RT6316B RICHTEK | Alldatasheet
Document overview
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Technical content
Features
4.5V to 23V (RT6316B) and 5.1V to 23V (RT6316C) Input Voltage Range 6A Output Current ACOT® Mode Performs Fast Transient Response ACOT® Architecture to Enable All MLCC Output Capacitor Usage Fixed 750kHz (RT6316C) and 500kHz (RT6316B) Switching Frequency High Efficient Internal Power MOSFET Switch- 30mΩΩΩΩΩ (High-Side) and 15m ΩΩΩΩΩ (Low-Side) Fixed 3.3V (RT6316B) and 5V (RT6316C) LDOs Output Supply 100mA Pre-biased Soft-Start Cycle-by-Cycle Over-Current Protection Input Under-Voltage Lockout Thermal Shutdown Protection Output Over-/Under-Voltage Protection Ultrasonic Mode (USM) General Description The RT6316B/C is an advanced constant on-time (ACOT®) mode synchronous buck converter. The main control loop of the RT6316B/C using an advanced constant on-time (ACOT ®) mode control which provides a very fast transient response. The RT6316B operates from 4.5V to 23V input voltage and RT6316C operates from 5.1V to 23V.
Applications
Industrial and Commercial Low Power Systems Computer Peripherals LCD Monitors and TVs Green Electronics/Appliances Point of Load Regulation for High-Performance DSPs, FPGAs, and ASICs 6A, 23V Synchronous Step-Down Converter with 3.3V/5V LDO Simplified Application Circuit RT6316B/C VCC LX VOUT VCC PGOOD VPGOOD VEN EN VINVIN PGND AGNDLDOVLDO BOOT VOUT FF
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Pin Configuration (TOP VIEW) RT6316B RT6316C UQFN-12HL 3x3 (FC) NC LX BOOT VIN EN PGND FF VOUT VCC LDO3 AGND PGOOD 11 10 9 8 NC LX BOOT VIN EN PGND LDO5 VOUT FF VCC AGND PGOOD 11 10 9 8 Marking Information RT6316BGQUF QR=YM DNN QR= : Product Code YMDNN : Date Code RT6316CGQUF QU=YM DNN QU= : Product Code YMDNN : Date Code Note : Richtek products are : RoHS compliant and compatible with the current require- ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes.
Ordering Information
QUF : UQFN-12HL 3x3 (FC) (U-Type) RT6316B/C Lead Plating System G : Green (Halogen Free and Pb Free) Output Voltage B : 3.3V C : 5.1V
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Functional Pin Description pin No. Pin Name Pin Function 1 BOOT Boot-strap pin. Supply high-side gate driver. A 0.1 F ceramic capacitor and at least 10 RBOOT are connected between this pin and LX pin. 2 LX Inductor pin. Connect this pin to the switching node of inductor. 3 NC No internal connection. 4 PGND Power ground. 5 VIN Input pin. Decouple this pin to GND pin with at least 10 F ceramic cap. EN (RT6316B) Enable control. Pull this pin high to turn on the Buck. Do not leave this pin floating. EN pin will also be used to set USM mode, when EN pin voltage is between 0.8V and 1.7V, it will enter USM mode, if EN pin voltage is between 2.3V and 23V, then it is normal mode. EN (RT6316C) Enable control. Pull this pin high to turn on the Buck. Do not leave this pin floating. EN pin will also be used to set USM mode, when EN pin voltage is between 0.8V and 1.7V, it will enter USM mode, if EN pin voltage is between 2.3V and 23V, then it is normal mode. 7 PGOOD Power good indicator. Open drain output when the output voltage is higher than 90% of regulation point. 8 AGND Analog ground. VCC (RT6316B) 5V linear regulator output for internal control circuit. A capacitor (typical 1F) should be connected to AGND. Don’t connect to external Load. FF (RT6316C) Output feedforward pin. Connect RC network from the output to this pin. VOUT (RT6316B) Output pin. Connect to the output of DC-DC regulator. VOUT (RT6316C) Output pin. Connect to the output of DC-DC regulator. The pin also provide the bypass input for 5V LDO. LDO3 (RT6316B) Internal 3.3V LDO output. Bypass a capacitor to GND. This pin is also capable sourcing 100mA current for external load. VCC (RT6316C) 5V linear regulator output for internal control circuit. A capacitor (typical 1F) should be connected to AGND. Don’t connect to external load. FF (RT6316B) Output feedforward pin. Connect RC network from the output to this pin. LDO5 (RT6316C) Internal 5V LDO output. Bypass a capacitor to GND. This pin is also capable sourcing 100mA current for external load.
