SGM61410XN6G/TR

SGM61410 1.2MHz, 600mA, 45V Synchronous Step-Down Converter GENERAL DESCRIPTION FEATURES The SGM61410 is a high frequency, synchronous step-down converter with integrated switches. It can deliver up to 600mA to the output over a wide input voltage range of 5V to 45V. It is suitable for various industrial or automotive applications with high input voltage or for power conditioning from unregulated sources. Moreover, the low 14µA quiescent current and ultra-low shutdown current of only 0.6µA make it a suitable choice for battery-powered applications. ● ● ● ● ● ● ● ● ● ● ● ● SGM61410 features high efficiency over a wide load range achieved by scaling down the switching frequency at light loads to reduce switching and gate driving losses. Other features include, internal compensation, internal monotonic soft-start even with pre-biased output and fast loop response thanks to the peak-current mode controller. Switching at 1.2MHz, the SGM61410 can prevent EMI noise problems, such as the ones found in AM radio, ADSL and PLC applications. ● ● ● ● ● Protection features include current limiting and short circuit protection, thermal shutdown with auto recovery and output over-voltage protection. Frequency foldback helps prevent inductor current runaway during startup. Wide 5V to 45V Operating Input Voltage Range 0.8V Internal Reference Low Quiescent Current: 14μA (TYP) 0.6μA (TYP) Shutdown Current Current Output up to 600mA 1.2MHz Switching Frequency Internal Compensation and Soft-Start Simple design and Minimal External Components Up to 95% Efficiency at 12V/400mA 0.8V to 20V Adjustable Output Voltage Current Limit and Short-Circuit Protection Output Over-Voltage Protection and Thermal Shutdown Power-Save Mode and PWM Mode Operation Monotonic Startup with Pre-biased Output 90% Maximum Duty Cycle Available in a Green SOT-23-6 Package -40℃ to +125℃ Operating Temperature Range APPLICATIONS High Voltage Power Conversions Automotive Systems Industrial Power Systems Distributed Power Systems Battery Powered Systems Power Meters SGM61410 is available in a Green SOT-23-6 package. It operates over a wide ambient temperature range of -40℃ to +125℃. TYPICAL APPLICATION VIN 1 2 CIN 10μF 5 EN 4 2 VIN EN BOOT SGM61410 GND 1 SW 6 FB 3 CBOOT 0.47μF L 10μH to 33μH C1 330pF COUT 22μF VOUT 5V R1 52.5kΩ R2 10kΩ Figure 1. Typical Application Circuit SG Micro Corp www.sg-micro.com JUNE 2019 – REV. A 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 PACKAGE/ORDERING INFORMATION MODEL PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE ORDERING NUMBER PACKAGE MARKING PACKING OPTION SGM61410 SOT-23-6 -40℃ to +125℃ SGM61410XN6G/TR MPEXX Tape and Reel, 3000 MARKING INFORMATION NOTE: XX = Date Code. YYY X X Date Code - Week Date Code - Year Serial Number Green (RoHS & HSF): SG Micro Corp defines "Green" to mean Pb-Free (RoHS compatible) and free of halogen substances. If you have additional comments or questions, please contact your SGMICRO representative directly. ABSOLUTE MAXIMUM RATINGS VIN to GND ........................................................ -0.3V to 50V EN to GND ................................................-0.3V to VIN + 0.3V FB to GND ........................................................ -0.3V to 5.5V SW to GND ...............................................-0.3V to VIN + 0.3V BOOT to SW ..................................................... -0.3V to 5.5V Package Thermal Resistance SOT-23-6, θJA .......................................................... 170℃/W Junction Temperature .................................................+150℃ Storage Temperature Range........................ -65℃ to +150℃ Lead Temperature (Soldering, 10s) ............................+260℃ ESD Susceptibility HBM ............................................................................. 2000V CDM ............................................................................ 