F72814SG

F72814 F72814 Datasheet Synchronous Buck PWM DC-DC Controller Release Date: July, 2007 Version: V0.23P V0.23P F72814 F72814 Datasheet Revision History Version 0.20P 0.21P 0.22P 0.23P Apr, 2006 May,2006 Jul, 2007 3 4 8 11 Re-compose Remove free run frequency Add dead time measurement loading Add typical characteristic diagram Update company address Date Page Revision History Preliminary version Please note that all data and specifications are subject to change without notice. All the trade marks of products and companies mentioned in this data sheet belong to their respective owners. LIFE SUPPORT APPLICATIONS These products are not designed for use in life support appliances, devices, or systems where malfunction of these products can reasonably be expected to result in personal injury. Customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Fintek for any damages resulting from such improper use or sales. V0.23P F72814 Table of Content 1. 2. 3. 4. 5. 6. 7. General Description ........................................................................................................................1 Feature List .....................................................................................................................................1 Pin Configuration............................................................................................................................2 Pin Description................................................................................................................................2 Electrical Characteristic ..................................................................................................................2 Block Diagram ................................................................................................................................4 Function Description.......................................................................................................................5 7.1 Bootstrap Operation ....................................................................................................................5 7.2 Power On Reset...........................................................................................................................5 7.3 Soft-Start .....................................................................................................................................6 7.4 Over-current Protection ..............................................................................................................6 7.5 Under-voltage Protection ............................................................................................................6 7.6 Shutdown ....................................................................................................................................7 7.7 VIN Sense ...................................................................................................................................7 8. Typical Characteristic .................................................................................................................8 9. Ordering Information ......................................................................................................................9 10. Package Dimensions (8-SOP/150 mil) .........................................................................................11 11. Application Circuit........................................................................................................................12 V0.23P F72814 1. General Description The F72814 is a high-efficiency synchronous buck PWM controller that generates logic-supply voltages in PC based systems. This high-performance , single output device includes internal soft-start, frequency-compensation networks, power good signal with delay, and integrates all of the control, output adjustment, monitoring and protection functions into a single package. This device operates at a fixed frequency, 300K Hz and provides an optimum compromise between efficiency, external component size, and cost. Adjustable over-current protection (OCP) monitors the voltage drop across the RDS (ON) of the lower MOSFET for synchronous buck PWM DC-DC controller. The over-current function cycles the soft-start in 4-times hiccup mode to provide fault protection, and in a routine hiccup mode for under-voltage protection. 2. Feature List Provides one synchronous rectified buck DC-DC PWM controller Fast transient response (high bandwidth error amplifier; full 0~80% duty cycle) Fixed operation frequency : 300KHz Single loop voltage-mode control Few external components Output range adjustable down to 0.8V Operates under 5V to 12V input Drives all low cost N-channel MOSFETs Uses MOSFET RDS(ON) as over current monitor, and no current sense resistor is required 0.8V internal reference voltage ±2% accuracy over line, load and temperature Internal soft-start (typically 3 ms) Internal loop compensation Under voltage fault monitoring and protection Over voltage protection Adaptive Non-Overlapping Gate Driver 8-SOP package (150 mil) F72814 -1- V0.23P F72814 3. Pin Configuration BOOT UGATE GND LGATE 1 2 3 4 8 7 6 5 PHASE OCSET FB VCC F72814 4. Pin Description Pin No 1 Pin Name BOOT Description Bootstrap supply pin for the upper gate driver. Connect the bootstrap capacitor between BOOT pin and the PHASE pin. The bootstrap capacitor provides the charge to turn on the upper MOSFET. 