RT6250BHGQUF

® RT6250A/B 18V, 10A, 500kHz ACOT® Synchronous Step-Down Converter General Description Features The RT6250A/B is a simple, easy-to-use, 10A synchronous step-down DC-DC converter with an input supply voltage range of 4.5V to 18V. The device build-in an accurate 0.6V reference voltage and integrates low RDS(ON) power  MOSFETs to achieve high efficiency in a UQFN-12HL 3x3 package. The RT6250A/B adopts Advanced Constant OnTime (ACOT®) control architecture to provide an ultrafast transient response with few external components and to operate in nearly constant switching frequency over the line, load, and output voltage range. The RT6250A/B operates in automatic PSM that maintains high efficiency during light load operation. The RT6250A/B operates in Forced PWM that helps meet tight voltage regulation accuracy requirements. The RT6250A/B senses both FETs current for a robust over-current protection. It features cycle-bycycle current limit protection and prevent the device from the catastrophic damage in output short circuit, over current or inductor saturation. A built-in soft-start function prevents inrush current during start-up. The device also includes input under-voltage lockout, output under-voltage protection, over-voltage protection, and over-temperature protection (thermal shutdown) to provide safe and smooth operation in all operating conditions. The RT6250A/B is offered in a UQFN-12HL 3x3 (FC) package.             Ω Low 10A Converter With Built-in 20mΩ Ω /10mΩ RDS(ON) Power FETs Input Supply Voltage Range : 4.5V to 18V Output Voltage Range : 0.6V to 6V Advanced Constant On-Time (ACOT®) Control  Ultrafast Transient Response  No Needs for External Compensations  Optimized for Low-ESR Ceramic Output Capacitors 0.6V ± 1% High-Accuracy Feedback Reference Voltage Optional for Operation Modes :  Power Saving Mode (PSM) (RT6250A)  Forced PWM Mode (RT6250B) Fixed Switching Frequency : 500kHz Built-in Internally Fixed Soft-Start (Typ. 0.4ms) Input Under-Voltage Lockout (UVLO) Output Under-Voltage Protection (UVP) with Hiccup Mode Output Over-Voltage Protection (OVP) with AutoRecovery Mode Ultrasonic Mode (USM) for RT6250A Available in UQFN-12HL 3x3 (FC) Package Ordering Information RT6250A/B Applications       Package Type QUF : UQFN-12HL 3x3 (FC) (U-Type) Industrial and Commercial Low Power Systems Computer Peripherals LCD Monitors and TVs Green Electronics/Appliances Point of Load Regulation for High-Performance DSPs, FPGAs, and ASICs Networking Communication Lead Plating System G : Green (Halogen Free and Pb Free) UVP Option H : Hiccup PSM/PWM A : PSM/PWM B : Force-PWM Note : Richtek products are :  RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.  Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS6250A/B-02 May 2020 Suitable for use in SnPb or Pb-free soldering processes. is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT6250A/B Pin Configuration Marking Information BOOT LX LX 1 AGND PGOOD 12 11 10 RT6250AHGQUF VCC FB BYP ILMT (TOP VIEW) 9 8 MA= : Product Code 7 5 EN VIN 4 PGND 6 DNN : Date Code MA=YM DNN 2 RT6250BHGQUF M9= : Product Code 3 DNN : Date Code M9=YM DNN UQFN-12HL 3x3 Simplified Application Circuit RT6250A/B PGOOD VPGOOD RBOOT BOOT VIN VIN CBOOT CIN L LX VCC VOUT VCC CFF (Optional) CVCC VILMT ILMT COUT FB REN VEN R1 RFF (Optional) R2 EN AGND PGND BYP CBYP Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 RBYP (Optional) VBYP is a registered trademark of Richtek Technology Corporation. DS6250A/B-02 May 2020 RT6250A/B Functional Pin Description Pin No. Pin Name Pin Function BOOT Boot-strap pin. Supply high-side gate driver. Decouple this pin to LX pin with 0.1F ceramic cap. LX Inductor pin. Connect this pin to the switching node of inductor. 4 PGND Power ground. 5 VIN Input pin. Decouple this pin to GND pin with at least 10F ceramic cap. 6 EN Enable control. Pull this pin high to turn on the Buck. Do not leave this pin floating. EN pin will also be used to set USM mode for RT6250A, when EN pin voltage is between 2.3V and 18V, it will enter USM mode, if EN pin voltage is between 0.8V and 1.7V, then it is normal mode. 7 PGOOD Power good Indicator. Open drain output when the output voltage is within 90% to 120% of regulation point. 8 AGND Analog ground. Connect AGND to a clean inner GND point with separate trace. 9 VCC 5V linear regulator output for internal control circuit. A capacitor (typical 1F) should be connected to PGND. Don’t connect to external Load. 10 FB Output feedback pin. Connect this pin to the center point of the output resistor divider to program the output voltage. 