RT6218AHRGJ8F

RT6218A/B TM 18V, 2A, ACOT Step-Down Converter in 8 Pin TSOT-23 General Description Features Input Supply Voltage Range : 4.5V to 18V The RT6218A/B is a simple, easy-to-use, 2A 2A Converter With Built-in 120m/65m Low synchronous step-down DC-DC converter with an input RDS(ON) Power FETs supply voltage range of 4.5V to 18V. The device TM Advanced Constant On-Time (ACOT ) Control integrates low R power MOSFETs to achieve DS(ON) for Ultrafast Transient Response high efficiency in a SOT23 package and build-in Fixed Switching Frequency : 650kHz (SOT23-8) accurate reference voltage (0.765V by product Optional for Operation Modes : options). Automatically Power Saving Mode (PSM) The RT6218A/B adopts Advanced Constant On-Time TM (RT6218A) (ACOT ) control architecture to provide an ultrafast transient response with few external components and Forced PWM Mode (RT6218B) to operate in nearly constant switching frequency over Optimized for Low-ESR Ceramic Output the line, load, and output voltage range. The RT6218A Capacitors operates in automatic PSM that maintains high 1.5% High-Accuracy Feedback Reference efficiency during light load operation. RT6218B Voltage operates in Forced PWM that helps meet tight voltage Output Voltage Range : up to 6.5V regulation accuracy requirements. Externally Adjustable Soft-Start The RT6218A/B senses both FETs current for a robust Monotonic Start-Up for Pre-biased Outputs over-current protection. The device features Both HS/LS FETs Protection for Robust Over cycle-by-cycle current limit protection and prevent the Current Protection device from the catastrophic damage in output short Input Under-Voltage Lockout (UVLO) circuit, over current or inductor saturation. The Output Under-Voltage Protection (UVP) with RT6218A/B series offers programmable start-up by Hiccup Mode connecting a capacitor at external SS pin. The device Over-Temperature Protection (OTP) (Thermal also includes input under-voltage lockout, output Shutdown) under-voltage protection, and over-temperature Enable Control protection (thermal shutdown) to provide safe and Power Good Indication smooth operation in all operating conditions. The RoHS Compliant and Halogen Free RT6218A/B are offered in TSOT-23-8(FC) package. Available in TSOT-23-8 Package Applications Marking Information Set-Top Boxes RT6218AHRGJ8F LCD TVs 25= : Product Code Home Networking Devices DNN : Date Code 25=DNN Surveillance General Purpose RT6218BHRGJ8F 26= : Product Code DNN : Date Code 26=DNN Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6218A/B-00 September 2017 www.richtek.com 1 RT6218A/B Pin Configuration Ordering Information (TOP VIEW) R RT6218A/B Package Type J8F : TSOT-23-8 (FC) Lead Plating System G : Green (Halogen Free and Pb Free) 8 7 6 5 Reference Voltage 2 3 4 V = 0.765V REF UVP Option H : Hiccup PWM Operation Mode A : Automatic PSM B : Forced PWM TSOT-23-8 (FC) Note : Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Functional Pin Description Pin No. Pin Name Pin Function Power ground. This pin, connected to analog ground, must be soldered to a 1 GND large PCB copper area for maximum power dissipation. Switch node between the internal switch and the synchronous rectifier. 2 LX Connect this pin to the inductor and bootstrap capacitor. Power input. The input voltage range is from 4.5V to 18V. Connect a suitable 3 VIN input capacitor between this pin and GND, with a typical capacitance of 22 F. Open-drain power-good indication output. Once being started-up, PGOOD will 4 PGOOD be pulled low to GND if any internal protection is triggered. Soft-start capacitor connection node. Connect an external capacitor between 5 SS this pin and ground to set the soft-start time. Do not leave this pin unconnected. A capacitor of 8.2nF is suggested. Feedback voltage input. Connect this pin to the midpoint of the external feedback resistive divider to set the output voltage of the converter to the 6 FB desired regulation level. The device regulates the FB voltage at Feedback Threshold Voltage, typically 0.765V. Enable control input. Floating this pin or connecting this pin to GND can disable 7 EN the device and connecting this pin to logic high can enable the device. Bootstrap capacitor connection node to supply the high-side gate driver. 8 BOOT Connect a 0.1F ceramic capacitor between this pin and LX pin. Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6218A/B-00 September 2017 2 GND BOOT LX EN VIN FB SS PGOOD