2 3 4 5 6 UGATE GND LGATE VCC FB Higher gate drive output. Connect this pin to gate of the high side MOSFET Power ground pin for the chip Lower gate drive output. Connect this pin to gate of the low side MOSFET IC supply voltage. This voltage is monitored for power-on-reset purpose. Inverting input of the error amplifier used to compensate the feedback loop of the PWM controller. 7 OCSET/SD This is multi-function pin. Connecting a resistor ROCSET from this pin to PHASE, and an internal 40uA current source from VCC. OCSET voltage can sense loading status when low side MOSFET turn on. When OCSET voltage is under 0.1V, shut down (SD) function will be enabled. 8 PHASE Connect this pin to the source of the upper MOSFET and the drain of the lower MOSFET. 5. Electrical Characteristic Absolute Maximum Ratings PARAMETER IC supply voltage PHASE to GND BOOT to PHASE SYMBOL VCC VPHASE – GND VBOOT - VPHASE RATINGS 15 15 15 UNIT V V V F72814 -2- V0.23P F72814 BOOT to GND PWM controller outputs PWM controller outputs Feedback voltages ESD classification ※ Maximum junction temperature (plastic package) ※ Maximum storage temperature ※ Maximum lead temperature (soldering 10s) VBOOT - GND UGATE LGATE FB HBM Tj TSTO VCC + 15 (VPHASE - 0.3) to (VBOOT + 0.3) (GND - 0.3) to (VCC + 0.3) (GND - 0.3) ~ 7 2 150 -65 ~ 150 260 V V V V kV °C °C °C Note: If ICs are stressed beyond the limits listed in the “absolute maximum ratings”, they may be permanently destroyed. These are stress ratings only and functional operations of the device at these or any other condition beyond those indicated under “recommended operating conditions” are not implied. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. Recommended Operating Conditions PARAMETER Supply Voltage Ambient Temperature Junction Temperature SYMBOL VCC RATINGS 5 ± 5%,12 ± 10% 0 ~ 70 0 ~ 125 UNIT V °C °C Package thermal information PARAMETER Thermal resistance junction-ambient SYMBOL Rth_ja SOIC 160 UNIT °C/W DC and AC electrical characteristics (VCC = 12V, TA = 25℃) PARAMETER SYMBOL TEST CONDITIONS MIN. TYP. MAX. UNIT VCC SUPPLY CURRENT/Regulated Voltage Nominal supply current 5VCC POWER-ON RESET Rising VCC threshold Falling VCC threshold OSCILLATOR AND Protection Free running frequency ※ Ramp Amplitude FB Under Voltage Trip OCSET Current Source Soft-start interval IOCSET TSS FOSC △VOSC FB Falling 0.48 35 1 250 300 1.5 0.5 40 3 0.52 45 6 350 kHz VP-P V uA ms 4.1 3.6 4.4 3.75 V V ICC UGATE, LGATE and DRIVE2 open 6 15 mA F72814 -3- V0.23P F72814 PARAMETER Dead time REFERENCE VOLTAGE Reference voltage PWM CONTROLLER GATE DRIVERS Upper Drive Source Upper Drive Sink Lower Drive Source Lower Drive Sink Error Amplifier ※ E/A Transconductance ※ DC Gain gm A0 1.67 85 * SYMBOL TDT TEST CONDITIONS 2V to 2V, Loading =2A MIN. 10 TYP. MAX. 100 UNIT ns VREF VCC=5V, T= 25 0.784 0.8 0.816 V RUGATE RUGATE RLGATE RLGATE VDS = 1V, VGS = 12V, VDS = 1V, VGS = 12V VDS = 1V, VGS = 12V VDS = 1V, VGS = 12V 5 4 4 3 10 8 8 5 Ω Ω Ω Ω u A/V dB ※: Design Guarantee 6. Block Diagram VDDA V3VAA 0.4V Reference Voltage Bias & Regulator (VDD & V3VAA) Power On Reset OC Comp 0.15V SD UVP UV Comp 40uA OCSET 0.6V Control Logic VDD 1.5V PH_M Comp 0.8V GM BOOT Comp FB UGATE PHASE VDDA LGATE 300KHz Tri-OSC GND Figure 1: Block Diagram F72814 -4- V0.23P F72814 7. Function Description The F72814 is a single PWM DC-DC converter controller for application which requires high current such as motherboard, graphic card etc. The F72814 uses voltage mode PWM controller with fast transient response (driving two external N-channel MOSFETs in a synchronous rectified buck converter topology) and integrates some functions such as soft-start, over current and short circuit protections etc. Over current protection is achieved by monitoring the PHASE negative voltage when heavy loading without the need of a current sensing resistor and short circuit condition is detected through FB pin. If over current condition occurs, the F72814 will initiate the soft start cycle. After two cycles and the fault condition persist, the controller will go into shut down status. In shut down status, both gate drive signals will be low. To restart the controller, either recycling VCC supply or momentarily pulling the OCSET pin below 0.15V. If under voltage condition occurs, it will keep hiccup mode in this event. 7.1 Bootstrap Operation In the single power supply system, UGATE is powered by an external bootstrap circuit as Figure 3. The Boot capacitor, CBOOT is charged and generated a floating reference voltage at PHASE pin. Typically, a 0.1uF CBOOT is enough for the most of applications. The CBOOT capacitor is refreshed and charged to a voltage of “VCC – Diode Drop” while low side power MOS turns on. 5V to 12V 3.3V/5V/12V VCC BOOT C BOOT UGATE PHASE LGATE Q1 VOUT Q2 Fig 2. Power Supply Operation. 