SGM6232YPS8G/TR

SGM6232 2A, 38V, 1.4MHz Step-Down Converter GENERAL DESCRIPTION FEATURES The SGM6232 is a current-mode step-down regulator ● 2A Output Current with an internal power MOSFET. This device achieves ● High Efficiency: Up to 91% 2A continuous output current over a wide input supply ● 4.5V to 38V Input Voltage Range range from 4.5V to 38V with excellent load and line ● < 18µA Shutdown Supply Current regulations. The switching frequency of SGM6232 is ● 100mΩ Internal Power MOSFET Switch 1.4MHz and current mode operation provides fast ● Fixed 1.4MHz Switching Frequency transient response and eases loop stabilization. ● Output Adjustable from 0.8V to 28V ● Cycle-by-Cycle Current Limit Protection The SGM6232 is highly efficient with peak efficiency at ● Thermal Shutdown Protection 91% when in operation. In shutdown mode the regulator ● Under-Voltage Lockout draws less than 18µA of supply current. Protection features include cycle-by-cycle current limit and thermal ● Stable with Low ESR Ceramic Capacitors ● -40℃ to +85℃ Operating Temperature Range shutdown. The device also includes an internal soft-start ● Available in Green SOIC-8 (Exposed Pad) Package and an external adjustable soft-start function to limit the APPLICATIONS inrush current and prevent the overshoot of output voltage. Distributed Power Systems The SGM6232 is available in Green SOIC-8 (Exposed Battery Chargers Pad) package and requires a minimum number of readily Flat Panel TVs available external components to complete a 2A step- Set-Top Boxes down DC/DC converter solution. Pre-Regulator for Linear Regulators Cigarette Lighter Powered Devices DVD/PVR Devices TYPICAL APPLICATION R4 C5 10Ω or shorted 10nF INPUT 4.5V to 38V 100 ENABLE BS EN SW SGM6232 SS CIN 22μF ceramic cap recommended C4 0.1μF OUTPUT 3.3V/2A R1 33kΩ FB GND COMP C6 Optional C3 5.6nF R3 10kΩ D1 B340A R2 10.5kΩ V OUT = 5.0V 90 Efficiency (%) IN L 4.7μH COUT 47μF 80 V OUT = 3.3V 70 60 50 40 V IN = 12V 30 0 0.5 1 1.5 2 2.5 3 3.5 Load Current (A) SG Micro Corp www.sg-micro.com REV. A. 2 SGM6232 2A, 38V, 1.4MHz Step-Down Converter PACKAGE/ORDERING INFORMATION MODEL PACKAGE DESCRIPTION SPECIFIED TEMPERATURE RANGE ORDERING NUMBER PACKAGE MARKING PACKING OPTION SGM6232 SOIC-8 (Exposed Pad) -40°C to +85°C SGM6232YPS8G/TR SGM 6232YPS8 XXXXX Tape and Reel, 2500 NOTE: XXXXX = Date Code and Vendor Code. 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 OVERSTRESS CAUTION Supply Voltage VIN................................................... -0.3V to 40V SW Voltage VSW .............................................-0.5V to VIN + 0.3V Boost Voltage VBS................................... VSW - 0.3V to VSW + 6V All Other Pins.............................................................-0.3V to 6V Package Thermal Resistance SOIC-8 (Exposed Pad), θJA.............................................50℃/W Operating Temperature Range............................-40°C to +85°C Junction Temperature........................................................150°C Storage Temperature Range.............................-65°C to +150°C Lead Temperature (Soldering, 10s)...................................260°C ESD Susceptibility HBM...................................................................................4000V MM.......................................................................................200V Stresses beyond those listed may cause permanent damage to the device. Functional operation of the device at these or any other conditions beyond those indicated in the operational section of the specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. ESD SENSITIVITY CAUTION This integrated circuit can be damaged by ESD if you don’t pay attention to ESD protection. 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, specification or other related things if necessary without notice at any time. SG Micro Corp www.sg-micro.com 2 SGM6232 2A, 38V, 1.4MHz Step-Down Converter PIN CONFIGURATION (TOP VIEW) 1 IN 2 SW 3 GND 4 GND BS 8 SS 7 EN 6 COMP 5 FB SOIC-8 (Exposed Pad) PIN DESCRIPTION PIN NAME 1 BS 2 IN 3 SW 4 GND 5 FB 6 COMP 7 EN 8 SS Exposed Pad GND FUNCTION High-side Gate Drive Boost Input. BS supplies the driver for the high-side N-Channel MOSFET switch. Connect a 10nF or greater capacitor from SW to BS to power the high-side switch. A 10Ω resistor placed between SW and BS cap is strongly recommended to reduce SW spike voltage. Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.5V to 38V power source. Bypass IN to GND with a sufficiently large capacitor to eliminate noise on the input to the IC. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a capacitor is required from SW to BS to power the high-side switch. Ground. (Connect the exposed pad on backside to pin 4.) Feedback Input. The voltage at this pin is regulated to 0.8V. Connected to the resistor divider between output and ground to set output voltage. Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation control loop. In some cases, an additional capacitor from COMP to GND is required. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator, and drive EN low to turn it off. Output voltage is discharged when the IC is off. For automatic startup, leave EN unconnected. Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1µF capacitor sets the soft-start period to 10ms. To disable the soft-start feature, leave SS unconnected. Power Ground Exposed Pad. Must be connected to GND plane. SG Micro Corp www.sg-micro.com 3 SGM6232 2A, 38V, 1.4MHz Step-Down Converter ELECTRICAL CHARACTERISTICS (VIN = 12V, TA = +25°C, unless otherwise noted.) PARAMETER Input Voltage Range Feedback Voltage Shutdown Supply Current Quiescent Supply Current SYMBOL CONDITIONS VIN IQ TYP 4.5 VFB ISHDN MIN 0.776 VEN = 0V VEN = 2.6V, VFB = 1V MAX UNITS 38 V 0.8 0.824 V 10 18 μA 0.8 1.7 mA High-side Switch (M1) On-Resistance RONH 100 mΩ Low-side Switch (M2) On-Resistance RONL 10 Ω Error Amplifier Transconductance GEA Error Amplifier Voltage Gain AEA SW Leakage Current ILSW Current Limit ILIM 4.2 A Current Sense to COMP Transconductance GCS 6.2 A/V Maximum Duty Cycle DMAX VFB = 0.6V 80 % Minimum Duty Cycle DMIN VFB = 1V 0 % EN Threshold Voltage VIH EN Threshold Voltage VIL EN Pull-Up Current Oscillator Frequency ∆VFB = ±12.5mV VEN = 0V, VSW = 0V fOSC 0.8 Under-Voltage Lockout Threshold Under-Voltage Lockout Threshold Hysteresis Soft-Start Period VIN Rising CSS = 0.1μF μA V 0.4 V 1.4 2 μA 1.4 1.6 MHz 140 3.5 μA/V V/V 1 1.15 VFB = 0V SG Micro Corp www.sg-micro.com 1120 1.2 VEN = 0V TSHDN 800 10000 Short Circuit Oscillator Frequency Thermal Shutdown Temperature 500 3.8 kHz 4.2 V 230 mV 10 ms 160 ℃ 4 SGM6232 2A, 38V, 1.4MHz Step-Down Converter TYPICAL PERFORMANCE CHARACTERISTICS VIN = 12V, CIN = 22µF, COUT = 47µF and TA = +25°C, unless otherwise noted. Efficiency vs. Load Current Feedback Voltage vs. Temperature 100 VOUT = 5.0V 90 0.82 80 0.81 Efficiency (%) Feedback Voltage (V) 0.83 0.80 0.79 0.78 VOUT = 3.3V 70 60 50 40 0.77 VIN = 12V 30 -50 -25 0 25 50 75 100 0 0.5 1 Temperature (℃) 80 Efficiency (%) Efficiency (%) 90 80 VOUT = 2.4V 60 50 40 3.5 100 VOUT = 5.0V 70 3 Efficiency vs. Load Current Efficiency vs. Load Current 100 90 1.5 2 2.5 Load Current (A) VOUT = 5.0V 70 60 50 40 VIN = 24V VIN = 36V 30 30 0 0.5 1 1.5 2 2.5 Load Current (A) SG Micro Corp www.sg-micro.com 3 3.5 0 0.5 1 1.5 2 2.5 Load Current (A) 3 3.5 5 SGM6232 2A, 38V, 1.4MHz Step-Down Converter TYPICAL PERFORMANCE CHARACTERISTICS VIN = 12V, CIN = 22µF, COUT = 47µF and TA = +25°C, unless otherwise noted. Startup Through Enable Startup Through Enable 2A/div IL 10V/div VSW Time (400μs/div) Time (4ms/div) Load Transient Response Shutdown Through Enable VOUT VSW IL VOUT = 3.3V, IOUT = 1.5A (Resistance Load) 2A/div Time (100μs/div) VOUT 10V/div 1A/div VOUT = 3.3V, IOUT = 1A to 2A Step VEN 1V/div 1A/div IL 1V/div 100mV/div AC Coupled ILOAD VOUT 1V/div IL C4 = 0.1μF, VOUT = 3.3V, IOUT = 1.5A (Resistance Load) 2A/div VSW VEN 10V/div VOUT 1V/div No Soft-Start Cap, VOUT = 3.3V, IOUT = 1.5A (Resistance Load) 1V/div 1V/div VEN Time (200μs/div) Steady State Operation 20mV/div AC Coupled VOUT 10V/div VSW VOUT = 1.8V, IOUT = 1.5A 2A/div IL Time (400ns/div) SG Micro Corp www.sg-micro.com 6 SGM6232 2A, 38V, 1.4MHz Step-Down Converter OPERATION The SGM6232 is a current-mode step-down regulator. It regulates input voltages from 4.5V