RT8097BHGB

RT8097B 2A, 1MHz, 6V CMCOT Synchronous Step-Down Converter General Description Features The RT8097B is a high efficiency synchronous stepdown 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. The RT8097B is available in the SOT-23-5/6 package.  Efficiency Up to 95% RDSON 100mΩ HS / 70mΩ LS VIN Range 2.7V to 6V VREF 0.6V with ±1.2% Accuracy at 25°C CMCOT ™ Control Loop Design for Best Transient Response, Robust Loop Stability with Low-ESR (MLCC) COUT Soft-Start 1.2ms; PGOOD Function in SOT-23-6 Ordering Information RT8097B Package Type B : SOT-23-5 E : SOT-23-6 Lead Plating System G : Green (Halogen Free and Pb Free) UVP Option H : Hiccup L : Latched-Off Applications  STB, Cable Modem, & xDSL Platforms LCD TV Power Supply & Metering Platforms  General Purpose Point of Load (POL)  B : Forced PWM Note : Richtek products are :  RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.  Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit RT8097B LX VIN VIN CIN L VOUT R1 EN PG* COUT FB GND R2 *For SOT-23-6 Package Only Copyright © 2021 Richtek Technology Corporation. All rights reserved. DS8097B-09 June 2021 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8097B Marking Information Pin Configuration RT8097BHGB (TOP VIEW) FB VIN FB 5 4 6 4L=DNN PG VIN 5 4L= : Product Code DNN : Date Code 4 RT8097BLGB 2 3 2 3 4K=DNN EN GND LX EN GND LX SOT-23-5 SOT-23-6 4K= : Product Code DNN : Date Code RT8097BHGE 1T=DNN 1T= : Product Code DNN : Date Code RT8097BLGE 1S=DNN 1S= : Product Code DNN : Date Code Functional Pin Description Pin No. Pin Name Pin Function SOT-23-5 SOT-23-6 1 1 EN Enable control input. 2 2 GND Power ground. 3 3 LX Switch node. 4 4 VIN Supply voltage input. The RT8097B operates from a 2.7V to 6V input. 5 6 FB Feedback voltage input. An external resistor divider from the output to GND, tapped to the FB pin, sets the output voltage. -- 5 PG Power good indicator. The output of this pin is an open-drain with external pull-up resistor. PG is pulled up when the FB voltage is within 90%, otherwise it is LOW. Copyright © 2021 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8097B-09 June 2021 RT8097B Functional Block Diagram For SOT-23-5 Package 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 Ton LX For SOT-23-6 Package EN VIN UVLO Shut Down Control OTP FB - VREF Error Amplifier Comparator + + RC CCOMP Logic Control - VIN Driver Current Limit Detector LX GND + Current Sense - LX PG Copyright © 2021 Richtek Technology Corporation. All rights reserved. DS8097B-09 June 2021 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8097B Operation The RT8097B 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 RT8097B uses a constant on-time, current mode architecture. In normal operation, the high side PMOSFET 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. Over Current Protection (OCP) The RT8097B provides over current protection by detecting low side MOSFET valley inductor current. If the sensed valley inductor current is over the current limit threshold (3.1A typ.), the OCP will be triggered. When OCP is tripped, the RT8097B will keep the over current threshold level then cause the UV protection. 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. UV Comparator Maximum Duty Cycle 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 mode for RT8097BH, Latch mode for RT8097BL. 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.). 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 PG MOSFET is typical 10Ω. The PGOOD signal delay time from EN is about 2ms. Enable Comparator A logic-high enables the converter; a logic-low forces the IC into shutdown mode. 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, RT8097B operates at high duty cycle. Once the operational duty cycle is larger than the maximum duty cycle (70%, min.), RT8097B 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 Soft-Start (SS) An internal current source charges an internal capacitor to build the soft-start ramp voltage. The VFB voltage will High-Side MOSFET Deadtime 30ns track the internal ramp voltage during soft-start interval. The typical soft-start time is 1.2ms. Deadtime 30ns Low-Side MOSFET Copyright © 2021 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS8097B-09 June 2021 RT8097B Absolute Maximum Ratings (Note 1)  Supply Input Voltage -------------------------------------------------------------------------------------------- −0.3V to 6.5V  LX Pin Switch Voltage------------------------------------------------------------------------------------------- −0.3V to (VIN + 0.3V)