AAT3105IJQ-T1

AAT3105 ANALOGICTECH | Alldatasheet

Document overview

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Technical content

Features

• Drives up to 4 LEDs at up to 30mA each
• Automatic Switching Between 1x and 2x Modes
• 0.85MHz Switching Frequency
• Linear LED Output Current Control
• Universal PWM Interface
• ±10% LED Output Current Accuracy
• ±3% LED Output Current Matching
• Low-current Shutdown Mode
• Built-in Thermal Protection
• Automatic Soft-start
• Available in 2x2mm SC70JW-10 Package

Applications

• Cell Phones
• Digital Still Cameras
• MP3 Players
• Personal Data Assistants (PDAs) Typical Application EN/PWM Interface IN EN/PWM OUT COUT 1µF GND AAT3105CP 1µF CIN 1µF

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Pin Description Pin # Name Function 1D 2 LED2 Current Source Output. D2 is the output of LED2 current source. Connect LED2’s anode to D2 and its cathode to GND. 2D 1 LED1 Current Source Output. D1 is the output of LED1 current source. Connect LED1’s anode to D1 and its cathode to GND. 3 OUT Charge Pump Output. OUT is the output of the charge pump. Bypass OUT to GND with a 1μF or larger ce- ramic capacitor. 4 C- Charge Pump Capacitor Negative Node. 5 C+ Charge Pump Capacitor Positive Node. Connect a 1 μF ceramic capacitor between C+ and C-. 6 GND Analog Ground. Connect this pin to the system’s analog ground plane. 7 EN/PWM LED Enable and control input. EN/PWM is the ON/OFF control for the LED and the PWM input for the AAT3105 to control the LED brightness. 8I N Power source input. Connect IN to the power source, typically the battery. Bypass IN to GND with a 1μF or larger ceramic capacitor. 9D 4 LED4 Current Source Output. D4 is the output of LED4 current source. Connect LED4’s anode to D4 and its cathode to GND. 10 D3 LED3 Current Source Output. D3 is the output of LED3 current source. Connect LED3’s anode to D3 and its cathode to GND. Pin Configuration SC70JW-10 (Top View) OUT IN EN/PWM GND

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Absolute Maximum Ratings1 Symbol Description Value Units VIN IN, C+, C-, OUT, D1, D2, D3, and D4 Pin Voltages to GND -0.3 to 6.0 V VEN EN/PWM Pin Voltage to GND -0.3 to VIN + 0.3 V TS Storage Temperature Range -65 to 150 °C TJ Operating Junction Temperature Range -40 to 150 °C TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C Thermal Information Symbol Description Value Units PD Maximum Power Dissipation2,3 625 mW θJA Maximum Thermal Resistance 3 160 °C/W 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. Mounted on an FR4 circuit board. 3. Derate 6.25mW/°C above 40°C ambient temperature.

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET

Electrical Characteristics

IN = EN = 3.6V, CIN = 1μF, COUT = 1μF, CP = 1μF, TA = -40°C to 85°C unless otherwise noted. Typical values are at T A = 25°C. Symbol Description Conditions Min Typ Max Units Input Power Supply IN Input Voltage Range 2.7 5.5 V IIN Input Operating Current IN = 5.5V, EN = IN, VD1 = VD2 = VD3= VD4 = 0V 6.1 8.0 mA IN = 5.5V, EN = IN, ID1 = ID2 = ID3 = ID4 = FS, VD1 = VD2 = VD3 = VD4 = IN – 1.5V, Excluding IDN current 3.0 4.6 mA Operating, ID1 = ID2 = ID3 = ID4 = OPEN 6.0 8.0 mA IIN(SHDN) Input Shutdown Current EN/PWM = GND 1 μA Charge Pump Section IOUT OUT Maximum Output Current 150 mA VOUT Charge Pump Output Voltage When charge pump is on 5 V fOSC Charge Pump Oscillator Frequency 0.60 0.85 1.05 MHz VIN_(TH) Charge Pump Mode Hysteresis I D1 = ID2 = ID3 = ID4 =30mA 150 250 mV tOUT LED Output Current Start-up Time EN/PWM =IN 110 μs LED Current Source Outputs ID_(MAX) D1 – D4 Current Accuracy Duty Cycle = 100% 27 30 33 mA ΔID_(MAX) D1 – D4 Current Matching Duty Cycle = 100%, VIN – VF = 1.5V -3 3 % ID_(10%) D1 – D4 Current Accuracy Duty Cycle = 10%, VIN – VF = 1.5V 3.2 mA VD_(TH) D1- D4 Charge Pump Mode Transition Threshold ID1 = ID2 = ID3 = ID4 =30mA, VIN – VD1 is measured. 380 mV EN/PWM Current Control VENH EN/PWM Input High Threshold Voltage 1.4 V V ENL EN/PWM Input Low Threshold Voltage 0.4 V I EN(LKG) EN/PWM Input Leakage Current EN/PWM = IN = 5V -1 1 μA tPWM(ON) PWM Control Turn-on Delay 2 μs tEN/PWM EN/PWM Input OFF Timeout 0.15 1 ms fPWM PWM Control Frequency Duty cycle = 80% 50 kHz

