or LED load fail short will be automatically disabled instead of wasting the programmed output current. The test cur- rent in the AAT3123A is higher (~150 μA) to accommo- date LEDs with lower impedance in failure mode. Thermal Protection The AAT3123/23A/24 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 AAT3123/23A/24 D1 to D6 outputs are true con- stant current sources capable of driving up to 20mA 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 D6) may be connected in parallel. The maximum total output current is a sum of how many current sources are parallel connected. This feature is particularly useful to power pre-manufactured display modules which are pre-wired with white LED backlights connected in a parallel circuit configuration. Any combination of outputs may be connected in parallel to drive groups of LEDs. The AAT3123 internal current source reference circuit bases feedback from current sensed on the D1 output. The AAT3124 internal current source reference circuit bases feedback from current sensed on the D1 and D5 outputs. For best operation, the only requirement for this type of application is the output D1 (and/or D5 for the AAT3124) should always be connected to the load circuit. The AAT3124 may be used to drive multiple LEDs having differing forward voltages. Using feedback techniques, the current in D1 to D4 output current sources are refer- enced to the current in the LED connected to D1. In the AAT3124 (six-output version), the D5 and D6 output cur- rent sources are referenced to the current in D5, not to D1. If all six LEDs are of similar type, the diodes will be matched in current, maintaining uniform LED brightness despite variations in manufacturer, production, etc.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET However, if the diodes are dramatically different in type comprising a mix of high-V F and low-V F LEDs, the AAT3124 has the capability to optimally and simultane- ously drive up to four LEDs of one type and up to two LEDs of another type. Such a feature can be useful for driving different color LEDs; driving both display back- light 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 LEDs typically require a high V F to operate (e.g., 3.7V), while the red LED needs a low forward volt- age (e.g., 2V). By connecting the green and blue diodes to outputs D1 to D4 and the red diodes to D5 and D6, good control and uniformity in brightness are maintained despite the 2V difference in the diode forward voltages. The AAT3124 determines if the 1.5X charge pump circuit is needed based on the voltage on D1 and D5, whichever is higher. If adequate voltage is available to drive the higher voltage LED (of output D1 or D5) without the charge pump running, the IC automatically switches into step-down (1X) mode to maximize efficiency. Similarly, if a 4V photo-flash LED array is connected to outputs D1 through D4 (with the outputs shorted togeth- er) and two 3.3V sub-LCD-display backlight LEDs are connected to outputs D5 and D6, then the AAT3124 can optimally drive each set of LEDs at the programmed cur- rent level (see application schematics). The photo flash can be disabled by an N-channel switch connected in series with the photo-flash LED. The AAT3123/23A/24 has only one programmed value of current and does not allow for separate on/off or bright- ness control of each current source output. This limita- tion can easily be circumvented by introducing grounded source N-channel MOSFET switches in series with the LEDs to turn any given LED (or bank of LEDs) on or off. The various LEDs can be turned on and off indepen- dently, simultaneously, or multiplexed to produce any variety of lighting effects. By reprogramming the current source (via the serial interface) between switching tran- sitions, the brightness of individual LEDs or banks of LEDs can also be controlled. Charge Pump Compatibility The four-output AAT3123 is pin compatible with the AAT3113 in both QFN and TSOPJW packages. The six- output AAT3124 is pin compatible with the AAT3114 in the QFN package. Compared to the AAT3113/14, the AAT3123/23A/24 offers an improved overall efficiency, wider operating range, and the ability to drive high-V F LEDs (up to 4.3V) at full current from a 3V input condi- tion. The AAT3123/23A/24 is well suited for battery- powered applications using single-cell lithium-ion (li-ion) batteries (4.2V to 2.8V), lithium-polymer batteries, and 3-series connected dry cells (3.6V).

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Additional Application Circuits CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF D4 D3 D2 D1 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3123 AAT3123A Typical AAT3123/23A Application Circuit. CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF D2 D3 D4 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3123 AAT3123A Display Module RB1 RB2 RB3 RB4 Resistor R is optional AAT3123/23A Driving a Display Module with Four Paralleled White LEDs.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Additional Application Circuits (continued) CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF D2 D3 D4 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3124 RB1 RB2 RB3 RB4 RB5 RB6 Resistor R is optional Resistor R is optional AAT3124 Driving Two Groups of Paralleled White LEDs (e.g., main and sub-LCD backlights). CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF D2 D3 D4 D5 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3124 D1 D6 Photo-Flash LED Resistor R is optional *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 AAT3124 Driving a High-Current Photo-Flash LED.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Additional Application Circuits (continued) CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF D2 D3 D4 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3124 Enable Display Backlight Enable Keyboard Backlight AAT3124 Driving Two Groups of Paralleled White LEDs (with series N-channel switch). CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF BLU2RED1 VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3124 GRN1 Enable Green Enable Red Enable Blue RED2 GRN2 BLU1 AAT3124 Separately Driving RGB Color LEDs.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Additional Application Circuits (continued) CIN 1μF VBATTERY COUT 1μF EN/SET 1μF 1μF RED VIN VOUT C1+ C1- C2+ C2- EN/SET GND AAT3124 GRN Enable Green Enable Red Enable Blue BLU Common-Anode RGB Color LED AAT3124 Driving Common-Anode RGB Color LED.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET

Ordering Information

Package Marking 1 Part Number (Tape and Reel)2 Description TSOPJW-12 IRXYY AAT3123ITP-20-T1 4-Channel Output TSOPJW-12 OIXYY AAT3123AITP-20-T1 4-Channel Output with Increased Start-Up Current (see “Test Current/Channel Disable” section on page 11) QFN44-16 ISXYY AAT3124ISN-20-T1 6-Channel Output TSOPJW-14 4BXYY AAT3124ITO-20-T1 6-Channel Output All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/about/quality.aspx.

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. 1. XYY = assembly and date code. 2. Sample stock is generally held on all part numbers listed in BOLD.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET QFN44-161 4.000 ± 0.050 Pin 1 Dot By Marking 2.400 ± 0.050 0.550 ± 0.020 2.400 ± 0.050 4.000 ± 0.050 2.280 REF

0.650 BSC

0.900 ± 0.100 Pin 1 Identification C0.3 13 16 0.025 ± 0.025 0.214 ± 0.036 0.330 ± 0.075 Top View Bottom View Side View All dimensions in millimeters. 1. 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.

High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET AAT3123/23A/24 High Efficiency 1X/1.5X Fractional Charge Pump for White LED ApplicationsChargePump TM PRODUCT DATASHEET Advanced Analogic Technologies, Inc.

3230 Scott Boulevard, Santa Clara, CA 95054

Phone (408) 737-4600 Fax (408) 737-4611 © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech pr oduct. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specifi c testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. TSOPJW-14 2.40 ± 0.10 2.85 ± 0.20

0.40 BSC

0.20 + 0.10 - 0.05 0.15 ± 0.05 0.45 ± 0.15 2.75 ± 0.25 4° ± 4° 1.05 + 0.05 - 0.00 1.00 + 0.000 - 0.075 3.05 + 0.05 - 0.10 0.05 + 0.05 - 0.04 Top View Side View End View All dimensions in millimeters.