Ordering number : ENA0089 CMOS IC LC410591FN Power Supply IC with Built-in White LED Charge Pump Overview The LC410591FN is a power supply IC for white LEDs. It incorporates a charge pump-type DC/DC converter circuit and has four constant-current outputs. The input voltage ranges from 2.7V to 5.5V. The maximum value of the current flowing to the LEDs can be determined by the resistance value of the external resistors. The LC410591FN can supply a total current of 105mA for one to four white LEDs. A maximum current of 26mA can be supplied to one white LED when driving four LEDs, and a maximum current of 35mA can be supplied to one white LED when driving three LEDs. The IC operates at a fixed frequency of 600kHz without using an inductor, resulting in very low EMI noise. The LED brightness is adjusted by a PWM pulse signal to the BRGT pin. When a low level is applied for 22ms or longer to the BRGT pin, the IC enters the shutdown mode. This IC comes in the VQFN16 package (4mm × 4mm). Features • Built-in low-noise and high-efficiency CMOS charge pump • Built-in constant-current generating circuit • Input voltage range of 2.7V to 5.5V • Driving of 1 to 4 white LEDs at a total current of 105mA • Automatic switching of charge pump voltage step-up ratio (×1, ×1.5) • ±1.5% (typ) LED to LED current matching • Soft start for preventing rush current • Charge pump frequency of 600kHz • Brightness adjustment control with a PWM signal • 1µA maximum shutdown current Applications • White LED display backlights • White LED keypad backlights • PDAs, cell phones, FPDs, and other equipment that operate with a single lithium-ion battery Any and all SANYO Semiconductor products described or contained herein do not have specifications that can handle applications that require extremely high levels of reliability, such as life-support systems, aircraft's control systems, or other applications whose failure can be reasonably expected to result in serious physical and/or material damage. Consult with your SANYO Semiconductor representative nearest you before usingany SANYO Semiconductor products described or contained herein in such applications. SANYO Semiconductor assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all SANYO Semiconductor products described or contained herein. N0106HKIM B8-9151 No.A0089-1/11 LC410591FN Specifications Absolute Maximum Ratings at Ta = 25°C Parameter Maximum supply voltage Symbol Conditions Ratings VDD Unit -0.3 to +7.2 V Maximum supply voltage VSS -0.3 to +0.3 V Storage Temperature Tstg -55 to +125 °C Allowable Operating Range at Ta=-40°C to 85°C (unless otherwise specified, Ta=25°C) Supply voltage (VIN)=3.6V, RSET=3.2kΩ, LED forward voltage (VF)=3.2V, input bypass capacitor (CIN)=2.2µF, output smoothing capacitor (CCP)=2.2µF Parameter Symbol Ratings Conditions min Supply voltage VIN typ Unit max 2.7 5.5 V Maximum output current Ta=25°C Maximum LED current (per 1 LED) Ta=25°C, 4 LEDs lit 26 mA Ta=25°C, 3 LEDs lit 35 mA No-load supply current (100% ILED) 105 mA VIN=4.1 to 5.5V (×1 mode) 2 mA VIN=2.7 to 4.1V (×1.5 mode) 5 mA 600 kHz 4.1 V 0.5 V Reference voltage output 1.2 V ISET bias 1.2 V LED current absolute accuracy ±3 % Charge pump frequency Charge pump mode-switching When switching from ×1 to ×1.5 supply voltage Charge pump mode-switching supply voltage hysteresis ±1.5 LED to LED current matching Shutdown time supply current VIN=2.7 to 5.5V,Ta=25°C % 1 µA 50k Hz Input signal frequency (PWM) BRGT input BRGT signal high threshold value Ta=25°C,VIN=4.5 to 5.5V 3 V Ta=25°C,VIN=2.7 to 4.5V 2.5 V BRGT signal low threshold value Ta=25°C,VIN=2.7 to 5.5V BRGT input current (H level) Ta=25°C BRGT input current (L level) Ta=25°C 100 0.5 1 -1 V µA µA (Note 1) Electrical characteristics at Ta=-40°C indicate design guaranteed values. No.A0089-2/11 LC410591FN Package Dimensions unit : mm (typ) 3316 TOP VIEW SIDE VIEW BOTTOM VIEW 4.0 3.75 9 9 8 16 5 16 0.6 4 1 0.65 0.9 MAX (1.025) 0.01 (0.85) SIDE VIEW 0.28 13 5 4 1 (2.50) 8 3.75 4.0 13 12 (2.50) 12 Exposed Die-Pad Do Not Connect SANYO : VQFN16(4.0X4.0) Application Example VCP 2.2µF 2.2µF VIN 1µF 1µF LED_IN1 C1A LED_IN2 C1B LED_IN3 C2A LED_IN4 C2B GND BRGT 1nF VREF ISET ILC01756 No.A0089-3/11 LC410591FN 9 LED_IN2 LED_IN3 LED_IN4 8 TEST* C1B 7 15 BRGT C2A 6 16 VREF VCP 5 C1A GND C2B 14 10 VIN ISET 11 NC** 13 12 LED_IN1 Pin Assignment Top view 1 2 3 4 ILC01757 Pin Functions Pin Name Pin No. Pin Description VIN 2 Power supply input pin. Connects a capacitor of 2.2µF between the VIN pin and GND pin. C1A 4 Flying capacitor (1)+ C1B 7 Flying capacitor (1)- C2A 6 Flying capacitor (2)+ C2B 3 Flying capacitor (2)- BRGT 15 LED brightness adjustment signal input. LED current is adjusted by PWM signal (max. 50kHz). The LED current changes linearly with respect to the PWM signal duty ratio and the brightness changes. When the low level continues for 22ms or longer, the LC410591FN enters the shutdown mode, and the LED turns off. ISET 13 VREF 16 External resistor pin. The maximum LED current is determined by ILED(mA)=48/RSET(kΩ). Internal reference voltage output (standard 1.2V). Connect a capacitor of 1nF between the VREF pin and GND pin. The VREF pin must always be set to a high impedance state. GND LED_IN1 to 4 8 9-12 Power supply GND. The switching current of the charge pump flows to this pin. Connect LEDs between the VCP pin and LED_IN1 to IN4. If not connected, set these pins to OPEN or connect to GND. VCP 5 Charge pump output. Connect a capacitor of 2.2µF between the VCP pin and GND pin. TEST 14 Not used. Always set to OPEN. No.A0089-4/11 LC410591FN Block Diagram 2.2µF 1µF Boost Mode Selector Current Mirror Soft Start Circuit Charge Pump LED_IN1 to 4 1µF Oscillator 2.2µF VCP VIN Clock Generator Brightness Controller BRGT Band Gap Reference 1nF VREF ISET RSET ILC01758 No.A0089-5/11 LC410591FN Standard Electrical Characteristics Unless otherwise specified, Supply voltage (VIN)=3.6V, RSET=3.2kΩ, LED forward voltage (VF)=3.2V, Ta=25°C, 4-light control input bypass capacitor (CIN)=2.2µF, output smoothing capacitor (CCP)=2.2µF, flying capacitor (C1,C2)=1µF LED Current - Supply Voltage Vf =3.2V LED Current - mA 15 10 5 25°C 10 5 3.5 4.0 4.5 Supply Voltage - V 100 60°C 15 Vf =3.4V 0 3.0 LED Current - Supply Voltage 20 LED Current - mA 20 0 3.0 5.0 3.5 4.0 4.5 5.0 Supply Voltage - V ILC01759 LED Efficiency - Supply Voltage ILC01760 LED Efficiency - Supply Voltage 80 80 60°C 60 LED Efficiency - % LED Efficiency - % 60 Vf = 3.6V Vf = 3.2V Vf =3 .4V 40 25°C 40 20 20 0 3.0 3.5 4.0 4.5 Supply Voltage - V 100 0 3.0 5.0 Supply Current - Supply Voltage 100 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 ILC01762 Supply Current - Supply Voltage 80 Supply Current - mA Supply Current - mA 3.4 Supply Voltage - V 80 Vf =3.2V 60 Vf =3.6V V f =3.4V 40 20 0 3.0 3.2 ILC01761 60°C 60 25°C 40 20 3.5 4.0 Supply Voltage - V 4.5 5.0 ILC01763 0 3.0 3.5 4.0 Supply Voltage - V 4.5 5.0 ILC01764 No.A0089-6/11 LC410591FN Unless otherwise specified, Supply voltage (VIN)=3.6V, RSET=3.2kΩ, LED forward voltage (VF)=3.2V, Ta=25°C, 4-light control input bypass capacitor (CIN)=2.2µF, output smoothing capacitor (CCP)=2.2µF, flying capacitor (C1,C2)=1µF Supply Current - Supply Voltage Charge Pump Efficiency - Supply Voltage 100 6 60°C 80 60 40 20 25°C 4 3 2 1 0 3.0 3.5 4.0 4.5 0 3.0 5.0 Supply Voltage - V 4.0 4.5 5.0 Supply Voltage - V LED Current - Duty Ratio of BRGT signal ILC01766 LED Current - BRGTs Duty Ratio 50 100 40 LED Current - mA Current of 4 LEDs - mA 3.5 ILC01765 120 80 kΩ =2 T E RS Ω = 3k RSET 60 40 30 °C 60 5°C 2 20 10 20 0 0 20 40 60 80 Duty Ratio - % 40 6 RSET=3.3kΩ 10 80 100 ILC01768 Output Voltage - Supply Voltage C 60° C 25° 5 20 60 Duty Ratio - % RSET=2kΩ 15 20 ILC01767 LED Current - Supply Voltage 25 4 3 2 1 5 0 3.0 0 0 100 Output Voltage- V 30 LED Current - mA 60°C 5 Supply Current - mA Charge Pump Efficiency - % 25°C 3.5 4.0 Supply Voltage - V 4.5 5.0 ILC01769 0 3.0 3.5 4.0 Supply Voltage - V 4.5 5.0 ILC01770 No.A0089-7/11 LC410591FN Functional Description Circuit description The LC410591FN is a white LED driver that uses a Li-ion battery as its power supply. The output voltage range of the Li-ion battery is approximately 2.7V to 5.5V, and a typical white LED forward voltage (VF) is approximately 3.6V. Therefore, when the supply voltage is 3.6V or less, the voltage must be stepped up internally. The LC410591FN incorporates a charge pump that steps up the supply voltage 1.5 times. This charge pump automatically switches to the optimum step-up mode. The 100% LED current is determined by the resistance values of the external resistors. In other words, the internal reference voltage (VREF≠1.2) is applied precisely to the external resistors by the internal Op amplifier, and the current flowing to the external resistors (IRSET) becomes IRSET=VREF/RSET. The LED current (ILED) is regulated by a current mirror circuit so that 40 times the IRSET current flows. For example, if VREF=1.2V and RSET=2kΩ, then IRSET=0.6mA, and ILED=IRSET×40=24mA. In this case, for 4-light control, the total current flowing to the LED is 24mA×4=96mA. However, this formula does not include the variation in the resistance values of the external