1000V ESD SENSITIVITY CAUTION This integrated circuit can be damaged if ESD precautions are not taken when handling. SGMICRO recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. DISCLAIMER SG Micro Corp reserves the right to make any change in circuit design, or specifications without prior notice. RECOMMENDED OPERATING CONDITIONS Supply Input Voltage Range ...................................5V to 45V Operating Junction Temperature Range ...... -40℃ to +125℃ Operating Ambient Temperature Range ...... -40℃ to +125℃ OVERSTRESS CAUTION Stresses beyond those listed in Absolute Maximum Ratings may cause permanent damage to the device. Exposure to absolute maximum rating conditions for extended periods may affect reliability. Functional operation of the device at any conditions beyond those indicated in the Recommended Operating Conditions section is not implied. SG Micro Corp www.sg-micro.com JUNE 2019 2 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 PIN CONFIGURATION (TOP VIEW) BOOT 1 6 SW GND 2 5 VIN FB 3 4 EN SOT-23-6 PIN DESCRIPTION PIN NAME FUNCTION 1 BOOT Bootstrap pin is used to provide a drive voltage, higher than the input voltage, to the topside power switch. Place a 0.47µF boost capacitor (CBOOT) as close as possible to the IC between this pin and SW pin. Do not place a resistor in series with this pin. 2 GND Ground pin is the reference for input and the regulated output voltages. Requires special layout considerations. 3 FB Feedback pin for programming the output voltage. The SGM61410 regulates the FB pin to 0.8V. Connect the feedback resistor divider tap to this pin. If the FB voltage exceeds 110% of 0.8V, over-voltage protection (OVP) will stop all PWM switching. 4 EN 5 VIN 6 SW SG Micro Corp www.sg-micro.com Enable pin should not be left open and it should not be driven above VIN + 0.3V. Device will operate when the EN pin is high and shut down when the EN pin is low. EN can be tied to VIN pin if the shutdown feature is not required or to a logic input for controlling shutdown. VIN pin is connected to the input supply voltage and powers the internal control circuitry. This voltage is monitored by a UVLO lockout comparator. VIN is also connected to the drain of the converter top switch. Due to power switching, this pin has high di/dt transition edges and must be decoupled to the GND by input capacitors as close as possible to the GND pin to minimize the parasitic inductances. Switching node pin is the output of the internal power converter and should be connect to the output inductor. Bootstrap capacitor also connects to this pin. This node should be kept small on the PCB to minimize capacitive coupling, noise coupling and radiation. JUNE 2019 3 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 ELECTRICAL CHARACTERISTICS (VIN = 18V, TJ = -40℃ to +125℃, typical values are at TJ = +25℃, unless otherwise noted.) PARAMETER Supply Input Voltage SYMBOL CONDITIONS MIN VIN 5 Under-Voltage Lockout Threshold VUVLO 4.45 Under-Voltage Lockout Threshold Hysteresis VUVLO_HYS VIN Quiescent Current Shutdown Sleep Mode IQ TYP MAX UNITS 45 V 4.7 4.95 V 370 mV VEN = 0V 0.6 1.2 VEN = 2V, Not Switching, VIN ≤ 36V 14 20 Feedback Reference Voltage VFB VIN = 6V 0.800 0.823 V Feedback Pin Input Current IFB VFB = 1V 0.1 1 µA ILOAD = 600mA 100 Minimum High-side Switch On-Time tON_MIN Minimum High-side Switch Off-Time tOFF_MIN Switching Frequency Switch Leakage Current Top Power NMOS Current Limit Top Power NMOS On-Resistance Bottom Power NMOS On-Resistance ISW_L ILIM RDSON EN Input High Voltage VIH EN Input Low Voltage VIL ns 100 fSW ISW_H 0.777 µA 0.85 VSW = 45V VSW = 0V TJ = +25℃ 0.9 ILOAD = 0.1A ILOAD = 0.1A ns 1.2 1.5 MHz 0.1 1 µA 0.1 1 µA 1.2 1.5 A 700 mΩ 300 mΩ 1.2 V 0.5 EN Threshold, Hysteresis VEN_HYS 120 Enable Leakage Current IEN 0.1 1 Output Over-Voltage Threshold VOUT_OV V mV OVP Rising 0.84 0.89 0.95 OVP Falling 0.80 0.85 0.90 μA V Thermal Shutdown TSHDN 150 ℃ Thermal Shutdown Hysteresis THYS 20 ℃ SG Micro Corp www.sg-micro.com JUNE 2019 4 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 TYPICAL PERFORMANCE CHARACTERISTICS TA = +25℃, VIN = 18V, L = 22μH and COUT = 10μF, unless otherwise noted. Steady State Steady State 5V/div 5V/div VIN VIN 5V/div 5V/div VSW VOUT VIN = 12V, VOUT = 5V, IOUT = 100mA 500mA/div IL VOUT IL VIN = 12V, VOUT = 5V, IOUT = 600mA Time (1μs/div) Time (1μs/div) Steady State Steady State VSW VOUT IL VIN = 18V, VOUT = 12V, IOUT = 600mA Time (1μs/div) Time (1μs/div) Power Up Power Down VSW VIN = 18V, VOUT = 12V, IOUT = 600mA Time (500μs /div) SG Micro Corp www.sg-micro.com IL VIN = 18V, VOUT = 12V, IOUT = 600mA 1A/div IL VSW VOUT 5V/div 1A/div VOUT 5V/div 20V/div 5V/div 20V/div 5V/div VEN VEN 500mA/div VIN = 18V, VOUT = 12V, IOUT = 100mA VIN 5V/div IL 5V/div 500mA/div VSW VOUT 10V/div 10V/div 10V/div 10V/div VIN 5V/div 500mA/div 5V/div VSW Time (200μs/div) JUNE 2019 5 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 TYPICAL PERFORMANCE CHARACTERISTICS (continued) TA = +25℃, VIN = 18V, L = 22μH and COUT = 10μF, unless otherwise noted. Power Up Power Down VOUT VIN = 24V, VOUT = 5V, IOUT = 600mA 500mA/div IL VSW VOUT IL VIN = 24V, VOUT = 5V, IOUT = 600mA Time (500μs/div) Time (200μs/div) Short Circuit Entry Short Circuit Recovery VSW VOUT VIN = 18V, VOUT = 5V VIN VSW VOUT IL VIN = 18V, VOUT = 5V Time (100μs/div) 500mA/div IL 10V/div 20V/div 5V/div 10V/div 20V/div 5V/div 500mA/div VIN 5V/div 20V/div 5V/div 500mA/div 5V/div 20V/div 5V/div VEN VSW VEN Time (800μs/div) Load Transient Response 20V/div 20V/div VIN VSW IOUT VOUT = 5V, IOUT = 50mA to 600mA 200mV/div 500mA/div VOUT Time (1ms/div) SG Micro Corp www.sg-micro.com JUNE 2019 6 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 TYPICAL PERFORMANCE CHARACTERISTICS (continued) TA = +25℃, VIN = 18V, L = 22μH and COUT = 10μF, unless otherwise noted. Efficiency vs. Load Current 100 90 90 80 80 70 70 Efficiency (%) Efficiency (%) Efficiency vs. Load Current 100 60 50 40 30 VIN = 12V VIN = 15V VIN = 18V 20 10 VOUT = 3.3V 0 0 100 200 300 400 500 60 50 40 30 VIN = 12V VIN = 18V VIN = 24V VIN = 36V 20 10 VOUT = 5V 0 600 0 100 Load Current (mA) 200 Efficiency vs. Load Current 400 500 600 Load Regulation 100 5.045 90 VOUT = 5V 5.040 80 Output Voltage (V) 70 Efficiency (%) 300 Load Current (mA) 60 50 40 30 VIN = 15V VIN = 18V VIN = 24V VIN = 36V 20 10 VOUT = 12V 0 0 100 5.035 5.030 5.025 VIN = 12V VIN = 18V VIN = 24V VIN = 36V 5.020 5.015 200 300 400 500 600 0 100 Load Current (mA) 200 300 400 500 600 Load Current (mA) Line Regulation Shutdown Current and Quiescent Current 5.045 100 VOUT = 5V ISLEEP Input Current (μA) Output Voltage (V) 5.040 5.035 5.030 5.025 IOUT = 100mA IOUT = 300mA IOUT = 600mA 5.020 5.015 5 14 23 32 Input Voltage (V) SG Micro Corp www.sg-micro.com 41 10 ISHUTDOWN 1 VOUT = 5V 0.1 50 0 5 10 15 20 25 30 35 40 45 50 Input Voltage (V) JUNE 2019 7 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 TYPICAL PERFORMANCE CHARACTERISTICS (continued) TA = +25℃, VIN = 18V, L = 22μH and COUT = 10μF, unless otherwise noted. Switching Frequency vs. Temperature 1.20 5.0 1.18 Switching Frequency (MHz) Output Voltage (V) Dropout Curve 5.5 4.5 4.0 IOUT = 10mA IOUT = 100mA IOUT = 300mA IOUT = 600mA 3.5 VOUT = 5V 3.0 4.7 5.1 1.16 1.14 1.12 1.10 5.5 5.9 6.3 6.7 7.1 7.5 -40 -25 -10 Input Voltage (V) Switch Leakage vs. Temperature Quiescent Current vs. Temperature 20 0.10 0.08 0.06 0.04 ISW_BOTTOM Quiescent Current (μA) 0.12 Switch Leakage (μA) 20 35 50 65 80 95 110 125 Junction Temperature (℃) 0.14 0.02 ISW_TOP 0.00 -40 -25 -10 5 16 12 8 4 0 20 35 50 65 80 95 110 125 -40 -25 -10 Junction Temperature (℃) 5 20 35 50 65 80 95 110 125 Junction Temperature (℃) Shutdown Current vs. Temperature EN Voltage vs. Temperature 1 1.2 Rising 1 0.8 EN Voltage (V) Shutdown Current (μA) 5 0.6 0.4 0.2 0.8 Falling 0.6 0.4 0.2 0 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 Junction Temperature (℃) SG Micro Corp www.sg-micro.com -40 -25 -10 5 20 35 50 65 80 95 110 125 Junction Temperature (℃) JUNE 2019 8 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 TYPICAL PERFORMANCE CHARACTERISTICS (continued) TA = +25℃, VIN = 18V, L = 22μH and COUT = 10μF, unless otherwise noted. Reference Voltage vs. Temperature Output Over-Voltage Protection vs. Temperature 0.9 Output Over-Voltage Protection (V) Reference Voltage (V) 0.820 0.810 0.800 0.790 0.780 0.89 OVPH 0.88 0.87 0.86 OVPL 0.85 0.84 -40 -25 -10 5 20 35 50 65 80 95 110 125 -40 -25 -10 Junction Temperature (℃) 20 35 50 65 80 95 110 125 Junction Temperature (℃) RDSON vs. Temperature Under-Voltage Lockout vs. Temperature 1200 4.9 Top Switch 800 600 400 200 Bottom Switch 0 Under-Voltage Lockout (V) 4.8 1000 RDSON (mΩ) 5 Rising 4.7 4.6 4.5 4.4 Falling 4.3 4.2 4.1 -40 -25 -10 5 20 35 50 65 80 95 110 125 Junction Temperature (℃) -40 -25 -10 5 20 35 50 65 80 95 110 125 Junction Temperature (℃) Temperature Derating 120 Rated Power (%) 100 80 60 40 20 0 -55 -35 -15 5 25 45 65 85 105 125 145 Ambient Temperature (℃) SG Micro Corp www.sg-micro.com JUNE 2019 9 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 FUNCTIONAL BLOCK DIAGRAM EN VIN Thermal Hiccup - Shutdown Logic + FB Reference Boot Charge Current Sense BOOT Boot UVLO Error Amplifier HS_FET Current Comparator + 0.8V EN Comparator Minimum Clamp Pulse Skip - + UVLO OV Comparator Power Stage and Dead Time Control Logic Voltage Reference SW VIN Regulator Slope Compensation Soft-Start Overload Protection Oscillator Current