RT5710A RICHTEK | Alldatasheet
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Technical content
Features
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 Cycle-by-Cycle Over-Current Protection Input Under-Voltage Lockout Output Under-Voltage Protection (UVP Hiccup) Thermal Shutdown Protection Power Saving at Light Load Marking Information 39 : Product Code W : Date Code 39W Pin Configuration (TOP VIEW) NC EN FB GND LXVIN GND WDFN-6L 2x2 Simplified Application Circuit VIN LX RT5710A EN FB VIN VOUT CIN L COUT GND
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5710A-04 November 2019 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 RT5710A operates from a 2.5V to 6V input. 4 LX Switch node. 5, 7 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum thermal dissipation. 6 FB Feedback. Functional Block Diagram Ton LX VIN VIN Driver GND UVLO FB Current Limit Detector Current Sense Logic Control+ VREF Comparator OTP Shut Down Control Error Amplifier LX LX EN RC CCOMP Operation The RT5710A is a synchronous low voltage step-down converter that can support the input voltage range from 2.5V to 6V and the output current can be up to 1A. The RT5710A 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. UV Comparator If the feedback voltage (V FB) 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. 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.
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com Over-Current Protection (OCP) The RT5710A provides over -current protection by detecting low-side MOSFET valley inductor current. If the sensed valley inductor current is over the current limit threshold ( 1.5A typ.), the OCP will be triggered. When OCP is tripped, the RT5710A 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.
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5710A-04 November 2019 Absolute Maximum Ratings (Note 1) Power Dissipation, PD @ TA = 25C Package Thermal Resistance (Note 2) ESD Susceptibility (Note 3) Recommended Operating Conditions (Note 4)
Electrical Characteristics
(VIN = 3.6V, TA = 25C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Input Voltage VIN 2.5 -- 6 V Feedback Reference Voltage VREF 0.588 0.6 0.612 V Feedback Leakage Current IFB VFB = 0.6V -- -- 0.1 A DC Bias Current Active, VFB = 0.63V, not switching -- 22 -- Shutdown -- -- 1 Switching Leakage Current -- -- 1 A Switching Frequency -- 1.5 -- MHz Switch On Resistance, High RPMOS ISW = 0.3A -- 160 -- m Switch On Resistance, Low RNMOS ISW = 0.3A -- 110 -- m Valley Current Limit ILIM 1.1 1.5 2 A Under-Voltage Lockout Threshold VUVLO VDD rising -- 2.25 2.5 V VDD falling -- 2 -- Over-Temperature Threshold -- 150 -- C Enable Input Voltage Logic-High VIH 1.5 -- -- V Logic-Low VIL -- -- 0.4 Soft-Start Time tSS -- 1.2 -- ms
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com Parameter Symbol Test Conditions Min Typ Max Unit Minimum Off Time -- 120 -- ns Output Discharge Switch On Resistance -- 1.8 -- k Note 1. Stresses beyond those listed under “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. JA is measured under natural convection (still air) at T A = 25 C with the component mounted on a high effective-thermal-conductivity four-layer test board on a JEDEC 51-7 thermal measurement standard. JC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution recommended. Note 4. The device is not guaranteed to function outside its operating conditions.
