RT6264A RICHTEK | Alldatasheet
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Technical content
Features
4A Converter Integrated 66m and 36m FETs Input Supply Voltage Range : 4.5V to 18V Output Voltage Range : 0.765V to 7V Advanced Constant On-Time (ACOT® ) Control Ultrafast Transient Response Optimized for Low -ESR Ceramic Output Capacitors High Accuracy Feedback Reference Voltage : Typ. 1% Optional for Operation Modes : RT6264A : Power Saving Mode (PSM) RT6264B : Forced PWM Mode Fixed Switching Frequency : 650kHz Enable Control and Internally Fixed Soft -Start with typ. 1ms Input Under-Voltage Lockout (UVLO) Protection Function Output Under -Voltage Protection (UVP) with Hiccup Mode High- / Low -side MOSFET OCP and OTP Function RoHS Compliant and Halogen Free EN RT6264A/B FBGND VINVIN BOOT LCBOOT COUT SW VOUT RFB1 RFB2 Enable RBOOT (Optional) CFF RT CIN
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021
Ordering Information
J6F : TSOT-23-6 (FC) Lead Plating System G : Green (Halogen Free and Pb Free) UVP Option H : Hiccup PWM Operation Mode A : Automatic PSM B : Forced PWM Note : Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Marking Information 39= : Product Code DNN : Date Code RT6264BHGJ6F 39=DNN 3A= : Product Code DNN : Date Code RT6264AHGJ6F 3A=DNN
Applications
Set-Top Boxes LCD TVs Home Networking Devices Surveillance General Purpose Pin Configuration (TOP VIEW) GND SW VIN BOOT EN FB 2 3 TSOT-23-6 (FC) Functional Pin Description Pin No. Pin Name Pin Function 1 GND Power ground. 2 SW Switch node between the internal switch and the synchronous rectifier. Connect this pin to the inductor and bootstrap capacitor.
3 VIN
Power input. The input voltage range is from 4.5V to 18V. Connect input bypass capacitors directly to this pin and GND pins. The MLCC with capacitance higher than 20F is recommended. 4 FB Feedback voltage input. Connect this pin to the midpoint of the external feedback resistive divider to set the output voltage of the converter to the desired regulation level. The device regulates the FB voltage at feedback reference voltage, typically 0.765V. 5 EN Enable control input. Connect this pin to logic high enable s the device and connect this pin to GND disables the device. 6 BOOT Bootstrap capacitor connection node to supply the high -side gate driver. Connect a 0.1F ceramic capacitor between this pin and the SW pin.
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com Functional Block Diagram Gate Driver & Dead-Time Control BOOT On- Time EN SW Ramp Gen. VIN FB MIN OFF VEN_TH UV Protection 65% OC Control SW GND PVCC VCCInternal RegulatorUVLO Comparator REN_DN Soft-Start
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021 Operation The RT6264A/B is a high -efficiency, synchronous step-down DC-DC converter that can deliver up to 4A output current from a 4.5V to 18V input supply. Advanced Constant On-Time Control and PWM Operation The RT6264A/B adopts ACOT® control for its ultrafast transient response, low external component counts and stable with low ESR MLCC output capacitors. When the feedback voltage falls below the feedback reference voltage, the minimum off -time one -shot (200ns, typ.) has timed out and the inductor current is below the current limit threshold, then the internal on-time one-shot circuitry is triggered and the high-side switch is turn -on. Since the minimum off -time is short, the device exhibits ultrafast transient response an d enables the use of smaller output capacitance. The on -time is inversely proportional to input voltage and directly proportional to output voltage to achieve pseudo-fixed frequency over the input voltage range. After the on-time one-shot timer expired, t he high-side switch is turned off and the low-side switch is turned on until the on -time one -shot is triggered again. To achieve stable operation with low -ESR ceramic output capacitors, an internal ramp signal is added to the feedback reference