BCT1813EUT-TR

BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter GENERAL DESCRIPTION FEATURES The BCT1813 is a high efficiency, high frequency synchronous DC-DC step-down converter. The 100% duty cycle feature provides low dropout operation, extending battery life in portable systems.      The internal synchronous switch increases efficiency and eliminates the need for external Schottky diode. At shutdown mode, the input supply current is less than 1µA.      The BCT1813 integrates current limit ，output Short protection and thermal protection.    The BCT1813 is available in a 6-pin SOT23-6 package, which provides a compact solution with minimal external components.  2.5V~5.5V Input Voltage Range 1.2A Output Current Power OK function 1.5MHz Switching Frequency Minimizes the External Components Up to 95% efficiency 100% Duty Cycle in Dropout Operation Output Voltage as Low as 0.6V No Schottky Diode Required Internal soft-start Output short protection Output Auto-Discharge When EN Low Thermal protection Output POK indication SOT23-6 Packages APPLICATIONS      Cellular and Smart Phones Portable Instruments Digital Cameras Set Top Box LCD TV ORDERING INFORMATION Order Number Package Type Temperature Range Marking QTY/Reel BCT1813EUT-TR SOT23-6 -40°C to +85°C PBXX 3000 Note: "XX" in Marking will be appeared as the batch code. REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 1 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter PIN CONFIGURATION TOP VIEW 1 GND 2 SW 3 MARKING EN 6 FB 5 POK 4 VIN PIN DESCRIPTION PIN NAME FUNCTION 1 EN Drive EN pin high to turn on the regulator and low to turn off the regulator. 2 GND Power ground pin. 3 SW Power Switching Output. Connect an inductor to the drains of internal high side PMOS and low side NMOS. 4 VIN Power Supply Input. Must be closely decoupled to GND with a 4.7µF or greater ceramic capacitor. 5 POK Open drain output.Setting high impedance once VOUT reaches 92% of its rating voltage. 6 FB Output feedback pin. FB senses the output voltage and is regulated by the control loop to 0.6V. Connect a resistive divider at FB. REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 2 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter Typical Operating Circuit (VOUT=1.8V) L INPUT C1 10uF OUTPUT SW VIN R1 200K BCT1813 C3 C2 10uF FB R2 100K ENABLE POK POK EN GND ABSOLUTE MAXIMUM RATINGS CAUTION Input Supply Voltage...................................-0.3V to 6.5V This integrated circuit can be damaged by ESD if you don’t EN, FB ,SW PIN .................................-0.3V to VIN+0.3V pay attention to ESD protection. Broadchip recommends Storage Temperature Range.................-65℃ to +150℃ that all integrated circuits be handled with appropriate Junction Temperature............................................150℃ precautions. Failure to observe proper handling and Operating Temperature Range..............-40℃ to +85℃ installation procedures can cause damage. ESD damage Lead Temperature (Soldering, 10 sec).................260℃ can range from subtle performance degradation to Package Thermal Resistance(ɵJA) complete device failure. Precision integrated circuits may SOT23-6............................................................250℃/W be more susceptible to damage because very small Package Thermal Resistance(ɵJC) parametric changes could cause the device not to meet its SOT23-6.............................................................100℃/W published specifications. NOTE: Broadchip reserves the right to make any change in circuit Stresses beyond those listed under “Absolute Maximum Ratings” design, specification or other related things if necessary may cause permanent damage to the device. These are stress without notice at any time. Please contact Broadchip sales ratings only, and functional operation of the device at these or any office to get the latest datasheet. other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 3 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter ELECTRICAL CHARACTERISTICS (VIN= 5V, TA = 25℃, unless otherwise specified.) PARAMETER SYM VIN Input Supply Voltage CONDITIONS MIN VIN VIN UVLO Threshold VIN_MIN TYP 2.5 MAX UNITS 5.5 V VIN Rising 2.4 V VIN Under Voltage Lockout Threshold VIN_MIN_HYST VIN Falling Hysteresis 200 mV Shutdown Supply Current ISD VEN=0V Supply Current IQ VEN=5V, VFB=0.63V