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. Table 1. Suggested Component Values
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com Typical Operating Characteristics Efficiency vs. Output Current 100 0 0.2 0.4 0.6 0.8 1 Output Current (A) Efficiency (%) VIN = 5V, VOUT = 3.3V VIN = 3.3V, VOUT = 1.2V Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VIN = 5V, VOUT = 3.3V VIN = 3.3V, VOUT = 1.2V Output Voltage vs. Output Current 1.12 1.14 1.16 1.18 1.20 1.22 1.24 1.26 1.28 0 0.2 0.4 0.6 0.8 1 Output Current (A) Output Voltage (V) VIN = 3.3V Output Voltage vs. Output Current 3.26 3.28 3.30 3.32 3.34 3.36 3.38 3.40 0 0.2 0.4 0.6 0.8 1 Output Current (A) Output Voltage (V) VIN = 5V Output Voltage vs. Input Voltage 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) Output Voltage (V) VIN = 2.5V to 5.5V, VOUT = 1.2V, IOUT = 1A Output Voltage vs. Input Voltage 3.00 3.05 3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 3.50 Input Voltage (V) Output Voltage (V) VIN = 4.5V to 5.5V, VOUT = 3.3V, IOUT = 1A
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5710A-04 November 2019 Reference Voltage vs. Input Voltage 0.55 0.56 0.57 0.58 0.59 0.60 0.61 0.62 0.63 0.64 0.65 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) Reference Voltage (V) VIN = 2.5V to 5.5V, IOUT = 1A Reference Voltage vs. Temperature 0.55 0.57 0.59 0.61 0.63 0.65 -50 -25 0 25 50 75 100 125 Temperature (°C) Reference Voltage (V) VIN = 3.6V, IOUT = 0.5A Switching Frequency vs. Temperature 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 -50 -25 0 25 50 75 100 125 Temperature (°C) Switching Frequency (MHz) 1 VIN = 5V, VOUT = 3.3V VIN = 3.3V, VOUT = 1.2V IOUT = 0.5A Shutdown Quiescent Current vs. Input Voltage -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) Shutdown Quiescent Current (μA) 1 VEN = 0 Shutdown Quiescent Current vs. Temperature 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -50 -25 0 25 50 75 100 125 Temperature (°C) Shutdown Quiescent Current (μA) 1 VEN = 0 Quiescent Current vs. Input Voltage 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) Quiescent Current (µA) VFB = 0.63V, LX No Switch
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com Quiescent Current vs. Temperature -50 -25 0 25 50 75 100 125 Temperature (°C) Quiescent Current (µA) VIN = 3.3V VIN = 5V Inductor Current Limit vs. Input Voltage 0.0 0.5 1.0 1.5 2.0 2.5 3.0 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) Inductor Current (A) VOUT = 1.2V Inductor Current Limit vs. Temperature 0.0 0.5 1.0 1.5 2.0 2.5 3.0 -50 -25 0 25 50 75 100 125 Temperature (°C) Inductor Current (A) VOUT = 1.2V Input UVLO vs. Temperature 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 -50 -25 0 25 50 75 100 125 Temperature (°C) Input UVLO (V) Turn On Turn Off Enable Threshold vs. Temperature 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 -50 -25 0 25 50 75 100 125 Temperature (°C) Enable Threshold (V) 1 Enable Off Enable On VIN = 3.3V Load Transient Response VOUT (50mV/Div) IOUT (500mA/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 0A to 1A Time (100s/Div)Time (100s/Div)
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5710A-04 November 2019 Time (100s/Div) Load Transient Response VIN = 3.3V, VOUT = 1.2V, IOUT = 0.5A to 1A VOUT (50mV/Div) IOUT (500mA/Div) Voltage Ripple VIN = 3.3V, VOUT = 1.2V, IOUT = 1A VOUT (10mV/Div) VLX (2V/Div) Time (500ns/Div) Voltage Ripple VIN = 5V, VOUT = 3.3V, IOUT = 1A VOUT (10mV/Div) VLX (2V/Div) Time (500ns/Div) Time (500s/Div) Power On from EN VEN (5V/Div) VOUT (1V/Div) IOUT (1A/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 1A Time (10s/Div) Power Off from EN VEN (5V/Div) VOUT (1V/Div) IOUT (1A/Div) VIN = 3.3V, VOUT = 1.2V, IOUT = 1A Time (500s/Div) Power On from EN VEN (5V/Div) VOUT (2V/Div) IOUT (1A/Div) VIN = 5V, VOUT = 3.3V, IOUT = 1A
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com Time (10s/Div) Power Off from EN VEN (5V/Div) VOUT (2V/Div) IOUT (1A/Div) VIN = 5V, VOUT = 3.3V, IOUT = 1A
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS5710A-04 November 2019
Application Information
The RT5710A is a single-phase step-down converter. It provides single feedback loop, constant on-time current mode control with fast transient response. An internal 0.6V reference allows the output voltage to be precisely regulated for low output voltage applications . A fixed switching frequency (1. 5MHz) oscillator and internal compensation are integrated to minimize external component count. Protection features include over-current protection, under -voltage protection and over-temperature protection. Output Voltage Setting Connect a resistive voltage divider at the FB between VOUT and GND to adjust the output voltage. The output voltage is set according to the following equation : OUT REF R1V = V 1 R2 where V REF is the feedback reference voltage 0.6V (typ.). FB GND VOUT Figure 1. Setting VOUT with a Voltage Divider (SS) automatically begins once the chip is enabled. converter resets and prepares the PWM for operation. to the average inductor current. The calculation above serves as a general refer ence.
