RT8070ZQW

® RT8070 4A, 2MHz, Synchronous Step-Down Converter General Description Features The RT8070 is a high efficiency synchronous, step-down DC/DC converter. Its input voltage range is from 2.7V to 5.5V and provides an adjustable regulated output voltage from 0.8V to 5V while delivering up to 4A of output current.  High Efficiency : Up to 95%  Adjustable Frequency : 200kHz to 2MHz No Schottky Diode Required 0.8V Reference Allows Low Output Voltage Low Dropout Operation : 100% Duty Cycle Enable Function External Soft-Start Power Good Function RoHS Compliant and Halogen Free The internal synchronous low on-resistance power switches increase efficiency and eliminate the need for an external Schottky diode. The default switching frequency is set at 2MHz, if the RT pin is left open. It can also be varied from 200kHz to 2MHz by adding an external resistor. Current mode operation with external compensation allows the transient response to be optimized over a wide range of loads and output capacitors.        Applications   Ordering Information RT8070 Package Type SP : SOP-8 (Exposed Pad-Option 1) QW : WDFN-8L 3x3 (W-Type) Lead Plating System Z : ECO (Ecological Element with Halogen Free and Pb free) Note :    LCD TV and Monitor Notebook Computers Distributed Power Systems IP Phones Digital Cameras Marking Information RT8070ZSP RT8070ZSP : Product Number RT8070 ZSPYMDNN YMDNN : Date Code Richtek products are :  RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.  RT8070ZQW Suitable for use in SnPb or Pb-free soldering processes. 25 : Product Code 25 YM DNN Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8070-08 February 2015 YMDNN : Date Code is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8070 Pin Configurations (TOP VIEW) SS 2 EN 3 VIN 4 GND 8 PGOOD 7 FB 6 RT 5 LX 9 COMP SS EN VIN SOP-8 (Exposed Pad) 3 6 4 9 5 2 PGOOD FB RT LX 8 1 GND COMP 7 WDFN-8L 3x3 Typical Application Circuit RT8070 4 VIN LX 5 VIN 2.7V to 5.5V R3 100k L VOUT CIN 10µF R1 8 PGOOD PGOOD ROSC 6 RT FB 7 COMP 1 COUT RCOMP R2 CCOMP Chip Enable 3 EN GND 9 (Exposed Pad) SS 2 CSS 10nF Table 1. Recommended Components Selection for fSW = 1MHz VOUT (V) R1 (k) R2 (k) RCOMP (k) CCOMP (pF) L (H) COUT (F) 3.3 75 24 33 560 2 22 2.5 51 24 22 560 2 22 1.8 30 24 15 560 1.5 22 1.5 21 24 13 560 1.5 22 1.2 12 24 11 560 1.5 22 1 6 24 8.2 560 1.5 22 Copyright © 2015 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8070-08 February 2015 RT8070 Functional Pin Description Pin No. SOP-8 WDFN-8L 3x3 (Exposed Pad) Pin Name Pin Function 1 1 COMP Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. Connect external compensation elements to this pin to stabilize the control loop. 2 2 SS Soft-Start Control Input. Connect a capacitor from SS to GND to set the soft-start period. A 10nF capacitor sets the soft-start period to 800s (typ.). 3 3 EN Enable Control Input. Float or connect this pin to logic high for enable. Connect to GND for disable. 4 4 VIN 5 5 LX 6 6 RT 7 7 FB Feedback. Receives the feedback voltage from a resistive divider connected across the output. 8 8 PGOOD Power Good Indicator. This pin is an open drain logic output that is pulled to ground when the output voltage is not within 12.5% of regulation point. 9 (Exposed Pad) 9 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Power Input Supply. Decouple this pin to GND with a capacitor. Internal Power MOSFET Switches Output. Connect this pin to the inductor. Oscillator Resistor Input. Connect a resistor from this pin to GND sets the switching frequency. If this pin is floating, the frequency will be set at 2MHz internally. Function Block Diagram RT SD VIN ISEN OSC Slope Com COMP 0.8V FB Output Clamp EA OC Limit 10µA Driver LX Hiccup SS Control Logic 0.7V EN Enable 0.4V P-G NISEN OTP UV GND N-MOSFET ILIM PGOOD Copyright © 2015 Richtek Technology Corporation. All rights reserved. DS8070-08 February 2015 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8070 Absolute Maximum Ratings           (Note 1) Supply Input Voltage, VIN ---------------------------------------------------------------------------------------LX Pin Switch Voltage --------------------------------------------------------------------------------------------