voltage to simulate the output voltage ripple. Power Saving Mode (RT6264A Only) The RT6264A automatically enters power saving mode (PSM) at light load to maintain high efficiency. As the load current decreases , the inductor current ripple valley eventually touches the zero current, which is the boundary between continuous conduction and discontinuous conduction modes. The low -side switch is turned off when the zero inductor current is detected. In this case, the output capacitor is only discharged by load current so that the switching frequency decreases. As the result, the light-load efficiency can be enhanced due to lower switching loss. Enable Control The RT6264A/B provides an EN pin, as an external chip enable control, to enable or disable the device. If VEN is held below a logic-low threshold voltage (VEN_L) of the enable input (EN), the converter will disable output voltage, that is, the converter is disabled and switching is inhibited even if the VIN voltage is above VIN under -voltage lockout threshold (V UVLO). During shutdown mode, the supply current can be reduced to ISHDN (10A or below). If the EN voltage rises above the logic-high threshold voltage (V EN_H) while the VIN voltage is higher than UVLO threshold, the device will be turned on, that is, switc hing being enabled and soft-start sequence being initiated. An internal resistor REN_DN from EN to GND allows EN float to shutdown the chip. Soft-Start (SS) The RT6264A/B provides an internal soft -start feature for inrush control. At power up, the internal capacitor is charged by an internal current source to generate a soft-start ramp voltage as a reference voltage to the PWM comparator. The device will initiate switching and the output voltage will smoothly ramp up to its targeted regulation voltage only after this ramp voltage is greater than the feedback voltage V FB to ensure the converters have a smooth start -up from pre -biased output. The output voltage starts to rise in 0.3ms from EN rising, and the soft-start ramp-up time (VFB from 0V to 0.765V) is 1ms. VOUT EN VIN 0.3ms 1ms VCC VIN = 12V VCC = 5V Input Under-Voltage Lockout In addition to the EN pin, the RT6264A/B also provides enable control through the VIN pin. It features an under-voltage lockout (UVLO) function that monitors the internal linear regulator (VCC). If V EN rises above VEN_H first, switching will still be inhibited until the VIN voltage rises above V UVLO. It is to ensure that the
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com internal regulator is ready so that operation with not-fully-enhanced internal MOSFET switches can be prevented. After the device is powered up, if the input voltage VIN goes below the UVLO falling threshold voltage (V UVLO VUVLO), this switching will be inhibited; if VIN rises above the UVLO rising threshold (VUVLO), the device will resume normal operation with a complete soft-start. Output Under-Voltage Protection and Hiccup Mode The RT6264A/B includes output under -voltage protection (UVP) against over -load or short -circuited condition by constantly monitoring the feedback voltage V FB. If V FB drops below the under -voltage protection trip threshold (typically 65% of the internal feedback reference voltage), the UV comparator will go high to turn off both the internal high-side and low-side MOSFET switches. If the output under -voltage condition continues for a period of time, the RT6264A/B will enter output under-voltage protection with hiccup mode. During hiccup mode, the IC will shut down for tHICCUP_OFF (15ms), and then attempt to recover automatically for tHICCUP_ON (1.8ms). Upon completion of the soft -start sequence, if the fault condi tion is removed, the converter will resume normal operation; otherwise, such cycle for auto -recovery will be repeated until the fault condition is cleared. The hiccup mode allows the circuit to operate safely with low input current and power dissipation, a nd