RY3740CT5

RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Features • • • • • • 2.5V to 5.5V Input Voltage Up to 40V Output Voltage 1.2MHz Fixed Switching Frequency 0.1/0.2/0.25/0.3/0.6V Feedback Voltage Internal 1.6A Switch Current Limit Support Analog and PWM Dimming Mode • • • • • • Internal 40V Over Voltage Protection Internal Compensation Thermal Shutdown Driving Up to 10 White LEDS Dimming with wide Frequency Range Available in SOT23-5, DFN2×2-6 package • PDA LED back light LCD Bias Supply Applications • • Camera Flash White LED Digital still cameras • General Description The RY3740 series is a step-up converter designed for driving up to 10 white LEDs or up to 40V output voltage from a single cell Lithium Ion battery. The device features integrated overvoltage protection and feedback voltage is regulated to 100mV to 600mV. Low feedback voltage helps to reduces power loss and improves efficiency. Customers can choose different FB voltages according to their application. Optimized operation frequency can meet the requirement of small LC filters value and low operation current with high efficiency. Internal soft start function can reduce the inrush current. Both SOT23-5 and DFN2×2-6 package type provides the best solution for PCB space saving and total BOM cost. Typical Application Circuit L1=6.8µH VIN D1 VOUT n·WLED CIN=10µF COUT=10µF VIN SW Dimming CTRL GND FB R1 Typical White LED Application Circuit L1=6.8µH VIN D1 CIN=10µF VOUT COUT=10µF VIN SW R2 Enable CTRL GND FB R1 Typical Boost Application Circuit Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 1 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Package and Pin Description Pin Configuration TOP VIEW TOP VIEW SW 1 GND 2 5 IN TOP VIEW VIN 3 4 CTRL GND 6 IN GND 2 5 NC FB 3 4 CTRL 5 NC 4 FB CTRL 3 SOT23-5 1 6 SW 1 NC 2 FB SW DFN2×2-6 SOT23-6 Pin Description SOT23-5 Pin No. DFN2×2-6 Pin No. SOT23-6 Pin No. Name Function Power Switch Output. SW is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to SW. SW can swing between GND and 40V. 1 6 1 SW 2 EPAD 2 GND 3 4 3 Ground Pin. FB Feedback Reference Voltage Pin. Series connect a resistor between WLED and ground as a current sense. Sense the current feedback voltage to set the current rating. CTRL pin of the boost converter. It is a multi-functional pin which can be used for enable control and PWM dimming. Should not be left floating. 4 3 4 CTRL 5 1 6 IN Input Supply Pin. Must be locally bypassed. NA 2, 3 5 NC No Connection. Order Information (1) Marking(2) Part No. Model Description Package T/R Qty KaYLL 70390100 RY3740AT5 RY3740AT5 Boost, VIN 2.5-5.5V, VOUT SOT23-5 VIN-40V, 1.2MHz, VFB0.1V, SOT23-5 3000PCS KbYLL 70390101 RY3740BT5 RY3740BT5 Boost, VIN 2.5-5.5V, VOUT SOT23-5 VIN-40V, 1.2MHz, VFB0.2V, SOT23-5 3000PCS KcYLL 70390102 RY3740CT5 RY3740CT5 Boost, VIN 2.5-5.5V, VOUT SOT23-5 VIN-40V, 1.2MHz, VFB0.25V, SOT23-5 3000PCS KcYLL 70390105 RY3740CT6 RY3740CT6 Boost, VIN 2.5-5.5V, VOUT SOT23-6 VIN-40V, 1.2MHz, VFB0.25V, SOT23-6 3000PCS KrYLL 70390113 RY3740CD6 RY3740CD6 Boost, VIN 2.5-5.5V, VOUT DFN2×2-6 VIN-40V, 1.2MHz, VFB0.25V, DFN2×2-6 3000PCS Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 2 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator KdYLL 70390103 RY3740DT5 RY3740DT5 Boost, VIN 2.5-5.5V, VOUT SOT23-5 VIN-40V, 1.2MHz, VFB0.3V, SOT23-5 3000PCS KeYLL 70390104 RY3740ET5 RY3740ET5 Boost, VIN 2.5-5.5V, VOUT SOT23-5 VIN-40V, 1.2MHz, VFB0.6V, SOT23-5 3000PCS KqYLL 70390112 RY3740ED6 RY3740ED6 Boost, VIN 2.5-5.5V, VOUT DFN2×2-6 VIN-40V, 1.2MHz, VFB0.6V, DFN2×2-6 3000PCS Note (1): All RYCHIP parts are Pb-Free and adhere to the RoHS directive. Note (2): Top Marking: KxYLL [ device code: Kx (x=a, b, c, d, e, r, q), Y=year code, LL= lot number code) Specifications Absolute Maximum Ratings (1) (2) Item Min Max Unit VIN, VCTRL voltage -0.3 6 V VSW, VOVP voltage -0.3 42 V VSW, VOVP voltage (10ns transient) -5 43 V All Other Pins –0.3 6 V Power dissipation (3) Internally Limited Operating junction temperature, TJ -40 150 °C Storage temperature, Tstg –65 150 °C 260 °C Lead Temperature (Soldering, 10sec.) Note (1): Exceeding these ratings may damage the device. Note (2): The device is not guaranteed to function outside of its operating conditions. Note (3): The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, RθJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: PD (MAX) = (TJ(MAX) − TA)/RθJA. Exceeding the maximum allowable power dissipation causes excessive die temperature, and the regulator goes into thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=160°C (typical) and disengages