RT8068AZSP Richtek

RT8068A 3A, 1MHz, Synchronous Step-Down Converter General Description Features zz z zz High Efficiency : Up to 95% The RT8068A is a high efficiency synchronous, step-down zz z zz Low R Internal Switches : 69m/49m at V DS(ON) IN DC/DC converter. It s input voltage range from 2.7V to 5.5V = 5V that provides an adjustable regulated output voltage from zz z zz Fixed Frequency : 1MHz 0.6V to V while delivering up to 3A of output current. IN zz z zz No Schottky Diode Required The internal synchronous low on resistance power zz z zz Internal Compensation switches increase efficiency and eliminate the need for zz z zz 0.6V Reference Allows Low Output Voltage an external Schottky diode. The switching frequency is zz z zz Low Dropout Operation : 100% Duty Cycle fixed internally at 1MHz. The 100% duty cycle provides zz z zz OCP, UVP, OVP, OTP low dropout operation, hence extending battery life in zz z zz RoHS Compliant and Halogen Free portable systems. Current mode operation with internal compensation allows the transient response to be optimized over a wide range of loads and output capacitors. Applications The RT8068A is available in WDFN-10L 3x3 and SOP-8 z Portable Instruments (Exposed Pad) packages. z Battery Powered Equipment z Notebook Computers Ordering Information z Distrib uted Power Systems RT8068A z IP Phones Package Type z Digital Cameras QW : WDFN-10L 3x3 (W-Type) SP : SOP-8 (Exposed Pad-Option 2) Pin Configurations Lead Plating System (TOP VIEW) Z : ECO (Ecological Element with Halogen Free and Pb free) LX 1 10 PVIN 9 LX 2 PVIN Note : 3 LX 8 SVIN PGOOD 4 7 NC Richtek products are : 11 EN 5 6 FB RoHS compliant and compatible with the current require- WDFN-10L 3x3 ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. LX 8 PVIN 2 7 LX PVIN GND 3 6 PGOOD SVIN Marking Information 9 4 EN 5 FB RT8068AZQW 13 : Product Code SOP-8 (Exposed Pad) YMDNN : Date Code 13 YM DNN RT8068AZSP RT8068AZSP : Product Code RT8068A YMDNN : Date Code ZSPYMDNN DS8068A-03 May 2011 www.richtek.com 1 GNDRT8068A Typical Application Circuit RT8068A L PGOOD PGOOD LX V OUT R1 C OUT 100k C PVIN FF V R IN FB1 C IN SVIN FB 10F C1 R FB2 1F Chip Enable GND EN Table 1. Recommended Component Selection V (V) R (k ) R (k) C(pF) L ( H) C ( F) OUT FB1 FB2 FF OUT 3.3 229.5 51 22 2 22 x 2 2.5 161.5 51 22 2 22 x 2 1.8 102 51 22 1.5 22 x 2 1.5 76.5 51 22 1.5 22 x 2 1.2 51 51 22 1.5 22 x 2 1.0 34 51 22 1.5 22 x 2 Functional Pin Description Pin No. Pin Pin Function SOP-8 Name WDFN-10L (Exposed Pad) 1, 2, 3 1, 2 LX Switch Node. Connect this pin to the inductor. Power Good Indicator. This pin is an open drain logic output that is 4 3 PGOOD pulled to ground when the output voltage is less than 90% of the target output voltage. Hysteresis = 5%. 5 4 EN Enable Control. Pull high to turn on. Do not float. Feedback Pin. This pin receives the feedback voltage from a 6 5 FB resistive voltage divider connected across the output. 7 -- NC No Internal Connection. Signal Input Pin. Decouple this pin to GND with at least 1F ceramic 8 6 SVIN cap. Power Input Pin. Decouple this pin to GND with at least 4.7F 9,10 7,8 PVIN ceramic cap. 11 9 Ground. The exposed pad must be soldered to a large PCB and GND (Exposed Pad) (Exposed Pad) connected to GND for maximum power dissipation. www.richtek.com DS8068A-03 May 2011 2