RT2702 Step-Down DC-DC Controller with Remote Sense General Description Features 4.5V to 19V Input Voltage Range The RT2702 is a high-efficiency and high-current Adjustable Output Range, 0.6V Reference with 1% synchronous buck controller designed to drive a DrMOS Accuracy Over-Temperature Protection module. A COT (Constant-On-Time) PWM controller and TM FCOT (Flexible Constant On Time) Control PWM signal for DrMOS are integrated so that the external Integrated 5V LDO 100mA for DrMOS module circuit is easily designed and the component count is Support Pre-Biased Output reduced. The RT2702 adopts FCOT control technology Programmable Soft-Start that responds instantly to input voltage change. Besides, Soft-Off through V Discharge OUT the RT2702 includes a 5V (VDRV) linear regulator, which Programmable Switching Frequency can provide 5V voltage and supply up to 100mA for DrMOS. Programmable Over Current Limit The RT2702 supports two modes transition function with Power Good Indication various operating states, which include audio skipping OVP, UVP, UVLO Protection mode (ASM) and forced-CCM mode (FCCM). Other features include power good indication, external soft- Applications start setting, soft-off discharge function, precise DCR High Current Distributed Power Systems sense, enable/disable control, over-voltage protection Datacom and Telecom Systems (OVP), under-voltage protection (UVP), current Limit, Industrial Power Supplies thermal shutdown into the WQFN-16L 3x3 package. Pin Configuration Ordering Information (TOP VIEW) RT2702 Package Type QW : WQFN-16L 3x3 (W-Type) 16 15 14 13 Lead Plating System MODE 1 12 EN G : Green (Halogen Free and Pb Free) 2 11 PWM POK GND 3 10 DISB ILIM Note : 17 4 9 THWN SS Richtek products are : 5 6 7 8 RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. WQFN-16L 3x3 Marking Information 8H= : Product Code YMDNN : Date Code 8H=YM DNN Copyright 2016 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS2702-00 October 2016 www.richtek.com 1 CSP VDRV CSN PHASE FB VIN RGND TONRT2702 Functional Pin Description Pin No Pin Name Pin Function 1 MODE Operation mode detection input. 2 PWM Logic gate driver. This pin provides PWM signal for the gate drive. External driver enable. Enable external driver when DISB is high, and disable 3 DISB external driver when is low. DISB Thermal shutdown detection input. DISB goes low when THWN is less than 4 THWN trip level. 5 CSP Non-inverting input of current sense amplifier. Inverting input of current sense amplifier. Connect a R from this pin to the CS current sensing R/C network for adjusting the over current trip threshold. V is OUT 6 CSN also discharged by this pin when system is shut down or any protection is toggled. Resistance of the discharge switch is around 30. 7 FB Feedback pin. This pin is the negative input node of the PWM comparator. Remote ground sense. This pin is intended to connect to the negative side of the 8 RGND load for remote sensing. External soft-start pin. Achieve programmable soft-start time function, also have a default internal soft-start time 3ms for minimum soft-start time. DO NOT force 9 SS this pin lower than 1.2V, otherwise soft-start procedure won t be finished. Refer to Application Information for further description. The 1.2V buffered output for current limit adjustment. Connect a R between ILIM 10 ILIM this pin and GND to set the over-current threshold corresponding to R . CS 11 POK Open drain power good indicator. High impedance indicates power is good. Enable control input. The device enters its 20A supply current shutdown mode if EN is less than the EN input falling edge trip level and does not restart until EN 12 EN is greater than the EN input rising edge trip level. Connect EN to VIN for automatically startup. EN can be connected to VIN through a resistive voltage divider to implement a programmable under-voltage lockout. On-time/switching frequency adjustment input. Connect a resistor to VIN for 13 TON adjusting switching frequency. And connect an another 100pF ceramic capacitor between TON and ground is optional for noise immunity enhancement. 14 VIN Power supply input. Switching node Input for zero current detection. Also provide V information OUT 15 PHASE through PHASE pin to on-time generation circuit. Output bypass for the 5V regulator. Connect a low-ESR bypass ceramic 16 VDRV capacitor of 4.7F from this pin to GND. Ground. The exposed pad must be soldered to a large PCB and connected to 17 (Exposed Pad) GND GND for maximum thermal dissipation. Copyright 2016 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS2702-00 October 2016 www.richtek.com 2