STI3508C

STI3508C STI3508CA 30V Output, 2.5A Current Limit, 1.2MHz High Efficiency Asynchronous Boost Regulator FEATURES GENERAL DESCRIPTION ⚫ 2.5V to 5.5V Input Voltage Range ⚫ Integrated 100mΩ Power MOSFET ⚫ 1.2MHz Fixed Switching Frequency ⚫ Internal 2.5A Switch Current Limit Typically ⚫ Adjustable Output Voltage with The STI3508C and STI3508CA are constant frequency, peak current mode step-up converter with SOT23-6 package intended for small, low power applications. The STI3508C and STI3508CA switch at 1.2MHz and allow the use of tiny, low cost capacitors and inductors 2mm or less in height. Internal soft-start results in small inrush current and extends battery life. The STI3508C and STI3508CA devices feature automatic shifting to pulse frequency modulation mode at light loads. The STI3508C and STI3508CA include under-voltage lockout, current limiting, and thermal overload protection to prevent damage in the event of an output overload. The STI3508C and STI3508CA are available in a small SOT23-6 package. 0.6V VFB for STI3508C 1.2V VFB for STI3508CA ⚫ Internal Compensation ⚫ Up to 30V Output Voltage ⚫ Automatic Pulse Frequency Modulation Mode at Light Loads ⚫ Available in a 6-Pin SOT23-6 Package APPLICATIONS ⚫ ⚫ ⚫ Portable Equipment Applications LED Application Digital Still and Video Cameras TYPICAL APPILCATION D VOUT=12V L 10µH VIN=2.5V to 5.5V Efficiency VOUT=12V, L=10μH, TA=25°C C1 22µF C2 22µF LX NC 130kΩ GND IN FB EN R2 6.8kΩ STI3508C Figure 1. Basic Application Circuit of STI3508C TMI and SUNTO are the brands of TOLL microelectronic . STI3508C_STI3508CA V1.0 2020.02 Efficiency R1 100% 95% 90% 85% 80% 75% 70% 65% 60% 55% 50% 0.001 3V-12V 3.8V-12V 4.2V-12V 5V-12V 0.01 0.1 Output Current (A) 1 www.toll-semi.com 1 STI3508C STI3508CA ABSOLUTE MAXIMUM RATINGS (Note 1) Parameter Min Max Unit Input Supply Voltages -0.3 7 V LX Voltages -0.3 35 V EN, FB Voltage -0.3 7 V Storage Temperature Range - 150 °C Junction Temperature (Note 2) -40 150 °C Power Dissipation - 600 mW Lead Temperature Soldering,10Sec - 260 °C PIN CONFIGURATION LX 1 6 NC GND 2 5 IN FB 3 4 EN SOT23-6 Top Mark: S35Cxxx (S35C: Device Code, xxx: Inside Code) for STI3508C Top Mark: S35Dxxx (S35D: Device Code, xxx: Inside Code) for STI3508CA Part Number Package Top Mark Quantity/ Reel STI3508C SOT23-6 S35Cxxx 3000 STI3508CA SOT23-6 S35Dxxx 3000 STI3508C and STI3508CA devices are Pb-free and RoHS compliant. www.toll-semi.com 2 TMI and SUNTO are the brands of TOLL microelectronic. STI3508C_STI3508CA V1.0 2020.02 STI3508C STI3508CA PIN FUNCTIONS Pin Name 1 LX 2 GND 3 FB Function Power Switch Output. LX is the drain of the internal MOSFET switch. Connect the power inductor and output rectifier to LX. Ground Pin Feedback Input. The FB voltage is 0.6V. Connect the resistor dividers to FB. Regulator On/Off Control Input. A high input at EN turns on the converter, and a 4 EN low input turns it off. When not used, connect EN to the input supply for automatic startup. 5 IN Input Supply Pin. Must be locally bypassed. 