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Typical Characteristics VIN = 3.6V, CIN = COUT = CP = 1μF; TA = 25°C, unless otherwise noted. Shutdown Current vs. Temperature Temperature (°C) ShutdownnCurrent (µA) -40 -15 10 35 60 85 0.00 0.02 0.04 0.06 0.08 0.10 VIN = 5.5V VIN = 2.7V Quiescent Current vs. Input Voltage (1x Mode) Supply Voltage (V) Quiescent Current (mA) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 85°C 25°C -40°C No Load Operating Current vs. Input Voltage (2x Mode) Supply Voltage (V) Operating Current (mA) 5.2 5.4 5.6 5.8 6.0 6.2 6.4 85°C 25°C -40°C Frequency vs. Temperature Temperature (°C) Frequency (KHz) -40 -20 0 20 40 60 80 800 820 840 860 880 900 Current Matching vs. Temperature Temperature (°C) LED Current per Channel (mA)-40 -15 10 35 60 85 0.2% 0.4% 0.0% 0.6% 0.8% 1.0% 1.2% Matching LED Current Control vs. PWM Duty Ratio (FPWM = 25KHz) Duty Ratio (%) Current per Channel (mA) 10 20 30 40 50 60 70 80 90 100

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Typical Characteristics VIN = 3.6V, CIN = COUT = CP = 1μF; TA = 25°C, unless otherwise noted. Efficiency vs. Input Voltage Input Voltage (V) Efficiency (%) 20% 40% 60% 80% 100% VF = 2.7V VF = 3.0V VF = 3.3V VF = 3.6V EN/SET Input OFF Timeout vs. Input Voltage Input Voltage (V) TEN/SET(OFF) (µs) 300 350 400 450 500 550 600 650 700 750 800 85°C 25°C -40°C EN Input High Threshold Voltage vs. Input Voltage Input Voltage (V) VEN(H) (V) 0.2 0.4 0.6 0.8 1.0 1.2 85°C 25°C -40°C EN Input Low Threshold Voltage vs. Input Voltage Input Voltage (V) VEN(L) (V) 0.2 0.4 0.6 0.8 1.0 1.2 85°C 25°C -40°C Turn On to 1X Mode (VIN = 4.2V; 30mA/ch) Time (100µs/div) EN (4V/div) VOUT (2V/div) IIN (100mA/div) VD1 (2V/div) Turn On to 2X Mode (VIN = 3.2V; 30mA/ch) Time (200µs/div) EN (4V/div) VOUT (2V/div) IIN (250mA/div) VD1 (2V/div)

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Typical Characteristics VIN = 3.6V, CIN = COUT = CP = 1μF; TA = 25°C, unless otherwise noted. Output Ripple Waveform (VIN = 3.2V; 2X Mode; 30mA/ch) Time (800ns/div) VOUT (50mV/div) VIN (20mV/div) Turn Off from 1X Mode (30mA/ch) Time (200µs/div) EN (2V/div) IIN (200mA/div) VD1 (2V/div)

