LTC3214 500mA Camera LED Charge Pump U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ DESCRIPTIO Low Noise Constant Frequency Operation* High Efficiency: Up to 94% Multi-Mode Operation: 1x, 1.5x or 2x Boost Modes Automatic Mode Switching High Output Current: Up to 500mA Tiny Application Circuit (3mm × 3mm DFN Package, All Components <1mm High) Automatic Soft-Start Output Disconnect Open, Shorted LED Protection No Inductors Internal 110mΩ LED Current Sense Resistor 3mm × 3mm 10-Lead DFN Package U APPLICATIO S ■ LED Torch/Camera Light Supply for Cell Phones, PDAs and Digital Cameras General Lighting and/or Flash/Strobe Applications Built-in soft-start circuitry prevents excessive inrush current during start-up. High switching frequency enables the use of small external capacitors. Output current level is programmed by an external resistor. LED current is regulated using an internal 110mΩ sense resistor. Automatic mode switching optimizes efficiency by monitoring the voltage across the charge pump and switching modes only when dropout is detected. The part is available in a low profile 3mm x 3mm 10-lead DFN package. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents including 6411531. U ■ The LTC®3214 is a low noise, high current charge pump DC/DC converter capable of driving high current LEDs at up to 500mA from a 2.9V to 4.5V input. Low external parts count (two flying capacitors, one programming resistor and two bypass capacitors at VIN and CPO) make the LTC3214 ideally suited for small, battery-powered applications. TYPICAL APPLICATIO C1 2.2µF Efficiency vs VIN C2 2.2µF 100 C1+ 2.9V TO 4.5V CIN 2.2µF C1– C2+ VIN C2– CPO LED LTC3214 ILED DISABLE ENABLE EN 0.11Ω ISET CCPO 4.7µF ILED UP TO 500mA EFFICIENCY (PLED/PIN) (%) 90 300mA 80 70 50mA 60 50 40 30 20 10 RSET 100mA 200mA 0 LED = AOT2015 VF = 2.9V TYP AT 100mA 2.9 3.1 3214 TA01a LED: AOT2015 3.3 3.5 3.7 3.9 VIN (V) 4.1 4.3 4.5 3214 TA01b 3214fa 1 LTC3214 U W W W ABSOLUTE AXI U RATI GS U W U PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW VIN to GND ............................................... –0.3V to 5.5V CPO to GND ............................................. –0.3V to 5.5V EN ................................................... –0.3V to VIN + 0.3V ICPO, IILED (Note 2) ............................................. 600mA CPO Short-Circuit Duration ............................ Indefinite Storage Temperature Range ................. –65°C to 125°C Operating Temperature Range (Note 3) .. –40°C to 85°C C2+ 1 C1+ 2 10 C1– CPO 3 ILED 4 7 VIN ISET 5 6 EN 9 GND 11 8 C2– DD PACKAGE 10-LEAD (3mm × 3mm) PLASTIC DFN TJMAX = 125°C, θJA = 43°C/W EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB GND ORDER PART NUMBER DD PART MARKING LTC3214EDD LBVQ Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V, CIN = C1 = C2 = 2.2µF, CCPO = 4.7µF. PARAMETER CONDITIONS MIN TYP MAX UNITS 4.5 V Input Power Supply ● VIN Operating Voltage 2.9 µA mA mA IVIN Operating Current ICPO = 0mA, 1x Mode ICPO = 0mA, 1.5x ICPO = 0mA, 2x Mode 980 4.8 6.7 IVIN Shutdown Current EN = LOW 2.5 7.5 2950 3190 µA LED Current LED Current Ratio (ILED/ISET) ILED = 150mA to 500mA 2715 ILED Dropout Voltage (VILED) Mode Switch Threshold, ILED = 200mA 40 mV 2.5 ms EN to LED Current On 100 µs 5 V 1x Mode Output Impedance 0.70 Ω 1.5x Mode Output Impedance 3.2 Ω 2x Mode Output Impedance 3.5 Ω Mode Switching Delay (LED Warmup Time) LED Current On Time mA/mA Charge Pump (CPO) Charge Pump Output Clamp Voltage ● 0.6 High Level Input Voltage (VIH) ● 1.4 Low Level