RY3751AT5

RY3751 High Performance, 40V Output, 1MHz Bias Driver Features • • • • • 2.5V to 5.5V Input Voltage Adjust Output Voltage Range Up to 40V 1.23V Feedback Voltage 1MHz Fixed Switching Frequency 0.6A Switch Peak Current Limit • • • • • Internal Compensation Thermal Shutdown Protection Over Voltage Protection –40°C to 125°C Operating Junction Temperature Available in SOT23-5 package • White-LED Supply for LCD Backlights • PDAs, Organizers, and Handheld PCs Applications • • LCD Bias Supply Digital still cameras General Description The RY3751 is a high-frequency boost converter dedicated for small to medium LCD bias supply. The device is ideal to generate output voltages up to 40V from a dual-cell NiMH/NiCd or a single-cell Li-Ion battery. The part can also be used to generate standard 3.3V or 5V to 12V power conversions. 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. The device has a 0.6A switch current limit, offering lower output voltage ripple and allows the use of a smaller form factor inductor for lower power applications. Low quiescent current allows device operation at very high efficiencies over the entire load current range. The RY3751 is available in SOT23-5 package. Typical Application Circuit D2 C3 C4 D1 L1 VIN D3 V2 -Voltage V1 +Voltage CIN VIN ON/ OFF SW R1 COUT FB R2 EN GND Typical Positive and Negative Output LCD Bias Supply Circuit Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 1 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Package and Pin Description Pin Configuration TOP VIEW SW 1 GND 2 FB 3 5 IN 4 EN SOT23-5 Pin Description Pin Name Function 1 SW 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. 2 GND 3 FB Feedback Input. The FB voltage is 1.23V. Connect a resistor divider to FB. 4 EN EN 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. 5 IN Input Supply Pin. Must be locally bypassed. Ground Pin. Order Information (1) Marking KfYLL Part No. 70390105 Model RY3751AT5 Description Package T/R Qty RY3751AT5 Bias Driver, VIN 2.5-5.5V, VOUT VIN-40V, 1MHz, VFB1.23V, SOT23-5 SOT23-5 3000PCS Note (1): All RYCHIP parts are Pb-Free and adhere to the RoHS directive. Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 2 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Specifications Absolute Maximum Ratings (1) (2) Item Min Max Unit VIN, VEN voltage -0.3 6 V VSW voltage -0.3 42 V VSW 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 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 Recommended Operating Conditions Item 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). Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 3 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Thermal Information Item Description (1)(2) Value Unit 180 °C/W RθJA Junction-to-ambient thermal resistance RθJC(top) Junction-to-case (top) thermal resistance 130 °C/W RθJB Junction-to-board thermal resistance 45 °C/W ψJT Junction-to-top characterization parameter 35 °C/W ψJB Junction-to-board characterization parameter 45 °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 Min Typ. Max Unit Input voltage range 2.5 5.5 V Output voltage range VIN 38 V Supply Current (Quiescent) VFB =110% 150 300 µA Supply Current (Shutdown) VEN =0 or EN = GND 0.1 1 µA 1.23 1.26 V SW On Resistance 400 650 mΩ Current Limit 0.6 A Output Over Voltage Protection Threshold 40 V Switching Frequency 1 MHz 90 % 80 ns Feedback Voltage Maximum Duty Cycle 1.20 VFB=90% Minimum On-Time EN Rising Threshold 1.2 V EN Falling Threshold Wake up VIN Voltage Under-Voltage Lockout Threshold Shutdown VIN Voltage 2.1 V 2.3 V 1.9 V 300 mV Soft Start 600 µS Thermal Shutdown 160 ℃ Thermal Hysteresis 30 ℃ Hysteresis VIN voltage 1.7 0.7 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 