SM8103ADC

SM8103 High Efficiency, 3.0A, 18V Input Synchronous Step Down Regulator General Description Features The SM8103 is a high efficiency, 500kHz synchronous step-down DC/DC regulator capable of delivering up to 3A load current. It can operate over a wide input voltage range from 4.2V to 18V and integrate main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. The SM8103 adopts the instant PWM architecture to achieve fast transient responses for high step down applications and high efficiency at light loads. In addition, it operates at pseudo-constant frequency of 500kHz to minimize the size of the inductor and the capacitor. Ordering Information SM8103 □(□□)□ Applications Temperature Code Package Code Optional Spec Code Ordering Number SM8103ADC Package type TSOT23-6  Low RDS(ON) for Internal Switches (Top/Bottom): 90mΩ/50mΩ  4.2-18V Input Voltage Range  3A Output Current Capability  500kHz Switching Frequency Minimize the External Components  Stable with 10µF COUT and 2.2µH Inductor  Instant PWM Architecture to Achieve Fast Transient Responses  Internal Soft-start Limits the Inrush Current  Cycle-by-cycle Peak/Valley Current Limitation  Hic-cup Mode Output Short Circuit Protection  Thermal Shutdown with Auto Recovery  Output Auto Discharge Function  Compact Package: TSOT23-6       Note ---- Set Top Box Portable TV DSL Modem LCD TV IP CAM Networking Typical Application CBS 100nF Efficiency vs. Load Current VIN :4.2~18V L 4.7uH BS IN 100 VOUT: 3.3V LX 95 SM8103 EN FB GND RH 100k CFF 100pF COUT 10uF RL 22.1k Figure1. Schematic Diagram 90 Efficiency (%) CIN 10uF 85 80 75 70 VIN=5V, VOUT=3.3V VIN=12V, VOUT=3.3V VIN=18V, VOUT=3.3V 65 Inductor and COUT Selection Table COUT [µF] L [µH] 4.7 10 22 1.5 √ 1.2 2.2 ☆ 2.2 √ √ 3.3 4.7 ☆ √ 3.3 √ √ 5 6.8 ☆ √ Note: ‘☆’ means recommended for most applications. VOUT [V] AN_SM8103 Rev0.9A © 2019 Silergy Corp. 60 0.01 0.1 1 10 Load Current (A) Figure2. Efficiency vs. Output Current Silergy Corp. Confidential- Prepared for Customer Use Only 1 All Rights Reserved. SM8103 Pinout (top view) BS 1 6 LX GND 2 5 IN 4 EN FB 3 TSOT23-6 Pin Name BS GND FB EN Top mark: J7xyz (Device code: J7, x=year code, y=week code, z= lot number code) Pin Number Pin Description Boot-strap pin. Supply high side gate driver. Connect a 0.1µF ceramic capacitor 1 between BS and LX pins. 2 Power ground pin. Output feedback pin. Connect this pin to the center point of the output resistor 3 divider (as shown in Figure 1) to program the output voltage: VOUT=0.6×(1+RH/RL). 4 Enable control. Pull high to turn on. Do not leave this pin floating. IN 5 Input pin. Decouple this pin to GND pin with at least a 10µF ceramic capacitor. LX 6 Inductor pin. Connect this pin to the switching node of inductor. Block Diagram IN Current Sense Internal Power BS Input UVLO 4.15V PWM Control & Protect Logic EN 1.2V FB LX Current Sense 0.6V Internal SST Thermal Protection GND Figure3. Block Diagram AN_SM8103 Rev0.9A © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 2 All Rights Reserved. SM8103 Absolute Maximum Ratings (Note 1) Supply Input Voltage ------------------------------------------------------------------------------------------------ -0.3V to 19V LX, EN Voltage----------------------------------------------------------------------------------------------- -0.3V to VIN + 0.3V FB, BS-LX Voltage---------------------------------------------------------------------------------------------------- -0.3V to 4V Power Dissipation, PD @ TA = 25°C TSOT23-6, ----------------------------------------------------------------------- 1.5W Package Thermal Resistance (Note 2) θ JA ---------------------------------------------------------------------------------------------------------------- 66°C/W θ JC ---------------------------------------------------------------------------------------------------------------- 15°C/W Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 150°C Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------------ 260°C Storage Temperature Range -------------------------------------------------------------------------------------- -65°C to 150°C Dynamic LX Voltage in 10ns Duration (Note3) ---------------------------------------------------------- IN+3V to GND-5V Recommended Operating Conditions (Note 3) Supply Input Voltage -------------------------------------------------------------------------------------------------- 4.2V to 18V Junction Temperature Range ------------------------------------------------------------------------------------- -40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------- -40°C to 85°C AN_SM8103 Rev0.9A © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 3 All Rights Reserved. SM8103 Electrical Characteristics (VIN = 12V, VOUT = 3.3V, L = 4.7µH, COUT = 10µF, TA = 25°C, IOUT = 1A unless otherwise specified) Parameter Input Voltage Range Input UVLO Threshold Input UVLO Hysteresis Quiescent Current Shutdown Current Feedback Reference Voltage FB Input Current Output Discharge Resistance Top FET RON Bottom FET RON EN Rising Threshold EN Falling Threshold Min ON Time Min OFF Time Symbol VIN VUVLO VHYS IQ ISHDN VREF IFB RDIS RDS(ON)1 RDS(ON)2 VEN,R VEN,F tON,MIN tOFF,MIN Test Conditions Min 4.2 Turn On Delay tON,DLY Soft-start Time Switching Frequency tSS FSW Top FET Current Limit ILIM,TOP 4.5 A Bottom FET Current Limit Output Under Voltage Protection Threshold Output UVP Delay UVP Hiccup ON Time UVP Hiccup OFF Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis ILIM,BOT 3 A IOUT=0, VFB=VREF×105% EN=0 VFB=3.3V 588 -50 1.08 0.9 from EN high to LX start switching VOUT from 0 to 100% VOUT=3.3V, CCM Typ 0.3 250 5 600 40 90 50 1.2 1.0 50 200 Max 18 4.15 10 612 50 1.32 1.1 300 0.5 1 500 Unit V V V µA µA mV nA Ω mΩ mΩ V V ns ns µs 1.5 ms kHz VUVP 33% VREF tUVP,DLY tUVP,ON tUVP,OFF 100 2 6 µs ms ms TSD 150 ˚C THYS 15 ˚C Note 1: Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note 2: θ JA is measured in the natural convection at T A = 25°C on a 2OZ two-layer Silergy evaluation board. Paddle of TSOT23-6 package is the case position for SM8103 θ JC measurement. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SM8103 Rev0.9A © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 4 All Rights Reserved. SM8103 Typical Performance Characteristics Efficiency vs. Load Current 100 95 95 90 90 Efficiency (%) Efficiency (%) Efficiency vs. Load Current 100 85 80 75 85 80 75 70 70 VIN=5V, VOUT=1.2V VIN=12V, VOUT=1.2V VIN=18V, VOUT=1.2V 65 VIN=5V, VOUT=1.8V VIN=12V, VOUT=1.8V VIN=18V, VOUT=1.8V 65 60 60 0.01 0.1 1 10 0.01 Load Current (A) 1 10 Efficiency vs. Load Current Efficiency vs. Load Current 100 100 95 95 90 90 Efficiency (%) Efficiency (%) 0.1 Load Current (A) 85 80 75 70 85 80 75 70 VIN=5V, VOUT=3.3V VIN=12V, VOUT=3.3V VIN=18V, VOUT=3.3V 65 VIN=7.4V,VOUT=5V VIN=12V,VOUT=5V VIN=18V,VOUT=5V 65 60 60 0.01 0.1 1 Load Current (A) 10 0.01 0.1 1 Load Current (A) Output Ripple Output Ripple (VIN=12V, VOUT=3.3V, ILOAD=0A) (VIN=12V, VOUT=3.3V, ILOAD=3A) ∆VOUT 200mV/div VLX 5V/div IL 1A/div ∆VOUT VLX IL Time (2μs/div) AN_SM8103 Rev0.9A © 2019 Silergy Corp. 10 100mV/div 5V/div 2A/div Time (2μs/div) Silergy Corp. Confidential- Prepared for Customer Use Only 5 All Rights Reserved. SM8103 Load Transient Load Transient (VIN=12V, VOUT=3.3V, ILOAD=0-1.5A) (VIN=12V, VOUT=3.3V, ILOAD=0.3-3A) ∆VOUT IL 200mV/div 1A/div Time (400μs/div) ∆VOUT IL 200mV/div 2A/div Time (400μs/div) Startup from Enable Shutdown from Enable (VIN=12V, VOUT=3.3V, ILOAD=3A) (VIN=12V, VOUT=3.3V, ILOAD=3A) EN 5V/div EN 5V/div VOUT 2V/div VOUT 2V/div VLX 10V/div VLX 10V/div IL 5A/div