SYV379FCC

Application Note: SYV379 High Efficiency, 60V Input, 3A Asynchronous Step Down Regulator General Description Features • The SYV379 develops a high efficiency, current mode adaptive constant off time controlled, asynchronous step-down DC/DC converter capable of delivering 3A output current. The SYV379 operates over a wide input voltage range from 4.5V to 60V and integrates main switch with very low RDS(ON) to minimize the conduction loss. The switching frequency is adjustable from 100kHz to 500kHz using an external resistor. And the device features cycle-by-cycle peak current limitation. • • • • • • • • • Ordering Information Low RDS(ON) for Internal N-channel Power FET(TOP):150mΩ 4.5-60V Input Voltage Range 3A Output Current Capability Adjustable Switching Frequency Range: 100kHz to 500kHz Internal Soft-start Limits the Inrush Current Hic-cup Mode Output Short Circuit Protection EN ON/OFF Control with Accurate Threshold Cycle-by-cycle Peak Current Limit 0.8V±1% Reference Voltage Accuracy Compact Package: SO8E SYV379 □(□□)□ Temperature Code Package Code Optional Spec Code Ordering Number SYV379FCC Package type SO8E Applications • • • • Note -- Non-isolated Telecommunication Buck Regulator Secondary High Voltage Post Regulator Automotive Systems Electric Bicycle Typical Applications Efficiency vs. Output Current (IOUT=0~3A, fsw=200kHz，L=15µH/PCMB104T-150MS) 100 CBS LX IN CIN RPG ON/ OFF VOUT EN R1 CFF COUT Efficiency (%) L1 BS VIN 90 80 70 60 VIN=7V, VOUT=5V VIN=12V, VOUT=5V VIN=24V, VOUT=5V VIN=48V, VOUT=5V FB PG 50 R2 FS RFS GND 40 0.001 0.01 0.1 1 3 Output Current (A) Figure1. Schematic Diagram AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. Figure2. Efficiency vs. Output Current Silergy Corp. Confidential- Prepared for Customer Use Only 1 All Rights Reserved. SYV379 Pinout (top view) IN 1 EN 2 FS 3 GND 4 8 LX 7 BS 6 PG 5 FB Exposed Pad (SO8E) Top Mark: DHAxyz (Device code: DHA; x=year code, y=week code, z= lot number code) Pin Name Pin Number Pin Description IN 1 Input pin. Decouple this pin to the GND pin with at least a 1μF ceramic capacitor. EN 2 Enable control. Pulled high to turn on. Do not leave it floating. Frequency programming pin. Connect a resistor to ground to program a switching FS 3 frequency between 100kHz to 500kHz. The switching frequency equals to: fsw(kHz)=105/RFS(kΩ) GND 4 Ground pin Output feedback pin. Connect this pin to the center point of the output resistor FB 5 divider (as shown in Figure 1) to program the output voltage: VOUT=0.8×(1+R1/R2). Power good Indicator. Open-drain output when the output voltage is within 90% PG 6 to120% of the regulation point. Boot-strap pin. Supply high side gate driver. Connect a 0.1μF ceramic capacitor BS 7 between the BS pin and the LX pin. LX 8 Inductor pin. Connect this pin to the switching node of the inductor. Exposed Exposed pad must be connected to the GND pin. Connect to system ground plane / Pad on application board for optimal thermal performance. Block Diagram IN Current Sense Comp Internal Power Input UVLO Current Limitation VCC BS Power FET VCC LX EN Enable Threshold OFF Timer FS PWM Control & Protection Logic OTP SCP PG Internal SST VREF FB GND EA Figure3. Block Diagram AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 2 All Rights Reserved. SYV379 Absolute Maximum Ratings (Note 1) Supply Input Voltage ------------------------------------------------------------------------------------------------ -0.3V to 66V BS-LX Voltage ------------------------------------------------------------------------------------------------------- -0.3V