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Functional Block Diagram VIN LX PWM Control Protect Logic PGND BOOT LDO VIN Current Sense RT6316B PGOOD Internal SST Thermal Protection Input UVLO EN LDO LDO3 VCC 0.6V VOUT AGND FF 3.1V VOUT RDIS VIN EN LX PWM Control Protect Logic PGND BOOT VCC LDO VIN Current Sense RT6316C Input UVLO Thermal Protection Internal SST PGOOD 0.6V VOUT AGND FF 4.7V LDO5 LDO VOUT RDIS
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Operation Overall The RT6316B/C is an advanced constant on-time (ACOT®) mode synchronous buck converter. The main control loop of the RT6316B/C using an ACOT ® mode control which provides a very fast transient response. Internal VCC Regulator The RT6316B/C includes a 5V linear regulator (VCC). The VCC regulator steps down input voltage to supply both internal circuitry and gate drivers. Do not connect the VCC pin to external loads. LDO The RT6316B/C includes a 3.3V/5V 100mA linear regulators (LDO). When VOUT is higher than the switch over threshold 3.1V (RT6316B) or 4.7V (RT6316C), an automatic circuit will change the power source of linear regulator from VIN path to VOUT path. Soft-Start The RT6316B/C provides an internal soft-start function to prevent large inrush current and output voltage overshoot. The typical soft-start duration is around 0.6ms. Over-Current Limit The RT6316B/C current limit is fixed 7A and it is a cycle- by-cycle “valley” type, measuring the inductor current through the synchronous rectifier during the off-time while the inductor current ramps down. If output voltage drops below the output under-voltage protection level, the RT6316B/C will stop switching to avoid excessive heat. Output Over-Voltage Protection (OVP) and Under- Voltage Protection (UVP) The RT6316B/C includes output over-voltage protection (OVP) and output under-voltage protection (UVP). If the output voltage rises above OVP threshold or drops below UVP threshold for longer than 20μs (typical), the OVP or UVP function is triggered. Power Good The power good output is an open drain output that requires a pull-up resistor. PGOOD will be pulled high after soft- start is over and the output reaches 90% of its set voltage. There is a 10μs delay built into PGOOD circuitry to prevent false transition.
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation.
Electrical Characteristics
(VIN = 12V, TA = 25°C, unless otherwise specified) Absolute Maximum Ratings (Note 1) Power Dissipation, PD @ TA = 25°C Package Thermal Resistance (Note 2) ESD Susceptibility (Note 3) Parameter Symbol Test Conditions Min Typ Max Unit Input Voltage Range V IN RT6316B 4.5 -- 23 V RT6316C 5.1 -- 23 Supply Current Supply Current (Shutdown) I SHDN V EN = 0 40 50 60 A Supply Current (Quiescent) I Q IOUT = 0, VOUT = VSET x 105%, VEN = 2V 80 100 130 A Logic Threshold EN Input Low Voltage V ENL -- -- 0.4 V EN Input High Voltage V ENH 0.8 -- -- V Ultra-Sonic Mode V EN -- -- 1.7 V Normal Mode V EN 2.3 -- -- V Recommended Operating Conditions (Note 4)