at TJ= 130°C (typical). ESD Ratings Item Description Value Unit V(ESD-HBM) Human Body Model (HBM) ANSI/ESDA/JEDEC JS-001-2014 Classification, Class: 2 ±2000 V V(ESD-CDM) Charged Device Mode (CDM) ANSI/ESDA/JEDEC JS-002-2014 Classification, Class: C0b ±200 V ILATCH-UP JEDEC STANDARD NO.78E APRIL 2016 Temperature Classification, Class: I ±150 mA Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 3 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Recommended Operating Conditions Item Min Max Unit –40 125 °C Operating temperature range -40 85 °C Input voltage VIN 2.5 5.5 V Output voltage VOUT VIN 38 V Operating junction temperature (1) Note (1): All limits specified at room temperature (TA = 25°C) unless otherwise specified. All room temperature limits are 100% production tested. All limits at temperature extremes are ensured through correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Thermal Information Item Description (1)(2) SOT23-5 DFN2×2-6 Unit 180 67.8 °C/W RθJA Junction-to-ambient thermal resistance RθJC(top) Junction-to-case (top) thermal resistance 130 88.5 °C/W RθJB Junction-to-board thermal resistance 45 37.2 °C/W ψJT Junction-to-top characterization parameter 35 2.0 °C/W ψJB Junction-to-board characterization parameter 45 37.6 °C/W RθJC Junction-to-case (Bottom) thermal resistance NA 7.9 °C/W Note (1): The package thermal impedance is calculated in accordance to JESD 51-7. Note (2): Thermal Resistances were simulated on a 4-layer, JEDEC board Electrical Characteristics (1) (2) VIN=5V, TA=25°C, unless otherwise specified. Parameter Test Conditions Input voltage range Min Typ. 2.5 Output voltage range Max Unit 5.5 V 38 V Supply Current (Quiescent) VFB =110% 200 250 µA Supply Current (Shutdown) VCTRL =0 or CTRL = GND 0.1 1 µA Typ. (1+2.5%) Typ. mV SW On Resistance 400 650 mΩ Internal SW Current Limit 1.6 A OVP Protection Threshold 40 V Switching Frequency 1.2 MHz 85 % 80 ns Feedback Voltage Maximum Duty Cycle (1-2.5%) Typ. VFB=90% Minimum On-Time EN Rising Threshold 1.1 V EN Falling Threshold Under-Voltage Lockout Threshold Wake up VIN Voltage 2.5 V V 400 mV Soft Start 600 µS Thermal Shutdown 160 ℃ Hysteresis VIN voltage 1.7 V 1.9 Email: support@rychip.com ©RYCHIP Semiconductor Inc. Shutdown VIN Voltage 2.3 0.6 http://www.rychip.com Page 4 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Thermal Hysteresis 30 ℃ Note (1): MOSFET on-resistance specifications are guaranteed by correlation to wafer level measurements. Note (2): Thermal shutdown specifications are guaranteed by correlation to the design and characteristics analysis. Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 5 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Typical Performance Characteristics (1) (2) Note (1): Performance waveforms are tested on the evaluation board. Note (2): VIN =5V, VOUT=18V, 5 LEDs, TA = +25ºC, unless otherwise noted. Efficiency vs. LED Current Efficiency vs. LED Current Efficiency vs. LED Current VOUT=9V, 3 LEDs VOUT=18V, 5 LEDs VOUT=36V, 10 LEDs Efficiency vs. Input Voltage LED Current Regulation vs. Input Voltage LED Current vs. PWM Duty Cycle Typical ILED=11.5mA Typical ILED=11.5mA VIN=5V, VOUT=18V, 5 LEDs Steady State Operation VIN Startup Enable Startup VIN=5V, VOUT=18V, 5LEDs, ILED=60mA VIN=5V, VOUT=18V, 5 LEDs, ILED=60mA VIN=5V, VOUT=18V, 5 LEDs, ILED=60mA Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 6 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Dimming Operation Dimming Operation Dimming Operation VIN=5V, VOUT=18V, 5LEDs, f=100Hz VIN=5V, VOUT=18V, 5LEDs, f=1KHz VIN=5V, VOUT=18V, 5LEDs, f=10KHz Open Load Protection Open Load Protection VIN=5V, VOUT Open VIN=5V, VOUT Open Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 7 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator Functional Block Diagram 1.0MHz OSC VIN Current Bias ibias OCP 1.6A BandGap PWM Logic VREF SW Protection Circuit Buffer OVP FB UVLO VREF GND CTRL Timer 2.5ms Soft Start Block Diagram Functions Description Under-Voltage Lockout (UVLO) Under-voltage lockout (UVLO) protects the chip from operating at an insufficient supply voltage. UVLO protection monitors the internal regulator voltage. When the voltage is lower than UVLO threshold voltage, the device is shut off. When the voltage is higher than UVLO threshold voltage, the device is enabled again. Enable and PWM Dimming When the input voltage is above maximal UVLO rising threshold and the CTRL pin is pulled high, the RY3740 series is enabled. When the CTRL pin is pulled low, the RY3740 series goes into shutdown mode. In shutdown mode, less than 1μA input