RT5712BHGQW

RT5712B 2A, 1MHz, 6V CMCOT Synchronous Step-Down Converter General Description Features The RT5712B 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.       RT5712BHGQW 3K : Product Code W : Date Code STB, Cable Modem, & xDSL Platforms LCD TV Power Supply & Metering Platforms General Purpose Point of Load (POL) 3KW Ordering Information RT5712BLGQW 3J : Product Code W : Date Code RT5712B Package Type QW : WDFN-6L 2x2 (W-Type) 3JW 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 :  NC 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.  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 LX RT5712B EN DS5712B-05 June 2021 R1 FB GND Copyright © 2021 Richtek Technology Corporation. All rights reserved. VOUT COUT R2 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT5712B Functional Pin Description Pin No. Pin Name Pin Function 1 NC No internal connection. 2 EN Enable control input. 3 VIN Supply voltage input. The RT5712B 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 Current Sense LX GND LX Operation The RT5712B 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 RT5712B 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. Enable Comparator A logic-high enables the converter; a logic-low forces the IC into shutdown mode. 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. is a registered trademark of Richtek Technology Corporation. DS5712B-05 June 2021 RT5712B Over-Current Protection (OCP) The RT5712B 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 RT5712B will keep the over-current threshold level until the over current condition is removed. 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. Maximum Duty Cycle 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.). 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, RT5712B operates at high duty cycle. Once the operational duty cycle is larger than the maximum duty cycle (70%, min.), RT5712B 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 High-Side MOSFET Deadtime 30ns Deadtime 30ns Low-Side MOSFET Copyright © 2021 Richtek Technology Corporation. All rights reserved. DS5712B-05 June 2021 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT5712B Absolute Maximum Ratings (Note 1)  Supply Input Voltage ---------------------------------------------------------------------------------------- −0.3V to 6.5V  LX Pin Switch Voltage--------------------------------------------------------------------------------------- −0.3V to (VIN + 0.3V)