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com X7R ceramic capacitors are usually selected for power regulator capacitors because the dielectric material has less capacitance variation and more temperature stability. Voltage rating and current rating are the key parameters when selecting an input capacitor. Generally, selecting an input capacitor with voltage rating 1.5 times greater than the maximum input voltage is a conservatively safe design. The input capacitor is used to supply the input RMS current, which can be approximately calculated using the following equation : OUT OUTIN_RMS LOAD IN IN VVI = I 1 VV The next step is selecting a proper capacitor for RMS current rating. One good design uses more than one capacitor with low equivalent series resistance (ESR) in parallel to form a capacitor bank. The input capacitance value determines the input ripple voltage of the regulator. The input voltage ripple can be approximately calculated using the following equation : OUT(MAX) OUT OUTIN IN SW IN IN I VVV = 1 C f V V Output Capacitor Selection The output capacitor and the inductor form a low pass filter in the Buck topology. In steady state condition, the ripple current flowing into/out of the capacitor results in ripple voltage. The output voltage ripple (V P-P) can be calculated by the following equation : P_P LOAD(MAX) OUT SW 1V = LIR I ESR + 8 C f When load transient occurs, the output capacitor supplies the load current befo re the controller can respond. Therefore, the ESR will dominate the output voltage sag during load transient. The output voltage undershoot (VSAG) can be calculated by the following equation : SAG LOADV = I ESR For a given output voltage sag speci fication, the ESR value can be determined. Another parameter that has influence on the output voltage sag is the equivalent series inductance (ESL). The rapid change in load current results in di/dt during transient. Therefore, the ESL contributes to par t of the voltage sag. Using a capacitor with low ESL can obtain better transient performance. Generally, using several capacitors connected in parallel can have better transient performance than using a single capacitor for the same total ESR. Thermal Considerations The junction temperature should never exceed the absolute maximum junction temperature TJ(MAX), listed under Absolute Maximum Ratings, to avoid permanent damage to the device. The maximum allowable power dissipation depends on the thermal resistance of the IC package, the PCB layout, the rate of surrounding airflow, and the difference between the junction and ambient temperatures. The maximum power dissipation can be calculated using the following formula : PD(MAX) = (TJ(MAX) TA) / JA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and JA is the junction-to-ambient thermal resistance. For continuous operation, the maximum operating junction temperature indicated under Recommended Operating Conditions is 125C. The junction-to-ambient thermal resistance, JA, is highly package dependent. For WDFN-6L 2x2 package, the thermal resistance, JA, is 120C/W on a standard JEDEC 51 -7 high effective-thermal-conductivity four-layer test board. The maximum power dissipation at T A = 25 C can be calculated as below : PD(MAX) = (125C 25C) / (120C/W) = 0.833W for a WDFN-6L 2x2 package. The maximum power dissipation depends on the operating ambient temperature for the fixed T J(MAX) and the thermal resistance, JA. The derating curve in Figure 2 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation.
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. Figure 2. Derating Curve of Maximum Power
Copyright © 2019 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS5710A-04 November 2019 www.richtek.com Outline Dimension Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.175 0.250 0.007 0.010 b 0.200 0.350 0.008 0.014 D 1.950 2.050 0.077 0.081 D2 1.000 1.450 0.039 0.057 E 1.950 2.050 0.077 0.081 E2 0.500 0.850 0.020 0.033 e 0.650 0.026 L 0.300 0.400 0.012 0.016 W-Type 6L DFN 2x2 Package Richtek Technology Corporation 14F, No. 8, Tai Yuen 1st Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.