RT5712FHGQW

RT5712F 2A, 1MHz, 6V CMCOT Synchronous Step-Down Converter General Description Features The RT5712F is a high efficiency synchronous step-down DC-DC converter. Its input voltage range is from 2.7V to 6V and provides an adjustable regulated output voltage from 0.6V to 3.4V while delivering up to 2A of output current.      The internal synchronous low on-resistance power switches increase efficiency and eliminate the need for an external Schottky diode. The Current Mode Constant-On-time (CMCOT) operation with internal compensation allows the transient response to be optimized over a wide range of loads and output capacitors.       RT5712FHGQW 3S : Product Code W : Date Code STB, Cable Modem, & xDSL Platforms LCD TV Power Supply & Metering Platforms General Purpose Point of Load (POL) 3SW Ordering Information RT5712FLGQW 3R : Product Code W : Date Code RT5712F 3RW Package Type QW : WDFN-6L 2x2 (W-Type) Lead Plating System G : Green (Halogen Free and Pb Free) Pin Configuration UVP Option H : Hiccup L : Latch-Off (TOP VIEW) Note : Richtek products are :  1 EN VIN 2 3 6 FB 5 7 4 GND LX RoHS compliant and compatible with the current WDFN-6L 2x2 requirements of IPC/JEDEC J-STD-020.  PGOOD GND  Fixed Soft-Start 1.2ms Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Output Under Voltage Protection (UVP Hiccup) Thermal Shutdown Protection Marking Information Applications  Efficiency Up to 95% RDSON 100mΩ HS / 70mΩ LS VIN Range 2.7V to 6V VREF 0.6V with ±1.5% Accuracy CMCOT ™ Control Loop Design for Best Transient Response, Robust Loop Stability with Low-ESR (MLCC) COUT Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit L VIN VIN CIN RT5712F EN PGOOD Copyright © 2021 Richtek Technology Corporation. All rights reserved. DS5712F-06 June 2021 LX VOUT R1 FB GND COUT R2 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT5712F Functional Pin Description Pin No. Pin Name Pin Function 1 PGOOD Power good indicator. The output of this pin is an open-drain with external pull-up resistor. PGOOD is pulled up when the FB voltage is within 90%, otherwise it is LOW. 2 EN Enable control input. 3 VIN Supply voltage input. The RT5712F operates from a 2.7V to 6V input. 4 LX Switch node. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum thermal dissipation. 5, 7 (Exposed Pad) GND 6 FB Feedback. Functional Block Diagram EN VIN UVLO Shut Down Control OTP - FB VREF Error Amplifier Ton Comparator + RC CCOMP + - Logic Control LX VIN Driver Current Limit Detector LX GND + - Current Sense LX PGOOD Operation The RT5712F is a synchronous low voltage step-down converter that can support the input voltage range from 2.7V to 6V and the output current can be up to 2A. The RT5712F uses a constant on-time, current mode architecture. In normal operation, the high side P-MOSFET is turned on when the switch controller is set by the comparator and is turned off when the Ton comparator resets the switch controller. Low side MOSFET peak current is measured by internal RSENSE. The error amplifier EA adjusts COMP voltage by comparing the feedback signal (VFB) from the output voltage with the internal 0.6V reference. When the load current increases, it causes a drop in the feedback voltage relative to the reference, then the COMP voltage rises to allow higher inductor current to match the load current. Copyright © 2021 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 UV Comparator If the feedback voltage (VFB) is lower than threshold voltage 0.2V, the UV comparator's output will go high and the switch controller will turn off the high side MOSFET. The output under voltage protection is designed to operate in Hiccup and Latch-off mode. PGOOD Comparator When the feedback voltage (VFB) is higher than threshold voltage 0.54V, the PGOOD open drain output will be high impedance. The internal PGOOD MOSFET is typical 100Ω. The PGOOD signal delay time from EN is about 2ms. is a registered trademark of Richtek Technology Corporation. DS5712F-06 June 2021 RT5712F Enable Comparator Maximum Duty Cycle A logic-high enables the converter; a logic-low forces the IC into shutdown mode. The maximum duty cycle (70%, min.) can be calculated by minimum off time (180ns, max.), dead time (60ns, max.) and switching frequency (1.2MHz, max.). Soft-Start (SS) An internal current source charges an internal capacitor to build the soft-start ramp voltage. The VFB voltage will track the internal ramp voltage during soft-start interval. The typical soft-start time is 1.2ms. Over-Current Protection (OCP) The RT5712F provides over-current protection by detecting low side MOSFET valley inductor current. If the sensed valley inductor current is over the current limit threshold (2.9A typ.), the OCP will be triggered. When OCP is tripped, the RT5712F will keep the over current threshold level until the over current condition is removed. DMAX = 1 - ( tOFF_MIN + tD ) x f SW Where tOFF_MIN is minimum off time, tD is dead time and f SW is switching frequency. If input voltage and output voltage are closed, RT5712F operates at high duty cycle. Once the operational duty cycle is larger than the maximum duty cycle (70%, min.), RT5712F keeps minimum off time (180ns, max.) and deadtime (60ns, max.), then the output voltage starts to drop. The input voltage at which the devices enter dropout changes depending on the input voltage, output voltage, switching frequency, load current, and the efficiency of the design. tOFF_MIN 180ns Thermal Shutdown (OTP) The device implements an internal thermal shutdown function when the junction temperature exceeds 150°C. The thermal shutdown forces the device to stop switching when the junction temperature exceeds the thermal shutdown threshold. Once the die temperature decreases below the hysteresis of 20°C, the device reinstates the power up sequence. Copyright © 2021 Richtek Technology Corporation. All rights reserved. DS5712F-06 June 2021 High-Side MOSFET Deadtime 30ns Deadtime 30ns Low-Side MOSFET is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT5712F Absolute Maximum Ratings (Note 1)  Supply Input Voltage ---------------------------------------------------------------------------------------- −0.3V to 6.5V  LX Pin Switch Voltage--------------------------------------------------------------------------------------- −0.3V to (VIN + 0.3V)