to 6V EN, FS, FB, PG, LX Voltage ------------------------------------------------------------------------------ -0.3V to VIN + 0.3V Power Dissipation, PD @ TA = 25°C, SO8E -------------------------------------------------------------------------------2.38W Package Thermal Resistance (Note 2) θ JA ------------------------------------------------------------------------------------------------------------------ 42°C/W θ JC ------------------------------------------------------------------------------------------------------------------- 4°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 10 ns duration ------------------------------------------------------------------ VIN + 3V to GND-5V Recommended Operating Conditions (Note 3) Supply Input Voltage ------------------------------------------------------------------------------------------------- 4.5V to 60V Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------- -40°C to 85°C AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 3 All Rights Reserved. SYV379 Electrical Characteristics (VIN =24V, VOUT = 5V, L =6.8μH, COUT = 22μF, 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 Top FET RON EN Rising Threshold EN Falling Threshold EN Leakage Current Min ON Time Min OFF Time Soft-start Time Switching Frequency Program Range Switching Frequency Setting Accuracy Power Good Threshold Power Good Delay Power Good Output Low PG High Leakage Current Top FET Current Limit Output Under Voltage Protection Threshold Output UVP Delay Symbol VIN VUVLO VHYS IQ ISHDN VREF IFB RDS(ON) VEN,R VEN,F IEN tON,MIN tOFF,MIN tSS Test Conditions fSW,RNG RFS=200k~1M 100 fSW ROSC=200k 400 VFB falling, PG from high to low VFB rising, PG from low to high VFB rising, PG from high to low VFB falling, PG from low to high High to low Low to high IPG=2mA 87 91 115 111 VPG tPG_F tPG_R VPG,L VFB=VREF×105% VEN=0V VFB=3.3V Min 4.5 3.9 0.19 70 2 792 -50 120 1 0.8 -1 Typ Max 60 4.5 0.35 130 16 808 50 180 1.2 1 1 Unit V V V µA µA mV nA mΩ V V µA ns ns ms 500 kHz 500 600 kHz 90 95 120 115 20 200 94 98 123 118 %VREF %VREF %VREF %VREF µs µs V µA A %VREF 4.2 0.27 100 6 800 150 1.1 0.9 150 250 2 ILMT,RNG 3.8 4.5 0.3 1 5 VUVP 45 50 55 tUVP,DLY 10 µs UVP Hiccup ON Time tUVP,ON 3 ms UVP Hiccup OFF Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis tUVP,OFF 20 ms TSD 150 ˚C THYS 15 ˚C Note 1: Stresses beyond “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. 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: θ JA is measured in the natural convection at TA = 25°C on a two-layer Silergy demo board. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 4 All Rights Reserved. SYV379 Typical Performance Characteristics Efficiency vs. Output Current Load Regulation (IOUT=0~3A, fsw=200kHz，L=15µH/PCMB104T-150MS) 100 5.035 Output Voltage (V) Efficiency (%) VIN=7V, VOUT=5V VIN=12V, VOUT=5V VIN=24V, VOUT=5V VIN=48V, VOUT=5V 5.030 90 80 70 60 VIN=7V, VOUT=5V VIN=12V, VOUT=5V VIN=24V, VOUT=5V VIN=48V, VOUT=5V 50 40 0.001 5.025 5.020 5.015 5.010 5.005 5.000 0.01 0.1 1 Output Current (A) 0.5 1.0 1.5 2.0 2.5 Output Ripple (VIN=24V, VOUT=5V, IOUT=3A) 50mV/div VLX 20V/div IL 0.5A/div ∆VOUT 50mV/div VLX 20V/div IL 2A/div Time (2µs/div) Startup from VIN Shutdown from VIN (VIN=24V, VOUT=5V, IOUT=0A) (VIN=24V, VOUT=5V, IOUT=0A) 20V/div VIN VOUT 5V/div 20V/div 5V/div VLX 20V/div VLX 20V/div IL 1A/div IL 1A/div Time (2ms/div) AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. 