4 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Typical Performance Characteristics (1) (2) Note (1): Performance waveforms are tested on the evaluation board. Note (2): VIN =5V, VOUT=12V, TA = +25ºC, unless otherwise noted. Efficiency vs. Load Current Load Regulation Efficiency vs. Load Current VOUT=12V VOUT=12V VOUT=12V/18V/24V Load Regulation Output Ripple Voltage Output Ripple Voltage VOUT=12V/18V/24V VIN=5V, VOUT=12V, IOUT=100mA VIN=5V, VOUT=12V, IOUT=200mA Enable Startup at No Load Enable Shutdown at No Load Enable Startup at Heavy Load VIN=5V, VOUT=12V VIN=5V, VOUT=12V VIN=5V, VOUT=12V, IOUT=200mA Enable Shutdown at Heavy Load Power Up at No Load Power Up at Heavy Load VIN=5V, VOUT=12V, IOUT=200mA VIN=5V, VOUT=12V, IOUT=0A VIN=5V, VOUT=12V, IOUT=200mA Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 5 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Functional Block Diagram 1MHz OSC VIN Current Bias BandGap ibias OCP 600mA PWM Logic VREF SW Buffer Protection Circuit FB OVP EN UVLO VREF Soft Start GND 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 Disable When the input voltage is above maximal UVLO rising threshold and the EN pin is pulled high, the RY3751 is enabled. When the EN pin is pulled low, the RY3751 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 enable pin needs to be terminated and should not be left floating. Soft-Start All inductive step-up converters exhibit high inrush current during start-up if no special precaution is made. This can cause voltage drops at the input rail during start up and may result in an unwanted or early system shut down. 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 reduces the inrush current during startup. Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 6 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver 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 overvoltage protection circuit is integrated. As soon as the output voltage exceeds the OVP threshold, the converter stops switching and the output voltage falls. 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. Applications Information Typical Application V2 -18V D3 C3 1µF L1=10µH VIN CIN 4.7µF VIN ON/ OFF SW FB EN GND D2 C4 44µF V1 18V D1 R1 136K COUT 44µF R2 10K Positive and Negative Output LCD Bias Supply Circuit L1=10µH VIN CIN 4.7µF VIN ON/ OFF SW D1 R1 136K VOUT 18V COUT 44µF FB EN GND R2 10K Boost Application Circuit Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 7 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Setting the Output Voltage The output voltage can be programmed by resistor divider, as shown in Equation: Inductor Selection 𝑉𝑉𝑂𝑂𝑂𝑂𝑂𝑂 = 1.23𝑉𝑉 × (1 + 𝑅𝑅1 ) 𝑅𝑅2 The recommended value of inductor for most applications are 4.7 to 22μH. Small size and better efficiency are the major concerns for portable device, such as RY3751 used for mobile phone. When selecting the inductor, the inductor saturation current should be rated as high as the peak inductor current at maximum load, and respectively, maximum LED current. The inductor value determines the maximum switching frequency of the converter. Therefore, select the inductor value that ensures the maximum switching frequency at the converter maximum load current is not exceeded. The maximum switching frequency is calculated by the following formula: 𝑉𝑉𝐼𝐼𝐼𝐼(𝑚𝑚𝑚𝑚𝑚𝑚) × (𝑉𝑉𝑂𝑂𝑂𝑂𝑂𝑂 − 𝑉𝑉𝐼𝐼𝐼𝐼 ) 𝑓𝑓𝑆𝑆(𝑀𝑀𝑀𝑀𝑀𝑀) = 𝐼𝐼𝑃𝑃 × 𝐿𝐿 × 𝑉𝑉𝑂𝑂𝑂𝑂𝑂𝑂 Where: IP = Peak current. L = Selected inductor value. VIN (min) = The highest switching frequency occurs at the minimum input voltage. If the selected inductor value does not exceed the maximum switching frequency of the converter, the next step is to calculate the switching frequency at the nominal load current using the following