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Functional Description The AAT3105 is a low-cost charge-pump solution designed to drive up to four white LEDs. The charge pump operates from a 2.7V to 5.5V power source and converts it to volt- age levels necessary to drive the LEDs. LED current is individually controlled through integrated current sources powered from the output of the charge pump. Low 1x charge-pump output resistance and low dropout voltage current sources allow the charge pump to stay in 1x mode with an input voltage as low as 3.8V and LED forward voltages of 3.5V. After entering 2x mode, the charge pump remains in 2x mode until the device resets. The AAT3105 requires only three external components: one 1 μF ceramic capacitor for the charge pump flying capacitor (C P), one 1 μF ceramic input capacitor (C IN), one 1μF ceramic output capacitor (C OUT). The four con- stant current outputs of the AAT3105 (D1 to D4) can drive four individual LEDs with a maximum current of 30mA each. A PWM interface enables the AAT3105 to change the LED current through the EN/PWM pin. PWM Interface The AAT3105 uses a simple PWM interface to control the effective LED current (RMS) of its current source out- puts. The PWM signal should fit the requirements listed in the electrical characteristic table for proper operation. When the EN/PWM pin is constantly pulled high, which means 100% duty ratio, the source current per channel is typically 30mA. When the EN/PWM pin is pulled low for less than 150μs, the current source will output 0mA of current and the charge pump status will remain Functional Block Diagram C–C+ OUT GND IN PWM Control 5 Bits DACEN/PWM Two-Mode CP Control VF Monitoring IREF5

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET unchanged. By feeding the EN/PWM pin with a proper PWM signal, the RMS current of current source outputs is proportional to the duty ratio of the PWM signal with very little error, which is introduced timing delay. If EN/ PWM is kept low for longer than 1ms, the device will enter shutdown mode. In shutdown mode, the device draws less than 1μA current and all current source out- puts are inactive. The relationship between PWM duty ratio and LED cur- rent per channel is shown in Table 1. The PWM signal should meet the timing requirements shown in the Electrical Characteristics section of this datasheet in order to guarantee proper operation and accuracy. For example, if the minimum PWM duty ratio is designed as 10%, then the PWM frequency should be higher than 6Khz to meet the minimum limit of the EN/PWM input off time, which is 150μs. EN/PWM Duty Cycle (FPWM = 25Khz) D1-D4 Current (mA) 100% 29.9 90% 26.7 80% 23.8 70% 20.8 60% 17.9 50% 15 40% 12 30% 9.1 20% 6.2 10% 3.2 Table 1: PWM Duty Cycle vs. LED Current. LED Current vs. PWM Duty Ratio (FPWM = 25KHz) Duty Ratio (%) Current per Channel (mA) 10 20 30 40 50 60 70 80 90 100 Figure 1: PWM Duty Cycle vs. LED Current.

Application Information

The AAT3105 is specifically designed for driving white LEDs. However, the device design will allow the AAT3105 to drive most types of LEDs with forward voltage specifications ranging from 2.2V to 4.7V. LED applications may include mixed arrangements for display backlighting, keypad display, and any other application that demands a constant current source generated from a varying input voltage. Since the D1 to D4 constant current sources are matched with negligible supply voltage dependence, the constant current channels will be matched regardless of their respective LED forward voltage (V F) levels. The low dropout current sources in the AAT3105 maximize performance and make it capable of driving LEDs with high forward voltages. Multiple channels can be combined to obtain a higher LED drive current without complication. Any unused channel should be connected to GND; the device will detect and shut down the channel. Do not connect any unused channel to the OUT pin. Device Switching Noise Performance The AAT3105 operates at a fixed frequency of approxi- mately 0.85MHz to control noise and limit harmonics that can interfere with the RF operation of mobile com- munication 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 backlight solutions. The AAT3105 soft-start feature prevents noise transient effects associ- ated with inrush currents during start-up of the charge pump circuit. Shutdown Since the current switches are the only power returns for all loads, there is no leakage current when all source switches are disabled. To enter shutdown operation, the EN/PWM input for the AAT3105 should be strobed low. After t OFF (500μs), the AAT3105 will be shut down and typically draws less than 1 μA from the input. Registers are reset to 0 in shutdown.