7.2 Power On Reset The F72814S Power-on-reset monitors VCC supply voltage and input voltage at OCSET pin. POR level is 4.1V with 0.5V hysteresis at VCC voltage and 0.15V at OCSET voltage, The POR function initiates soft-start operation and resets control logic after the supply voltages exceeds its POR threshold voltage. F72814 -5- V0.23P F72814 7.3 Soft-Start When the POR function initiates the digital soft-start sequence, PWM error amplifier reference inputs are forced to track a voltage level proportional to the soft-start voltage. As the soft-start voltage slews up, the PWM comparator regulates the output relative to the tracked soft-start voltage, and slowly charges the output capacitor(s). In the digital soft-start sequence initiated by the POR function, the soft start function is used to prevent surge current from power supply input during power on. The soft start duration is 3mS in typical case. 12V VCC = 12V 6V VCC = 5V VOUT 0V 3mS TIME Figure 3 : Soft start duration 7.4 Over-current Protection To sense the low-side MOSFET’s RDS (ON) to set over-current trip point. Connecting a resistor (ROCSET) from this pin to PHASE to set the over-current trip point, ROCSET, an internal 40μA current source, and the lower MOSFET on resistance, RDS (ON), sets the converter over-current trip point (IOCSET) according to the following equation: 7.5 Under-voltage Protection If the FB voltage drops under 0.5V, a fault signal is generated. When under voltage condition occurs, it will keep hiccup mode in this event. F72814 -6- V0.23P F72814 3V 1.5V VOUT 0V t0 tss 2tss 3tss 4tss TIME Figure 4 : Under voltage event occur But UV_FB has some differences from OC, it always trigger VIN power sensing after 4 times hiccup. 7.6 Shutdown It can shut down the F72814 PWM controller to pull low the OCSET pin under 0.15V. 7.7 VIN Sense The F72814 Vin power is sensed by OCSET voltage at first soft start event, when soft start event occurs. UGATE pulse will be enabled, and the F72814 detects the first ten UGATE high pulse. If there are four PH_M pulse during the ten pulse period, it means Vin ready, If Vin is ready, VOUT will be ramped up in next soft start event. Otherwise, we will check Vin voltage at the next soft start event. 5V VCC PWOK VOUT 0V 1 UGATE Figure 5 : 2 3 4 5 6 7 TIME (ms F72814 -7- V0.23P F72814 8. Typical Characteristic Efficiency V.S. Output Current 95 90 Efficiency (%) 85 80 75 70 0 5 10 Output Current (A) 15 20 Efficiency (%) 95 90 85 80 75 70 0 5 10 Output Current (A) 15 20 Efficiency V.S. Output Current VCC=12V, VIN=5V, VOUT=2.5V VCC=5V, VIN=5V, VOUT=2.5V Reference Voltage V.S. Temperature 0.806 Reference Voltage (V) 0.802 0.798 0.794 0.79 0.786 -10 5 20 35 50 65 80 95 110 Temperature (℃) Frequency V.S. Temperature 350 330 310 290 270 250 -10 5 20 35 50 65 80 95 110 Temperature (℃) POR V.S. Temperature 4.6 Rising Voltage (V) 4.2 3.8 Falling 3.4 -10 5 20 35 50 65 80 95 110 Temperature (℃) F72814 Frequency (KHz) -8- V0.23P F72814 Dead Time (Rising) Dead Time (Falling) UGATE UGATE LGATE LGATE Time 20.0ns/Div. VCC=12V, VIN=5V, IOUT=2.5A Time 20.0ns/Div. Under Voltage Protection UGATE UGATE FB FB FB > 0.5V FB < 0.5V F72814 -9- V0.23P F72814 Transient Response Time Rising UGATE, 20.0V/Div. VOUT, 100mV/Div. IOUT, 5.0A/Div VCC=5V VIN=5V IOUT=0-15A Falling UGATE, 20.0V/Div. VOUT, 100mV/Div. IOUT, 5.0A/Div VCC=5V VIN=5V IOUT=15-0A 9. Ordering Information Part Number F72814SG Package Type 8-SOP (Green Package) Production Flow Commercial, 0°C to +70°C F72814 -10- V0.23P F72814 10. Package Dimensions (8-SOP/150 mil) 8 5 c E HE L 1 D 4 0.25 O A Y SEATING PLANE b e A1 GAUGE PLANE Control demensions are in milmeters . SYMBOL A A1 b c E D e HE Y L θ DIMENSION IN MM MIN. MAX. 1.35 1.75 0.10 0.25 0.33 0.51 0.19 0.25 3.80 4.00 4.80 5.00 1.27 BSC 6.20 5.80 0.10 0.40 1.27 0 10 DIMENSION IN INCH MIN. MAX. 0.053 0.069 0.010 0.004 0.013 0.020 0.008 0.010 0.150 0.157 0.188 0.196 0.050 BSC 0.228 0.016 0 0.244 0.004 0.050 10 Feature Integration Technology Inc. Headquarters 3F-7, No 36, Tai Yuan St., Chupei City, Hsinchu, Taiwan 302, R.O.C. TEL : 886-3-5600168 FAX : 886-3-5600166 www: http://www.fintek.com.tw Taipei Office Bldg. K4, 7F, No.700, Chung Cheng Rd., Chungho City, Taipei, Taiwan 235, R.O.C. TEL : 866-2-8227-8027 FAX : 866-2-8227-8037 Please note that all datasheet and specifications are subject to change without notice. All the trade marks of products and companies mentioned in this datasheet belong to their respective owner F72814 -11- V0.23P F72814S 11. Application Circuit VIN(5V/12V) L1 1u VCC(5V/12V) C1 1u C2 470u C3 470u D1 DIODE C4 0.1u R3 20k R1 2.2 VCC1P8V Q1 MOSFET_EN_GDS L2 3.3u R2 2.2 U1 1 2 3 4 BOOT UGATE GND LGATE F72814SG PHASE OCSET FB VCC 8 7 6 5 C5 1000u C6 1000u C7 1000u C8 1u Q2 MOSFET_EN_GDS R4 2.2 C9 1u R5 R6 200 2.5k C10 0.1u FB R7 2k 12 F72814S 13