Sense LS_FET Current Limit GND Figure 2. Functional Block Diagram SG Micro Corp www.sg-micro.com JUNE 2019 10 SGM61410 1.2MHz, 600mA, 45V Synchronous Step-Down Converter DETAILED DESCRIPTION Figure 2 shows the simplified block diagram of the SGM61410. The two integrated MOSFET switches of the power stage are both overcurrent protected and can provide up to 600mA of continuous current for the load. Current limiting of the switches also prevents inductor current runaway. The converter switches are optimized for high efficiency at low duty cycle. At the beginning of each switching cycle, the high-side switch is turned on. This is the time that feedback voltage (VFB) is below the reference voltage (VREF) and power must be delivered to the output. After the on-period, the high-side switch is turned off and the low-side switch is turned on until the end of switching cycle. For reliable operation and preventing shoot through, a short dead time is always inserted between gate pulses of the converter complimentary switches. During dead time, both switch gates are kept off. The device is designed for safe monotonic start-up even if the output is pre-biased. If the junction temperature exceeds a maximum threshold (TSHDN, typically +150℃), thermal shutdown protection will happen and switching will stop. The device will automatically recover with soft-start when the junction temperature drops back well below the trip point. This hysteresis is typically 20℃. The SGM61410 has current limit on both the high-side and low-side MOSFET switches. When current limit is activated frequency fold-back is also activated. This occurs in the case of output overload or short circuit. Note that SGM61410 will continue to provide its maximum output current and will not shut down or hiccup. In such a case, the junction temperature may rise rapidly and trigger thermal shutdown. SG Micro Corp www.sg-micro.com Peak-Current Mode (PWM Control) Figure 2 shows the functional block diagram and Figure 3 shows the switching node operating waveforms of the SGM61410. Switching node voltage is generated by controlling the duty cycles of the complementary high-side and low-side switches. The duty cycle of the high-side switch is used as control parameter of the buck converter to regulate output voltage and is defined as: D = tON/tSW , where tON is the high-side switch on-time and tSW is the switching period. During high-side switch on-time, the SW pin voltage swings up to approximately VIN, and the inductor current, IL, linearly rises with a slope of (VIN - VOUT)/L. When control logic turns off the high-side switch, the low-side switch will turn on after a small dead time. During off-time, inductor current discharges through the low-side switch with a slope of (-VOUT/L). In ideal case, where losses are ignored, D is proportional to the output voltage and inversely proportional to the input voltage: D = VOUT/VIN. The SGM61410 employs fixed-frequency peak-current mode control in continuous conduction mode (when inductor minimum current is above zero). In light load conditions (when the inductor current reaches zero) the SGM61410 will enter discontinuous conduction mode and the control mode will change to shift frequency, peak-current mode to reduce the switching frequency and the associated switching and gate driving losses (power saving mode). VSW SW Voltage The SGM61410 is an internally compensated wide input range current mode controlled synchronous step-down converter. It is designed for high reliability and is particularly suitable for power conditioning from unregulated sources or battery-powered applications that need low sleep/shutdown currents. It also features a power-save mode in which operating frequency is adaptively reduced at light load conditions to reduce switching and gate losses and keep high efficiency. At no load and with switching stopped, the total operating current is approximately 14μA. If the device is disabled, the total consumption is typically less than 0.6μA. During initial power up of the device (soft-start), current limit and frequency fold-back are activated to prevent inductor current runaway while the output capacitor is charging to the desired VOUT. D = tON/tSW VIN tON tOFF t 0 tSW IL Inductor Current Overview ILPK IOUT 0 ΔIL t Figure 3. SW Node and Inductor Current Waveforms in Continuous Conduction Mode (CCM) JUNE 2019 11 SGM61410 1.2MHz, 600mA, 45V Synchronous Step-Down Converter DETAILED