4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 FEATURES z Two LED Configurations Available: The FSP3302/FSP3303 are high performance, white FSP3302: Up to 4 LEDs LED bias generators for systems consisting of multiple FSP3303: Up to 6 LEDs white LEDs. The FSP3302/FSP3303 are identical z High Efficiency Proprietary Charge Pump except for the number of LEDs they drive; FSP3302 z Automatic 1x/1.5x Mode-Switching supports up to four LEDs, while FSP3303 can supply up Ensures Maximum Efficiency to six LEDs. z Wide 2.7V to 5.2V Input Voltage Range These devices integrate proprietary constant-frequency z 0.3% White LED Brightness Matching charge z Digitally Programmed 1dB Brightness Steps mode-switching to maximize efficiency with accurate, Up to 44mA per LED matched current sources that drive the white LEDs. z Automatic Programming Finish Detection Current matching is better than 0.3%, resulting in highly z 1.2MHz Operation for Low Ripple uniform brightness across different LED channels. z Simple Serial Interface The FSP3302/FSP3303 feature adjustable LED bias z Thermal Shutdown Protection currents, which are programmable through a simple z Tiny QFN16L and µQFN16L Packages serial interface. Charge pump operation at 1.2MHz GENERAL DESCRIPTION pump circuitry that includes automatic allows the use of small capacitors and minimizes ripple. APPLICATIONS The devices also feature soft-start circuitry to limit z Cell Phones inrush current during startup, and thermal shutdown z Portable Devices protection. The FSP3302/FSP3303 are available in space saving QFN16L and µQFN16L packages. PIN CONFIGURATION (Top View) 1/10 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 PIN DESCRIPTION Pin Number Pin Name Pin Description 1 D2 LED Output 2 2 D3 LED Output 3 3 D4 LED Output 4 4 (D5) LED Output 5 (FSP3303 only) 5 (D6) LED Output 6 (FSP3303 only) 6 C1P Flying Capacitor 1 Positive Terminal 7 C1N Flying Capacitor 1 Negative Terminal 8 N/C Not Connected 9 OUT Charge Pump Output. Bypass to G with a 1µF ceramic capacitor. 10 C2P Flying Capacitor 2 Positive Terminal 11 C2N Flying Capacitor 2 Negative Terminal 12 G 13 N/C 14 IN 15 EN/PROG 16 D1 Ground Not Connected Input Supply. Bypass to G with a 1µF ceramic capacitor. IC Enable and Current Programming Pin LED Output 1 ABSOLUTE MAXIMUM RATINGS(NOTE ) Parameter Value Unit IN Supply, OUT, EN/PROG to G -0.3 to 6 V D1, D2, D3, D4, D5, D6, C1P, C1N, C2P, C2N to G -0.3 to VOUT + 0.3 V C1N, C2N Voltage -0.3 to VOUT + 1 V D1, D2, D3, D4, (D5), (D6) Current 58 mA Junction to Ambient Thermal Resistance (θJA) QFN16L 66 µQFN16L 66 °C/W Operating Junction Temperature -40 to 150 °C Storage Temperature -55 to 150 °C Lead Temperature (Soldering, 10 sec) 300 °C Note : Exceeding these limits may damage the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability. 2/10 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 ELECTRICAL CHARACTERISTICS (Circuit of the below Figure 1, VIN = 3.5V, TA = 25°C unless otherwise specified.) Parameter Symbol Input Supply Range VIN Supply Current IQ Test Conditions Min. Typ. 2.7 Shutdown Supply Current Full Scale Output Current IDMAX Output Current Matching VIN = 3V to 5.5V, 4 LED channels active 38 44 Between any two channels Output Current Line Regulation Charge Pump Switching Frequency Soft-Start Time fQP 1000 tSS Thermal Shutdown Temperature Hysteresis = 20°C Max. Unit 5.2 V 3.5 mA 1 µA 49 mA 0.3 % 0.4 %/V 1200 1700 kHz 330 µs 160 °C EN/PROG Logic Low Threshold VIL Logic High Threshold VIH 1.4 Programming Low Time tLOW 0.3 75 µs tLOW1 5 75 µs Programming Low Time to Reinitialize DAC after Finish Programming Minimum High Time tHIGHMIN Programming High Time tHIGH Finish High Time tFINISH Off Timeout tOFF 0.5 V 50 500 µs µs 300 TYPICAL APPLICATION CIRCUIT Figure 1 3/10 ns 75 Input Current V 2007-4-10 500 µs 1 µA 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 FUNCTIONAL BLOCK DIAGRAM C1P C1N IN 1x /1.5x CHARGE PUMP THERMAL SHUTDOWN REFERENCE C2N C2P OUT D1 DISCHARGE OSCILLATOR CHARGE D2 CHARGE FEEDBACK MATCHED CURRENT SOURCES EN/ PROG INTERFACE CONTROL 32-LEVEL LOGARITHMIC DAC D3 D4 D5 D6 G FUNCTIONAL DESCRIPTION As shown in the Functional Block Diagram, the FSP3302/FSP3303 incorporate proprietary charge pump technology that includes automatic 1x/1.5x mode-switching to maximize efficiency. Accurate matched current sources are controlled by a 32-level logarithmic DAC in order to provide an accurate, efficient, and programmable bias supply for white LEDs. CHARGE PUMP The FSP3302/FSP3303 charge pump operates at 1.2MHz, and alternately charges and discharges the flying capacitors at C1P, C1N, C2P and C2N to generate sufficient output voltage at OUT to allow accurate biasing of white LEDs. These devices feature an automatic 1x/1.5x mode-switching charge pump architecture to ensure the highest possible efficiency for a charge pump solution. These devices utilize a proprietary regulation technique that minimizes the output impedance of the charge pump, allowing operation that is superior to competing products down to lower input voltages. EN/PROG PIN EN/PROG is a multi-function pin, providing both an enable/disable function as well as permitting the user a simple means to digitally program the LED current ENABLE/DISABLE If EN/PROG is driven low for more than 500µs (tOFF), a DISABLE condition is detected and the IC is