FA7700V

Quality is our message FUJI Power Supply Control IC FA7700V/01V Application Note Dec -2000 Fuji Electric Co., Ltd. Matsumoto Factory 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 1 Quality is our message WARNING 1.This Data Book contains the product specifications, characteristics, data, materials, and structures as of Dec 2000. The contents are subject to change without notice for specification changes or other reasons. When using a product listed in this Data Book, be sure to obtain the latest specifications. 2. All applications described in this Data Book exemplify the use of Fuji's products for your reference only. No right or license, either express or implied, under any patent, copyright, trade secret or other intellectual property right owned by Fuji Electric Co., Ltd. is (or shall be deemed) granted. Fuji makes no representation or warranty, whether express or implied, relating to the infringement or alleged infringement of other's intellectual property rights which may arise from the use of the applications described herein. 3. Although Fuji Electric is enhancing product quality and reliability, a small percentage of semiconductor products may become faulty. When using Fuji Electric semiconductor products in your equipment, you are requested to take adequate safety measures to prevent the equipment from causing a physical injury, fire, or other problem if any of the products become faulty. It is recommended to make your design fail-safe, flame retardant, and free of malfunction. 4.The products introduced in this Data Book are intended for use in the following electronic and electrical equipment which has normal reliability requirements. • Computers • OA equipment • Communications equipment (terminal devices) • Measurement equipment • Machine tools • Audiovisual equipment • Electrical home appliances • Personal equipment • Industrial robots etc. 5.If you need to use a product in this Data Book for equipment requiring higher reliability than normal, such as for the equipment listed below, it is imperative to contact Fuji Electric to obtain prior approval. When using these products for such equipment, take adequate measures such as a backup system to prevent the equipment from malfunctioning even if a Fuji's product incorporated in the equipment becomes faulty. • Transportation equipment (mounted on cars and ships) • Trunk communications equipment • Traffic-signal control equipment • Gas leakage detectors with an auto-shut-off feature • Emergency equipment for responding to disasters and anti-burglary devices • Safety devices 6. Do not use products in this Data Book for the equipment requiring strict reliability such as (without limitation) • Space equipment • Aeronautic equipment • Atomic control equipment • Submarine repeater equipment • Medical equipment 7. Copyright © 1995 by Fuji Electric Co., Ltd. All rights reserved. No part of this Data Book may be reproduced in any form or by any means without the express permission of Fuji Electric. 8. If you have any question about any portion in this Data Book, ask Fuji Electric or its sales agents before using the product. Neither Fuji nor its agents shall be liable for any injury caused by any use of the products not in accordance with instructions set forth herein. 