DESCRIPTION (continued) Continuous Conduction Mode (CCM) In continuous conduction mode, SGM61410 operates at fixed-frequency using peak-current mode control scheme. The controller has an outer voltage feedback loop to get accurate DC voltage regulation. The output of the outer loop is fed to an inner peak current control loop as reference command that adjusts the peak current of the inductor. The inductor peak-current is sensed from the high-side switch and is compared to the peak-current reference to control the duty cycle. In other words, as soon as the inductor current reaches the reference peak current determined by voltage loop, the high-side switch is turned off and the low side switch is turned on after deadtime. The voltage feedback loop is internally compensated, which allows for fewer external components, simpler design, and stable operation with almost any combination of output capacitors. Power-Save Mode When the load is reduced, the inductor minimum (valley) current eventually reaches zero level (boundary condition). Synchronous rectifier (low-side switch) current is always sensed and when it reaches zero, the controller turns off the low-side switch and does not let the low-side switch sink current. This prevents inductor current from going below zero (negative). This results in discontinuous conduction mode (DCM) operation in which inductor current remains zero until next switching cycle. Both switches are off during this period and do not act as complementary switches. This off-time will extend (that means lower frequency) until output voltage falls below reference voltage again and triggers a new switching cycle. With a new cycle, the high-side switch is turned on again for almost the same tON time as CCM. Therefore, the output capacitors take almost the same charge in each cycle and with lighter loads it will take longer off-times until output capacitor voltage falls below reference. The extended off-times mean lower switching frequency that is called frequency foldback and significantly reduces the switching losses, but usually increases the output ripple a little bit. Note that the on-time of synchronous rectifier switch should always be long enough to fully charge the bootstrap capacitor and prevent bootstrap under voltage lockout due to insufficient voltage for the high-side switch gate driver. SG Micro Corp www.sg-micro.com Floating Driver and Bootstrap Charging UVLO Protection The high-side MOSFET driver is powered by a floating supply provided by an external bootstrap capacitor. The bootstrap capacitor is charged and regulated to about 5V by the dedicated internal bootstrap regulator. When the voltage between BOOT and SW nodes is below regulation, a PMOS pass transistor turns on and connects VIN and BOOT pins internally, otherwise it will turn off. The power supply for the floating driver has its own UVLO protection. The rising UVLO threshold is about 4.75V and with 350mV hysteresis, the falling threshold is about 4.4V. In case of UVLO, the reference voltage of the controller is reset to zero and after recovery a new soft-start process will start. Output Over-Voltage Protection (OVP) The SGM61410 contains an over-voltage comparator that monitors the FB pin voltage. The over-voltage threshold is approximately 110% of nominal FB voltage. When the voltage at the FB pin exceeds the over-voltage threshold (VOUT_OV), PWM switching will be stopped and both high-side and low-side switches will be turned off. If the over-voltage fault is removed, the regulator will automatically recover. The error amplifier is normally able to maintain regulation since the synchronous output stage has excellent sink and source capability. However it is not able to regulate output when the FB pin is disconnected or when the output is shorted to a higher supply like input supply. Also when VOUT is set to its minimum (0.8V) usually there is no voltage divider and VOUT is directly connected to FB through a resistor (R1 in the divider) and there is no resistor to ground (no R2). In such case and with no load an internal current source of 5~6μA from BOOT into the SW pin, can slowly charge the output capacitor and pull VOUT up, toward VIN. Therefore a minimum load of at least 10μA must be always present on VOUT (for example an 80kΩ resistor: 0.8V/10μA = 80kΩ). If the FB pin is disconnected, a tiny internal current source will force the voltage at the FB pin to rise above VOUT_OV that triggers