RT5796CHGJ5

RT5796C 1.5A, 1MHz, 6V CMCOT Synchronous Step-Down Converter Features General Description  The RT5796C is a high efficiency synchronous step-down DC/DC converter. Its input voltage range is from 2.5V to 6V and provides an adjustable regulated output voltage from 0.6V to 3.4V while delivering up to 1.5A 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 Efficiency Up to 95% RDSON 160m HS / 110m LS VIN Range 2.5V to 6V VREF 0.6V with 2% Accuracy CMCOT ™ Control Loop Design for Best Transient Response, Robust Loop Stability with  Low-ESR (MLCC) COUT Fixed Soft-Start 1.2ms; PGOOD Function in  TSOT-23-6 Cycle-by-Cycle Over Current Protection compensation allows the transient response to be optimized over a wide range of loads and output capacitors. The RT5796C is available in the TSOT-23-5 and TSOT-23-6 packages.  Ordering Information Applications     RT5796C  Package Type J5 : TSOT-23-5 J6 : TSOT-23-6  Input Under Voltage Lockout Output Under Voltage Protection (UVP Hiccup) Thermal Shutdown Protection Power Saving at Light Load STB, Cable Modem, & xDSL Platforms LCD TV Power Supply & Metering Platforms General Purpose Point of Load (POL) Marking Information Lead Plating System G : Green (Halogen Free and Pb Free) RT5796CHGJ5 UVP Trim Option H: Hiccup 0R=DNN 0R= : Product Code DNN : Date Code PWM/PSM Mode C : PSM/PWM RT5796CHGJ6 Note : 17=DNN Richtek products are :  17= : Product Code DNN : Date Code 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 RT5796C LX VIN VIN CIN L VOUT R1 EN COUT FB PG* GND R2 *For TSOT-23-6 Package Only Copyright © 2019 Richtek Technology Corporation. All rights reserved. DS5796C-02 December 2019 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT5796C Pin Configurations (TOP VIEW) FB VIN FB 5 4 6 2 3 PG VIN 5 4 2 3 EN GND LX EN GND LX TSOT-23-5 TSOT-23-6 Functional Pin Description Pin No. Pin Name Pin Function TSOT-23-5 TSOT-23-6 1 1 EN Enable Control Input. 2 2 GND Power Ground and Quiet Ground for Controller Circuits. 3 3 LX Switch Node. 4 4 VIN Supply Voltage Input. The RT5796C operates from a 2.5V to 6V unregulated input. C1 is needed to prevent large voltage spikes from appearing at the input. Quiet ground for controller circuits. 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 to IN. PG is pulled up to IN when the FB voltage is within 90%, otherwise it is LOW. Copyright © 2019 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS5796C-02 December 2019 RT5796C Function Block Diagram For TSOT-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 TSOT-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 Operation The RT5796C is a synchronous low voltage step-down Low side MOSFET peak current is measured by converter that can support the input voltage range from 2.5V to 6V and the output current can be up to 1.5A. internal RSENSE. The error amplifier EA adjusts COMP voltage by comparing the feedback signal (VFB) from The RT5796C uses a constant on-time, current mode architecture. In normal operation, the high side the output voltage with the internal 0.6V reference. When the load current increases, it causes a drop in the 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. feedback voltage relative to the reference, then the COMP voltage rises to allow higher inductor current to match the load current. Copyright © 2019 Richtek Technology Corporation. All rights reserved. DS5796C-02 December 2019 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT5796C 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 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 PG MOSFET is typical 100. 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. Over Current Protection (OCP) The RT5796C provides over current protection by detecting low side MOSFET valley inductor current. If the sensed valley inductor current is over the current limit threshold (1.8A typ.), the OCP will be triggered. When OCP is tripped, the RT5796C 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. 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. Copyright © 2019 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS5796C-02 December 2019 RT5796C Absolute Maximum Ratings (Note 1)  Supply Input Voltage -------------------------------------------------------------------------------------------0.3V to 6.5V  LX Pin Switch Voltage----------------------------------------------------------------------------------------- 0.3V to (VIN + 0.3V)