Input Voltage (VIL) ● CLK Frequency VIN = 3V 0.9 1.2 MHz EN Input Current (IIH) Input Current (IIL) VEN = 3.6V ● ● V 14.4 –1 0.4 V 20 µA 1 µA 3214fa 2 LTC3214 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 3.6V, CIN = C1 = C2 = 2.2µF, CCPO = 4.7µF. PARAMETER CONDITIONS MIN TYP MAX UNITS 1.18 1.21 1.24 V 184 µA ISET VISET ● ISET = 50µA ● IISET Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Based on long-term current density limitations. Assumes an operating duty cycle of ≤ 10% under absolute maximum conditions for durations less than 10 seconds. Max current for continuous operation is 300mA. Note 3: The LTC3214E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40°C to 85°C ambient operating temperature range are assured by design, characterization and correlation with statistical process controls. U W TYPICAL PERFOR A CE CHARACTERISTICS ILED vs RSET 0.12 600 0.10 500 0.08 400 ILED (mA) DROPOUT VOLTAGE (V) ILED Dropout Voltage vs LED Current 0.06 300 0.04 200 0.02 100 0 (TA = 25°C unless otherwise specified) 0 0 100 200 300 400 LED CURRENT (mA) 500 0 50 100 150 200 250 300 350 400 RSET (kΩ) 3216 G01 1573 G02 2x Mode Charge Pump Open-Loop Output Resistance (2VIN – VCPO)/ICPO vs Temperature 1x Mode Charge Pump Open-Loop Output Resistance vs Temperature 1.0 5 ICPO = 100mA OUTPUT RESISTANCE (Ω) OUTPUT RESISTANCE (Ω) 0.9 VIN = 2.9V 0.8 VIN = 3.6V 0.7 VIN = 4.5V 0.6 3 2 1 0.5 0.4 –40 4 –15 10 35 TEMPERATURE (°C) 60 85 3216 G03 VIN = 3.6V CIN = C1 = C2 = 2.2µF CCPO = 4.7µF 0 –40 –15 35 10 TEMPERATURE (°C) 60 85 3216 G05 3214fa 3 LTC3214 U W TYPICAL PERFOR A CE CHARACTERISTICS Input Shutdown Current vs Input Voltage Oscillator Frequency vs Supply Voltage 910 4.5 4.0 900 TA = –40°C 3.5 TA = –40°C 890 TA = 25°C 3.0 FREQUENCY (kHz) INPUT SHUTDOWN CURRENT (µA) (TA = 25°C unless otherwise specified) TA = 85°C 2.5 2.0 1.5 TA = 25°C 880 TA = 85°C 870 860 850 1.0 840 0.5 0 2.9 830 3.1 3.3 3.5 3.7 3.9 4.1 INPUT VOLTAGE (V) 2.9 4.5 4.3 3.1 3.3 3.5 3.7 3.9 4.1 SUPPLY VOLTAGE (V) 3214 G06 100mA 200mA 50mA 60 50 40 30 20 0 3200 500 7.15k 70 10 600 300mA 80 CURRENT RATIO EFFICIENCY (PLED/PIN) (%) 90 ILED Current vs Input Voltage 3300 3.3 3.5 3.7 3.9 VIN (V) 3100 400 85°C 3000 –40°C 2900 4.1 4.3 11.8k 17.4k 36.6k 100 2700 4.5 300 200 2800 LED = AOT2015 VF = 2.9V TYP AT 100mA 2.9 3.1 25°C ILED (mA) 100 4.5 3214 G07 ISET/ILED Current Ratio vs ILED Current Efficiency vs VIN 4.3 0 100 400 200 300 ILED CURRENT (mA) 3215 G08 72.2k 0 500 2.9 3.1 3.3 3.5 3.7 3.9 VIN (V) 3214 G09 1.5x Mode CPO Output Ripple 4.1 4.3 4.5 3214 G10 2x Mode CPO Output Ripple VCPO 50mV/DIV A/C COUPLED VCPO 50mV/DIV VIN = 3.6V ICPO = 200mA 500ns/DIV 3214 G11 VIN = 3.6V ICPO = 400mA 500ns/DIV 3214 G12 3214fa 4 LTC3214 U U U PI FU CTIO S C2+, C1+, C2–, C1– (Pins 1, 2, 8, 10): Charge Pump Flying Capacitor Pins. A 2.2µF X5R or X7R ceramic capacitor should be connected from C1+ to C1– and from C2+ to C2–. EN (Pin 6): Input. The EN pin is used to enable the part and bring it into shutdown mode. An internal 250kΩ resistor pulls this pin to GND when left floating. VIN (Pin 7): Power. Supply voltage for the LTC3214. VIN should be bypassed with a 2.2µF to 4.7µF low impedance ceramic capacitor to GND. CPO (Pin 3): Output. CPO is the output of the charge pump. This pin may be enabled or disabled using the EN input. A 4.7µF X5R or X7R ceramic capacitor is required from CPO to GND. GND (Pin 9): Charge Pump Ground. This pin should be connected directly to a low impedance ground plane. ILED (Pin 4): Input. ILED is the LED current sense