to 38V down to an output voltage as low as 0.8V, and is able to supply up to 2A of load current. The SGM6232 uses current-mode control to regulate the output voltage. The output voltage is measured at FB through a resistive voltage divider and amplified through the internal error amplifier. The output current of the transconductance error amplifier is presented at COMP where a network compensates the regulation control system. The voltage at COMP is compared to the switch current measured internally to control the output voltage. The converter uses an internal N-Channel MOSFET switch to step-down the input voltage to the regulated output voltage. A boost capacitor connected between SW and BS drives the gate of MOSFET, and makes it greater than input voltage while SW is high. Thus, the MOSFET will be in low resistance conducting state. The capacitor is internally charged while SW is low. Soft-Start The device includes a soft-start to limit the inrush current and prevent the overshoot of output voltage. The soft-start time can be programmed by the external soft-start capacitor and it is calculated as: tSS = 100kΩ × CSS For example, CSS =0.1μF corresponds to a 10ms softstart time. To get perfect power on start performance, right soft-start time must be added to adjust the sequence between power supply and the output voltage in order to guarantee the self-boost capacitor is charged correctly. Usually a 1μF CSS is good enough, if the power supply is decoupled by big input capacitor, a long soft-start time is preferred. An internal 10Ω switch from SW to GND is used to ensure that SW is pulled to GND during shutdown to fully charge the BS capacitor. SG Micro Corp www.sg-micro.com 7 SGM6232 2A, 38V, 1.4MHz Step-Down Converter APPLICATION INFORMATION Setting the Output Voltage The output voltage is set using a resistive voltage divider from the output voltage to FB pin. The voltage divider divides the output voltage down to the feedback voltage by the ratio: VFB  VOUT R2 R1  R2 Where VFB is the feedback voltage and VOUT is the output voltage. Thus the output voltage is: VOUT  0.8  R1  R2 R2 The value for R2 can be as high as 100kΩ, but a typical value is 10kΩ. Using that value, R1 is determined by: R1 = 12.5 × (VOUT - 0.8) (kΩ) For example, for a 3.3V output voltage, R2 is 10kΩ, and R1 is 31.25kΩ. Choose an inductor that will not saturate under the maximum inductor peak current. The peak inductor current can be calculated by: ILP  ILOAD   VOUT V    1  OUT  2  fOSC  L  VIN  ILOAD is the load current. Output Rectifier Diode The output rectifier diode supplies the current to the inductor when the high-side switch is off. To reduce losses due to the diode forward voltage and recovery times, use a Schottky diode. Choose a diode whose maximum reverse voltage rating is greater than the maximum input voltage, and whose current rating is greater than the maximum load current. Table 1 lists example Schottky diodes and manufacturers. Table 1. Diode Selection Guide Inductor Diode Voltage, Current Rating Manufacturer The inductor is required to supply constant current to the output load while being driven by the switched input voltage. A larger value inductor will result in less ripple current that will result in lower output ripple voltage. However, the larger value inductor will have a larger physical size, higher series resistance, and/or lower saturation current. A good rule for determining the inductance to use is to allow the peak-to-peak ripple current in the inductor to be approximately 30% of the maximum switch current limit. Also, make sure that the peak inductor current is below the maximum switch current limit. The inductance value can be calculated by: SK33 30V, 3A Diodes Inc. SK34 40V, 3A Diodes Inc. B330 30V, 3A Diodes Inc. L  VOUT V    1  OUT  fOSC  ΔIL  VIN  Where VIN is the input voltage, fOSC is the 1.4MHz switching frequency, and ΔIL is the peak-to-peak inductor ripple current. SG Micro Corp www.sg-micro.com B340 40V, 3A Diodes Inc. MBRS330 30V, 3A On Semiconductor MBRS340 40V, 3A On Semiconductor Input Capacitor The input current to the step-down converter is discontinuous, therefore a capacitor is required to supply the AC current to the step-down converter while maintaining the DC input voltage. Use low ESR capacitors for the best performance. Ceramic capacitors are recommended. Since the input capacitor absorbs the input switching current, it requires an adequate ripple current rating. 