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit Output Voltage Output Voltage Setpoint V OUT RT6316B 3.267 3.3 3.333 V RT6316C 5.049 5.1 5.151 VCC Regulator Voltage V CC 4.95 5 5.05 V On Resistance High-Side Switch On-Resistance R DS(ON)_H 25 30 40 m Low-Side Switch On-Resistance R DS(ON)_L 12 15 18 m Discharge FET Ron R DIS 40 50 63 Current Limit Top FET Current Limit I LIM_T -- 11 -- A Bottom FET Current Limit I LIM_B 7 8.4 9.3 A Oscillator Frequency Oscillator Frequency f OSC RT6316B 0.42 0.5 0.58 MHz RT6316C 0.62 0.75 0.9 MHz On-Time Timer Control Minimum On-Time t ON_MIN V IN = VIN(MAX) 40 50 80 ns Minimum Off-Time t OFF_MIN 150 200 300 ns Ultrasonic Mode Operation Period t USM 20 30 40 s Soft-Start Soft-Start Time t SS From EN high to PGOOD high 1.3 1.65 2 ms Output Rising Time t R From 10% to 90% V OUT -- 0.6 -- ms UVLO Input UVLO Threshold V UVLO Wake up RT6316B -- -- 4.5 V Wake up RT6316C -- -- 5.4 UVLO Hysteresis V HYS -- 0.3 -- V Output Over-Voltage Protection Output Over Voltage Threshold V OUT rising 115 120 125 % Output Over Voltage Hysteresis -- 3 -- % Output Over Voltage Delay Time -- 20 -- s Output Under-Voltage Protection Output Under Voltage Threshold V FB falling 54 60 64 % Output Under Voltage Delay Time FB forced below UV threshold -- 20 -- s UV Blank Time From EN high -- 1.65 -- ms Power Good Power Good Threshold V TH_PGLH V OUT rising (Good) 88 90 92 % Power Good Hysteresis VTH_PGLH -- 15 -- % Power Good Delay Time -- 10 -- s
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Parameter Symbol Test Conditions Min Typ Max Unit LDO Regulator LDO Output Voltage VLDO3 RT6316B 3.25 3.3 3.35 V VLDO5 RT6316C 4.925 5 5.075 LDO Dropout Voltage V DROPOUT -- 200 -- mV LDO Output Current Limit I LMTLDO 150 -- -- mA Thermal Shutdown Thermal Shutdown Threshold T SD -- 150 -- °C 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. θJA is measured in the natural convection at T A = 25°C on a four-layer Richtek evaluation board. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions.
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Typical Application Circuit RT6316B VCC9 LX VOUT VCC 2 L COUT PGOOD 7 VPGOOD 3.3V/6A CVCC 1µF 1µH 22µF x 4 VEN EN6 VINVIN 5 4.5V to 23V CIN 10µF x 2 PGND 4 AGND 8LDO3VLDO3 11 3.3V/100mA CLDO3 4.7µF BOOT 1 CBOOT RBOOT 0.1µF VOUT 10 CFF 10pF FF 12 REN 1K RFF 1k 10 RT6316C VEN EN6 VINVIN 5 CIN 5.1V to 23V 10µF x 2 LDO5VLDO5 12 5V/100mA CLDO5 4.7µF BOOT LX VOUT COUTVOUT 10 CBOOT L CBUFF 5.1V/6A 0.1µF 1µH 0.1µF 22µF x 4 4PGND FF 9 CFF 10pF AGND 8 PGOOD 7 VPGOOD REN VCC CVCC 1µF VCC RFF RBOOT 10