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 2 Quality is our message CONTENTS page 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Description Features Outline Block diagram Pin assignment Ratings and characteristics Characteristics curves Description of each circuit Design advice Application circuit ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ ･･･････････････････ 4 4 4 5 5 6 9 13 17 18 Note • Parts tolerance and characteristics are not defined in all application described in this Data book. When design an actual circuit for a product, you must determine parts tolerances and characteristics for safe and stable operation. 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 3 Quality is our message 1． Description FA7700V/FA7701V are the PWM type DC to DC converter control ICs with 1ch output that can directly drive power MOSFETs. CMOS devices with high breakdown voltage are used in these ICs and low power consumption is achieved. These ICs have the many functions equivalent to those which our conventional version bipolar ICs – FA76XX series- have,and have merits of output ON/OFF control function,directly driving Nch/Pch MOSFETs,low power consumption , higher frequency operation, and less external discrete components. 2． Features ・Wide range of supply voltage.: VCC=2.5 to 20V ・FA7700V—for boost, flyback converter (Maximum output duty cycle is 80%) 　FA7701V—for buck converter (Maximum output duty cycle is 100%) ・output stage consist of CMOS push-pull circuit, and achieves a high speed switching of external MOSFETs. (FA7700V: for Nch-MOSFET driving, FA7701V: for Pch-MOSFET driving) ・High accuracy reference voltage (Error amplifier): 0.88V±2% ・Soft start function. ・Adjustable built-in timer latch for short-circuit protection. ・Output ON/OFF control function ・Less external discrete components needed (2 components less than conventional version of the equivalent products) ・Low power consumption Stand-by current: 40μA(typ.) Operating current: 1.2mA(typ.) (including error amplifier output current and oscillator current) ・High frequency operation: 50kHz to 1MHz ・Package: TSSOP-8(thin and small) 3． Outline units:mm 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 4 Quality is our message 4． Block diagram ＦＡ７７００Ｖ ＲＴ 1 ＶＲＥＦ ＵＶＬＯ 8 0.3V 5.5V 1.5V S.C.DET ON/OFF + S.C.P + 2.2V ＣＳ VREF ＲＥＦ 2 3 4 2.2V BIAS ＯＳＣ 7 6 5 ＶＣＣ 1.5V Power Good Signal ＩＮ− + ON/OFF OFF 0.88V ＯＵＴ + - + + + ＥＲ．ＡＭＰ ＰＷＭ ＦＢ ＧＮＤ ＦＡ７７０１Ｖ ＲＴ 1 ＶＲＥＦ ＵＶＬＯ 8 0.3V 5.5V 1.5V S.C.DET ON/OFF + S.C.P + 2.2V ＣＳ VREF ＲＥＦ 2 3 4 2.2V BIAS ＯＳＣ 7 6 5 ＶＣＣ 1.5V Power Good Signal ＩＮ− + ON/OFF OFF ＯＵＴ 0.88V + - + + ＰＷＭ ＥＲ．ＡＭＰ ＦＢ ＧＮＤ 5． Pin assignment Pin No. 1 2 3 4 5 6 7 8 Pin Name RT REF IN(-) FB GND OUT VCC CS Oscillator timing resistor Internal bias voltage Error amplifier inverting input Error amplifier output Ground Output for driving switching device Power supply ON/OFF, Soft start, Timer latched short circuit protection Function 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 5 Quality is our message 6． Ratings and Characteristics (1) Absolute maximum ratings Item Power supply voltage REF terminal output current OUT terminal source current OUT terminal sink current RT，REF，IN−，FB terminal voltage CS terminal voltage CS terminal sink current Power dissipation Operating ambient temperature Operating junction temperature Storage temperature Symbol Vcc IREF ISOpeak ISOcont ISIpeak ISIcont VRT，VREF