IL 5A/div Time (400µs/div) VIN VOUT Time (400µs/div) Startup from VIN Shutdown from VIN (VIN=12V, VOUT=3.3V, ILOAD=3A) (VIN=12V, VOUT=3.3V, ILOAD=3A) 10V/div VIN 2V/div VOUT 10V/div 2V/div VLX 10V/div VLX 10V/div IL 5A/div IL 5A/div Time (2ms/div) AN_SM8103 Rev0.9A © 2019 Silergy Corp. Time (2ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 6 All Rights Reserved. SM8103 Short Circuit Protection Short Circuit Protection (VIN=12V, VOUT=3.3V, Open to Short) (VIN=12V, VOUT=3.3V, 3A to Short) VOUT 2V/div IL 2A/div Time (20ms/div) AN_SM8103 Rev0.9A © 2019 Silergy Corp. VOUT 2V/div IL 2A/div Time (20ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 7 All Rights Reserved. SM8103 Operation The SM8103 is a high efficiency, 500kHz synchronous step-down DC/DC regulator capable of delivering up to 3A load current. It can operate over a wide input voltage range from 4.2V to 18V and integrate main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. The SM8103 adopts the instant PWM architecture to achieve fast transient responses for high step down applications and high efficiency at light loads. The SM8103 provides protection functions such as cycle-by-cycle current limit and thermal shutdown protection. The SM8103 will sense the output voltage conditions for the fault protection. Applications Information Because of the high integration in the SM8103, the application circuit based on this IC is rather simple. Only the input capacitor CIN, the output capacitor COUT, the inductor L and the feedback resistors (RH and RL) need to be selected for the targeted applications specifications. Feedback Resistor Dividers RH and RL Choose RH and RL to program the proper output voltage. To minimize the power consumption under light loads, it is desirable to choose large resistance values for both RH and RL. A value of between 10kΩ and 1MΩ is highly recommended for both resistors. If VOUT is 3.3V, RH=100k is chosen, then using the following equation, RL can be calculated to be 22.1k: RL  Place a typical X5R or a better grade ceramic capacitor really close to the IN and GND pins to minimize the potential noise problem. Care should be taken to minimize the loop area formed by CIN, and IN/GND pins. In this case, a 10μF low ESR ceramic capacitor is recommended. Output Capacitor COUT The output capacitor is selected to handle the output ripple noise requirements. Both steady state ripple and transient requirements must be taken into consideration when selecting this capacitor. For the best performance, it is recommended to use X5R or a better grade ceramic capacitor with 16V rating and more than 22µF capacitance. Output Inductor L There are several considerations in choosing this inductor. 1) Choose the inductance to provide the desired ripple current. It is suggested to choose the ripple current to be about 40% of the maximum output current. The inductance is calculated as: L VOUT (1  VOUT /VIN, MAX ) FSW  IOUT, MAX  40% Where FSW is the switching frequency and IOUT,MAX is the maximum load current. The IC is quite tolerant of different ripple current amplitudes. Consequently, the final choice of the inductance can be slightly off the calculation value without significantly impacting the performance. 2) The saturation current rating of the inductor must be selected to be greater than the peak inductor current under full load conditions. 0.6V RH VOUT  0.6V ISAT, MIN  IOUT, MAX  VOUT(1-VOUT/VIN,MAX) 2  FSW  L VOUT 3) RH FB RL GND Input Capacitor CIN The ripple current through the input capacitor is calculated as： I CIN _ RMS  IOUT  D(1  D) AN_SM8103 Rev0.9A © 2019 Silergy Corp. The DCR of the inductor and the core loss at the switching frequency must be low enough to achieve the desired efficiency requirement. It is desirable to choose an inductor with DCR