• DATA SHEET LND34063A DC-to-DC Converter Control Circuits GENERAL DESCRIPTION The LND34063A is a monolithic control circuit containing the primary functions required for DC-to-DC converters This device consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This device was specifically designed to be incorporated in Step-down and Step-up and Voltage-Inverting applications with a minimum number of external components. FEATURES • • • • • • Operation from 3.0V to 40V Input Low Standby Current Current Limiting Output Switch Current to 1.5A Frequency Operation to 100kHz Precision 2% Reference PIN CONNECTIONS Driver Collector Switch Collector Switch Emitter Timing Capacitor Ground LND34063A Ipk Sense V CC Comparator Inverting Input • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND34063A ABSOLUTE MAXIMUM RATINGS Rating Symbol Value Unit Power Supply Voltage Vcc 40 Vdc Comparator Input Voltage Range VIR -0.3 to +40 Vdc Switch Collector Voltage VC(Switch) 40 Vdc Switch Emitter Voltage(Vpin=40V) VE(switch) 40 Vdc Switch Collector to Emitter Voltage VCE(switch) 40 Vdc Driver Collector Voltage Vc(driver) 40 Vdc Driver Collector Current(Note 1) Ic(driver) 100 mA Switch Current Isw 1.5 A Operating Junction Temperature TJ +150 ºC Operating Ambient Temperature TA 0 to +70 ºC Storage Temperature Tstg -65 to +150 ºC SCHEMATIC DIAGRAM 8 Driver CollectorO 1 OSwitch Collector 1 3 2 S Q Q2 Q1 CR I pk Sense O 7 100 I pk 2 Switch O Emitter 3 O Timing Capacitor C Oscillator T V O6 CC + - Comparator 5 Inverting O Input 1.25 V Reference 4 O Ground • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND34063A ELECTRICAL CHARACTERISTICS Vcc=5.0V,TA=Tlow to Thigh, unless otherwise specified.) Characteristics Symbol Min Typ Max Unit fOSC 24 33 42 kHz Ichg 24 35 42 µA Idischg 140 220 260 µA Idischg/Ichg 5.2 6.5 7.5 - Vipk(sense) 250 300 350 mV Vce(sat) - 1.0 1.3 V Vce(sat) - 0.45 0.7 V hFE 50 75 - - Ic(off) - 40 100 µA Vth 1.225 1.21 1.25 - 1.275 1.29 V Regline - 1.4 5.0 mV IIB - -20 -400 nA Icc - - 4.0 mA Oscillator Frequency (Vpin5=0V, CT=1.0nF, TA=25ºC) Charge Current (Vcc=5.0V to 40V, TA =25ºC) Discharge Current (Vcc=5.0V to 40V, TA=25ºC Discharge to charge Current ratio (Pin 7 to Vcc, TA =25ºC Current Limit Sense Voltage (Ichg=I dischg, T=25ºC Output Switch(Note 2) Saturation Voltage Darlington Connection (Isw=1.0 A, Pins 1,8 connected) Saturation Voltage, Darlington Connection (Isw=1.0A, Rpin8=82Ω to Vcc, forcedβ=20) DC Current Gain (Isw=1.0A, Vce=5.0V TA = 25º C Collector Off-State Current (Vce=40V) Comparator Threshold Voltage (TA=25ºC) (TA=Tlow to Thigh) Threshold Voltage Line Regulation (Vcc=3.0V to 40V) Input Bias Current (Vin=0V) Total Device Supply Current (Vcc=5.0V to 40V, Ct=1.0nF, Pin 7=Vcc,Vpin 5>Vth, Pin 2=Gnd, remaining pins open) Notes: 1. Maximum package power dissipation limits must be observed. 