VIN-，VFB VCS ICS Pd Ta Tj Tstg Ratings 20 2 -400(peak) -50(continuos) +150(peak) +50(continuos) +2.5(max.) -0.3(min.) Self Limiting≒5.5(max.) -0.3(min.) 200 250(Ta≦25℃) -30∼+85 +125 -40∼+150 Units V mA mA mA V V μA mW ℃ ℃ ℃ Maximum power dissipation curve 300 Maximum power dissipation [mW］ 250 200 150 100 50 0 -30 0 30 60 90 Ambient temperature [℃] 120 150 (2) Recommended operating conditions Item Symbol MIN. TYP. MAX. Supply voltage VCC 2.5 6 18 DC feedback resistor 100 RNF of error amplifier VCC terminal capacitance CVCC 0.1 REF terminal capacitance CREF 0.047 0.1 1 CS terminal capacitance CS 0.01 10 CS terminal sink current Icsin 1 (*1) 50 Oscillation frequency fosc 50 1000 (*1)Lower Limit of ICSIN does not include leak current “IＬ” for capacitor Cs. Set a resistor   “Rcs［ＭΩ］” connected between VCC terminal and CS terminal to satisfy the following equation. Units V kΩ μF μF μF μA kHz VCC − 1.5 VCC − 1.5 < RCS[ MΩ] < 50uA + IL 1uA + IL 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 6 Quality is our message (3) Electrical characteristics (Unless otherwise standard, Ta=25℃,Vcc=6V,RT=22kΩ) (1)Internal Bias Section (REF terminal voltage) Item Symbol Conditions REF terminal source current Output Voltage VREF IREF = 0mA Line Regulation VLINE Vcc = 2.5 to 20V，IREF = 0mA Load Regulation VLOAD IREF = 0 to 2mA VTC1 Ta = -30 to 25℃ Variation with temperature VTC2 Ta = 25 to 85℃ (2)Oscillator Section (Frequency set by RT terminal ) Item Symbol Conditions Oscillation fosc RT = 22kΩ frequency Line Regulation fLINE Vcc = 2.5 to 20V fTC1 Ta = -30 to 25℃, 50k to 1MHz Variation with temperature fTC2 Ta = 25 to 85℃, 50k to 1MHz (3)Error Amplifier Section (IN- terminal , FB terminal ） Item Symbol Conditions IN- terminal, FB terminal Reference Voltage VB :shorted (Voltage Follower) Input current IIN“VB” Vcc = 2.5 to 20V VBLINE Line Regulation VBTC1 Ta = -30 to 25℃ “VB” variation with temperature VBTC2 Ta = 25 to 85℃ Open Loop Gain AVO Unity Gain fT Bandwidth Source IOHE FB terminal = VREF- 0.5V Output Current FB terminal = 0.5V Sink IOLE MIN. 2.16 TYP. 2.23 ±2 ±2 ±0.3 ±0.3 MAX. 2.30 ±14 ±12 Units V mV mV % % MIN. 155 TYP. 185 ±0.1 ±2 ±3 MAX. 215 Units kHz % % % MIN. 0.863 -500 TYP. 0.880 MAX. 0.897 +500 Units Ｖ nA mV % % dB MHz ±1 ±0.3 ±0.3 70 1.5 -220 3 -160 6 ±5 -100 12 μA mA (4)Pulse Width Modulation (PWM) Section (FB terminal voltage and Duty Cycle) Item Symbol Conditions MIN. FB 0% threshold VFB0 Duty Cycle = 0% 0.560 FB 50% threshold VFB50 Duty Cycle = 50% DMAX1 85 RT = 100kΩ,ｆ≒ 50kHz Maximum FA7700 DMAX2 83 RT = 22kΩ,ｆ≒185kHz Duty DMAX3 80 RT = 3kΩ,ｆ≒1MHz Cycle 100 DMAX FA7701 (5)Under Voltage Lock-Out Section (VCC terminal voltage) Item Symbol Conditions ON threshold VCCON OFF threshold VCCOF Hysteresis Voltage VCCHY Ta = -30 to 25℃ Variation with VCCHY temperature Ta = 25 to 85℃ TYP. 0.660 0.880 90 88 86 MAX. 0.760 95 93 92 Units Ｖ Ｖ % % % % MIN. 1.60 0.04 TYP. 2.07 1.93 0.14 ＋0.2 −0.2 MAX. 2.30 0.24 Units Ｖ Ｖ Ｖ mV/℃ mV/℃ 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 7 Quality is our message (6)ON/OFF Section (CS terminal voltage) Item Symbol ON/OFF threshold VONOF Threshold Variation with temperature Conditions MIN. 0.150 TYP. 0.300 +0.5 MAX. 0.450 Units Ｖ mV/℃ VONTC Ta = -30 to 85℃ (7)Soft Start Section (CS terminal voltage) Item Symbol Conditions Threshold Voltage 1 VCS0 Duty Cycle = 0% Threshold