over voltage protection and disables the regulator to protect the loads from a significant over-voltage. Also, if by accident a higher external voltage is shorted to the output, VFB will rise above the over-voltage threshold and trigger an OVP event to protect the low-side switch. JUNE 2019 12 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 DETAILED DESCRIPTION (continued) Minimum High-side On/Off-Time and Frequency Fold-Back Minimum high-side switch on-time (tON_MIN) is the smallest duration that the high-side switch can be turned on. The tON_MIN is typically 100ns. Minimum high-side switch off-time (tOFF_MIN), is the smallest duration that the high-side switch can be turned off. The tOFF_MIN is typically 100ns. In CCM operation, tON_MIN and tOFF_MIN limit the voltage conversion ratio without switching frequency fold-back. Note that at 1.2MHz the total cycle time is tSW = 833ns. The minimum and maximum duty cycles without frequency fold-back are given by: DMIN = tON_MIN × fSW (1) and DMAX = 1 - tOFF_MIN × fSW (2) Given a required output voltage, the maximum VIN without frequency fold-back is given by: VIN_MAX = VOUT fSW × t ON_MIN (3) and the minimum VIN without frequency fold-back can be calculated by: VIN_MIN = VOUT 1 - fSW × t OFF_MIN (4) Input Voltage The SGM61410 can operate efficiently for inputs as high as 45V. For CCM operation (continuous conduction mode) keep duty cycle between 12% and 88%. Output Voltage The output voltage can be stepped down to as low as the 0.8V reference voltage (VREF). As explained before, when the output voltage is set to 0.8V and there is not a SG Micro Corp www.sg-micro.com voltage divider, a minimum small load will be needed. An 80kΩ resistor to ground will prevent the output voltage floating up. Soft-Start The integrated soft-start circuit in SGM61410 limits the input inrush current right after power up or enabling the device. Soft-start is implemented by slowly ramping up the reference voltage that in turn slowly ramps up the output voltage to its target regulation value. Enable EN pin turns the SGM61410 operation on or off. An applied voltage of less than 0.5V shuts down the device, and a voltage of more than 1.2V is required to start the regulator. The EN pin is an input and must not be left open. The simplest way to enable the device is to connect the EN pin to VIN. This allows for self-startup of the SGM61410 when VIN is within the operating range. An external logic signal can be used to drive the EN input for power savings, power supply sequencing and/or protection. If the EN pin is driven by an external logic signal a 100kΩ resistor in series with the input is recommended. Note: Voltage on the EN pin should never exceed VIN + 0.3V. Do not drive the EN pin with a logic level if VIN is not present. This can damage the EN pin and the device. Thermal Shutdown The SGM61410 provides an internal thermal shutdown to protect the device when the junction temperature exceeds +150 ℃ . Both switches stop switching in thermal shutdown. Once the die temperature falls below +130 ℃ , the device reinitiates the power up sequence by the internal soft-start. JUNE 2019 13 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 TYPICAL APPLICATION CIRCUITS VIN 5 CIN 10μF 4 2 VIN BOOT SGM61410 EN SW FB GND 1 6 CBOOT 0.47μF L 22μH 3 R1 52.5kΩ COUT 22μF VOUT 5V/0.2A R2 10kΩ Figure 4. 5V Output Typical Application Circuit for Power Meters VIN 5 CIN 10μF 4 2 VIN BOOT SGM61410 EN GND SW FB 1 6 CBOOT 0.47μF L 47μH 3 R1 140kΩ COUT 47μF VOUT 12V/0.6A R2 10kΩ Figure 5. 12V Output Typical Application Circuit for Power Meters SG Micro Corp www.sg-micro.com JUNE 2019 14 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 APPLICATION INFORMATION AND DESIGN GUIDLINES External Components The following guidelines can be used to select external components. fSW (MHz) VOUT (V) R1 (kΩ) R2 (kΩ) L (µH) CBOOT (µF) CIN (µF) COUT (µF) 3.3 31.2 10 10 0.47 10 10 5 52.5 10 22 0.47 10 22 12 140 10 47 0.47 10 47 1.2 Output Voltage Programming Output voltage can be set with a resistor divider feedback network between output and FB pin as shown in Figure 4 and Figure 5. Usually, a design is started by selecting lower resistor R1 and calculating R2 with the following equation:  R  VOUT = VREF ×  1 + 1  R 2   (5) where VREF = 0.8V. To keep operating quiescent current small and prevent voltage errors due to leakage currents, it is recommended to choose R1 in the range of 10kΩ to 100kΩ. If