6 NC No Connection. ESD RATING Items Description Value Unit VESD_HBM Human Body Model for all pins ±2000 V VESD_CDM Charge Device Model for all pins ±1000 V JEDEC specification JS-001 RECOMMENDED OPERATING CONDITIONS Items Description Min Max Unit Input Voltage Range VIN 2.5 5.5 V Output Voltage Range VOUT VIN 30 V TJ Operating Junction Temperature Range -40 125 °C THERMAL RESISITANCE (Note 3) Items Description Value Unit θJA Junction-to-ambient thermal resistance 200 °C/W θJC Junction-to-case thermal resistance 65 °C/W TMI and SUNTO are the brands of TOLL microelectronic . STI3508C_STI3508CA V1.0 2020.02 www.toll-semi.com 3 STI3508C STI3508CA ELECTRICAL CHARACTERISTICS (VIN=VEN=3.7V, VOUT=12V, TA = 25°C, unless otherwise noted.) Parameter Test Conditions Min Input Voltage Range UVLO Threshold Typ 2.5 VIN Rising 2.4 UVLO Hysteresis Max Unit 5.5 V 2.48 V 200 mV Quiescent Current VFB=120%*VREF, No switch 30 Standby Current VIN=VEN=3.7V, IOUT=0A 450 Shutdown Current VEN=0V 0.1 1 µA Regulated Feedback Voltage Oscillation Frequency 100 µA µA STI3508C, TA = 25°C 0.588 0.600 0.612 V STI3508CA, TA = 25°C 1.176 1.20 1.224 V 1.0 1.2 1.4 MHz VOUT=100% On Resistance of LX 100 mΩ Switching Current Limit 2.5 A EN Input Low Level 0.3 EN Input High Level 1.5 EN Leakage Current LX Leakage Current VEN=0V, VIN=VLX=25V V V 0.1 1.0 µA 0.1 1.0 µA Thermal Shutdown Threshold (Note 4) 160 °C Thermal Shutdown Hysteresis (Note 4) 25 °C Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD) x θJA. Note 3: Measured on JESD51-7, 4-layer PCB. Note 4: Guaranteed by design. www.toll-semi.com 4 TMI and SUNTO are the brands of TOLL microelectronic. STI3508C_STI3508CA V1.0 2020.02 STI3508C STI3508CA FUNCTION DESCRIPTION The STI3508C and STI3508CA, TA = 25°C uses a fixed frequency, peak current mode boost regulator architecture to regulate voltage at the feedback pin. The operation of the STI3508C and STI3508CA can be understood by referring to the block diagram of Figure 2. At the start of each oscillator cycle the MOSFET is turned on through the control circuitry. To prevent sub-harmonic oscillations at duty cycles greater than 50 percent, a stabilizing ramp is added to the output of the current sense amplifier and the result is fed into the negative input of the PWM comparator. When this voltage equals the output voltage of the error amplifier the power MOSFET is turned off. The voltage at the output of the error amplifier is an amplified version of the difference between the bandgap reference voltage and the feedback voltage. In this way the peak current level keeps the output in regulation. If the feedback voltage starts to drop, the output of the error amplifier increases. These results in more current to flow through the power MOSFET, thus increasing the power delivered to the output. The STI3508C and STI3508CA have internal soft start to limit the amount of input current at startup and to also limit the amount of overshoot on the output. FUNCTIONAL BLOCK DIAGRAM IN EN LX Regulator UVLO OTP Oscillator 1.2MHz FB + EA + Voltage Reference VCOMP Logic Control PWM Comparator OCP Soft Start + + Current Sense Slope Compensation GND Figure 2. STI3508C and STI3508CA Block Diagram TMI and SUNTO are the brands of TOLL microelectronic . STI3508C_STI3508CA V1.0 2020.02 www.toll-semi.com 5 STI3508C STI3508CA APPLICATION INFORMATION Setting the Output Voltage The internal reference VREF is 0.6V for STI3508C, and 1.2V of STI3508CA. The output voltage is divided by a resistor divider, R1 and R2 to the FB pin. The output voltage is given by VOUT =VREF × (1+ R1 ) R2 Inductor Selection Inductor selection is important for ST3508C and STI3508CA