then the converter resumes normal operation as soon as the over -load or short-circuit condition is removed. The Over-Current Protection The RT6264A/B features cycle -by-cycle current -limit protection on both the high -side and low -side MOSFETs and prevents the device from the catastrophic damage in output short -circuit, over-current or inductor saturation conditions. The high -side MOSFET over -current pro tection is achieved by an internal current comparator that monitors the current in the high -side MOSFET during each on-time. The switch current is compared with the high-side switch peak -current limit (I LIM_H) after a certain amount of delay when the high -side switch being turned on each cycle. If an over-current condition occurs, the converter will immediately turns off the high-side switch and turns on the low -side switch to prevent the inductor current exceeding the high -side current limit. The low -side MOSFET over -current protection is achieved by measuring the inductor current through the synchronous rectifier (low -side switch) during the low-side on -time. Once the current rises above the low-side switch valley current limit (I LIM_L), the on-time one-shot will be inhibited until the inductor current ramps down to the current limit level (I LIM_L), that is, another on -time can only be triggered when the inductor current goes below the low-side current limit. If the output load current exceeds the available inductor current (clamped by the low -side current limit), the output capacitor needs to supply the extra current such that the output voltage will begin to drop. If it drops below the output under-voltage protection trip threshold, the IC will stop switching to avoid excessive heat. Negative Over-Current Limit The RT6264B is the part which is forced to PWM and allows negative current operation. In case of PWM operation, high negative current may be generated as an external power source is tied to output te rminal unexpectedly. As the risk described above, the internal circuit monitors negative current in each on -time interval of low -side MOSFET and compares it with NOC threshold. Once the negative current exceeds the NOC threshold, the low -side MOSFET is tur ned off immediately, and then the high -side MOSFET will be turned on to Fault condition removed Resume normal operation Output short 10ms/Div VSW, 10/Div ISW, 4A/Div VOUT, 2V/Div
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021 discharge the energy of output inductor. This behavior can keep the valley of negative current at NOC threshold to protect low -side MOSFET. However, the negative current can’t be limit ed at NOC threshold anymore since minimum off-time is reached. Thermal Shutdown The RT6264A/B includes an over -temperature protection (OTP) circuitry to prevent overheating due to excessive power dissipation. The OTP will shut down switching operation when junction temperature exceeds a thermal shutdown threshold (TSD). Once the junction temperature cools down by a thermal shutdown hysteresis (TSD), the IC will resume normal operation with a complete soft-start. Note that the over-temperature protection is intended to protect the device during momentary overload conditions. The protection is activated outside of the absolute maximum range of operation as a secondary fail-safe and therefore should not be relied upon operationally. Co ntinuous operation above the specified absolute maximum operating junction temperature may impair the reliability of the device or permanently damage the device.
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com Absolute Maximum Ratings (Note 1) Power Dissipation, PD @ TA = 25C ESD Ratings ESD Susceptibility (Note 2) Recommended Operating Conditions (Note 3) Thermal Information (Note 4 and Note 5) Thermal Parameter TSOT-23-6 (FC) Unit JA Junction-to-ambient thermal resistance (JEDEC standard) 88.7 C/W JC(Top) Junction-to-case (top) thermal resistance 76.9 C/W JC(Bottom) Junction-to-case (bottom) thermal resistance 6 C/W JA(EVB) Junction-to-ambient thermal resistance (specific EVB) 59 C/W JC(Top) Junction-to-top characterization parameter 15.3 C/W JB Junction-to-board characterization parameter 30.19 C/W