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Typical Operating Characteristics Output Voltage vs. Output Current 4.9 5.0 5.1 5.2 5.3 0.001 0.01 0.1 1 10 Output Current (A) Output Voltage (V) RT6316C, EN = 2.4V, VOUT = 5.1V, Normal Mode VIN = 19V VIN = 12V VIN = 7.4V Output Voltage vs. Output Current 3.20 3.25 3.30 3.35 3.40 0.001 0.01 0.1 1 10 Output Current (A) Output Voltage (V) RT6316B, EN = 2.4V, VOUT = 3.3V, Normal Mode VIN = 19V VIN = 12V VIN = 7.4V Switching Frequency vs. Output Current 100 200 300 400 500 600 700 800 0.001 0.01 0.1 1 10 Output Current (A) Switching Frequency (kHz) 1 RT6316C, EN = 2.4V, VOUT = 5.1V, Normal Mode VIN = 7.4V VIN = 12V VIN = 19V Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) RT6316C, EN = 2.4V, VOUT = 5.1V, Normal Mode VIN = 7.4V VIN = 12V VIN = 19V Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VIN = 7.4V VIN = 12V VIN = 19V RT6316B, EN = 2.4V, VOUT = 3.3V, Normal Mode Switching Frequency vs. Output Current 100 200 300 400 500 600 0.001 0.01 0.1 1 10 Output Current (A) Switching Frequency (kHz) 1 RT6316B, EN = 2.4V, VOUT = 3.3V, Normal Mode VIN = 7.4V VIN = 12V VIN = 19V
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Time (40 μs/Div) Power Off from EN VOUT (2V/Div) IL (5A/Div) RT6316B, VIN = 12V, EN = 2.4V, VOUT = 3.3V, IOUT = 6A PGOOD (5V/Div) EN (2V/Div) Shutdown Current vs. Input Voltage 4 6 8 1 01 21 41 61 82 02 22 4 Input Voltage (V) Shutdown Current (μA) 1 RT6316B, EN = 0V VLDO5 vs. ILDO5 4.90 4.92 4.94 4.96 4.98 5.00 5.02 5.04 5.06 5.08 5.10 0 1 02 03 04 05 06 07 08 09 0 1 0 0 ILDO5 (mA) VLDO5 (V) RT6316C, VIN = 12V, EN = 0V VLDO3 vs. ILDO3 3.20 3.22 3.24 3.26 3.28 3.30 3.32 3.34 3.36 3.38 3.40 0 1 02 03 04 05 06 07 08 09 0 1 0 0 ILDO3 (mA) VLDO3 (V) RT6316B, VIN = 12V, EN = 0V Quiescent Current vs. Input Voltage 100 105 110 115 120 4 6 8 1 01 21 41 61 82 02 22 4 Input Voltage (V) Quiescent Current (μA) RT6316B, EN = 2.4V, No Switching Time (200 μs/Div) Power On from EN VOUT (2V/Div) IL (5A/Div) RT6316B, VIN = 12V, EN = 2.4V, VOUT = 3.3V, IOUT = 6A PGOOD (5V/Div) EN (2V/Div)
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Time (10 μs/Div) Over Current Limit VOUT (1V/Div) IL (10A/Div) LX (10V/Div) RT6316B, VIN = 12V, EN = 2.4V, VOUT = 3.3V VOUT IL LX Time (20 μs/Div) VOUT OVP VOUT (1V/Div) PGOOD (5V/Div) LX (5V/Div) RT6316B, VIN = 12V, EN = 2.4V, VOUT = 3.3V, No Load Time (10 μs/Div) VOUT UVP VOUT (1V/Div) PGOOD (5V/Div) LX (10V/Div) RT6316B, VIN = 12V, EN = 2.4V, VOUT = 3.3V Time (40 μs/Div) Load Transient Response VOUT (100mV/Div) IOUT (5A/Div) RT6316B, VIN = 12V, EN = 2.4V, VOUT = 3.3V, IOUT = 0.6A to 6A LX (10V/Div) Time (40 μs/Div) Load Transient Response VOUT (200mV/Div) IOUT (5A/Div) RT6316C, VIN = 12V, EN = 2.4V, VOUT = 5.1V, IOUT = 0.6A to 6A LX (10V/Div)
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation.