applications. Inductor value determines input inductor current ripple value. ∆IL = VIN×D VIN VIN ×η = × (1 − ) fs ×L fs ×L VOUT Where: D = duty cycle of boost converter η = efficiency of the converter, e.g. estimated 90% The inductor current ripple determines maximum output current according to device switching current limit value. IOUT_max =IL_max ×(1 − D)= (ISW_LIM − ∆IL ) ×(1 − D) 2 Where： ISW_LIM = current limit of STI3508C, it is 2.5A typically. Generally, the inductor current ripple is estimated 10% to 40% of the input inductor average current. The recommended value of inductor is 2.2μH to 10μH for most application. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should be considered according to the switching current limit of STI3508C and STI3508CA. Capacitor Selection Input and output ceramic capacitors of 22μF are recommended for STI3508C and STI3508CA applications. As to output capacitor, the voltage rating is important for high voltage application and ceramic capacitor’s derating under DC bias. Ceramic capacitors could reduce more than 50% its capacitance at its rated voltage. 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. Table 1: Recommended Selection for Common Output Voltages R2 (kΩ) R2 (kΩ) STI3508C STI3508CA 110 15 9 130 12 24 VOUT (V) R1 (kΩ) 5 www.toll-semi.com 6 COUT (μF) L (μH) 34.8 22 2.2 - 6.8 9.31 20.5 22 4.7 - 10 130 6.8 14.3 22 10 200 5.11 10.5 22 10 TMI and SUNTO are the brands of TOLL microelectronic. STI3508C_STI3508CA V1.0 2020.02 STI3508C STI3508CA Diode Selection Schottky diode is a good choice for STI3508C and STI3508CA because of its low forward voltage drop and fast reverses recovery. Using Schottky diode can get better efficiency. The high-speed rectification is also a good characteristic of Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication as following: ID (RMS) ≈√IOUT × IPEAK The diode’s reverse breakdown voltage should be larger than the output voltage. Layout Consideration For best performance of the STI3508C and STI3508CA, 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. Input Capacitor should be placed close to IN pin and GND. Output capacitor must be placed close to diode output node and GND to reduce switching loop. 2. Keep the main current traces as possible as short and wide. 3. LX node of DC-DC converter is with high frequency voltage swing. It should be kept at a small area. 4. Place the feedback divider resistor R1 and R2 as close as possible to the IC FB pin and keep away from the noisy devices since FB is a high impedance input pin that is sensitive to noise. TMI and SUNTO are the brands of TOLL microelectronic . STI3508C_STI3508CA V1.0 2020.02 www.toll-semi.com 7 STI3508C STI3508CA TYPICAL PERFORMANCE CHARACTERISTICS Efficiency at VOUT = 5V Efficiency at VOUT = 9V VOUT=9V, L=6.8μH, TA=25°C 100% 100% 95% 95% 90% 90% 85% 85% Efficiency Efficiency VOUT=5V, L=4.7μH, TA=25°C 80% 75% 2.7V-5V 70% 3V-5V 65% 55% 4.2V-5V 50% 0.001 0.01 0.1 1 2.7V-9V 3V-9V 3.3V-9V 3.8V-9V 4.2V-5V 5V-9V 70% 60% 3.8V-5V 55% 75% 65% 3.3V-5V 60% 80% 50% 0.001 10 0.01 0.1 Output Current (A) Output Current (A) Efficiency at VOUT = 12V Efficiency at VOUT = 24V VOUT=24V, L=10μH, TA=25°C 100% 100% 95% 95% 90% 90% 85% 85% Efficiency Efficiency VOUT=12V, L=10μH, TA=25°C 80% 75% 2.7V-12V 3V-12V 3.3V-12V 3.8V-12V 4.2V-12V 5V-12V 70% 65% 60% 55% 50% 