pin. The LED is connected between CPO (anode) and ILED (cathode). The current into the ILED pin is set by a resistor connected to the ISET pin and regulated internally. Exposed Pad (Pin 11): Control Signal Ground. This pad must be soldered to a low impedance ground plane for optimum thermal and electrical performance. ISET (Pin 5): LED Current Programming Resistor Pin. A resistor connected between this pin and GND is used to set the LED current level. W BLOCK DIAGRA 2 10 C1+ 1 C1– 8 C2+ C2– CPO OSCILLATOR 3 – VOLTAGE CLAMP + MODE CONTROL 7 VREF VIN ILED 4 CURRENT SOURCE CONTROL VIN EN CONTROL LOGIC 6 58Ω 0.11Ω 250k ISET GND 9 5 GND 11 3214 BD 3214fa 5 LTC3214 U OPERATIO The LTC3214 uses a fractional switched capacitor charge pump to power a high current LED with a programmed regulated current. The part starts up into the 1x mode. In this mode, VIN is directly connected to CPO. This mode provides maximum efficiency and minimum noise. The LTC3214 will remain in this mode until the forward voltage (VF) approaches the maximum CPO voltage possible in this mode. When this dropout condition occurs, the LTC3214 will switch to 1.5x mode after a soft-start period. Any subsequent dropout detected will cause the part to enter 2x mode. A two phase nonoverlapping clock activates the charge pump switches. In the 2x mode, the flying capacitors are charged on alternate clock phases from VIN. While one capacitor is being charged from VIN, the other is stacked on top of VIN and connected to the output. Alternatively, in the 1.5x mode the flying capacitors are charged in series during the first clock phase, and stacked in parallel on top of VIN on the second clock phase. This sequence of charging and discharging the flying capacitors continues at a free running frequency of 900kHz (typ). The current delivered to the LED load is controlled by the internal programmable current source. The current is programmed by a resistor connected between the ISET pin and GND. The resistor value needed to attain the desired current level can be determined by Equation 1. RSET = 3570/ILED (1) Overcurrent shutdown mode will prevent damage to the part by shutting down the high power sections of the chip. Choosing an RSET value of 5k or greater will ensure that the part stays out of this mode. Regulation is achieved by sensing the voltage at the ILED pin and modulating the charge pump strength based on the error signal. In shutdown mode all circuitry is turned off and the LTC3214 draws a very low current from the VIN supply. The output is disconnected from VIN and is pulled down by a resistance of approximately 43kΩ. The LTC3214 enters shutdown mode when the EN pin is brought low. Thermal Protection The LTC3214 has built-in overtemperature protection. Thermal shutdown circuitry will shut down the part when the junction temperature exceeds approximately 165°C. It will re-enable the part once the junction temperature drops back to approximately 150°C. The LTC3214 will cycle in and out of thermal shutdown indefinitely without latch up or damage until the heat source is removed. Short-Circuit Protection When EN is brought high, the part will connect VIN and CPO through a weak pull-up. If the CPO capacitor fails to charge up to over 1V (i.e. CPO is shorted), the chip will not be enabled. Similarly, during operation if CPO is pulled down below 1V, the part will be disabled. Soft-Start To prevent excessive inrush current during start-up and mode switching, the LTC3214 employs built-in soft-start circuitry. Soft-start is