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021
Electrical Characteristics
(VIN = 12V, TA = 25C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Supply Voltage VIN Supply Input Operating Voltage VIN 4.5 -- 18 V Under-Voltage Lockout Threshold VUVLO 3.7 4 4.3 V Under-Voltage Lockout Threshold Hysteresis VUVLO -- 400 -- mV Shutdown Current ISHDN VEN = 0V -- 3 10 µA Quiescent Current IQ VEN = 2V, VFB = 0.8V -- 180 -- µA Soft-Start Soft-Start Time tSS -- 1 -- ms Enable Voltage Enable Voltage Threshold VEN_H EN high-level input voltage 1.16 1.25 1.34 V VEN_L EN low-level input voltage 1.01 1.1 1.19 EN Pin Pull-Down Resistance REN_DN EN pin resistance to GND, VEN = 12V 225 450 900 k Feedback Voltage and Discharge Resistance Feedback Threshold Voltage VFB VOUT = 1.05V 758 765 772 mV Feedback Input Current IFB VFB = 0.8V, TA = 25°C 0.1 0 0.1 A Internal MOSFET High-Side On-Resistance RDS(ON)_H VBOOT – VSW = 4.8V -- 66 -- mΩ Low-Side On-Resistance RDS(ON)_L -- 36 -- Current Limit High-Side Switch Current Limit ILIM_H 5.4 6.5 -- A Low-Side Switch Valley Current Limit ILIM_L 3.9 5.3 -- Low-Side Switch Negative Current Limit INOC Forced PWM mode only -- 2.5 -- A Switching Frequency Switching Frequency fSW VOUT = 1.05V, PWM mode -- 650 -- kHz On-Time Timer Control Minimum On-Time tON_MIN -- 60 -- ns Minimum Off-Time tOFF_MIN VFB = 0.5V -- 200 260 ns Output Under-Voltage Protections UVP Trip Threshold VUVP Hiccup detect -- 65 -- % Hiccup Power On-Time tHICCUP_ON -- 1.8 -- ms Hiccup Power Off-Time tHICCUP_OFF -- 15 --
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com Parameter Symbol Test Conditions Min Typ Max Unit Thermal Shutdown Thermal Shutdown Threshold TSD -- 155 -- Thermal Shutdown Hysteresis TSD -- 35 -- 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. Devices are ESD sensitive. Handling precaution is recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. θJA and θJC are measured or simulated at TA = 25C based on the JEDEC 51-7 standard. Note 5. θJA(EVB), ΨJC(TOP) and ΨJB are measured on a high effective-thermal-conductivity four-layer test board which is in size of 70mm x 50mm; furthermore, all layers with 1 oz. Cu. Thermal resistance/parameter values may vary depending on the PCB material, layout, and test environmental conditions.
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. Table 1. Recommended Components Selection regulation, checking the load regulation is suggested if higher CFF is applied. Table 2. Recommended External Components
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com Typical Operating Characteristics L : WE-74437346022 (DCR = 18mΩ) for VOUT = 1V and 1.8V. L : WE-74437346047 (DCR = 37mΩ) for VOUT = 3.3V and 5V. Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VOUT = 3.3V VOUT = 1.8V VOUT = 1V RT6264A, VIN = 5V Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VOUT = 5V VOUT = 3.3V VOUT = 1.8V VOUT = 1V RT6264A, VIN = 12V Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VOUT = 3.3V VOUT = 1.8V VOUT = 1V RT6264B, VIN = 5V Efficiency vs. Output Current 100 0.001 0.01 0.1 1 10 Output Current (A) Efficiency (%) VOUT = 5V VOUT = 3.3V VOUT = 1.8V VOUT = 1V RT6264B, VIN = 12V Output Voltage vs. Output Current 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 0 0.5 1 1.5 2 2.5 3 3.5 4 Output Current (A) Output Voltage (V) RT6264A, VIN = 5V RT6264B, VIN = 5V RT6264A, VIN = 12V RT6264B, VIN = 12V VOUT = 1V Output Voltage vs. Output Current 4.50 4.75 5.00 5.25 5.50 0 0.5 1 1.5 2 2.5 3 3.5 4 Output Current (A) Output Voltage (V) VOUT = 5V RT6264A, VIN = 9V RT6264B, VIN = 9V RT6264A, VIN = 12V RT6264B, VIN = 12V