Voltage 2 VCS50 Duty Cycle = 50% MIN. 0.560 TYP. 0.660 0.880 MAX. 0.760 Units Ｖ Ｖ (8)Timer Latched Short circuit Protection Section (FB terminal, CS terminal) Item Symbol Conditions MIN. Short Detection Threshold Voltage Latched Mode Threshold Voltage Latched Mode Reset Voltage Latched Mode Hysteresis TYP. 1.500 2.200 2.030 170 1.500 5.500 MAX. 1.650 2.350 2.300 350 1.600 6.500 Units Ｖ Ｖ Ｖ mV Ｖ Ｖ VFBTH VCSTH VCSRE VCSHY VCSCL1 VCSCL2 FB terminal voltage CS terminal voltage CS terminal voltage CS terminal voltage FB terminal1.65V CS sink current = +150μA 1.350 2.050 1.700 50 1.400 4.500 ＣＳ terminal Clamped Voltage (9)Output Stage Section (OUT terminal) Item Symbol Conditions VCC = 6V, Source Current = -50ｍA RONH High Side On Resistance VCC = 2.5V,Source Current = -50ｍA RONH VCC = 6V,  Sink Current = +50ｍA RONL Low Side On Resistance VCC = 2.5V, Sink Current = +50ｍA RONL 330pF Load to GND terminal FA7700 Rise Time tr 330pF Load to VCC terminal FA7701 330pF Load to GND terminal FA7700 Fall Time tf 330pF Load to VCC terminal FA7701 (10)Overall Section (Supply Current to VCC terminal) Item Symbol Conditions OFF mode CS terminal=0V ICCST1 Supply Current Duty Cycle = 0%, OUT:open ICC0 IN- =0V, FB:open Operating mode Supply Current Duty Cycle = 50%, OUT:open ICC1 IN-, FB:shorted Latched mode CS terminal >2.35V ICCLAT Supply Current IN- = 0V, FB:open MIN. TYP. 10 18 5 5 20 25 45 40 MAX. 20 36 10 10 Units Ω Ω Ω Ω ns ns ns ns MIN. TYP. 40 0.9 1.2 0.9 MAX. 100 1.5 2.0 1.5 Units μA mA mA mA 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 8 Quality is our message 7． characteristics　curve Timing resistor vs. Oscillation frequency Oscillation frequency variation[％] 10000 Oscillation frequency ［kHz］ Oscillation frequency vs. ambient temperature 5 4 3 2 1 0 -1 -2 -3 -4 -5 -40 fosc=1MHz 1000 fosc= 1 85kHz fosc=50 kHz 100 10 1 10 Timing resistor R T ［k Ω］ 100 -20 0 20 40 60 80 1 00 Ambient temperature Ta　[℃] FB terminal voltage vs. Duty cycle 100 90 80 Duty cycle　[％] fosc=1MHz Duty cycle　[％] 70 60 50 40 30 20 10 0 0.5 0.7 0.9 1.1 FB terminal voltage　[V] 1.3 fosc=185kHz FA7700 100 90 80 70 60 50 40 30 20 10 0 0.5 CS terminal voltage vs. Duty cycle FA7700 fosc＝1MHz fosc=185kHz 0.7 0.9 1.1 CS terminal voltage　[V] 1.3 FB terminal voltage vs. Duty cycle FA7701 100 90 80 Duty cycle　[％] Duty cycle　[％] 70 60 50 40 30 20 10 0 0.5 0.7 0.9 1.1 FB terminal voltage　[V] 1.3 fosc=185kHz fosc=1MHz CS terminal voltage vs. Duty cycle FA7701 100 90 80 70 60 50 40 30 20 10 0 0.5 0.7 0.9 1.1 CS terminal voltage　[V] 1.3 fosc=185kHz fosc＝1MHz 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 9 Quality is our message Maximum Duty cycle vs. ambient temperature FA7700 94 fosc=50 kHz Maximum Duty cycle　[％] 92 Reference voltage　[V] 0.89 90 88 86 fosc=1MHz 84 82 80 -40 -20 0 20 40 60 Ambient temperature Ta　[℃] 80 100 0.86 -40 -20 0 20 40 60 Ambient temperature Ta　[℃] 80 100 fosc=185kHz Error Amp. Reference voltage vs. ambient temperature 0.90 0.88 0.87 Internal bias voltage vs. ambient temperature 2.28 VCC terminal ON/OFF threshold 2.26 2.24 2.22 2.20 2.18 -40 -20 0 20 40 60 Ambient temperature Ta　[℃] 80 100 2.20 2.15 2.10 2.05 2.00 1.95 1.90 1.85 1.80 Under voltage lock-out vs. ambient temperature Internal bias voltage [V] V CCON V CCOFF -40 -20 0 20 40 60 Ambient temperatureTa　[℃] 80 100 0.40 CS terminal ON/OFF threshold [V] CS terminal ON/OFF