2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient temperature as possible. • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND34063A SOME TYPICAL APPLICATIONS 170µH L 8 180 1 1 3 2 S Q Q2 Q1 CR 7 100 I pk Rsc 0.22 Oscillator T 6 V O IN 12 V 2 C 3 100 CT 1500pf 1.25 V Reference + + - 4 5 47k + 330 2.2k R1 1.0 µH V OUT O 28V/175mA R2 O VOUT + 100 Co Optional Filter Fig 1 : STEP UP CONVERTER 8 1 1 3 S 2 Q 8 O VOUT 1 Q2 3 2 S I 6 pk Oscillator 100 2 C T - I Rsc 3 O + Q1 7 100 Rsc 1.25 V Reference 6 V O IN C 2 T 3 O - 1.25 V Reference 4 5 O O pk Oscillator + 4 5 O VOUT R --> 0 for Constant V IN Q2 CR 7 V O IN Q Q1 CR R 1 O O 2a: External NPN Switch 2b: External NPN Saturated Switch Fig 2 : External Boost Connections for Ic Peak Greater than 1.5A • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND34063A 8 1 1 3 2 S Q Q2 Q1 CR 7 100 I Rsc 0.33 V O IN 25 V pk 2 C Oscillator T 6 3 + 100 CT 470pf 1.25 V Reference + - 220µH L 4 5 V OUT O 5.0V/500mA R2 3.6k + 470 1.2k R1 1.0 µH O VOUT + 100 Co Optional Filter Fig 3 : STEP DOWN CONVERTER 8 8 1 1 1 1 3 S 2 Q 3 Q2 S 2 Q1 CR I V O IN Q1 CR 100 100 6 O VOUT Q2 7 7 Rsc Q pk C Oscillator 2 3 O + - I pk Rsc T O VOUT 6 V O IN - 3 1.25 V Reference 4 5 4 5 2 T O + 1.25 V Reference O O C Oscillator O O 4b: External NPN Saturated Switch 4a: External NPN Switch Fig4 : External Boost Connections for Ic Peak Greater than 1.5A • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND34063A 8 1 1 3 2 S Q Q2 Q1 CR 7 100 I Rsc 0.33 C Oscillator T 6 V O IN 25 V 2 pk 3 100 CT 470pf 1.25 V Reference + + - 220µH L 4 5 3.6k R1 1.0 µH V OUT O 5.0V/500mA R2 + 470 1.2k O VOUT + 100 Co Optional Filter Fig 5 : VOLTAGE INVERTING CONVERTER 8 1 1 3 2 S Q 8 I pk Oscillator 2 C T - I Rsc 3 1.25 V Reference O VOUT 6 V O IN pk Oscillator Q1 2 C T 3 O + - 4 5 1.25 V Reference 4 5 O O O VOUT Q2 100 O + Q 7 100 6 S CR 7 Rsc 3 2 Q1 CR V O IN 1 1 Q2 O O 6a: External NPN Switch 6b: External NPN Saturated Switch Fig6 : External Boost Connections for Ic Peak Greater than 1.5A • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com • LND34063A Figure 7: Design Formula Table Calculation Step-Up Step-down Voltage-Inverting tON/tOFF (Vout+VF-VIN(min) ) / (VIN(min) -Vsat) (Vout+VF ) / (Vin(min) -Vsat -Vout) ( Vout|+VF ) / (Vin -Vsat ) (tON/tOFF) max 1/ f MIN 1/ f MIN 1/ f MIN CT 4.0 x 10 ton 4.0 x 10 ton 4.0 x 10 ton IPK(switch) 2 Iout (max)(ton/toff + 1) 2 Iout(max) 2 Iout (max)(ton/toff + 1) RSC 0.3 / Ipk(switch) 0.3 / Ipk(switch) 0.3 / Ipk(switch) L(min) (Vin(min) –Vsat )/(Ipk(switch))=tout(max) (Vin(min) – Vsat -Vout ) / (Ipk(switch)) = tout(max) (Vin(min) –Vsat ) / (Ipk(switch)) = tout(max) CO 9(Ioutt on) / (Vripple(pp)) Ipk(switch) (ton + toff) / 8V ripple(pp) 9(Ioutt on) / (Vripple(pp)) -5 -5 -5 Terms and Definitions Vsat-Saturation voltage of the output switch VF –Forward voltage drop of the output rectifier. The following power supply characteristics must be chosen: VIN-Nominal input voltage Vout-Desired output voltage, |Vout |=1.25 (1 +R2 / R1) IOUT-Desired output current fmin-Minmum desired output switching frequency at the selected values of VIN and IO Vripple(p-p)- Desired peak-to-peak output ripple voltage. In pratice, the calculated capacitor value will need to be increased due to its equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it will directly affect the line and load regulation. • Linear Dimensions, Inc. • 445 East Ohio Street, Chicago IL 60611 USA • tel 312.321.1810 • fax 312.321.1830 • www.lineardimensions.com •