3.0 Output Current (A) Output Ripple Time (20ms/div) VOUT 0 (VIN=24V, VOUT=5V, IOUT=0A) ∆VOUT VIN 3 Time (20ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 5 All Rights Reserved. SYV379 VIN VOUT Startup from VIN Shutdown from VIN (VIN=24V, VOUT=5V, IOUT=3A) (VIN=24V, VOUT=5V, IOUT=3A) 20V/div VIN 5V/div VOUT 20V/div 5V/div VLX 20V/div VLX 20V/div IL 2A/div IL 2A/div VEN VOUT Time (2ms/div) Time (20ms/div) Startup from Enable Shutdown from Enable (VIN=24V, VOUT=5V, IOUT=0A) (VIN=24V, VOUT=5V, IOUT=0A) 5V/div 5V/div VEN 5V/div VOUT 5V/div VLX 20V/div VLX 20V/div IL 1A/div IL 1A/div Time (2ms/div) Time (1s/div) Startup from Enable Shutdown from Enable (VIN=24V, VOUT=5V, IOUT=3A) (VIN=24V, VOUT=5V, IOUT=3A) VEN 5V/div VEN 5V/div VOUT 5V/div VOUT 5V/div VLX 20V/div VLX 20V/div IL 2A/div IL 2A/div Time (2ms/div) AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. Time (2ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 6 All Rights Reserved. SYV379 Short Circuit Protection Short Circuit Protection (VIN=24V, VOUT=5V, IOUT=0A - Short) (VIN=24V, VOUT=5V, IOUT=3A - Short) VOUT 5V/div VOUT 5V/div IL 2A/div IL 2A/div Time (10ms/div) Time (10ms/div) Load transient (VIN=24V, VOUT=5V, IOUT=0.2A–2A) ∆VOUT IL 500mV/div 2A/div Time (200µs/div) AN_SYV379 Rev. 0.9 © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 7 All Rights Reserved. SYV379 Operation The SYV379 is a high efficiency asynchronous step down DC/DC regulator capable of delivering 3A output current. The device adopts current mode adaptive constant OFF time control. The SYV379 operates over a wide input voltage range from 4.5V to 60V and integrates main switch with very low RDS(ON) to minimize the conduction loss. The switching frequency is adjustable from 100kHz to 500kHz using an external resistor. And the device features cycle-by-cycle peak current limitation. Applications Information Because of the high integration in the SYV379, the application circuit based on this IC is rather simple. Only the input capacitor CIN, the output capacitor COUT, the output inductor L1 and the feedback resistors (R1 and R2) need to be selected for the target applications. Feedback Resistor Dividers R1 and R2: Choose R1 and R2 to program the proper output voltage. To minimize the power consumption under light load, it is desirable to choose large resistance values for both R1 and R2. A value of between 10kΩ and 1MΩ is highly recommended for both resistors. If VOUT is 5V, R1=105kΩ is chosen, then using the following equation, R2 can be calculated to be 20kΩ: VFB R2 = R1 , VFB is typical 0.8V. VOUT -VFB 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 an X5R or better grade ceramic capacitor greater 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= GND fSW  IOUT,MAX  40% Where fsw is the switching frequency and the IOUT,MAX is the maximum load current. The SYV379 regulator is quite tolerant of different ripple current amplitude. Consequently, the final choice of 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. ISAT, MIN  IOUT, MAX + VOUT FB VOUT (1 − VOUT /VIN,MAX ) VOUT(1-VOUT/VIN,MAX) 2  fSW  L R1 3) R2 Input Capacitor CIN: The ripple current through the input capacitor is calculated as： ICIN, RMS =IOUT  D(1-D) To minimize the potential noise problem, a typical X5R or better grade ceramic capacitor should be placed really close to the IN and the GND pins. Care should be taken to minimize the loop area formed by CIN, and the IN/GND pins. In this case, a 1μF low ESR ceramic capacitor is recommended. AN_SYV379 Rev. 0.9 © 2020 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