disabled. Conversely, if EN/PROG remains high for more than 500µs (tFINISH), an ENABLE condition is detected, and the DAC is initialized to -31dB upon the next high to low transition of EN/PROG. To properly reset the DAC upon enabling the IC, the input voltage should be applied first while EN/PROG is driven low. A subsequent low to high transition on EN/PROG pin turns the IC on. PROGRAMMING LED CURRENT The interface control block decodes the digital serial input signal at EN/PROG and produces a programming code for the 32-level logarithmic DAC. The logarithmic DAC sets the output currents to one of 32 different levels, in 1dB steps, with the highest level of 0dB corresponding to the full-scale current of 44mA. Logarithmic current scaling results in linear increments in LED brightness. When enabled (on an EN/PROG rising edge), the DAC initializes to its -31dB level. Thereafter, each high to low transition of the EN/PROG pin that occurs within 75µs increments the 4/10 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 DAC, and therefore the LED current, by 1dB. Once the maximum current level of 0dB is reached, an additional high to low transition on EN/PROG resets the DAC level to its minimum value of -31dB. Figure 2 demonstrates the EN/PROG serial protocol. tHIGH OFF 31dB t > tFINISH tLOW 30dB tOFF 29dB OFF tLOW1 31dB 30dB 29dB 28dB Figure2. EN/PROG Serial Protocol To ensure proper DAC initialization, the first low pulse after programming is completed should be at least 5µs. SOFT START When enabled, the FSP3302/FSP3303 operate in a low power state for 330µs (tSS) to limit inrush current. After this time has expired, the devices operate in full-power mode. THERMAL SHUTDOWN In order to protect themselves under thermal overload and short circuit conditions, the FSP3302/FSP3303 incorporate thermal shutdown circuitry that monitors the die temperature and disables the IC if it exceeds 160°C. TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 1, VIN = 3.5V, TA = 25°C unless otherwise specified.) 5/10 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) (Circuit of Figure 1, VIN = 3.5V, TA = 25°C unless otherwise specified.) 6/10 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) (Circuit of Figure 1, VIN = 3.5V, TA = 25°C unless otherwise specified.) APPLICATION INFORMATION CAPACITOR SELECTION For best performance, use only ceramic capacitors, as they offer small size, low ESR, low cost, and high reliability. Since the dropout resistance is dependent on the ESR of the capacitors, lower ESR also allows the circuit to supply the required output currents at lower input voltage. X7R and X5R ceramic types are most stable (±15%) over bias voltage and temperature ranges and thus are highly recommended. Lower cost Y5V and Z5U ceramic types vary widely with voltage and temperature, and they should only be used after careful verification of the effects the capacitance degradation has on the application. Choose values for the flying capacitors of at least 1µF. For best results choose input and output capacitors of at least 1µF. WHITE LED SELECTION The FSP3302/FSP3303 are designed to bias multiple parallel white LEDs. The LED currents are internally matched and change very little with each LED's forward voltage. For best operation, ensure that the maximum LED forward voltage is 4.2V. The FSP3302/FSP3303 utilizes a proprietary design that results in significantly better dropout performance than competing products. Whereas other products maintain constant current for input voltages down to 3.0V, the FSP3302/FSP3303 are capable of providing constant output current for input voltages extending down to as low as 2.7V. EFFICIENCY The FSP3302/FSP3303 automatically adjust their operating mode to ensure the highest possible efficiency for a given set of operating conditions. The theoretical maximum efficiency of a charge pump is a function of its operating mode, and is given by ηMAX = VLED / KVIN where K is equal to 1 for a 1x operating mode and 1.5 for a 1.5x operating mode. Compared to this theoretical maximum efficiency, the FSP3302/FSP3303 achieve efficiency that is within just 2% of the theoretical maximum for full scale output currents. This ensures the lowest possible battery current and the maximum possible battery life in portable applications. 7/10 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 ORDERING INFORMATION FSP3302/FSP3303XXX Package: Q: QFN16L μQ: μQFN 16L 8/10 Packing: A: Tape & Reel Temperature Grade: D: -40~85℃ MARKING INFORMATION 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 PACKAGE INFORMATION (1) QFN16L Symbol Dimensions In Millimeters Min. Max. Min. Max. A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A2 0.200 REF 0.008 REF D 2.900 3.100 0.114 0.122 E 2.900 3.100 0.114 0.122 D1 1.500 1.700 0.059 0.067 E1 1.500 1.700 0.059 0.067 b 0.180 0.280 0.007 0.011 e 9/10 Dimensions In Inches 0.500 BSC 0.020 BSC L 0.350 0.450 0.014 0.018 K 0.200 0.400 0.008 0.016 2007-4-10 4 & 6 CHANNEL CHARGE PUMPS FOR WHITE LED BIAS FSP3302/FSP3303 (2) µQFN16L Symbol Dimensions In Millimeters Min. Max. A Min. Max. 0.900 0.035 A1 0.010 0.090 0.0004 0.0035 D 2.900 3.100 0.114 0.122 E 2.900 3.100 0.114 0.122 D1 1.700 0.067 E1 1.700 0.067 b 0.150 e 10/10 Dimensions In Inches 0.250 0.006 0.500 BSC 0.010 0.020 BSC L 0.350 0.450 0.014 0.018 L1 0.000 0.050 0.000 0.002 2007-4-10