current is consumed. Because there is a conductive path from the input to the output through the inductor and Schottky diode, the output voltage is equal to the input voltage during shutdown. The CTRL pin allows disabling and enabling of the device as well as brightness control of the LEDs by applying a PWM signal up to typically 1kHz. When a PWM signal is applied, the LED current is turned on when the CTRL is high and off when CTRL is pulled low. Changing the PWM duty cycle therefore changes the LED brightness. Soft-Start The RY3740 series begins soft start when the CTRL pin is pulled high. At the beginning of the soft start period, the isolation FET is turned on slowly to charge the output capacitor. After the pre-charge phase, the RY3740 series starts switching. This is called switching soft start phase. An internal soft start circuit limits the peak inductor current according to the output voltage. The switching soft start phase is about 600µs typically. The soft start function Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 8 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator reduces the inrush current during startup. Over-Voltage Protection As with any current source, the output voltage rises when the output gets high impedance or disconnected. To prevent the output voltage exceeding the maximum switch voltage rating of the main switch, an over voltage protection circuit is integrated. As soon as the output voltage exceeds the OVP threshold, the converter stops switching and the output voltage falls. Efficiency and Feedback Voltage The feedback voltage has a direct effect on the converter efficiency. Because the voltage drop across the feedback resistor does not contribute to the output power (LED brightness), the lower the feedback voltage, the higher the efficiency. Especially when powering only three or less LEDs, the feedback voltage impacts the efficiency around 2% depending on the sum of the forward voltage of the LEDs. Thermal Shutdown Thermal shutdown prevents the chip from operating at exceedingly high temperatures. When the silicon die temperature exceeds 160°C, it shuts down the whole chip. When the temperature falls below its lower threshold (Typ. 130°C) the chip is enabled again. LED Applications Information (1) Note (1): The following dimming methods are based on the RY3740CT5 250mV FB voltage value. Different FB need to choose different resistors and external DC voltage signals to get the desired ILED value. Setting the LED Current The LED current is controlled by the feedback resistor, R1. The current through the LEDs is given by the equation 𝑉 FB/𝑅1. ILED is average LED current. According to the Superposition Theorem, we can implement the analog dimming function, and we provide a variety of different FB voltage to choose from, which can help customers more easily adapt to their application needs. Dimming Control 1. Using a PWM Signal to CTRL Pin For controlling the LED brightness, the RY3740 series can perform the dimming control by applying a PWM signal to CTRL pin. The internal soft start and the wide range dimming frequency can eliminate inrush current and audio noise when dimming. The average LED current is proportional to the PWM signal duty cycle. The magnitude of the PWM signal should be higher than the minimum enables voltage of CTRL pin, in order to let the dimming control perform correctly for preventing the flicker issue, the selected PWM frequency is ≥100Hz and ≤10KHz. 2. Using a DC Voltage When CTRL remains high level, using a variable DC voltage to adjust the brightness is a popular method in some applications. According to the Superposition Theorem, as the DC voltage increases, the voltage contributed to VFB increases and the voltage drop on R2 decreases, i.e. the LED current decreases. For example, the 250mV FB voltage RY3740CT5 can use a DC voltage ranging from 0V-2.8V to adjust the LED current, the selection of resistors sets dimming control of LED current from 20mA to 0mA. Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 9 / 14 RY3740 Series 2.5V-5.5VIN, 40VOUT, 1.2MHz Boost Regulator n·WLED R2 10K RY3740CT5 FB R3 102K R1 13.5Ω VDC Dimming 0V to 2.8V The LED current can be calculated by the following Equation: 𝑉𝐹𝐵 − I𝐿𝐸𝐷 = 𝑅2 × (𝑉𝐷𝐶 − 𝑉𝐹𝐵 ) 𝑅3 𝑅1 3. Using a Filtered PWM signal Another common application is using a filtered PWM signal as an adjustable DC voltage for LED dimming control. A filtered PWM signal acts as the DC voltage to regulate the output current. In this circuit, the output ripple depends on the frequency of PWM signal. For smaller output voltage ripple (