8 SGM6232 2A, 38V, 1.4MHz Step-Down Converter APPLICATION INFORMATION The RMS current in the input capacitor can be estimated by: IRMS  ILOAD  VOUT  VOUT   1  VIN  VIN  In the case of ceramic capacitors, the impedance at the switching frequency is dominated by the capacitance. The output voltage ripple is mainly caused by the capacitance. For simplification, the output voltage ripple can be estimated by: ΔVOUT  The worst-case condition occurs at VIN = 2VOUT, where: IRMS(MAX)  ILOAD 2 For simplification, choose the input capacitor whose RMS current rating is greater than half of the maximum load current. The input capacitor can be electrolytic, tantalum or ceramic. When using electrolytic or tantalum capacitors, a small, high quality ceramic capacitor, i.e. 0.1µF, should be placed as close to the IC as possible. When using ceramic capacitors, make sure that they have enough capacitance to provide sufficient charge to prevent excessive voltage ripple at input. The input voltage ripple caused by capacitance can be estimated by: ΔVIN   V  ILOAD V  OUT   1  OUT  fOSC  CIN VIN  VIN  CIN is the input capacitance value. Output Capacitor The output capacitor (COUT) is required to maintain the DC output voltage. Ceramic, tantalum, or low ESR electrolytic capacitors are recommended. Low ESR capacitors are preferred to keep the output voltage ripple low. The output voltage ripple can be estimated by: ΔVOUT    V   VOUT 1   1  OUT    RESR   fOSC  L  VIN   8  fOSC  COUT  Where L is the inductor value, COUT is the output capacitance value, and RESR is the equivalent series resistance (ESR) value of the output capacitor. SG Micro Corp www.sg-micro.com  VOUT V    1  OUT  8  fOSC 2  L  COUT  VIN  In the case of tantalum or electrolytic capacitors, the ESR dominates the impedance at the switching frequency. For simplification, the output ripple can be approximated to: ΔVOUT   VOUT V    1  OUT   RESR fOSC  L  VIN  The characteristics of the output capacitor also affect the stability of the regulation system. The SGM6232 can be optimized for a wide range of capacitance and ESR values. Compensation Components SGM6232 employs current mode control for easy compensation and fast transient response. The system stability and transient response are controlled through the COMP pin. COMP pin is the output of the internal transconductance error amplifier. A serial capacitor and resistor combination sets a pole-zero combination to control the characteristics of the control system. The DC gain of the voltage feedback loop is given by: A VDC  RLOAD  GCS  A EA  VFB VOUT Where AEA is the error amplifier voltage gain, 10000V/V, GCS is the current sense transconductance, 6.2A/V, and RLOAD is the load resistor value. The system has two poles of importance. One is due to the compensation capacitor (C3) and the output resistor of error amplifier, and the other is due to the output capacitor and the load resistor. These poles are located at: GEA 1 fP1  fP2  2π  C3  A EA 2π  COUT  RLOAD 9 SGM6232 2A, 38V, 1.4MHz Step-Down Converter APPLICATION INFORMATION GEA is the error amplifier transconductance, 800µA/V. The system has one zero of importance, due to the compensation capacitor (C3) and the compensation resistor (R3). This zero is located at: f Z1  1 2π  C3  R3 The system may have another zero of importance, if the output capacitor has a large capacitance and/or a high ESR value. The zero, due to the ESR and capacitance of the output capacitor, is located at: fESR  1 2π  COUT  RESR In this case, a third pole set by the compensation capacitor (C6) and the compensation resistor (R3) is used to compensate the effect of the ESR zero on the loop gain. This pole is located at: Table 2 lists the typical values of compensation components for some standard output voltages with various output capacitors and inductors. The values of the compensation components have been optimized for