Feedback Voltage VFB 1 40 0.585 0.600 uA uA 0.615 V Top Switch On-Resistance RDS(ON)T 200 mΩ Bottom Switch On-Resistance RDS(ON)B 150 mΩ FSW 1.5 MHz ILIM_TOP 1.8 A Switch Frequency Top Switch Current Limit Max Duty Cycle 100 Minimum On Time TON_MIN 100 EN Rising threshold voltage VEN_H VEN rising EN Falling threshold VEN_L VEN falling EN Input current IIN Soft-Start Time tSS % ns 1.5 V 0.4 V 1 uA VEN = 0V to VIN 1 ms POK Rising Threshold VREF Rising 92 % POK Hysteresis VREF falling 8 % POK Sink Capability VIN=2.5V to 5.5V VPOK=0.5V 12 mA -40°C ~85°C 2.7 mS POK Delay tPGD Thermal Shutdown Temperature TSD 160 ℃ Thermal Shutdown Hysteresis THYS 15 ℃ REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 4 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter FUNCTIONAL DESCRIPTION The BCT1813 is a high performance, 1.2A, 1.5MHz monolithic step-down converter. The BCT1813 requires only three external power components (CIN, COUT and L). The adjustable version can be programmed with external feedback to any voltage, ranging from 0.6V to the input voltage. At dropout operation, the converter duty cycle increases to 100% and the output voltage tracks the input voltage minus the RDS(ON) drop of the high-side MOSFET. The internal error amplifier and compensation provides excellent transient response, load, and line regulation. Soft start function prevents input inrush current and output overshoot during start up. Power OK The POK pin is an open-drain output, and can be connects to VOUT or other rail through an external pull-up resistor. As the output voltage arrives 92% of normal output voltage, an internal delay function starts to perform a delay time and then output the POK pin high to indicate the output is ready. As the output voltage falls below the falling Power-OK threshold or one of the two supply voltages falls below its falling POR threshold, the POK pin will output low immediately without a delay time. EN 8% 92% VOUT POK tPDG REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 5 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter APPLICATION INFORMATION Setting the Output Voltage The internal reference VREF is 0.6V (Typical).The output voltage is divided by a resistor, R1 and R2 to the FB pin. The output voltage is given by: V𝑂𝑈𝑇 = 0.6 × (1 + 𝑅1 ) 𝑅2 Inductor Selection For most designs, the BCT1813 operates with inductors of 1µH to 4.7µH. Low inductance values are physically smaller but require faster switching, which results in some efficiency loss. The inductor value can be derived from the following equation: 𝑉𝑂𝑈𝑇 × (𝑉𝐼𝑁 − 𝑉𝑂𝑈𝑇 ) 𝐿= 𝑉𝐼𝑁 × ∆𝐼𝐿 × 𝑓𝑆 Where ΔIL is inductor Ripple Current. Large value inductors result in lower ripple current and small value inductors result in high ripple current. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the 50mΩ to 150mΩ range. Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency should be less than input source impedance to prevent high frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 4.7µF ceramic capacitor for most applications is sufficient. A large value may be used for improved input voltage filtering. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current ratings.The output voltage ripple can be estimated by: VOUT  VOUT  VOUT  1  fS  L  VIN    1    RESR   8 fS  C 2    PCB Layout Recommendations When laying out the printed circuit board, the following checking should be used to ensure proper operation of the BL1813 Check the following in your layout: power traces, consisting of the GND trace, the SW trace and the VIN trace should be kept short, direct and wide current to the internal power MOSFETs. p the switching node, SW, away from the sensitive VOUT node. -) plates of CIN and COUT as close as possible REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 6 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter PACKAGE OUTLINE DIMENSIONS SOT23-6 Symbols A e b B B1 C C1 C2 L ɵ Dimmensions in millimeters Min. Max. 2.82 3.02 0.95 (BSC) 0.28 0.45 1.5 1.7 2.75 3.05 1.05 1.15 0.03 0.15 0.12 0.23 0.35 0.55 0 。 8 。 SOT23-6 Surface Mount Package REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 7 BCT1813 1.2A, 1.5MHz Synchronous Step-Down Converter PCB Layout Pattern: SOT23-6 0.95 2.8 1.0 0.5 RECOMMENDED PCB LAYOUT PATTERN (Unit: mm) REV1.2 www.broadchip.com Copyright © BROADCHIP TECHNOLOGY CO., LTD 8