formula: 2 × 𝐼𝐼𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 × (𝑉𝑉𝑂𝑂𝑂𝑂𝑂𝑂 − 𝑉𝑉𝐼𝐼𝐼𝐼 + 𝑉𝑉𝑑𝑑 ) 𝑓𝑓𝑆𝑆 (𝐼𝐼𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙 ) = 𝐼𝐼𝑃𝑃2 × 𝐿𝐿 Where: IP = Peak current. L = Selected inductor value. Iload=Nominal load current. Vd= Rectifier diode forward voltage. A smaller inductor value gives a higher converter switching frequency, but lowers the efficiency. The inductor value has less effect on the maximum available load current and is only of secondary order. The best way to calculate the maximum available load current under certain operating conditions is to estimate the expected converter efficiency at the maximum load current. 𝐼𝐼𝑙𝑙𝑙𝑙𝑙𝑙𝑙𝑙(𝑚𝑚𝑚𝑚𝑚𝑚) = 𝜂𝜂 𝐼𝐼𝑃𝑃2 × 𝐿𝐿 × 𝑓𝑓𝑠𝑠(𝑚𝑚𝑚𝑚𝑚𝑚) 2 × (𝑉𝑉𝑂𝑂𝑂𝑂𝑂𝑂 − 𝑉𝑉𝐼𝐼𝐼𝐼 ) Where: IP = Peak current. L = Selected inductor value. fSmax= Maximum switching frequency as calculated previously. η = Expected converter efficiency. The selected inductor should have a saturation current that meets the maximum peak current of the converter. Another important inductor parameter is the dc resistance. The lower the dc resistance, the higher the efficiency of the converter. Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 8 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Output Capacitor Selection The device is designed to operate with a wide selection of ceramic output capacitors. The selection of the output capacitor value is a trade-off between output voltage ripple and capacitor cost and form factor. In general, capacitor values of 10µF up to 44µF can be used. For better voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Input Capacitor Selection For good input voltage filtering, low ESR ceramic capacitors are recommended. A 4.7µF ceramic input capacitor is sufficient for most of the applications. For better input voltage filtering and EMI reduction, this value can be increased. The input capacitor should be placed as close as possible to the input pin of the converter. Diode Selection A Schottky diode should be used for the output diode. The forward current rating of the diode should be higher than the load current, and the reverse voltage rating must be higher than the output voltage. Do not use ordinary rectifier diodes, since slow switching speeds and long recovery times cause the efficiency and the load regulation to suffer. Layout Guidelines For best performance of the RY3751, the following guidelines must be strictly followed. 1. Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling. 2. The GND should be connected to a strong ground plane for heat sinking and noise protection. 3. Keep the main current traces as possible as short and wide. 4. SW node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area. 5. Place the feedback components as close as possible to the IC and keep away from the noisy devices. Top Layer Bottom Layer Sample Board Layout Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 9 / 10 RY3751 High Performance, 40V Output, 1MHz Bias Driver Package Description SOT23-5 2.80 3.00 0.95 BSC 0.60 TYP 1.20 TYP EXAMPLE TOP MARK AAAAA 1.50 2.60 1.70 3.00 2.60 TYP PIN 1 TOP VIEW RECOMMENDED PAD LAYOUT GAUGE PLANE 0.25 BSC 0.90 1.30 1.45 MAX SEATING PLANE 0.30 0.50 0.95 BSC FRONT VIEW 0.00 0.15 0° ~8° 0.30 0.55 0.09 0.20 SIDE VIEW NOTE: 1. CONTROL DIMENSION IS IN INCHES. DIMENSION IN BRACKET IS IN MILLIMETERS. 2. PACKAGE LENGTH DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. 3. PACKAGE WIDTH DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. 4. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.004" INCHES MAX. 5. DRAWING CONFORMS TO JEDEC MS-012, VARIATION BA. 6. DRAWING IS NOT TO SCALE. Email: support@rychip.com ©RYCHIP Semiconductor Inc. http://www.rychip.com Page 10 / 10