F72814 F72814 Datasheet Synchronous Buck PWM DC-DC Controller Release Date: July, 2007 Version: V0.23P V0.23P F72814 F72814 Datasheet Revision History Version Date Page 0.20P Revision History Preliminary version 0.21P Apr, 2006 0.22P May,2006 0.23P Jul, 2007 Re-compose 3 Remove free run frequency 4 Add dead time measurement loading 8 Add typical characteristic diagram 11 Update company address 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 F72814 ±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) -1- V0.23P F72814 3. Pin Configuration BOOT UGATE 1 2 GND 3 LGATE 4 F72814 8 7 PHASE OCSET 6 FB 5 VCC 4. Pin Description Pin No Pin Name Description 1 BOOT 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 UGATE 3 GND 4 LGATE 5 VCC 6 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 F72814 SYMBOL RATINGS UNIT VCC 15 V VPHASE – GND 15 V VBOOT - VPHASE 15 V -2- V0.23P F72814 BOOT to GND VBOOT - GND VCC + 15 V PWM controller outputs UGATE (VPHASE - 0.3) to (VBOOT + 0.3) V PWM controller outputs LGATE (GND - 0.3) to (VCC + 0.3) V Feedback voltages FB (GND - 0.3) ~ 7 V ESD classification HBM 2 kV Tj 150 °C TSTO -65 ~ 150 °C 260 °C ※ Maximum junction temperature (plastic package) ※ Maximum storage temperature ※ Maximum lead temperature (soldering 10s) 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 SYMBOL RATINGS UNIT Supply Voltage VCC 5 ± 5%,12 ± 10% V Ambient Temperature 0 ~ 70 °C Junction Temperature 0 ~ 125 °C Package thermal information PARAMETER Thermal resistance junction-ambient SYMBOL SOIC UNIT Rth_ja 160 °C/W DC and AC electrical characteristics (VCC = 12V, TA = 25℃) TYP. MAX. UNIT 6 15 mA Rising VCC threshold 4.1 4.4 V Falling VCC threshold 3.6 3.75 V 300 350 kHz PARAMETER SYMBOL TEST CONDITIONS MIN. VCC SUPPLY CURRENT/Regulated Voltage Nominal supply current 5VCC ICC UGATE, LGATE and DRIVE2 open POWER-ON RESET OSCILLATOR AND Protection Free running frequency ※ Ramp Amplitude FOSC Soft-start interval F72814 1.5 △VOSC FB Under Voltage Trip OCSET Current Source 250 FB Falling VP-P 0.48 0.5 0.52 V IOCSET 35 40 45 uA TSS 1 3 6 ms -3- V0.23P F72814 SYMBOL PARAMETER Dead time MIN. TEST CONDITIONS TDT 2V to 2V, Loading =2A VREF VCC=5V, T= 25 TYP. MAX. UNIT 100 ns 0.8 0.816 V 10 REFERENCE VOLTAGE Reference voltage 0.784 PWM CONTROLLER GATE DRIVERS Upper Drive Source RUGATE VDS = 1V, VGS = 12V, 5 10 Ω Upper Drive Sink RUGATE VDS = 1V, VGS = 12V 4 8 Ω Lower Drive Source RLGATE VDS = 1V, VGS = 12V 4 8 Ω Lower Drive Sink RLGATE VDS = 1V, VGS = 12V 3 5 Ω Error Amplifier ※ E/A Transconductance gm 1.67 ※ DC Gain A0 85 u A/V * dB ※: Design Guarantee 6. Block Diagram VDDA V3VAA 0.4V Reference Voltage Bias & Regulator (VDD & V3VAA) OC Power On Reset Comp 40uA OCSET 0.15V SD 0.6V UVP Comp UV Control Logic 1.5V PH_M Comp VDD 0.8V BOOT GM FB Comp 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 BOOT VCC C BOOT UGATE Q1 PHASE LGATE 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. VCC = 12V 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. VCC 5V PWOK VOUT 0V 1 2 3 4 5 6 7 TIME (ms UGATE Figure 5 : F72814 -7- V0.23P F72814 8. Typical Characteristic Efficiency V.S. Output Current 95 95 90 90 Efficiency (%) Efficiency (%) Efficiency V.S. Output Current 85 80 75 85 80 75 70 70 0 5 10 15 20 0 5 10 Output Current (A) VCC=12V, VIN=5V, VOUT=2.5V Frequency V.S. Temperature 350 0.802 330 Frequency (KHz) 0.806 0.798 0.794 0.79 310 290 270 250 0.786 -10 5 20 35 50 65 80 95 -10 110 5 20 35 50 65 80 Temperature (℃) Temperature (℃) POR V.S. Temperature 4.6 Voltage (V) Rising 4.2 3.8 Falling 3.4 -10 5 20 35 50 65 80 95 110 Temperature (℃) F72814 20 VCC=5V, VIN=5V, VOUT=2.5V Reference Voltage V.S. Temperature Reference Voltage (V) 15 Output Current (A) -8- V0.23P 95 110 F72814 Dead Time (Rising) Dead Time (Falling) UGATE UGATE LGATE LGATE Time 20.0ns/Div. Time 20.0ns/Div. VCC=12V, VIN=5V, IOUT=2.5A Under Voltage Protection UGATE UGATE FB FB FB > 0.5V F72814 FB < 0.5V -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 F72814 Part Number Package Type Production Flow F72814SG 8-SOP (Green Package) Commercial, 0°C to +70°C -10- V0.23P F72814 10. Package Dimensions (8-SOP/150 mil) 8 5 c E HE L 4 1 0.25 D O A Y e SEATING PLANE GAUGE PLANE A1 b Control demensions are in milmeters . SYMBOL A A1 b c E D e HE Y L θ DIMENSION IN INCH MIN. MAX. 0.053 0.069 0.010 0.004 0.013 0.020 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 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 Taipei Office 3F-7, No 36, Tai Yuan St., Bldg. K4, 7F, No.700, Chung Cheng Rd., Chupei City, Hsinchu, Taiwan 302, R.O.C. Chungho City, Taipei, Taiwan 235, R.O.C. TEL : 886-3-5600168 TEL : 866-2-8227-8027 FAX : 886-3-5600166 FAX : 866-2-8227-8037 www: http://www.fintek.com.tw 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) Q1 MOSFET_EN_GDS VCC1P8V L2 C5 C6 C7 C8 1000u 1000u 1000u 1u C1 C2 C3 1u 470u 470u R2 C4 0.1u 2.2 U1 3.3u Q2 MOSFET_EN_GDS D1 DIODE R4 2.2 1 2 3 4 BOOT UGATE GND LGATE PHASE OCSET FB VCC 8 7 6 5 R3 20k R1 2.2 C9 F72814SG 1u R5 R6 12 200 2.5k C10 0.1u FB R7 2k F72814S 13