fast transient responses and good stability at given conditions. Table 2. Compensation Values for Typical Output Voltage/ Capacitor Combinations VOUT (V) L (µH) COUT (µF) R3 (kΩ) C3 (nF) R1 (kΩ) R2 (kΩ) 0.8 2.2 47/22×2 1.2 3.3 0 10.5 1.2 2.2 47/22×2 3 3.3 4.99 10 1.8 2.2 47/22×2 3.9 3.3 10.2 8.2 2.5 2.2 - 4.7 47/22×2 6.49 4.7 22.6 10.7 3.3 2.2 - 4.7 47/22×2 10 5.6 33 10.5 5 4.7 - 6.8 47/22×2 15 4.7 52.3 10 12 6.8 - 10 47/22×2 39 2.2 140 10 R4 C5 10Ω or shorted 10nF INPUT fP3  1 2π  C6  R3 The goal of compensation design is to shape the converter transfer function to get a desired loop gain. The system crossover frequency where the feedback loop has the unity gain is important. Lower crossover frequencies result in slower line and load transient responses, while higher crossover frequencies could cause system unstable. A good rule of thumb is to set the crossover frequency to approximately one-thirtieth of the switching frequency. Switching frequency for the SGM6232 is 1.4MHz, so the desired crossover frequency is around 47kHz. SG Micro Corp www.sg-micro.com IN ENABLE BS EN L SW OUTPUT SGM6232 SS GND CIN 10μF ×2 C4 0.1μF R1 FB COMP C6 Optional C3 D1 B340A R2 COUT R3 Figure 2. Typical Application Circuit 10 SGM6232 2A, 38V, 1.4MHz Step-Down Converter APPLICATION INFORMATION To optimize the compensation components for conditions not listed in Table2, the following procedure can be used. 1. Choose the compensation resistor (R3) to set the desired crossover frequency. Determine the R3 value by the following equation: 2π  COUT  fC VOUT R3   GEA  GCS VFB Where fC is the desired crossover frequency (which typically has a value no higher than 47kHz). 2. Choose the compensation capacitor (C3) to achieve the desired phase margin. For applications with typical inductor values, setting the compensation zero, fZ1, below one-forth of the crossover frequency provides sufficient phase margin. Determine the C3 value by the following equation: C3  3. Determine if the second compensation capacitor (C6) is required. It is required if the ESR zero of the output capacitor is located at less than half of the 1.4MHz switching frequency, or the following relationship is valid: 1 2π  COUT  RESR  fOSC 2 Where, COUT is the output capacitance value, RESR is the ESR value of the output capacitor, and fOSC is the 1.4MHz switching frequency. If this is the case, then add the second compensation capacitor (C6) to set the pole fP3 at the location of the ESR zero. Determine the C6 value by the equation: C6  COUT  RESR R3 Where, COUT is the output capacitance value, RESR is the ESR value of the output capacitor, and R3 is the compensation resistor. 4 2π  R3  f C Where, R3 is the compensation resistor value and fC is the desired crossover frequency, 47kHz. SG Micro Corp www.sg-micro.com 11 SGM6232 2A, 38V, 1.4MHz Step-Down Converter PACKAGE OUTLINE DIMENSIONS SOIC-8 (Exposed Pad) 3.302 D e E1 E 2.413 E2 5.56 1.91 b D1 1.27 0.61 RECOMMENDED LAND PATTERN (Unit: mm) L A θ A1 c A2 Symbol Dimensions In Millimeters MIN MAX A Dimensions In Inches MIN MAX 1.700 0.067 A1 0.000 0.100 0.000 0.004 A2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.170 0.250 0.007 0.010 D 4.700 5.100 0.185 0.201 D1 3.202 3.402 0.126 0.134 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 E2 2.313 2.513 0.091 0.099 e 1.27 BSC 0.050 BSC L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° SG Micro Corp www.sg-micro.com 12 SGM6232 2A, 38V, 1.4MHz Step-Down Converter 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 P1 A0 K0 DIRECTION OF FEED Reel Width (W1) NOTE: The picture is only for reference. Please make the object as the standard. KEY PARAMETER LIST OF TAPE AND REEL Package Type Reel Diameter Reel Width W1 (mm) A0 (mm) B0 (mm) K0 (mm) P0 (mm) P1 (mm) P2 (mm) W (mm) Pin1 Quadrant SOIC-8 (Exposed Pad) 13″ 12.4 6.4 5.4 2.1 4.0 8.0 2.0 12.0 Q1 SG Micro Corp www.sg-micro.com 13 SGM6232 2A, 38V, 1.4MHz Step-Down Converter CARTON BOX DIMENSIONS NOTE: The picture is only for reference. Please make the object as the standard. KEY PARAMETER LIST OF CARTON BOX Reel Type Length (mm) Width (mm) Height (mm) Pizza/Carton 13″ 386 280 370 5 SG Micro Corp www.sg-micro.com 14