the output has no load other than the FB divider, make sure the divider draws at least 10μA from VOUT or an internal current source (5~6μA) from BOOT to SW will slowly charge the output capacitor beyond the desired voltage. Inductor Selection The critical parameters for selecting the inductor are the inductance (L), saturation current (Isat) and the maximum RMS current (Irms,max). The inductance is selected based on the desired peak-to-peak ripple current ΔIL that is given in Equation 6 for CCM. Since the ripple current increases with the input voltage, the maximum input voltage is usually considered to calculate the minimum inductance LMIN that is given in Equation 7. KIND is a design parameter that represents the ratio of inductor ripple current to its maximum operating dc current. Lower KIND means higher inductance value that needs a larger size and higher KIND results in more ripple and loss in the core. Typically, a reasonable value for KIND is around 20%~40%. Inductor peak current should never exceed the saturation even in transients to avoid over current protection. Also inductor RMS rating should always be SG Micro Corp www.sg-micro.com larger than operating RMS current even at maximum ambient temperature. ∆IL = = LMIN VOUT × (VIN_MAX - VOUT ) VIN_MAX × L × fSW VIN_MAX - VOUT IOUT × K IND × VOUT VIN_MAX × fSW (6) (7) where KIND = ΔIL/IOUT (max DC current). Note that lower inductance is usually preferred in a switching power supply, because it usually corresponds to faster transient response and bandwidth, smaller DCR, and reduced size for a more compact design. On the other hand, if the inductance is too small, current ripple will increase which can trigger over current protection. Larger inductor current ripple also implies larger output voltage ripple with the same output capacitors. For peak-current mode control, it is recommended to choose large current ripple, because controller comparator performs better with higher signal to noise ratio. So, for this design example, KIND = 0.4 is chosen, and the minimum inductor value is calculated to be 16.3µH. The nearest standard value would be a 22µH ferrite inductor with a 1A RMS current rating and 1.5A saturation current that are well above the designed converter output current RMS and DC respectively. Bootstrap Capacitor Selection The SGM61410 requires a small external bootstrap capacitor, CBOOT, between the BOOT and SW pins to provide the gate drive supply voltage for the high-side MOSFET. The bootstrap capacitor is refreshed when the high-side MOSFET is off and the low-side switch conducts. An X7R or X5R 0.47µF ceramic capacitor with a voltage rating of 16V or higher is recommended for stable operating performance over temperature and voltage variations. JUNE 2019 15 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 APPLICATION INFORMATION AND DESIGN GUIDELINES (continued) Input Capacitor Selection The SGM61410 requires high frequency input decoupling capacitor(s). The recommended high frequency decoupling capacitor value is 10μF X5R or X7R or higher. It is recommended to choose the voltage rating of the capacitor(s) at least twice the maximum input voltage to avoid derating of the ceramic capacitors with DC voltage. Some bulk capacitance may be needed, especially if the SGM61410 is not located within 5cm distance from the input voltage source for input stability. Bulk capacitors have high ESR and can provide the damping needed to prevent input voltage spiking due to the wiring inductance of the input. The value for this capacitor is not critical but must be rated to handle the maximum input voltage including ripple. For this design, one 10μF, X7R, 50V is used for the input decoupling capacitor. The Equivalent Series Resistance (ESR) is approximately 10mΩ, and the current rating is 1A. To improve high frequency filtering a small parallel 0.1μF capacitor may be placed as close as possible to the device pins. Output Capacitor Selection The device is designed to be used with a wide variety of LC filters. It is generally desired to use as little output capacitance as possible to keep cost and size down and bandwidth high. The output capacitor(s), COUT, should be chosen carefully since it directly affects the steady state output voltage ripple, loop stability and the voltage over/undershoot during load current transients. The output voltage ripple is essentially composed of two parts. One is caused by the inductor current ripple