MC34063(A) Description. Features. Applications. Function Diagram DC/ DC CONVERTER CONTROL IC

Transcription

1 DC/ DC CONVERTER CONTROL IC Description The MC34063 is a monolithic control circuit containing the primary functions required for DC/ DC converters. The device consists of internal temperature compensated reference, comparator, controlling duty cycle oscillator with an active current limit circuit, driver and high current output switch. This device is specifically designed to be incorporated in step down, step- up and voltage- inverting application with few external components. The accuracy of ± 2% internal voltage reference and low quiescent current of 1.6mA are also major configurations. Features 3V to 26V Input Voltage Operation. Internal 1.2A Peak Current Switch. Internal ±2% Voltage Reference. Low Quiescent Current at 1.6mA. Frequency Operation from 100Hz to 100KHz. Low Dropout Operation: 100% Duty Cycle Current Limiting. Standard SOP8/ DIP8 Package Applications DC- DC Converter Module ADSL Modems Automotive Battery Chargers Function Diagram 第 1 页共 10 页

2 Pin Configuration Symbol Pin NO. Description SC 1 1.2A Switch Collector SE 2 Darlington Switch Emitter TC 3 Oscillator Timing Capacitor GND 4 Power GND FB 5 Feedback Comparator Inverting Input VCC 6 Power Supply Input IPK 7 High- side Current Sense Input, VCC - VIPK=300mV DRI 8 Drive Collector Absolute Maximum Ratings Supply voltage.. 26V Comparator input voltage range V~26V Switch collector voltage Switch emitter voltage. 26V 26V Switch collector to emitter voltage...26v Driver collector voltage. 26V Switch current.. 1.2A Power dissipation and thermal characteristics DIP package Ta= W P Package Thermal Resistance /W P Package SOP package Ta= mW D Package Thermal resistance /W D Package Operating junctiontemperature Operating ambient temperature range ~70 Storage temperature range ~150 第 2 页共 10 页

3 Electrical Characteristics (Vcc= 5V, Ta=25 unless otherwise specified.) Oscillator Parameter Test Conditions Symbol MIN. TYP. MAX. Unit Frequency VPIN5 = 0V,CT = 1nF fosc KHZ Charging Current 5.0V~VCC~26V ICHG µa Discharge Current 5.0V~VCC~26V IDISCHG µa Voltage Swing PIN 3 VOSC 0.6 V Discharge to Charge Current Ratio VIPK(SENSE) = VCC IDISCHG/ ICHG 6.0 Current Limit Sense Voltage ICHG= IDISCHG VIPK(SENSE) mv Output Switch Saturation Voltage Darlington Connection Saturation Voltage ISW= 800mA; Pins 1, 8 connected RPin 8 = 82Ω to VCC ISW = 1.0A, Forced β = 20 VCE(SAT) V VCE (SAT) V DC Current Gain ISW= 1.0A; VCE= 5.0V hfe Collector Off- State Current VCE = 26V IC(OFF) 10 na Comparator Threshold Voltage Ta= 25 VFB V TA = Tlow to Thigh V Threshold Voltage Line Regulation 3.0V~ VCC~ 26V REG line mv Input Bias Current Supply Current Vcc=5V Pin5=0V Pin2,3,4=GND VIPK(SENSE)= VCC VPIN 5>VFB 5.0V~ VCC~ 26V CT=0.001µF, PIN2=GND Remaining Pins Open IIB µa ICC ma 第 3 页共 10 页

4 Typical Performance Characterist 第 4 页共 10 页

5 Application Information Design Tables for Application V SAT = Saturation voltage of the output switch. V F = voltage drop of the ringback rectifier The following power supply characteristics must be chosen: V IN -Nominal input voltage. V OUT -Desired output voltage, V OUT =1.25 (1 + RB/RA) F MIN - Minimum desired output switching frequency at the selected values for V IN and l OUT V RIPPLE (P-P) - Desired peak-to-peak output ripple voltage.in practice, the calculated value will need to be increased due to the capacitor equivalent series resistance and board layout. The ripple voltage should be l OUT - Desired output current. kept to a low value since it will directly effect the line and load regulation 第 5 页共 10 页

6 Typical Application Fig.1 Step-Down Converter Line Regulation VIN = 10V IO=500mA 40mV Load Regulation VIN = IO=10mA ~ 500mA 5mV Short Circuit Current VIN RL = 0.1Ω 1.3A Fig.2 Step-Down Converter with External PNP Saturation Switch 第 6 页共 10 页

7 Typical Application (Continued) Fig.3 Step-Up Converter Line Regulation VIN = 8V IO=180mA 50mV Load Regulation VIN = IO=80mA ~ 180mA 10mV Fig.4 Step-up Converter with External NPN Switch 第 7 页共 10 页

8 Typical Application (Continued) Fig.5 lnverting Converter Fig 6. Voltage lnverting Converter With PNP Saturated Switch Line Regulation 20mV Load Regulation 100mV 第 8 页共 10 页

9 Package description SOP8 Package outline dimenesions Symbol Dimensions ln Millimeters(mm) Min. Max. A A A b C D E E e 1.270(BSC) L θ 0 8 第 9 页共 10 页

10 DIP8 Package outline dimenesions Symbol Min. Dimensions ln Millimeters(mm) Max. A A A B B (BSC0) C D E E e 2.540(BSC) L E 第 10 页共 10 页