resistors. If accurate LED current is required, high-precision resistors (with a variation of 1% or less, for instance) may be required. The LED brightness is adjusted by a serial signal to the BRGT pin. Shutdown mode The LC410591FN enters a shutdown mode when the low level is applied to the BRGT pin for 22ms or longer. In the shutdown mode, the LEDs turn off, and the supply current is reduced to 1µA or less. Soft start The LC410591FN performs a soft start to prevent rush current, and then 100% current flows to the LEDs. A rush current is generated if the charge pump is activated when the flying capacitor is discharged. If the impedance of the capacitor is low, an excessive current will flow in from the battery. Soft start is performed to reduce the stress on the battery and external components. During the soft start, the resistance of the switch connected to the flying capacitor and output smoothing capacitor is adjusted to prevent a rush current. Brightness adjustment LED brightness can be adjusted by controlling the current to the LED with the PWM signal supplied to the BRGT pin. The average current flowing to the LEDs depends on the PWM signal. [LED average current=ILED×Duty ratio] …(Fig. 2) The current flowing to the LED (average value) changes in a nearly linear fashion with respect to the duty ratio of the PWM signal input to the BRGT pin. …(Fig. 3) The upper limit of the PWM signal frequency is 50kHz. Fix the BRGT signal to the low level for at least 22ms from power supply (VIN) rising.…(Fig. 4) T ILED - BRGT Duty 70 t LED current VIN=3.6V,Rset=3.3kΩ BRGT=1kHz,4LEDs 60 ILED (Fig. 2) Frequency=1/T 22ms or longer ILED - mA 50 Duty ratio=t/T 40 30 20 10 VIN 0 0 BRGT 20 40 60 BRGT Duty - % (Fig. 4) 80 100 ILC01771 (Fig. 3) No.A0089-8/11 LC410591FN Selection of external capacitors Low ESR capacitors are recommended for the input bypass capacitor, output smoothing capacitor, and charge pump flying capacitor. Also, ceramic capacitors are recommended for their low fluctuations due to temperature (such as X5R or X7R). Adding LEDs for driving Shown in Figures 5 and 6 are sample circuit diagrams illustrating the use of output voltage (VCP) of this IC when an LED is added. Note that the IC may not be able to conform to its specifications if the total LED current exceeds 105mA. To limit the amount of current to the additional LED, or to control the on/off switching of the current, it is necessary to connect a resistor or switch in series with the added LED. VCP 2.2µF 2.2µF VIN 1µF 1µF LED_IN1 C1A LED_IN2 C1B LED_IN3 C2A LED_IN4 C2B GND BRGT 1nF VREF ISET ILC01772 (Fig. 5) No.A0089-9/11 LC410591FN The connection shown in the figure below is also possible. VCP 2.2µF 2.2µF VIN 1µF 1µF LED_IN1 C1A LED_IN2 C1B LED_IN3 C2A LED_IN4 C2B GND BRGT 1nF VREF ISET ILC01773 (Fig.6) However, in the case of the above connection, LED current differences due to the characteristic differences of the LEDs connected to the same LED_IN by the cathode (Fig. 7) are not adjusted. VCP LED_IN1 ILC01774 (Fig.7) No.A0089-10/11 LC410591FN Specifications of any and all SANYO Semiconductor products described or contained herein stipulate the performance, characteristics, and functions of the described products in the independent state, and are not guarantees of the performance, characteristics, and functions of the described products as mounted in the customer's products or equipment. To verify symptoms and states that cannot be evaluated in an independent device, the customer should always evaluate and test devices mounted in the customer's products or equipment. SANYO Semiconductor Co., Ltd. strives to supply high-quality high-reliability products. However, any and all semiconductor products fail with some probability. It is possible that these probabilistic failures could give rise to accidents or events that could endanger human lives, that could give rise to smoke or fire, or that could cause damage to other property. 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Any and all information described or contained herein are subject to change without notice due to product/technology improvement, etc. When designing equipment, refer to the "Delivery Specification" for the SANYO Semiconductor product that you intend to use. Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO Semiconductor believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of intellectual property rights or other rights of third parties. This catalog provides information as of November, 2006. Specifications and information herein are subject to change without notice. PS No.A0089-11/11