going through the Equivalent Series Resistance (ESR) of the output capacitors: ΔVOUT_ESR = ΔIL × ESR = KIND × IOUT × ESR (8) DVOUT_C = KIND × IOUT DIL (9) = 8 × fSW × COUT 8 × fSW × COUT The two components in the voltage ripple are not in phase, so the actual peak-to-peak ripple is smaller than the sum of the two peaks. Output capacitance is usually limited by transient performance specifications if the system requires tight voltage regulation in presence of large current steps and/or fast slew rate. When a large load step happens, output capacitors provide the required charge before the inductor current can slew up to the appropriate level. The regulator’s control loop usually needs 8 or more clock cycles to regulate the inductor current equal to the new load level. The output capacitance must be large enough to supply the current difference for 8 clock cycles to maintain the output voltage within the specified range. Equation 10 shows the minimum output capacitance needed for specified output over/undershoot. COUT > 8 × (IOH − IOL ) 1 × 2 fSW × ∆VOUT_SHOOT (10) where IOL = Low level of the output current step during load transient, IOH = High level of the output current during load transient, VOUT_SHOOT = Target output voltage over/undershoot. For this design example, the target output ripple is 30mV. Assuming ΔVOUT_ESR = ΔVOUT_C = 30mV, and choosing KIND = 0.4, Equation 8 requires ESR to be less than 125mΩ and Equation 9 requires COUT > 0.91μF. The target over/undershoot range of this design is ΔVOUT_SHOOT = 5% × VOUT = 250mV. From Equation 10, COUT > 8.3μF. So, in summary, the most stringent criteria for the output capacitor is transient constrain of COUT > 8.3μF. For the derating margin, one 22μF, 10V, X7R ceramic capacitor with 10mΩ ESR is used. The other part is caused by the inductor current ripple charging and discharging the output capacitors: SG Micro Corp www.sg-micro.com JUNE 2019 16 1.2MHz, 600mA, 45V Synchronous Step-Down Converter SGM61410 APPLICATION INFORMATION AND DESIGN GUIDELINES (continued) Layout Guideline Careful layout is always important to ensure good performance and stable operation to any kind of switching regulator. Place the capacitors close to the device, use the GND pin of the device as the center of star-connection to other grounds, and minimize the trace area of the SW node. With smaller transient current loops, lower parasitic ringing will be achieved. Figure 6. Suggested PCB VIN 1 2 CIN 10μF 5 EN 4 2 VIN EN BOOT SGM61410 GND 1 SW 6 FB 3 CBOOT 0.47μF L 10μH to 33μH C 1* 330pF * NOTE: An optional feed-forward capacitor can be used across R1 (as shown) to improve transient performance and reduce the over/undershoot peaks during load steps. COUT 22μF VOUT 5V R1 52.5kΩ R2 10kΩ Figure 7. Typical Application Circuit SG Micro Corp www.sg-micro.com JUNE 2019 17 SGM61410 1.2MHz, 600mA, 45V Synchronous Step-Down Converter REVISION HISTORY NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Original (JUNE 2019) to REV.A Page Changed from product preview to production data ............................................................................................................................................. All SG Micro Corp www.sg-micro.com JUNE 2019 18 PACKAGE INFORMATION PACKAGE OUTLINE DIMENSIONS SOT-23-6 D e1 e 2.59 E E1 0.99 b 0.95 0.69 RECOMMENDED LAND PATTERN (Unit: mm) L A A1 θ A2 Symbol Dimensions In Millimeters MIN MAX c 0.2 Dimensions In Inches MIN MAX A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 e 0.950 BSC 0.037 BSC e1 1.900 BSC 0.075 BSC SG Micro Corp www.sg-micro.com L 0.300 0.600 0.012 0.024 θ 0° 8° 0° 8° TX00034.000 PACKAGE INFORMATION TAPE AND REEL INFORMATION REEL DIMENSIONS TAPE DIMENSIONS P2 W P0 Q1 Q2 Q1 Q2 Q1 Q2 Q3 Q4 Q3 Q4 Q3 Q4 B0 Reel Diameter A0 P1 K0 Reel Width (W1) DIRECTION OF FEED NOTE: The picture is only for reference. Please make the object as the standard. KEY PARAMETER LIST OF TAPE AND REEL Reel Diameter Reel Width W1 (mm) A0 (mm) B0 (mm) K0 (mm) P0 (mm) P1 (mm) P2 (mm) W (mm) Pin1 Quadrant SOT-23-6 7″ 9.5 3.17 3.23 1.37 4.0 4.0 2.0 8.0 Q3 SG Micro Corp www.sg-micro.com TX10000.000 DD0001 Package Type PACKAGE INFORMATION CARTON BOX DIMENSIONS NOTE: The picture is only for reference. Please make the object as the standard. KEY PARAMETER LIST OF CARTON BOX Length (mm) Width (mm) Height (mm) Pizza/Carton 7″ (Option) 368 227 224 8 7″ 442 410 224 18 SG Micro Corp www.sg-micro.com DD0002 Reel Type TX20000.000