RT8097AHGB

RT8097A 6V, 2A, 1MHz, CMCOT Synchronous Step-Down Converter General Description Features The RT8097A is a simple, easy-to-use, 2A synchronous step-down DC-DC converter with an input supply voltage range of 2.7V to 6V. The device build-in an accurate 0.6V (typ.) reference voltage and integrates low RDS(ON) power MOSFETs to achieve high efficiency in a SOT-23-5 and SOT-23-6 packages.      The RT8097A adopts Current Mode Constant On-Time (CMCOT) control architecture to provide an ultrafast transient response with few external components and to operate in nearly constant switching frequency over the line, load, and output voltage range. The RT8097A operates in automatic PSM that maintains high efficiency during light load operation.     The RT8097A senses low-side FETs current for a robust over-current protection. It features cycle-by-cycle current limit protection and prevent the device from the catastrophic damage in output short circuit, over current or inductor saturation. An internally adjustable soft-start function prevents inrush current during start-up. The device also includes input under-voltage lockout, output under-voltage protection, and over-temperature protection (thermal shutdown) to provide safe and smooth operation in all operating conditions. The RT8097A is offered in a SOT-23-5 and SOT-23-6 packages.           Efficiency Up to 95% 2A Converter With Built-In 100mΩ/70mΩ Low RDS(ON) Power FETs Input Supply Voltage Range : 2.7V to 6V Output Voltage Range : 0.6V to 3.4V Current Mode Constant On-Time (CMCOT) Control Ultrafast Transient Response No Needs For External Compensations Optimized for Low-ESR Ceramic Output Capacitors 0.6V ±1.2% High-Accuracy Feedback Reference Voltage LS FETs Protection for Robust Over-Current Protection Power Saving in Light Load Fixed Switching Frequency : 1MHz (typ.) Internally Soft-Start Function Monotonic Start-Up for Pre-Biased Output Input Under-Voltage Lockout (UVLO) Output Under-Voltage Protection (UVP) with Hiccup Mode Power Good Indication in SOT-23-6 Package Enable Control Available In SOT-23-5 and SOT-23-6 Packages Applications    STB, Cable Modem, & xDSL Platforms LCD TV Power Supply & Metering Platforms General Purpose Point of Load (POL) Simplified Application Circuit RT8097A 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. DS8097A-12 June 2021 is a registered trademark of Richtek Technology Corporation www.richtek.com 1 RT8097A Pin Configuration Ordering Information (TOP VIEW) RT8097A 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 A : PSM/PWM FB 5 4 6 2 PG VIN 3 5 4 2 3 EN GND LX EN GND LX SOT-23-5 SOT-23-6 RT8097AHGB Richtek products are : 4N=DNN 4N= : Product Code DNN : Date Code RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.  VIN Marking Information Note :  FB RT8097ALGB Suitable for use in SnPb or Pb-free soldering processes. 4M=DNN 4M= : Product Code DNN : Date Code RT8097AHGE 1V=DNN 1V= : Product Code DNN : Date Code RT8097ALGE 1U=DNN 1U= : 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 RT8097A 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% (typ.) otherwise it is LOW. Copyright ©2021 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8097A-12 June 2021 RT8097A 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. DS8097A-12 June 2021 is a registered trademark of Richtek Technology Corporation www.richtek.com 3 RT8097A Operation The RT8097A 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 RT8097A 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 (typ.) 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 RT8097A 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 RT8097A 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 (typ.). 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 (typ.), the device reinstates the power up sequence. UV Comparator Maximum Duty Cycle If the feedback voltage (VFB) is lower than threshold voltage 0.2V (typ.), 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 RT8097AH, Latch mode for RT8097AL. 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 If input voltage and output voltage are closed, RT8097A operates at high duty cycle. Once the operational duty cycle is larger than the maximum duty cycle (70%, min.), RT8097A 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 When the feedback voltage (VFB) is higher than threshold voltage 0.54V (typ.), 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 (typ.). 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. 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. DS8097A-12 June 2021 RT8097A Absolute Maximum Ratings (Note 1)  Supply Input Voltage ------------------------------------------------------------------------------------------- −0.3V to 6.5V  LX Pin Switch Voltage------------------------------------------------------------------------------------------ −0.3V to (VIN + 0.3V)