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021 Output Voltage vs. Input Voltage 0.90 0.95 1.00 1.05 1.10 5 6 7 8 9 10 11 12 13 14 15 16 17 Input Voltage (V) Output Voltage (V) VOUT = 1V RT6264A, IOUT = 0A RT6264B, IOUT = 0A RT6264A, IOUT = 2A RT6264B, IOUT = 2A Output Voltage vs. Input Voltage 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 9 10 11 12 13 14 15 16 17 Input Voltage (V) Output Voltage (V) RT6264A, IOUT = 0A RT6264B, IOUT = 0A RT6264A, IOUT = 2A RT6264B, IOUT = 2A VOUT = 5V Quiescent Current vs.Temperature 150 160 170 180 190 200 210 220 -50 -25 0 25 50 75 100 125 Temperature (°C) Quiescent Current (μA) VIN = 17V VIN = 12V VIN = 9V VIN = 5V Shutdown Current vs.Temperature 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 -50 -25 0 25 50 75 100 125 Temperature (°C) Shutdown Current (μA) 1 VIN = 17V VIN = 12V VIN = 9V VIN = 5V Reference Voltage vs.Temperature 0.70 0.72 0.74 0.76 0.78 0.80 0.82 -50 -25 0 25 50 75 100 125 Temperature (°C) Reference Voltage (V) Frequency vs. Input Voltage 600 620 640 660 680 5 6 7 8 9 10 11 12 13 14 15 16 17 Input Voltage (V) Frequency (kHz) 1
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com Frequency vs. Output Current 100 200 300 400 500 600 700 0.001 0.01 0.1 1 10 Output Current (A) Frequency (kHz) 1 Frequency vs. Temperature 500 550 600 650 700 750 -50 -25 0 25 50 75 100 125 Temperature (°C) Frequency (kHz) 1 EN Threshold vs. Temperature 0.9 1.0 1.1 1.2 1.3 -50 -25 0 25 50 75 100 125 Temperature (°C) EN Threshold (V) EN VIL EN VIH UVLO vs. Temperature 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 -50 -25 0 25 50 75 100 125 Temperature (°C) Input Voltage (V) UVLO_H UVLO_L Time (500s/Div) Power On from EN VEN (5V/Div) IL (2A/Div) VOUT (1V/Div) VSW (10V/Div) VIN = 12V, VOUT = 1V IOUT = 4A, L = 2.2H Time (10s/Div) Power Off from EN VEN (5V/Div) IL (2A/Div) VOUT (1V/Div) VSW (10V/Div) VIN = 12V, VOUT = 1V IOUT = 4A, L = 2.2H
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021 Time (500s/Div) Power On from VIN VIN (10V/Div) IL (2A/Div) VOUT (1V/Div) VSW (10V/Div) VIN = 12V, VOUT = 1V IOUT = 4A, L = 2.2H Time (5ms/Div) Power Off from VIN VIN (10V/Div) IL (2A/Div) VOUT (1V/Div) VSW (10V/Div) VIN = 12V, VOUT = 1V IOUT = 4A, L = 2.2H Time (1ms/Div) Output Ripple as IOUT = 10mA VIN = 12V, VOUT = 1V IOUT = 10mA, L = 2.2H IL (500mA/Div) VOUT (10mV/Div) VSW (5V/Div) Time (1s/Div) Output Ripple as IOUT = 4A IL (2A/Div) VOUT (20mV/Div) VSW (5V/Div) VIN = 12V, VOUT = 1V IOUT = 4A, L = 2.2H Time (100s/Div) Load Transient (No Load to Full Load) IOUT (1A/Div) VOUT (20mV/Div) VIN = 12V, VOUT = 1V IOUT = 0A to 4A, L = 2.2H Time (100s/Div) Load Transient (Half Load to Full Load) IOUT (1A/Div) VOUT (20mV/Div) VIN = 12V, VOUT = 1V IOUT = 2A to 4A, L = 2.2H
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com IL (2A/Div) VOUT (500mV/Div) Time (20s/Div) Over Current Protection and UVP VSW (5V/Div) VIN = 12V, VOUT = 1V L = 2.2H Time (10ms/Div) Short Circuit Protection IL (4A/Div) VOUT (500mV/Div) VSW (5V/Div) VIN = 12V, VOUT = 1V, L = 2.2H Time (10ms/Div) Short Circuit before Power On VIN (10V/Div) IL (4A/Div) VOUT (500mV/Div) VSW (5V/Div) VIN = 12V, VOUT = 1V, L = 2.2H
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021
Application Information
The output stage of a synchronous buck converter is composed of an inductor and capacitor, which stores and delivers energy to the load, and forms a second-order low-pass filter to smooth out the switch node voltage to maintain a regulated output voltage. Inductor Selection The inductor selection trade -offs among size, co st, efficiency, and transient response requirements. Generally, three key inductor parameters are specified for operation with the device: inductance value (L), inductor saturation current (I SAT), and DC resistance (DCR). A good compromise between size and loss is to choose the peak-to-peak ripple current equals to 20% to 50% of the IC rated current. The switching frequency, input voltage, output voltage, and