Application Information
The RT6316B/C is high-performance 6A step-down regulators with internal power switches and synchronous rectifiers. They feature an Advanced Constant On-Time (ACOT ®) control architecture that provides stable operation for ceramic output capacitors without complicated external compensation, among other benefits. The input voltage range is from 4.5V to 23V. The output voltage are fixed 3.3V (RT6316B) or 5.1V (RT6316C). The proprietary ACOT ® control scheme improves conventional constant on-time architectures, achieving nearly constant switching frequency over line, load, and output voltage ranges. Since there is no internal clock, response to transients is nearly instantaneous and inductor current can ramp quickly to maintain output regulation without large bulk output capacitance. The RT6316B and RT6316C include 3.3V and 5V linear regulator(LDO), respectively. The linear regulator provides an automatic saving power function, when VOUT rises above 3.1V (RT6316B)/4.7V (RT6316C), an automatic circuit will change the power source of linear regulator from VIN path to VOUT path, therefore the power dissipation of linear regulator will be decrease efficiently. ACOT ® Control Architecture The conventional CFCOT (constant frequency constant on-time) control which making the on-time proportional to VOUT and inversely proportional to VIN is not sufficient to achieve good constant-frequency behavior. Because voltage drops across the MOSFET switches and inductor cause sensing mismatch as sensing input and output voltage from LX pin. When the load change, the voltage drops across the MOSFET switches and inductor cause a switching frequency variation with load current. One way to reduce these effects is to measure the actual switching frequency and compare it to the desired range. This has the added benefit eliminating the need to sense the actual output voltage, potentially saving one pin connection. ACOT ® uses this method, measuring the actual switching frequency and modifying the on-time with a feedback loop to keep the average switching frequency in the desired range. In order to achieve good stability with low-ESR ceramic capacitors, ACOT ® uses a virtual inductor current ramp generated inside the IC. This internal ramp signal replaces the ESR ramp normally provided by the output capacitor’s ESR. The ramp signal and other internal compensations are optimized for low-ESR ceramic output capacitors. ACOT ® One-Shot Operation The RT6316B/C control algorithm is simple to understand. The feedback voltage, with the virtual inductor current ramp added, is compared to the reference voltage. When the combined signal is less than the reference, the on-time one-shot is triggered as long as the minimum off-time one- shot is clear and the measured inductor current (through the synchronous rectifier) is below the current limit. The on-time one-shot turns on the high-side switch and the inductor current ramps up linearly. After the on-time, the high-side switch is turned off and the synchronous rectifier is turned on and the inductor current ramps down linearly. At the same time, the minimum off-time one-shot is triggered to prevent another immediate on-time during the noisy switching time and allow the feedback voltage and current sense signals to settle. The minimum off-time is kept short (200ns typical) so that rapidly-repeated on- times can raise the inductor current quickly when needed. Average Output Voltage Control Loop In continuous conduction mode, the RT6316B/C provides a average output voltage control loop to cancel the DC error between V FB(average) and V REF by adjusting the comparator input VREF to make VFB(average) always follow designed value. This loop can efficiently improves the load and line regulation without affecting the transient performance. The operation figure is shown in Figure 1. Figure 1. Average output voltage control loop operation
©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Table 1. RT6316B/C Power Logic from an internal resistor(50Ω) to ground. exceeds the UVLO-rising threshold. operation when the junction temperature exceeds 150°C. the junction temperature does not exceed 150°C. Table 1 for the RT6316B/C power logic. high-side N-channel MOSFET switch. best mix of cost, physical size, and circuit efficiency.
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. OUT IN OUT IN SW L V( V V )L Vf I Once an inductor value is chosen, the ripple current (ΔIL) is calculated to determine the required peak inductor current. OUT IN OUTL IN SW LL(PEAK) OUT(MAX) V( V V )I a n d Vf L III 2 To guarantee the required output current, the inductor needs a saturation current rating and a thermal rating that exceeds I L(PEAK). These are minimum requirements. To maintain control of inductor current in overload and short- circuit conditions, some applications may desire current ratings up to the current limit value. However, the IC's output under-voltage shutdown feature make this unnecessary for most applications. For best efficiency, choose an inductor with a low DC resistance that meets the cost and size requirements. For low inductor core losses some type of ferrite core is usually best