Design Sample & Tools Buy RT7270 3A, 18V, 340kHz Synchronous Step-Down Converter General Description Features 1.5% High Accuracy Reference Voltage The RT7270 is a high efficiency, monolithic synchronous 4.5V to 18V Input Voltage Range step-down DC/DC converter that can deliver up to 3A 3A Output Current output current from a 4.5V to 18V input supply. The Integrated N-MOSFET Switches RT7270 s current mode architecture and external Current Mode Control compensation allow the transient response to be Fixed Frequency Operation : 340kHz optimized over a wide input voltage range and loads. Output Adjustable from 0.925V to 15V Cycle-by-cycle current limit provides protection against Up to 95% Efficiency shorted outputs, and soft-start eliminates input current Programmable Soft-Start surge during start-up. The RT7270 also provides under Stable with Low ESR Ceramic Output Capacitors voltage protection and thermal shutdown protection. The Cycle-by-Cycle Over Current Protection low current (<3A) shutdown mode provides output Input Under Voltage Lockout disconnection, enabling easy power management in Output Under Voltage Protection battery-powered systems. The RT7270 is available in an Thermal Shutdown Protection SOP-8 (Exposed Pad) package. RoHS Compliant and Halogen Free Ordering Information RT7270 Applications Wireless AP/Router Package Type SP : SOP-8 (Exposed Pad-Option 2) Set-Top-Box Lead Plating System Industrial and Commercial Low Power Systems Z : ECO (Ecological Element with LCD Monitors and TVs Halogen Free and Pb free) Green Electronics/Appliances H : UVP Hiccup Point of Load Regulation of High-Performance DSPs N : UVP Disabled Note : Pin Configurations Richtek products are : (TOP VIEW) RoHS compliant and compatible with the current require- 8 BOOT SS ments of IPC/JEDEC J-STD-020. 2 7 VIN EN Suitable for use in SnPb or Pb-free soldering processes. GND 3 6 SW COMP 9 4 5 GND FB Marking Information SOP-8 (Exposed Pad) RT7270xZSP : Product Number RT7270x x : H or N ZSPYMDNN YMDNN : Date Code Copyright 2018 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS7270-03 March 2018 www.richtek.com 1RT7270 Typical Application Circuit 2 1 V IN VIN BOOT 4.5V to 18V C C BOOT IN L RT7270 10F x 2 0.1F 10H V 3 OUT SW 3.3V R 100k EN R1 7 EN 26.1k C OUT 8 5 SS FB 22F x 2 C C C R SS C R2 3.9nF 6.8k 0.1F 4, 9 (Exposed Pad) 10k 6 COMP GND C P Open Table 1. Recommended Component Selection V (V) R1 (k) R2 (k) R (k) C (nF) L (H) C (F) OUT C C OUT 15 153 10 30 3.9 33 22 x 2 10 97.6 10 20 3.9 22 22 x 2 8 76.8 10 15 3.9 22 22 x 2 5 45.3 10 13 3.9 15 22 x 2 3.3 26.1 10 6.8 3.9 10 22 x 2 3.9 22 x 2 2.5 16.9 10 6.2 6.8 1.8 9.53 10 4.3 3.9 4.7 22 x 2 1.2 3 10 3 3.9 3.6 22 x 2 Functional Pin Description Pin No. Pin Name Pin Function Bootstrap for High Side Gate Driver. Connect a 0.1F or greater ceramic 1 BOOT capacitor from BOOT to SW pins. Input Supply Voltage, 4.5V to 18V. Must bypass with a suitable large ceramic 2 VIN capacitor. 3 SW Switch Node. Connect this pin to an external L-C filter. 4, Ground. The exposed pad must be soldered to a large PCB and connected to GND 9 (Exposed Pad) GND for maximum power dissipation. Feedback Input. It is used to regulate the output of the converter to a set value 5 FB via an external resistive voltage divider. Compensation Node. COMP is used to compensate the regulation control 6 COMP loop. Connect a series RC network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. Enable Input Pin. A logic high enables the converter a logic low forces the IC 7 EN into shutdown mode reducing the supply current to less than 3A. Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor 8 SS from SS to GND to set the soft-start period. A 0.1F capacitor sets the soft-start period to 15.5ms. Copyright 2018 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS7270-03 March 2018 2