selected inductor ripple current determines the inductor value as follows : OUT IN OUT IN SW L V V VL = V f I Once an inductor value is chosen, the ripple current (IL) is calculated to determine the required peak inductor current. OUT IN OUT LL L(PEAK) OUT(MAX) IN SW V V V II = and I = IV f L 2 IL(PEAK) should not exceed the minimum value of IC's upper current limit level. Besides, the current flowing through the inductor is the inductor ripple current plus the output current. During power up, faults , or transient load conditions, the inductor current can increase above the calculated peak inductor current level calculated above. In transient conditions, the inductor current can increase up to the switch current limit of the device. For this reason, the most conservative approach is to specify an inductor with a saturation current rating which is equal to or greater than the switch current limit rather than the peak inductor current. Considering the Typical Application Circuit for 1.2V output at 4A and an input voltage of 12V, using an inductor ripple of 1A (25% of the IC rated current ), the calculated inductance value is : 1.2 12 1.2L = = 1.66 μH12 650kHz 1A For the typical application, a standard inductance value of 1.5H can be selected. L 1.2 12 1.2I = = 1.1A (28% of the IC rated current)12 650kHz 1.5 μH L(PEAK) 1.1Aand I = 4A + = 4.55A2 For the 1.5H value, the inductor's saturation and thermal rating should exceed at least 4.55A. For more conservative, the rating for inductor saturation current must be equal to or greater than switch current limit of the device rather than the inductor peak current. For EMI sensitive application, choosing shielding type inductor is preferred. Input Capacitor Selection Input capacitance, CIN, is needed to filter the pulsating current at the drain of the high -side power MOSFET. CIN should be sized to do this without causing a large variation in input voltage. The waveform of C IN ripple voltage and ripple current are shown in Figure 1. The peak-to-peak voltage ripple on input capacitor can be estimated as the equation below : CIN OUT OUT IN SW where OUT IN VD = V For ceramic capacitors, the equivalent series resistance (ESR) is very low, the ripple which is caused by ESR can be ignored, and the minimum input capacitance can be estimated as the equation below : IN_MIN OUT_MAX CIN_MAX SW D 1 DC I Vf = CIN_MAXwhere V 200mV
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. Figure 1. CIN Ripple Voltage and Ripple Current ESR to damp the voltage ringing. capacitor should be 0402 or 0603 in size. load apply) and soar (overshoot on load release).
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. load step edges, with the chosen inductor value. minimum off -times, which is as fast as allowed. Figure 2. Output Voltage Setting Place the FB resistors within 5mm of the FB pin.
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. stray capacitive noise pickup. An example of PCB layout guide is shown in Figure 14. components next to the FB pin.
1 REN
Figure 14. Layout Guide
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. www.richtek.com DS6264A/B-02 August 2021 Outline Dimension Symbol Dimensions In Millimeters Dimensions In Inches Min. Max. Min. Max. A 0.700 1.000 0.028 0.039 A1 0.000 0.100 0.000 0.004 B 1.397 1.803 0.055 0.071 b 0.300 0.559 0.012 0.022 C 2.591 3.000 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.950 0.037 H 0.080 0.254 0.003 0.010 L 0.300 0.610 0.012 0.024 TSOT-23-6 (FC) Surface Mount Package
Copyright © 2021 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation. DS6264A/B-02 August 2021 www.richtek.com Footprint Information Package Number of Pin Footprint Dimension (mm) Tolerance P1 A B C D M 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 ver ify 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 righ ts of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent righ ts of Richtek or its subsidiaries.