achieved by increasing the amount of current available to the output charge storage capacitor linearly over a period of approximately 150µs. Charge Pump Strength When the LTC3214 operates in either the 1.5x mode or 2x mode, the charge pump can be modeled as a Thevenin equivalent circuit to determine the amount of current available from the effective input voltage and effective open-loop output resistance, ROL(Figure 1). ROL 1.5VIN OR 2VIN + + – CPO 3214 F01 – Figure 1. Charge Pump Open-Loop Thevenin-Equivalent Circuit 3214fa 6 LTC3214 U OPERATIO ROL is dependent on a number of factors including the oscillator frequency, flying capacitor values and switch resistances. From Figure 1, we can see that the output current is proportional to: For applications requiring multiple current levels, several schemes may be used to change the resistance for the RSET resistor. Figure 2 shows one such scheme. The circuit in Figure 2 uses the I/O output of a microcontroller to switch a second resistor (R2) in parallel or series with R1, changing the effective ISET current. 1.5VIN – CPO 2V – CPO OR IN ROL ROL Mode Switching in the 1.5x mode or 2x mode respectively. The LTC3214 will automatically switch from 1x mode to 1.5x mode, and subsequently from 1.5x mode to 2x mode whenever the LED forward voltage approaches the maximum CPO voltage for that mode. The part will wait approximately 2.5ms before switching to the next mode. This delay allows the LED to warm up and reduce its forward voltage which may remove the dropout condition. The part may be reset to 1X mode by bringing the part into shutdown by setting the EN pin low. Once the EN pin is low, it may be immediately brought high to re-enable the part. LED Current Programming The LTC3214 includes an accurate, programmable current source that is capable of driving LED currents up to 300mA continuously and up to 500mA for pulsed operation. Pulsed operation may be achieved by toggling the EN pin. In either continuous or pulsed operation, proper board layout is required for effective heat sinking. The current may be programmed using a single external resistor. Equation 1, used to calculate the resistor value from the desired current level is repeated below: RSET = 3570/ILED 2.2µF C1+ C1– C2+ VIN 2.9V TO 4.5V µP VIO 2.2µF C2– CPO 2.2µF 4.7µF LTC3214 ILED ON/OFF ILED* EN VIO R2 ISET TORCH/FLASH R1 3214 F02 *ITORCH = [(1.21V/R1) – ((VIO – 1.21V)/R2)] • 2950 IFLASH = [(1.21V/(R1 • R2/(R1 + R2))] • 2950 Figure 2. Recommended Circuit for Attaining Two Current Levels (Torch and Flash Modes) 3214fa 7 LTC3214 U W U U APPLICATIO S I FOR ATIO VIN, CPO Capacitor Selection The value and type of capacitors used with the LTC3214 determine several important parameters such as regulator control loop stability, output ripple, charge pump strength and minimum start-up time. To reduce noise and ripple, it is recommended that low equivalent series resistance (ESR) ceramic capacitors be used for both CVIN and CCPO. Tantalum and aluminum capacitors are not recommended because of their high ESR. The value of CCPO directly controls the amount of output ripple for a given load current. Increasing the size of CCPO will reduce the output ripple at the expense of higher start-up current. The peak-to-peak output ripple for 1.5x mode is approximately given by the expression: VRIPPLE(P-P) = IOUT/(3fOSC • CCPO) small (~15ns), these missing “notches” will result in only a small perturbation on the input power supply line. Note that a higher ESR capacitor such as tantalum will have higher input noise due to the input current change times the ESR. Therefore, ceramic capacitors are again recommended for their exceptional ESR performance. Input noise can be further reduced by powering the LTC3214 through a very small series inductor as shown in Figure 3. A 10nH inductor will reject the fast current notches, thereby presenting a nearly constant current load to the input power supply. For economy, the 10nH inductor can be fabricated on the PC board with about 1cm (0.4") of PC board trace. 