threshold vs. ambient temperature 200 CS terminal voltage vs.CS terminal sink current 0.35 0.30 0.25 0.20 0.15 -40 -20 0 20 40 60 Amient temperature Ta　[℃] 80 100 CS terminal sink current　[uA] 180 160 140 120 100 80 60 40 20 0 0 1 2 3 4 5 CS terminal voltage　[V] 6 7 FB1.65V Ta=25℃ Ta=-30℃ Ta=85℃ 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 10 Quality is our message Vcc vs. Operating mode supply current 2.0 Operating mode supply current　 [mA] Vcc vs. operating mode supply current 3.0 Operating mode supply current　[mA] Duty=50% IN(-)-FB:shorted fosc=1MHz Duty=50% IN(-)-FB:shorted fosc=1MHz fosc=185kHz 2.5 2.0 1.5 1.0 0.5 0.0 1.5 1.0 fosc=185kHz 0.5 0.0 0 0.5 1 1.5 Vcc　[V] 2 2.5 3 4 6 8 10 12 14 Vcc　[V] 16 18 20 OFF mode supply current vs. temperature 60 OFF mode supply current　[uA] 55 50 45 40 Vcc= 6V 35 30 -40 -20 0 20 40 60 Temperature Ta　[℃] 80 100 Vcc=20V CS=0V Operating mode supply current　[mA] Operating mode supply current vs. temperature 1.5 1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 -40 -20 0 20 40 60 Temperature Ta　[℃] 80 100 Vcc= 6V (Duty=0%) Vcc= 6V (Duty=50%) RT=22k Ω Vcc=20V (Duty=50%) Latched mode supply current vs. temperature 1.00 Latched mode supply current　[mA] 0.95 0.90 0.85 0.80 0.75 0.70 -40 -20 0 20 40 60 Temperature Ta　[℃] 80 100 Vcc=6V RT=22k Ω CS>2.35V 3.0 Operating mode supply current　[mA] Oscillation frequency vs. operating mode supply current VCC=6V Duty=50% 2.5 2.0 1.5 1.0 0.5 0.0 10 100 Oscillation frequency　[kHz] 1000 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 11 Quality is our message 450 OUT terminal source current　[mA] OUT terminal High side voltage vs. source current 200 OUT terminal sink current　[mA] OUT terminal Low side voltage vs. sink current 400 350 300 250 200 1 50 1 00 50 0 0 5 10 15 20 25 OUT terminal voltage 　[V] Vcc=2.5V Vcc= 6V Vcc= 1 2V Vcc=20V 150 100 50 0 0 0.5 1 OUT terminal voltage　[V] 1.5 Error Amplifier Gain and Phase vs. frequency 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 12 Quality is our message 8． Description of each circuit (1) Reference Voltage Circuit This circuit consists of the reference voltage circuit using band gap reference, and also serves as the power supply of the internal circuit. The precision of output is 2.23V±3%. It is stabilized under the supply voltage of 2.5V or over. The precision of reference voltage of error amplifier circuit is 0.88V±2%, and the reference voltage circuit is connected to the non-inverting input of the error amplifier circuit. (2) Oscillator The oscillator generates a triangular waveform by charging and discharging the built-in capacitor. A desired oscillation frequency can be determined by the value of the resistor “RT”connected to the RT terminal (Fig. 1). The built-in capacitor voltage oscillates between approximately 0.66V and 1.1V with almost the same charging and discharging gradients. You can set the desired oscillation frequency by changing the gradients using the resistor connected to the RT terminal. (Large RT: low frequency, small RT: high frequency) The oscillator waveform cannot be observed from the outside because a RT value : small 1.1V terminal for this purpose is not provided. The oscillator output is connected to the PWM comparator. 