RT7243 6A, 18V, Synchronous Step-Down Converter General Description Features zz z zz Low R Power MOSFET Switches 26m/19m DS(ON) The RT7243 is a high efficiency, monolithic synchronous zz z zz Input Voltage Range : 4.5V to 18V step-down DC/DC converter that can deliver up to 6A output zz z zz Adjustable Switching Frequency : 200kHz to 1.6MHz current from a 4.5V to 18V input supply. The RT7243 zz z zz Current-Mode Control current-mode architecture with external compensation zz z zz Synchronous to External Clock : 200kHz to 1.6MHz allows the transient response to be optimized over a wide zz z zz Accurate Voltage Reference 0.8V 1.25% range of loads and output capacitors. Cycle-by-cycle zz z zz Monotonic Start-Up into Pre-biased Outputs current limit provides protection against shorted outputs zz z zz Adjustable Soft-Start and soft-start eliminates input current surge during start- zz z zz Power Good Indicator up. Fault condition protections include output under-voltage zz z zz Under-Voltage and Over-Voltage Protection protection, output over-voltage protection, and over- zz z zz Input Under-Voltage Lockout temperature protection. The low current shutdown mode zz z zz RoHS Compliant and Halogen Free provides output disconnection, enabling easy power management in battery-powered systems. Applications z High Performance Point of Load Regulation Marking Information 02= : Product Code z Notebook Computers YMDNN : Date Code z High Density and Distributed Power Systems 02=YM DNN Simplified Application Circuit RT7243 V VIN BOOT IN C IN C BOOT L PVIN LX V OUT Enable EN R1 FB C OUT PGOOD PGOOD R COMP1 R OSC COMP R2 RT/SYNC C C COMP2 COMP1 C SS SS/TR GND Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS7243-00 August 2013 www.richtek.com 1RT7243 Ordering Information Pin Configurations (TOP VIEW) RT7243 Package Type QW : WQFN-14AL 3.5x3.5 (W-Type) Lead Plating System 1 14 G : Green (Halogen Free and Pb Free) GND 2 13 BOOT Note : GND 3 12 LX 4 11 PVIN GND LX Richtek products are : PVIN 5 10 EN RoHS compliant and compatible with the current require- 15 6 9 VIN SS/TR ments of IPC/JEDEC J-STD-020. 7 8 Suitable for use in SnPb or Pb-free soldering processes. WQFN-14AL 3.5x3.5 Functional Pin Description Pin No. Pin Name Pin Function Oscillator Resistor and External Frequency Synchronization Input. Connecting a 1 RT/SYNC resistor from this pin to GND sets the switching frequency or connecting an external clock to this pin changes the switching frequency. System Ground. Provide the ground return path for the control circuitry and 2, 3, GND low-side power MOSFET. The exposed pad must be soldered to a large PCB 15 (Exposed Pad) and connected to GND for minimum power dissipation. 4, 5 PVIN Power Input. Supplies the power switches of the device. Supply Voltage Input. Supplies the control circuitry and internal reference of the 6 VIN device. Feedback Voltage Input. This pin is used to set the desired output voltage via an 7 FB external resistive divider. The feedback reference voltage is 0.8V typically. Compensation Node. The current comparator threshold increases with this 8 COMP control voltage. Connect external compensation elements to this pin to stabilize the control loop. Soft-Start and Tracking Control Input. Connect a capacitor from SS to GND to 9 SS/TR set the soft-start period. The soft-start period can be used to track and sequence when the external voltage on this pin overrides the internal reference. Enable Control Input. Floating this pin or connecting this pin to logic high can 10 EN enable the device and connecting this pin to GND can disable the device. Switch Node. LX is the switching node that supplies power to the output and 11, 12 LX connect the output LC filter from LX to the output load. Bootstrap Supply for High-Side Gate Driver. Connect a 100nF or greater 13 BOOT capacitor from LX to BOOT to power the high-side switch. Power Good Indicator Output. This pin is an open-drain logic output that is pulled 14 PGOOD to ground when the output voltage is lower or higher than its specified threshold under the conditions of OVP, OTP, dropout, EN shutdown, or during slow start. Copyright 2013 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS7243-00 August 2013 2 FB RT/SYNC COMP PGOOD