RT5788A/B TM 6V, 4A, 1.5MHz ACOT Synchronous Step-Down Converter in TSOT-23-8 package General Description Features 4A Converter With Built-In 22m/////20m Low The RT5788A/B is a simple, easy-to-use, 4A synchronous R Power FETs DS(ON) step-down DC-DC converter with an input supply voltage Input Supply Voltage Range : 2.5V to 6V range of 2.5V to 6V. The device build-in an accurate 0.6V Output Voltage Range : 0.6V to 6V (1.5%) reference voltage and can operate in 100% duty Operates Up to 100% Duty Cycle cycle as a very low dropout voltage regulator. The TM Advanced Constant On-Time (ACOT ) Control RT5788A/B integrates low R power MOSFETs to DS(ON) Ultrafast Transient Response achieve high efficiency and is available in TSOT-23-8 (FC) No Needs for External Compensations package. Optimized for Low-ESR Ceramic Output Capacitors The RT5788A/B adopts Advanced Constant On-Time 0.6V 1.5% High-Accuracy Feedback Reference TM (ACOT ) control architecture to provide an ultrafast Voltage transient response with few external components and to 35A Operation Quiescent Current (RT5788A) operate in nearly constant switching frequency over the Robust Over-Current Protection for Both FETs line, load, and output voltage range. The RT5788A/B is Optional for Operation Modes : designed to operate at 1.5MHz fixed frequency. While Power Saving Mode (PSM) (RT5788A) the RT5788A automatically enters power saving mode Forced PWM Mode (RT5788B) (PSM) operation at light load to maintain high efficiency. Fixed Switching Frequency : 1.5MHz The RT5788B operates in Forced PWM over the loading Monotonic Start-Up for Pre-Biased Output range, that helps meet tight voltage regulation accuracy Individual Enable Control Input requirements. Power Good Indicator The RT5788A/B senses both FETs current for a robust Built-In Internally Fixed Soft-Start (Typ. 1.5ms) over-current protection. It prevents the device from the 100% Duty Cycle Mode catastrophic damage in output short circuit, over current Internal Output Discharge or inductor saturation. The individual enable control input Input Under-Voltage Lockout (UVLO) and power good indicator provides flexible system power Output Under-Voltage Protection (UVP) with Hiccup sequence control a built-in soft-start function prevents Mode inrush current during start-up. The device also includes Over-Temperature Protection input under-voltage lockout, output under-voltage Available in TSOT-23-8 (FC) Package protection, and over-temperature protection (thermal shutdown) to provide safe and smooth operation in all operating conditions. Simplified Application Circuit L V IN V VIN LX OUT CIN R PGOOD RT5788A/B R1 C OUT FB PGOOD PGOOD R2 Enable EN VOUT AGND PGND Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5788A/B-01 October 2017 www.richtek.com 1RT5788A/B Ordering Information Pin Configuration (TOP VIEW) RT5788A/B Package Type J8F : TSOT-23-8 (FC) Lead Plating System 8 7 6 5 G : Green (Halogen Free and Pb Free) 2 34 PWM Operation Mode A : Automatic PSM B : Forced PWM Note : Richtek products are : TSOT-23-8 (FC) RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Marking Information Suitable for use in SnPb or Pb-free soldering processes. RT5788AGJ8F 20= : Product Code 20=DNN DNN : Date Code Applications WLAN ASIC Power / Storage (SSD and HDD) RT5788BGJ8F Mobile Phones and Handheld Devices 1Z= : Product Code STB, Cable Modem, and xDSL Platforms 1Z=DNN DNN : Date Code General Purpose for POL LV Buck Converter Functional Pin Description Pin No. Pin Name Pin Function Open-drain power-good indication output. The power-good function is activated after 1 PGOOD soft-start is finished. Power input. The input voltage range is from 2.5V to 6V. Connect a suitable input 2 VIN bypass capacitor (typically of greater than 10F) between this pin and PGND. The bypass capacitor should be placed as close to the IC as possible. Switch node between the internal switch and the synchronous rectifier. Connect the 3 LX output LC filter from this pin to the output load. Power ground. This pin, connected to analog ground, must be soldered to a large 4 PGND PCB copper area for maximum power dissipation. Output voltage sense input. This pin is used to monitor and adjust output voltage to 5 VOUT enhance load transient regulation. Analog ground. It provides a ground return path for the control circuitry and internal 6 AGND reference. 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 desired regulation 7 FB level. The device regulates the FB voltage at a feedback reference voltage, typically 0.6V. Enable control input. A logic-high enables the converter a logic-low forces the device 8 EN into shutdown mode. Copyright 2017 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5788A/B-01 October 2017 2 EN PGOOD VIN FB LX AGND PGND VOUT