10nH VIN 0.1µF Where fOSC is the LTC3214’s oscillator frequency (typically 900kHz) and CCPO is the output storage capacitor. Both the style and value of the output capacitor can significantly affect the stability of the LTC3214. As shown in the Block Diagram, the LTC3214 uses a control loop to adjust the strength of the charge pump to match the current required at the output. The error signal of this loop is stored directly on the output charge storage capacitor. The charge storage capacitor also serves as the dominant pole for the control loop. To prevent ringing or instability, it is important for the output capacitor to maintain at least 3µF of actual capacitance over all conditions. Likewise, excessive ESR on the output capacitor will tend to degrade the loop stability of the LTC3214. To prevent poor load transient response and instability, the ESR of the output capacitor should be kept below 50mΩ. Multilayer ceramic chip capacitors typically have exceptional ESR performance. MLCCs combined with a tight board layout will yield very good stability. As the value of CCPO controls the amount of output ripple, the value of CVIN controls the amount of ripple present at the input pin (VIN). The input current to the LTC3214 will be relatively constant while the charge pump is on either the input charging phase or the output charging phase but will drop to zero during the clock nonoverlap times. Since the nonoverlap time is LTC3214 2.2µF GND 3214 F03 Figure 3. 10nH Inductor Used for Input Noise Reduction (Approximately 1cm of Wire) Flying Capacitor Selection Warning: Polarized capacitors such as tantalum or aluminum should never be used for the flying capacitors since their voltage can reverse upon start-up of the LTC3214. Ceramic capacitors should always be used for the flying capacitors. The flying capacitors control the strength of the charge pump. In order to achieve the rated output current it is necessary to have at least 1.6µF of actual capacitance for each of the flying capacitors. Capacitors of different materials lose their capacitance with higher temperature and voltage at different rates. For example, a ceramic capacitor made of X7R material will retain most of its capacitance from – 40°C to 85°C whereas a Z5U or Y5V style capacitor will lose considerable capacitance over that range. Z5U and Y5V capacitors may also have a very poor voltage coefficient causing them to lose 60% or more of their capacitance when the rated voltage is applied. Therefore, when comparing different capacitors, it is often more appropriate to 3214fa 8 LTC3214 U W U U APPLICATIO S I FOR ATIO compare the amount of achievable capacitance for a given case size rather than comparing the specified capacitance value. For example, over rated voltage and temperature conditions, a 1µF, 10V, Y5V ceramic capacitor in a 0603 case may not provide any more capacitance than a 0.22µF, 10V, X7R available in the same case. The capacitor manufacturer’s data sheet should be consulted to determine what value of capacitor