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Power Efficiency and Device Evaluation The charge pump efficiency discussion in the following sections accounts only for efficiency of the charge pump section itself. Due to the unique circuit architecture and design of the AAT3105, it is very difficult to measure efficiency in terms of a percent value comparing input power over output power. Since the AAT3105 outputs are pure constant current sources and typically drive individual loads, it is difficult to measure the output voltage for a given output 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 output power over input power efficiency. The AAT3105 efficiency may be quantified under very specific conditions and is dependent upon the input volt- age versus the output voltage across the loads applied to outputs D1 through D4 for a given constant current setting. Depending on the combination of V IN and volt- ages sensed at the current sources, the device will oper- ate in load switch mode. When any one of the voltages sensed at the current sources nears dropout, the device will operate in 2x charge pump mode. Each of these modes will yield different efficiency values. Refer to the following two sections for explanations for each operational mode. 1x Mode Efficiency The AAT3105 1x mode is operational at all times and functions alone to enhance device power conversion effi- ciency when V IN is higher than the voltage across the load. When in 1x mode, voltage conversion efficiency is defined as output power divided by input power. POUT PIN VF · ILED VIN · IIN VF · ILED VIN · IOUT VF VIN η = = = ≈ An expression for the ideal efficiency ( η) in 1x charge- pump mode can be expressed as: VF VIN η (%) = · 100 For a charge pump led driver with V F of 3.2V and 4.2V input voltage, the theoretical efficiency is 76%. Due to internal switching losses and IC quiescent current con- sumption, the actual efficiency can be measured at 73%. 2x Charge Pump Mode Efficiency The AAT3105 contains a charge pump which will boost the input supply voltage in the event where V IN is less than the voltage required to supply the output. The effi- ciency ( η) can be simply defined as a linear voltage regulator with an effective output voltage that is equal to one and two times the input voltage. Efficiency (η) for an ideal 2x charge pump can typically be expressed as the output power divided by the input power. η = PF PIN In addition, with an ideal 2x charge pump, the output current may be expressed as 1/3 of the input current. The expression to define the ideal efficiency ( η) can be rewritten as POUT PIN VF · ILED VIN · IIN VF · ILED VIN · 2 · IOUT VF 2 · VIN η = = = ≈ -or- VF 2 · VIN η (%) = · 100 For a charge pump current source driver with VF of 3.2V and 2.7V input voltage, the theoretical efficiency is 59%. Due to internal switching losses and IC quiescent current consumption, the actual efficiency can be measured at 57%. Efficiency will decrease substantially as load current drops below 1mA or when the voltage level at V IN approaches the voltage level at VOUT.

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Evaluation Board Bill of Materials (BOM) Component Part Number Description Manufacturer U1 AAT3105IJQ-T1 High Effi ciency 1x/2x Charge Pump for White LED; SC70JW-10 Package AnalogicTech U2 PIC12F675 8-Bit CMOS, FLASH-Based μC; 8-Pin MCU Microchip C1, C2, C3 GRM188R61A105KA61 Cap Ceramic 1uF10V X5R 10% 0603 Murata C4 GRM219R71C104KA01 Cap Ceramic 0.1μF10V X7R 10% 0805 Murata C6 GRM219R61A475KE19 Cap Ceramic 4.7μF10V X5R 10% 0805 Murata C N/A Not Soldered N/A D1-D4 LW M673 Mini TOPLED White LED; SMD Osram LED1 21UGC/TR8 Green LED; 0805 LED0 CMD15 Chicago Miniature Lamp LED2 21SRC/TR8 Red LED; 0805 LED7 CMD15 Chicago Miniature Lamp R2 Chip Resistor 20K, 1/16W 1% 0603 SMD Vishay R3-R5 Chip Resistor 1K, 1/16W 1% 0603 SMD Vishay R6-R7 Chip Resistor 330R, 1/16W 1% 0603 SMD Vishay R8 Chip Resistor 1M, 1/16W 1% 0603 SMD Vishay R9-R12 Chip Resistor 0R, 1/16W 1% 0603 SMD Vishay S1 PTS645TL50 Switch Tact, SPST, 5mm ITT Industries S2 PTS645TL50 Switch Tact, SPST, 5mm ITT Industries S3 PTS645TL50 Switch Tact, SPST, 5mm ITT Industries VR1 EVN-5ESX50B14 10K POT; 3mm Squared SMD Panasonic-ECG

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET

Ordering Information

Package Interface Current Control, Inverting Marking 1 Part Number (Tape and Reel)2 SC70JW-10 PWM Linear 5WXYY AAT3105IJQ-T1 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. Packaging Information SC70JW-10 0.45 ± 0.10 0.05 ± 0.05 2.10 ± 0.30 4° ± 4° 0.15 ± 0.05 2.00 ± 0.20 7° ± 3° 0.85 ± 0.15

1.10 MAX

0.100 0.225 ± 0.075 1.75 ± 0.10 2.20 ± 0.20

0.40 BSC

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

Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET AAT3105178 Low Cost 1x/2x 4 Channel Charge Pump WLED DriverChargePump TM PRODUCT DATASHEET Advanced Analogic Technologies, Inc.

3230 Scott Boulevard, Santa Clara, CA 95054

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