and a shielded core type, although possibly larger or more expensive, will probably give fewer EMI and other noise problems. Input Capacitor Selection High quality ceramic input decoupling capacitor, such as X5R or X7R, with values greater than 20 μF are recommended for the input capacitor. The X5R and 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 efficiency, but the inductor will either be physically larger or have higher resistance since more turns of wire are required and transient response will be slower since more time is required to change current (up or down) in the inductor. Calculate the approximate inductor value by selecting the input and output voltages, the switching frequency (f SW), the maximum output current (IOUT(MAX)) and estimating a ΔIL as some percentage of that current. current, which can be calculated using the following equation : 2OUT OUT LRMS OUT IN IN VV II( 1 ) I VV 1 2 The next step is to select 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 IN OUTIN IN SW OUT IN IV VV( 1 )Cf V V The typical operating circuit is recommended to use two 10μF low ESR ceramic capacitors on the input. Output Capacitor Selection The IC is optimized for ceramic output capacitors and best performance will be obtained by using them. The total output capacitance value is usually determined by the desired output voltage ripple level and transient response requirements for sag (undershoot on positive load steps) and soar (overshoot on negative load steps). Output ripple at the switching frequency is caused by the inductor current ripple and its effect on the output capacitor's ESR and stored charge. These two ripple components are called ESR ripple and capacitive ripple. Since ceramic capacitors have extremely low ESR and relatively little capacitance, both components are similar in amplitude and both should be considered if ripple is critical. RIPPLE RIPPLE(ESR) RIPPLE(C) RIPPLE(ESR) L ESR LRIPPLE(C) OUT SW VV V VI R IV 8C f In addition to voltage ripple at the switching frequency, the output capacitor and its ESR also affect the voltage sag (undershoot) and soar (overshoot) when the load steps up and down abruptly. The ACOT ® transient response is very quick and output transients are usually small. However, the combination of small ceramic output capacitors (with little capacitance), low output voltages (with little stored charge in the output capacitors), and
©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Figure 7. Derating Curve of Maximum Power Dissipation noise path caused by parasitic capacitance. Table 2. Dividing Resistors of RT6316B/C on the maximum power dissipation.
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. For system stability and coupling noise elimination, the sensitive components and signals, such as control signal and feedback loop, should keep away from LX node. For enhancing noise immunity on VCC pin, the decoupling capacitor must be connected from VCC to AGND, and the capacitor should be placed close to IC. The feedback signal path from VOUT to IC should be wide and kept away from high switching path. The trace width and numbers of via should be based on application current to design. Make sure the switching power supply has great thermal performance and good efficiency. An example of PCB layout guides are shown in Figure 8 and Figure 9 for reference.
DS6316B/C-01 November 2020 www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Trace Width Design For thermal, efficiency and PCB handling current capability, the trace width design is very important. According to IPC- 2221 formally IDC-D-275 PWB, the following formulas can be used to calculate the trace width for printed circuit boards. Inner trace : 0.5453 2 0.7349I(Amp) = 0.015 T( C) Area(mils ) Outer trace : 0.4281 2 0.6732I(Amp) = 0.0647 T( C) Area(mils ) 2Area(mils )Width(mil) = milThickness(oz) 1.37 oz where I(Amp) = Current, ΔT(°C) = Temperature rise, Area(mils 2) = Cross sectional area = Width x Thickness, Width(mil) = Trace width, and Thickness(oz) = Layer Cu thickness. Trace PCB Cooper Plane Area Width Thickness
DS6316B/C-01 November 2020www.richtek.com ©Copyright 2020 Richtek Technology Corporation. All rights reserved. is a registered trademark of Ric htek Technology Corporation. Outline Dimension Min Max Min Max A 0.500 0.600 0.020 0.024 A1 0.000 0.050 0.000 0.002 A3 0.100 0.200 0.004 0.008 D 2.900 3.100 0.114 0.122 E 2.900 3.100 0.114 0.122 b 0.100 0.200 0.004 0.008 b1 0.180 0.280 0.007 0.011 L 0.800 1.000 0.031 0.039 L1 1.730 1.930 0.068 0.076 L2 0.250 0.450 0.010 0.018 e K 0.018 0.500 0.020 0.950 0.037 Symbol Dimensions In Millimeters Dimensions In Inches 0.720 0.028 0.900 0.035 0.450 U-Type 12HL QFN 3x3 (FC) Package
DS6316B/C-01 November 2020 www.richtek.com 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. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. 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 furnish ed 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 infringeme nts 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. Footprint Information P P 1P 2A xC * 8 C 1 * 2 C 2 * 2 D * 1 2 K K 1K 2K 3 UQFN3*3- TolerancePackage Number of Pin Footprint Dimension (mm)