is needed to ensure minimum capacitances at all temperatures and voltages. pins can couple energy capacitively to adjacent PCB runs. Magnetic fields can also be generated if the flying capacitors are not close to the LTC3214 (i.e., the loop area is large). To decouple capacitive energy transfer, a Faraday shield may be used. This is a grounded PCB trace between the sensitive node and the LTC3214 pins. For a high quality AC ground, it should be returned to a solid ground plane that extends all the way to the LTC3214. The following guidelines should be followed when designing a PCB layout for the LTC3214. Table 1 shows a list of ceramic capacitor manufacturers and how to contact them. • The Exposed Pad should be soldered to a large copper plane that is connected to a solid, low impedance ground plane using plated, through-hole vias for proper heat sinking and noise protection. Table 1. Recommended Capacitor Vendors AVX www.avxcorp.com Kemet www.kemet.com Murata www.murata.com Taiyo Yuden www.t-yuden.com Vishay www.vishay.com TDK www.tdk.com • Input and output capacitors (CIN and CCPO) must also be placed as close to the part as possible. • The flying capacitors must also be placed as close to the part as possible. The traces running from the pins to the capacitor pads should be as wide as possible. Layout Considerations and Noise • VIN, CPO and ILED traces must be made as wide as possible. This is necessary to minimize inductance, as well as provide sufficient area for high current applications. Due to the high switching frequency and the transient currents produced by the LTC3214, careful board layout is necessary. A true ground plane and short connections to all capacitors will improve performance and ensure proper regulation under all conditions. An example of such a layout is shown in Figure 4. • LED pads must be large and should be connected to as much solid metal as possible to ensure proper heat sinking. The flying capacitor pins C1+, C2+, C1– and C2– will have very high edge rate waveforms. The large dv/dt on these C1 PIN 1 C2 CIN RSET CCPO 3214 F04 Figure 4. Example Board Layout 3214fa 9 LTC3214 U W U U APPLICATIO S I FOR ATIO Power Efficiency To calculate the power efficiency (η) of a white LED driver chip, the LED power should be compared to the input power. The difference between these two numbers represents lost power whether it is in the charge pump or the current sources. Stated mathematically, the power efficiency is given by: η≡ PLED PIN The efficiency of the LTC3214 depends upon the mode in which it is operating. Recall that the LTC3214 operates as a pass switch, connecting VIN to CPO, until dropout is detected at the ILED pin. This feature provides the optimum efficiency available for a given input voltage and LED forward voltage. When it is operating as a switch, the efficiency is approximated by: η≡ PLED VLED • ILED VLED = ≈ PIN VIN • IIN VIN since the input current will be very close to the LED current. At moderate to high output power, the quiescent current of the LTC3214 is negligible and the expression above is valid. Once dropout is detected at the ILED pin, the LTC3214 enables the charge pump in 1.5x mode. In 1.5x boost mode, the efficiency is similar to that of a linear regulator with an effective input voltage of 1.5 times the actual input voltage. This is because the input current for a 1.5x charge pump is approximately 1.5 times the load current. In an ideal 1.5x charge pump, the power efficiency would be given by: ηIDEAL ≡ PLED V •I V = LED LED ≈ LED PIN VIN • 1.5ILED 1.5VIN Similarly, in 2x boost mode, the efficiency is similar to that of a linear regulator with an effective input voltage of 2 times the actual input voltage. In an ideal 2x charge pump, the power efficiency would be given by: ηIDEAL ≡ PLED VLED • ILED VLED = ≈ PIN VIN • 2 • ILED 2VIN Thermal Management For higher input voltages and maximum output current, there can be substantial power dissipation in the LTC3214. If the junction temperature increases above approximately 165°C, the thermal shutdown circuitry will automatically deactivate the output. To reduce maximum junction temperature, a good thermal connection to the PC board is recommended. Connecting the Exposed Pad to a ground plane and maintaining a solid ground plane under the device can reduce the thermal resistance of the package and PC board considerably. 3214fa 10 LTC3214 U PACKAGE DESCRIPTIO DD Package 10-Lead Plastic DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1698) 0.675 ±0.05 3.50 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC 2.38 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 6 3.00 ±0.10 (4 SIDES) 0.38 ± 0.10 10 1.65 ± 0.10 (2 SIDES) PIN 1 TOP MARK (SEE NOTE 6) (DD10) DFN 1103 5 0.200 REF 1 0.75 ±0.05 0.00 – 0.05 0.25 ± 0.05 0.50 BSC 2.38 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 3214fa Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 11 LTC3214 U TYPICAL APPLICATIO High Power Camera Light and Flash 2.2µF C1+ 2.9V TO 4.5V µP 2.8V 2.2µF C1– C2+ VIN C2– CPO 2.2µF 4.7µF LTC3214 ILED ON/OFF EN 2.8V 41.2k 1% ILED 100mA/300mA ISET TORCH/FLASH 16.9k 1% 3214 TA02 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1618 Constant Current, 1.4MHz, 1.5A Boost Converter VIN: 1.6V to 18V, VOUT(MAX) = 36V, IQ = 1.8mA, ISD < 1µA MS Package LT1961 1.5A (ISW), 1.25MHz, High Efficiency Step-Up DC/DC Converter VIN: 3V to 25V, VOUT(MAX) = 35V, IQ = 0.9mA, ISD < 6µA MS8E Package LTC3205 250mA, 1MHz, Multi-Display LED Controller VIN: 2.8V to 4.5V, VOUT(MAX) = 5.5V, IQ = 50µA, ISD < 1µA DFN Package LTC3206 400mA, 800kHz, Multi-Display LED Controller VIN: 2.8V to 4.5V, VOUT(MAX) = 5.5V, IQ = 50µA, ISD < 1µA DFN Package LTC3208 High Current Software Configurable Multidisplay LED Controller 95% Efficiency, VIN: 2.9V to 4.5V, VOUT(MAX): 5.5V, IQ = 280µA, ISD < 1µA, (5mm × 5mm) QFN-32 Package LTC3215 700mA Low Noise High Current LED Charge Pump VIN: 2.9V to 4.4V, VOUT(MAX) = 5.5V, IQ = 300µA, ISD < 2.5µA (3mm × 3mm) DFN Package LTC3216 1A Low Noise High Current LED Charge Pump with Independent Flash/Torch Current Control VIN: 2.9V to 4.4V, VOUT(MAX) = 5.5V, IQ = 300µA, ISD < 2.5µA (3mm × 4mm) DFN Package LTC3440/LTC3441 600mA/1.2A IOUT, 2MHz/1MHz, Synchronous Buck-Boost DC/DC Converter VIN: 2.4V to 5.5V, VOUT(MAX) = 5.25V, IQ = 25µA/50µA, ISD <1µA MS, DFN Packages LTC3443 600mA/1.2A IOUT, 600kHz, Synchronous Buck-Boost DC/DC Converter VIN: 2.4V to 5.5V, VOUT(MAX) = 5.25V, IQ = 28µA, ISD <1µA DFN Package LTC3453 1MHz, 800mA Synchronous Buck-Boost High Power LED Driver VIN: 2.7V to 5.5V, VOUT: 2.7V to 4.5V, IQ = 2.5mA, ISD < 6µA QFN Package LT3467/LT3467A 1.1A (ISW), 1.3/2.1MHz, High Efficiency Step-Up DC/DC Converters with Integrated Soft-Start VIN: 2.4V to 16V, VOUT(MAX) = 40V, IQ = 1.2mA, ISD < 1µA ThinSOT Package LT3479 3A, 42V, 3.5MHz Boost Converter VIN: 2.5V to 24V, VOUT(MAX) = 40V, IQ = 2µA, ISD < 1µA DFN, TSSOP Packages 3214fa 12 Linear Technology Corporation LT 0306 REV A • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com © LINEAR TECHNOLOGY CORPORATION 2005