0.001 0.01 0.1 80% 75% 2.7V-24V 3V-24V 3.3V-24V 3.8V-24V 4.2V-24V 5V-24V 70% 65% 60% 55% 50% 0.001 1 0.01 Output Current (A) Load Regulation 0.1 0.2 0.3 Line Regulation at VOUT = 12V 0.4 Output Voltage (V) Output Voltage (V) Vin=3.3V Vin=4.2V 0.5 Output Current (A) www.toll-semi.com 8 1 VOUT =12V, L=10μH, TA=25°C Vin=3V Vin=3.8V Vin=5V 0 0.1 Output Current (A) VOUT=12V, L=10μH, TA=25°C 12.5 12.4 12.3 12.2 12.1 12 11.9 11.8 11.7 11.6 11.5 1 0.6 0.7 0.8 12.5 12.4 12.3 12.2 12.1 12 11.9 11.8 11.7 11.6 11.5 Io=0A Io=10mA Io=100mA 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) TMI and SUNTO are the brands of TOLL microelectronic. STI3508C_STI3508CA V1.0 2020.02 STI3508C STI3508CA TYPICAL PERFORMANCE CHARACTERISTICS (continued) Steady State Steady State Vin=5V, VOUT=12V, IOUT=0A, TA=25°C Vin=5V, VOUT=12V, IOUT=0.6A, TA=25°C VOUT=100mV/div AC coupled VOUT=10mV/div AC coupled SW=10V/div SW=10V/div VIN=20mV/div AC coupled VIN=20mV/div AC coupled IL=1A/div IL=100mA/div Time: 1μs/div Time: 1μs/div VIN Power On VIN Power Off VIN=5V, VOUT=12V, No load VIN=5V, VOUT=12V, No Load VOUT=10V/div VOUT=10V/div VIN=2V/div VIN=2V/div SW=10V/div SW=10V/div Time: 10ms/div IL=200mA/div IL=200mA/div Time: 400ms/div VIN Power On VIN Power Off VIN=5V, VOUT=12V, Io=0.5A VIN=5V, VOUT=12V, Io=0.5A VOUT=10V/div VOUT=10V/div VIN=2V/div SW=10V/div VIN=2V/div SW=10V/div IL=2A/div IL=2A/div Time: 10ms/div TMI and SUNTO are the brands of TOLL microelectronic . STI3508C_STI3508CA V1.0 2020.02 Time: 400μs/div www.toll-semi.com 9 STI3508C STI3508CA TYPICAL PERFORMANCE CHARACTERISTICS (continued) Power On through EN Power Off through EN VIN=5V, VOUT=12V, IOUT=0.5A VIN=5V, VOUT=12V, IOUT=0.5A VOUT=10V/div VOUT=10V/div SW=10V/div SW=10V/div VEN=5V/div VEN=5V/div IL=1A/div IL=1A/div Time: 800μs/div Time: 100μs/div Load Transient Load Transient VIN=5V, VOUT=12V, IOUT=0.1A to 0.5A VIN=5V, VOUT=12V, IOUT=0.1A to 0.3A VOUT=1V/div AC Coupled VOUT=1V/div AC Coupled IO=200mA/div IO=200mA/div Time: 200μs/div Overt Current Limit Entrance VIN=5V, VOUT=12V, IOUT=0.5A to 1A Time: 200μs/div Overt Current Limit Release VIN=5V, VOUT=12V, IOUT=1A to 0.5A VOUT=5V/div VOUT=5V/div SW=5V/div SW=5V/div IL=1A/div IL=1A/div Time: 100μs/div www.toll-semi.com 10 Time: 200μs/div TMI and SUNTO are the brands of TOLL microelectronic. STI3508C_STI3508CA V1.0 2020.02 STI3508C STI3508CA PACKAGE INFORMATION SOT23-6 Unit: mm Symbol Dimensions In Millimeters Min Max L 2.82 3.02 B 1.50 C Symbol Dimensions In Millimeters Min Max E1 0.85 1.05 1.70 a 0.35 0.50 0.90 1.30 c 0.10 0.20 L1 2.60 3.00 b 0.35 0.55 E 1.80 2.00 F 0 0.15 Note: 1) All dimensions are in millimeters. 2) Package length does not include mold flash, protrusion or gate burr. 3) Package width does not include inter lead flash or protrusion. 4) Lead popularity (bottom of leads after forming) shall be 0.10 millimeters max. 5) Pin 1 is lower left pin when reading top mark from left to right. TMI and SUNTO are the brands of TOLL microelectronic . STI3508C_STI3508CA V1.0 2020.02 www.toll-semi.com 11 STI3508C STI3508CA TAPE AND REEL INFORMATION TAPE DIMENSIONS: SOT23-6 REEL DIMENSIONS: SOT23-6 Note: 1) All Dimensions are in Millimeter 2) Quantity of Units per Reel is 3000 3) MSL level is level 3. www.toll-semi.com 12 TMI and SUNTO are the brands of TOLL microelectronic. STI3508C_STI3508CA V1.0 2020.02