RT8072GQW

® RT8072 5A, 2MHz, High Efficiency Synchronous Step-Down Converter General Description Features The RT8072 is a high efficiency PWM step-down converter and capable of delivering 5A output current over a wide input voltage range from 2.9V to 5.5V.     The RT8072 provides accurate regulation for a variety of loads with an ±1% reference voltage at room temperature. For reducing inductor size, it provides up to 2MHz switching frequency. The efficiency is maximized through the integrated 50mΩ for high side, 35mΩ for low side MOSFETs and 250μA typical supply current.       The RT8072 features over current protection, frequency fold back function in shorted circuit, hiccup mode under voltage protection and over temperature protection.    The RT8072 is available in SOP-8 (Exposed Pad) and WDFN-12L 3x3 packages. Ω MOSFETs Integrated 50mΩ Ω and 35mΩ 5A Output Current High Efficiency Up to 95% 2.9V to 5.5V Input Range Adjustable PWM Frequency : 300kHz to 2MHz 0.8V ±1% Reference Voltage Adjustable External Soft-Start Power Good Indicator (WDFN-12L 3x3 Only) Over Current Protection Under Voltage Protection Over Temperature Protection SOP-8 (Exposed Pad) and 12-Lead WDFN Packages RoHS Compliant and Halogen Free Applications  Ordering Information   RT8072 Package Type SP : SOP-8 (Exposed Pad-Option 2) QW : WDFN-12L 3x3 (W-Type) (Exposed Pad-Option 1) Low Voltage, High Density Power Systems Distributed Power Systems Point-of-Load Conversions Marking Information RT8072GSP RT8072GSP : Product Number RT8072 GSPYMDNN Lead Plating System G : Green (Halogen Free and Pb Free) YMDNN : Date Code Note : RT8072GQW Richtek products are :  6C= : Product Code RoHS compliant and compatible with the current require-  YMDNN : Date Code 6C=YM DNN ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Simplified Application Circuit VIN VIN BOOT RT8072 CIN CBOOT L LX EN RC CC RT RT RFB1 FB GND Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS8072-03 August 2020 VOUT COUT COMP RFB2 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT8072 Pin Configuration COMP GND 2 EN 3 VIN 4 PGND 8 FB 7 RT 6 LX 5 BOOT 9 COMP PGOOD SS EN VIN VIN SOP-8 (Exposed Pad) 1 2 3 4 5 6 PGND (TOP VIEW) 13 12 11 10 9 8 7 FB RT LX LX LX BOOT WDFN-12L 3x3 Functional Pin Description Pin No. Pin Function Pin Name SOP-8 (Exposed Pad) WDFN-12L 3x3 1 1 COMP Compensation Node. 2 -- GND Analog Ground. 3 4 EN Chip Enable. Externally pulled high to enable and pulled low to disable this chip, and it is internally pulled up to high when the pin is floating. 4 5, 6 VIN Power Input. 5 7 BOOT Bootstrap Supply for High Side Gate Driver. 6 8, 9, 10 LX Switch Node. 7 11 RT Frequency Setting. 8 12 FB Feedback Voltage Input. 9 13 (Exposed Pad) PGND Power Ground. The exposed pad must be shouldered to a large PCB and connected to PGND for maximum power dissipation. -- 2 PGOOD Power Good Indicator with Open Drain Output. It is high impedance when the output voltage is regulated. It is internally pulled low when the chip is shutdown, thermal shutdown or VIN is under UVLO threshold. -- 3 SS Soft-Start Control. Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DS8072-03 August 2020 RT8072 Functional Block Diagram For SOP-8 (Exposed Pad) Package VIN VIN Over Temperature Protection Internal pull up current EN EN Threshold UVLO Shutdown Control Current Sense GND BOOT RT Oscillator Control Logic Slope Compensation Soft-Start Driver LX PWM Comparator Voltage Reference Error Amplifier FB PGND COMP For WDFN-12L 3x3 Package VIN VIN Internal pull up current EN EN Threshold RT UVLO Shutdown Control Current Sense BOOT Oscillator VIN SS Over Temperature Protection SoftStart Voltage Reference Control Logic Slope Compensation Driver LX PWM Comparator Error Amplifier PGND FB PGOOD Power Good Threshold COMP Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS8072-03 August 2020 is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT8072 Operation The RT8072 is a current mode synchronous step-down DC/DC converter with two integrated power MOSFETs. It can deliver up to 5A output current from a 2.9V to 5.5V input supply. The RT8072's current mode architecture allows the transient response to be optimized over a wide input voltage and load range. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. PGOOD Comparator When the feedback voltage (VFB) rises above 94% or falls below 106% of reference voltage, the PGOOD open drain output will be high impedance. The PGOOD open drain output will be internally pulled low when the feedback voltage (VFB) falls below 90% or rises above 110% of reference voltage. Soft-Start (SS) Error Amplifier The error amplifier adjusts COMP voltage by comparing the feedback signal (VFB) from the output voltage with the internal 0.8V reference. When the load current increases, it causes a drop in the feedback voltage relative to the reference. The COMP voltage then rises to allow higher inductor current to match the load current. Oscillator (OSC) The internal oscillator provides switching frequency from 300kHz to 2MHz, and is adjusted by an external resistor. Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 An internal current source charges an external capacitor to build the soft-start ramp voltage (VSS). The VFB voltage will track the VSS during soft-start interval. The chip will use internal soft-start if the SS pin is floating. The nominal internal soft-start time is 800μs. Over Temperature Protection (OTP) The RT8072 implements an internal over temperature protection. When junction temperature is higher than 165°C, it will stop switching operation. Once the junction temperature decreases below 145°C, the RT8072 will automatically resume switching. is a registered trademark of Richtek Technology Corporation. DS8072-03 August 2020 RT8072 Absolute Maximum Ratings          (Note 1) Supply Input Voltage, VIN ----------------------------------------------------------------------------------------BOOT to LX ----------------------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOP-8 (Exposed Pad) --------------------------------------------------------------------------------------------WDFN-12L 3x3 ------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOP-8 (Exposed Pad), θJA ---------------------------------------------------------------------------------------SOP-8 (Exposed Pad), θJC --------------------------------------------------------------------------------------WDFN-12L 3x3, θJA ------------------------------------------------------------------------------------------------WDFN-12L 3x3, θJC ------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ---------------------------------------------------------------------------------------- Recommended Operating Conditions    −0.3V to 6.5V −0.3V to 6V −0.3V to (VIN + 0.3V) 2.041W 1.667W 49°C/W 15°C/W 60°C/W 7.5°C/W 260°C 150°C −65°C to 150°C 2kV (Note 4) Supply Input Voltage, VIN ----------------------------------------------------------------------------------------- 2.9V to 5.5V Junction Temperature Range -------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 5V, CIN = 10μF, TA = 25°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Input Power Supply Under Voltage Lockout Threshold VUVLO VIN Rising -- 2.6 2.8 V Quiescent Current IQ Active, VFB = 0.9V, Not switching -- 250 -- A Shutdown Current ISHDN -- 2 5 A VREF 0.792 0.8 0.808 V Voltage Reference Voltage Reference Enable Logic-High VIH 1.5 -- 5.5 Logic-Low VIL -- -- 0.4 300 -- 2000 RT = 28.7k -- 1400 -- RT pin is floating -- 300 -- WDFN-12L 3x3 Only -- ±7 -- % Minimum On-Time -- 80 -- ns Minimum Off-Time -- 60 -- ns EN Input Voltage V Switching Frequency Setting Switching Frequency Power Good Range fOSC Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS8072-03 August 2020 kHz is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT8072 Parameter Symbol Test Conditions Min Typ Max Unit MOSFET High Side MOSFET On-resistance VIN = 5V, BOOT  LX = 5V -- 50 -- m Low Side MOSFET On-resistance VIN = 5V -- 35 -- m 6 8 -- A VFB Rising (Good) -- 94 -- VFB Falling (Fault) -- 90 -- VFB Rising (Fault) -- 110 -- VFB Falling (Good) -- 106 -- Rising -- 165 -- C -- 20 -- C Current Limit Current Limit Threshold Power Good Power Good Range % VREF Over Temperature Protection Thermal Shutdown Thermal Shutdown Hysteresis Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS8072-03 August 2020 RT8072 Typical Application Circuit VIN VIN CIN1 10µF CIN2 10µF BOOT RT8072 RPG 100k CBOOT 0.22µF VOUT L LX PGOOD Chip Enable EN COUT1 10µF PGND RFB1 SS CSS 10nF COMP CHF* COUT3 47µF to 100µF GND RT RT 28.7k COUT2 10µF FB RC RFB2 CC * : Option Table 1. Recommended Component Selection RFB2 CC (nF) L (H) RC (k) (k) 1.2 33 0.33 0.47 3.3 RFB1 (k) 3.75 2.5 2.55 1.2 24 0.47 0.47 Cer. 20F + E-Cap 100F 1.8 1.5 1.2 18 0.56 0.47 Cer. 20F + E-Cap 100F 1.5 1.05 1.2 15 0.68 0.33 Cer. 20F + E-Cap 100F 1.2 2.55 5.1 12 1 0.33 Cer. 20F + E-Cap 100F 1 1.27 5.1 10 1 0.33 Cer. 20F + E-Cap 100F VOUT (V) Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS8072-03 August 2020 COUT Cer. 20F + E-Cap 100F is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT8072 Typical Operating Characteristics Output Voltage vs. Input Voltage 1.20 90 1.18 80 1.16 70 Output Voltage (V) Efficiency (%) Efficiency vs. Load Current 100 VIN = 3.3V VIN = 4V VIN = 5V 60 50 40 30 1.14 1.12 1.10 1.08 1.06 1.04 20 10 1.02 VOUT = 1.1V VOUT = 1.1V 1.00 0 0.001 0.01 0.1 1 2.5 10 3 3.5 4 4.5 5 5.5 Input Voltage (V) Load Current (A) Output Voltage vs. Output Current Output Voltage vs. Temperature 1.16 1.18 1.15 1.16 1.14 Output Voltage (V) Output Voltage (V) 1.14 1.13 1.12 1.11 1.10 1.09 1.12 1.10 VIN = 5V VIN = 4V 1.08 1.06 1.08 1.04 1.07 VIN = 5V, VOUT = 1.1V, IOUT = 1.5A VOUT = 1.1V 1.02 1.06 -50 -25 0 25 50 75 100 0.0 125 0.5 1.0 1.5 Temperature (°C) Frequency vs. Input Voltage 2.5 3.0 3.5 4.0 4.5 5.0 Switching Frequency vs. Temperature 1.8 1.8 1.7 1.7 Switching Frequency (MHz)1 Frequency (MHz)1 2.0 Output Current (A) 1.6 1.5 1.4 1.3 1.2 1.1 1.6 1.5 1.4 1.3 1.2 1.1 VOUT = 1.1V, IOUT = 1.3A VOUT = 1.1V, IOUT = 1.3A 1.0 1.0 2.5 3 3.5 4 4.5 5 Input Voltage (V) Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 5.5 -50 -25 0 25 50 75 100 125 Temperature (°C) is a registered trademark of Richtek Technology Corporation. DS8072-03 August 2020 RT8072 Current Limit vs. Temperature Current Limit vs. Input Voltage 11.0 10.0 9.5 10.5 10.0 8.5 Current Limit (A) Current Limit (A) 9.0 8.0 7.5 7.0 6.5 9.5 9.0 8.5 8.0 6.0 7.5 5.5 VOUT = 1.1V VIN = 5V, VOUT = 1.1V 7.0 5.0 -50 -25 0 25 50 75 100 2.5 125 3 3.5 4 4.5 5 Temperature (°C) Input Voltage (V) Load Transient Response Load Transient Response VOUT (200mV/Div) VOUT (100mV/Div) IOUT (2A/Div) IOUT (2A/Div) VIN = 5V, VOUT = 1.1V, IOUT = 0A to 3A VIN = 5V, VOUT = 1.1V, IOUT = 0A to 5A Time (100μs/Div) Time (100μs/Div) Output Ripple Voltage Output Ripple Voltage VOUT (20mV/Div) VOUT (20mV/Div) VLX (5V/Div) VLX (5V/Div) VIN = 5V, VOUT = 1.1V, IOUT = 5A Time (250ns/Div) Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS8072-03 August 2020 5.5 VIN = 5V, VOUT = 3.3V, IOUT = 5A Time (250ns/Div) is a registered trademark of Richtek Technology Corporation. www.richtek.com 9 RT8072 Power On from VIN Power Off from VIN VIN (5V/Div) VIN (5V/Div) VOUT (2V/Div) VOUT (2V/Div) ILX (5A/Div) ILX (5A/Div) VIN = 5V, VOUT = 3.3V VIN = 5V, VOUT = 3.3V Time (1ms/Div) Time (10ms/Div) Power On from EN Power Off from EN VEN (5V/Div) VEN (5V/Div) VOUT (2V/Div) VOUT (2V/Div) ILX (5A/Div) ILX (5A/Div) VIN = 5V, VOUT = 3.3V Time (250μs/Div) Copyright © 2020 Richtek Technology Corporation. All rights reserved. www.richtek.com 10 VIN = 12V, VOUT = 3.3V Time (10ms/Div) is a registered trademark of Richtek Technology Corporation. DS8072-03 August 2020 RT8072 Application Information The basic RT8072 application circuit is shown in Typical Application Circuit. External component selection is determined by the maximum load current and begins with the selection of the inductor value and operating frequency followed by CIN and COUT. Output Voltage Setting The output voltage is set by an external resistive divider according to the following equation :  R  VOUT  VREF   1 FB1   RFB2  The operating frequency of the RT8072 is determined by an external resistor that is connected between the SHDN/ RT pin and GND. The value of the resistor sets the ramp current that is used to charge and discharge an internal timing capacitor within the oscillator. The RT resistor value can be determined by examining the frequency vs. RT curve. Although frequency as high as 2MHz is possible, the minimum on-time of the RT8072 imposes a minimum limit on the operating duty cycle. The minimum on-time is typically 80ns. Therefore, the minimum duty cycle is equal to 100 x 80ns x f (Hz). 3.0 The resistive divider allows the FB pin to sense a fraction of the output voltage as shown in Figure 1. VOUT RFB1 FB RT8072 RFB2 GND Figure 1. Setting the Output Voltage Switching Frequency (MHz)1 where VREF equals to 0.8V (typical) 2.5 2.0 1.5 1.0 0.5 0.0 0 20 40 60 80 RT (k Ω) Soft-Start (SS) An internal current source charges an external capacitor to build the soft-start ramp voltage (VSS). The VFB voltage will track the VSS during soft-start interval. The chip will use internal soft-start if the SS pin is floating. The nominal internal soft-start time is 800μs. With external soft-start, the typical soft-start time can be calculated as following equation : tSS (ms) = 0.1 x CSS (nF) For example, if CSS = 10nF, the soft-start time is 1ms. Operating Frequency Selection of the operating frequency is a tradeoff between efficiency and component size. High frequency operation allows the use of smaller inductor and capacitor values. Operation at lower frequency improves efficiency by reducing internal gate charge and switching losses but requires larger inductance and/or capacitance to maintain low output ripple voltage. Copyright © 2020 Richtek Technology Corporation. All rights reserved. DS8072-03 August 2020 100 120 140 160 180 200 Figure 2 Chip Enable Operation The EN pin is the chip enable input. Pulling the EN pin low (1.5V,