0.66V (3) Error Amplifier Circuit The IN(-) terminal (Pin3) is an inverting input terminal. The nonInverting input is internally connected to the reference voltage (0.88V±2%; 25℃). The FB terminal (Pin4) is the output of the error amplifier. Gain setting and phase compensation setting is done by connecting a capacitance and a resistor between the FB terminal and the IN(-) terminal. Vout which is the output voltage of DC to DC converter can be calculated by: 　　　　Vout = VB × OSC 1 RT RT Fig.1 RT value : large fig.2 Vout RNF R1 3 IN(-) R2 + Er.AMP 4 FB VB (0.88V) PWM R1 + R 2 R2 fig.3 Gain AV between the Vout and the FB terminal can be calculated by: 　　　　 AV = − RNF R1 ①Oscillation output ②CS terminal voltage ③Error Amplifier output ④DT voltage (4) PWM comparator The PWM comparator has 4 input terminals. (Fig. 4) The oscillator output ① is compared with the CS terminal voltage ② , and the error amplifier voltage ③ ,then, the lower voltage between ② and ③ is preferred. While the preferred voltage is lower than the oscillator output, the PWM comparator output is LOW. While the preferred voltage is higher than the oscillator output, the PWM comparator output is HIGH(Fig. 5). When the IC starts, the capacitor connected to the + + + ③Error Amplifier output PWM output fig.4 ②CS terminal voltage ④DT voltage ①Oscillation output PWM output pulse fig.5 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 13 Quality is our message CS terminal is charged through the resistor connected to the power supply , and then the output pulses begin to widen gradually as the operation of soft start. In steady operation, the pulse width is determined based on the voltage of the error amplifier③, and then the output voltage is stabilized. The Dead Time control voltage (④DT voltage) of FA7700 and FA7701 has different characteristics to adjust the ICs to various types of power supply circuits being controlled and also to reduce external discrete components as many as possible. FA7700 is developed for fly-back circuits, and boost circuits, and the DT voltage is set in the IC so that the maximum output duty cycle is fixed to 80%(min.). (Maximum output duty cycle changes according to operation frequencies.— See P10 “Maximum output duty vs. temperature”.) It prevents magnetic saturation of the transformer or the like when a short-circuit in the output circuit occurs. FA7701 is developed for buck circuits, and it is designed for the maximum output duty cycle of 100%. The timing chart of PWM comparator is described in Fig. 5. (5) Soft start function As described in Fig. 6, RCS is connected between CS terminal and VCC terminal, and Cs is connected between CS terminal and GND. The voltage of CS terminal rises when starting the power supply, because Cs is charged by Vcc through Rcs. The soft start function starts by charging a capacitor Cs connected to PWM comparator. To estimate the soft start period, the time(ts) between the start and the moment when the width of output pulse reaches 50% is calculated by: VCC Rcs 0.3 V REF OFF C3 ON/OFF + CS Cs 8 5.5V FB 1.5V C1 Output off S.C.P + 2.2V C2 + 1.5V S.C.DET Vcc ts [ms]≒Cs × Rcs × ln( )  Vcc − 0.88 Cs: Capacity of Cs [μF] Rcs: resistance of Rcs [kΩ] Vcc: supply voltage [V] The maximum current flowing in Rcs should be within the recommended value(50μA max.). fig.6 VCC − 1.5 VCC − 1.5 < RCS[ MΩ] < 50uA + IL 1uA + IL (IL: leak current of capacitor Cs) Note) This IC operates ON/OFF function by the CS terminal(CS