11 BYP Bypass input for the internal LDO. BYP is externally connected to the output of switching regulator. When the BYP voltage rises above the bypass switch turn-on threshold, the LDO regulator shuts down and the VCC pin is connected to the BYP pin through an internal switch. But when BYP pin is not used, it should be connected to ground. 12 ILMT Current limit setting pin. The current limit is set to 8A, 10A or 12A when this pin is pull low, floating or pull high respectively. 1 2, 3 Functional Block Diagram VIN BOOT Input UVLO 4.2V LX ILMT - EN Internal SST Thermal Protection 0.6V FB PWM Control & Protect Logic + Current Sense PGND PGOOD AGND + EN 4.7V + - VIN 5V LDO VCC BYP Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS6250A/B-02 May 2020 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT6250A/B Operation The RT6250A/B is a high-efficiency, synchronous stepdown DC-DC converter that can deliver up to 10A output current from a 4.5V to 18V input supply. The RT6250A/B adopts ACOT® control mode, which can reduce the output capacitance and provide ultrafast transient responses, and allow minimal component sizes without any additional external compensation network. Input Under-Voltage Lockout In addition to the EN pin, the RT6250A/B also provides enable control through the VIN pin. It features an undervoltage lockout (UVLO) function that monitors the internal linear regulator (VCC). If VEN rises above VENH first, switching will still be inhibited until the VIN voltage rises above VUVLO. It is to ensure that the internal regulator is ready so that operation with not-fully-enhanced internal MOSFET switches can be prevented. After the device is powered up, if the input voltage VIN goes below the UVLO falling threshold voltage (VUVLO − ΔVUVLO), this switching will be inhibited; if VIN rises above the UVLO rising threshold (VUVLO), the device will resume switching. Soft-Start The soft-start function is used to prevent large inrush currents while the converter is being powered up. The RT6250A/B provides an internal soft-start feature for inrush control. During the start-up sequence, the internal capacitor is charged by an internal current source ISS to generate a soft-start ramp voltage as a reference voltage to the PWM comparator. The device will initiate switching and the output voltage will smoothly ramp up to its targeted regulation voltage only after this ramp voltage is greater than the feedback voltage VFB to ensure the converters have a smooth start-up. The typical soft-start time is 0.4ms. Output Over-Voltage Protection (OVP) and UnderVoltage Protection (UVP) The RT6250A/B includes output under-voltage protection (UVP) against over-load or short-circuited condition by constantly monitoring the feedback voltage VFB. If FB drops below the under-voltage protection trip threshold (typically 60% of the internal reference voltage), the UV comparator will go high to turn off both the internal high-side and lowside MOSFET switches. Power Good The PGOOD pin is an open-drain output and is connected to an external pull-up resistor. It is controlled by a comparator, which the feedback signal FB is fed to. If FB is above 90% of the internal reference voltage, the PGOOD pin will be in high impedance and VPGOOD will be held high. Otherwise, the PGOOD output will be pulled low. Over-Temperature Protection (Thermal Shutdown) The RT6250A/B includes an over-temperature protection (OTP) circuitry to prevent overheating due to excessive power dissipation. The OTP will shut down switching operation when junction temperature exceeds a thermal shutdown threshold TSD. Once the junction temperature cools down by a thermal shutdown hysteresis (ΔTSD), the IC will resume normal operation with a complete soft-start. Over-Current Limit The RT6250A/B current limit is (8A, 10A, 12A) it is a cycleby-cycle “valley” type, measuring the inductor current through the synchronous rectifier during the off-time while the inductor current ramps down. If output voltage drops below the output under-voltage protection level, the RT6250A/B will stop switching to avoid excessive heat. Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS6250A/B-02 May 2020 RT6250A/B Absolute Maximum Ratings (Note 1) Supply Voltage, VIN -------------------------------------------------------------------------------------------Enable Pin Voltage, EN -------------------------------------------------------------------------------------- FB Pin Voltage, FB ------------------------------------------------------------------------------------------- Switch Voltage, LX --------------------------------------------------------------------------------------------