DATA SHEET LND494 Pulse-Width-Modulation Control Circuits GENERAL DESCRIPTION FEATURES The LND494 incorporate on a single monolithic chip all the functions required in the construction of a pulse-width-modulation control circuit. Designed primarily for power supply control, these devices offer the systems engineer the flexibility to tailor the power supply control circuitry to his application. The LND494 contains an error amplifier, an on-chip adjustable oscillator, a dead time control comparator, pulse -steering control flip-flop, a 5volt, 5% precision regulator, and output-control circuits. The error amplifier exhibits a commonmode voltage range from -0.3 volts to Vcc-2 volts. The dead-time control compactor has a fixed offset that provides approximately 5% dead time when externally altered. The on-chip oscillator may be by passed by terminating RT (pin 6) to the reference output and providing a sawtooth input to CT (pin 5), or it may be used to drive the common circuits in synchronous multiple-rail power supplies. The uncommitted NON INV INPUT output transistors provide either common-emitter or emitter-follower output capability. Each INV INPUT device provides for push-pull or single-ended output operation, which may be selected through the output-control function. The architecture of FEEDBACK these devices prohibits the possibility of either output being pulsed twice during push-pull DEAD-TIME CONTROL operation. * * * * * * Complete PWM Circuitry Power Control Uncommitted Outputs for 200mA Sink or source current Output Control Selects Single-Ended or Push-Pull operation Internal Circuitry Prohibits Double Pulse at Either Output Variable Dead-Time Provides a stable 5-V Reference Supply, 5% Circuit Architecture Allows Easy Synchronization LND494 (Top View) 1 16 NON INV INPUT 15 INV INPUT 3 14 REF OUT 4 13 OUTPUT CONTROL CT 5 12 Vcc RT 6 11 C2 GND 7 10 E2 C1 8 9 E1 2 Error Amp1 Error Amp2 * Linear Dmensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND494 ABSOLUTE MAXIMUM RATINGS Rating Supply voltage, Vcc Amplifier input voltage Collector output voltage Collector output current Operating free-air temperature range Storage temperature range Lead temperature 1,6 mm from case for 10 seconds Value 41 Vcc+0.3 41 250 Unit V mA 0 to 70 -65 to 150 C 260 RECOMMENDED OPERATING CONDITIONS Value Parameter Unit Supply voltage, Vcc Amplifier input voltage, Vi Collector output voltage,Vo Collector output current(each transistor) Current into feedback terminal Timing capacitor,CT Timing resistor, RT Oscillator Frequency Operating free-air temperature, TA MIN 7 -0.3 MAX 40 Vcc-2 40 V 200 mA 0.47 1.8 1 0.3 10000 500 300 nF k kHz 0 70 C FUNCTIONAL BLOCK DIAGRAM OUTPUT CONTROL RT OSCILLATOR CT C1 DEAD TIME CONTROL COMPARATOR Q1 0.1V DEAD TIME CONTROL E1 C1 C2 NON INVERTING INPUT INVERTING INPUT NON INVERTING INPUT INVERTING INPUT Q2 ERROR AMPLIFIER + PWM COMPARATOR 1 PULSE STEERING FLIP - FLOP E2 - 2 - VCC ERROR AMPLIFIER + REFERENCE FEEDBACK VREF GND * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND494 PARAMETER MEASUREMENT INFORMATION Vc c = 15V V { 150 2W DEAD TIME TEST INPUTS 150 2W CC C1 E1 OUTPUT 1 C2 E2 OUTPUT 2 FEEDBACK 12k RT .01uF CT +1 -1 +2 -2 } ERROR 50k OUTPUT CONTROL REF OUT GND TEST CIRCUIT Vcc Voltage At C1 0 Vcc Voltage At C2 0 Voltage At CT Threshold Voltage Dead-Time Control Input + AMPLIFIER UNDER TEST FEEDBACK TERMINAL VI - 0V Threshold Voltage + Feedback 0.7V MAX Duty Circle 0% VREF OTHER AMPLIFIER - 0% VOLTAGE WAVEFORMS Figure 1: Operational Test Circuit and Waveforms Figure 2: Amplifier Characteristics * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND494 15V 15V 68 2W 90% tf OUTPUT tr 90% OUTPUT 90% 68 2W C L = 15pF C = 15pF L 10% tr 10% TEST CIRCUIT 90% 10% tf 10% OUTPUT VOLTAGE WAVEFORM Figure 3: Common-Emitter Configuration OUTPUT VOLTAGE WAVEFORM TEST CIRCUIT Figure 4: Emitter-Follower Configuration ELECTRICAL CHARACTERISTICS Electrical characteristics over recommended operating free-air temperature range Vcc=15V, f=10kHz(unless otherwise noted) Reference Section Value Parameter Test conditions* Output voltage(Vref) Input regulation Output regulation Output voltage change with temperature Short-circuit output current*** Io=1mA Vcc=7V to 40V Io=1mA to 10mA MIN TYP** MAX 4.75 5 2 1 5.25 25 15 TA = MIN to MAX 0.2 1 Vref=0 35 Unit V mV % mA Oscillator Section (See Figure 1) Value Parameter Test conditions* Unit MIN Frequency Standard deviation of frequency **** Frequency change with voltage Frequency change with temperature***** CT=0.01F,RT =12k All values of VCC, CT, RT and TA constant Vcc=7V to 40V, TA=25C CT =0.01F, RT =12k,TA=MIN TO MAX TYP MAX 10 kHz 10 0.1 % 1 * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND494 Amplifier Section (See Figure 2) Value Parameter Test conditions Input Offset Voltage Input Offset Current Input Bias Current Vo=(pin 3)=2.5V Vo=(pin 3)= 2.5V Vo=(pin 3)=2.5V Common Mode Input Voltage Range Vcc=7V to 40V Open Loop Voltage Amplification Unity Gain Bandwidth Common- Mode Rejection Ratio Output Sink Current Output Source Current Vo=3V,RL=2k Vo=0.5 to 3.5V Vo=0.5 to 3.5V, RL=2k Vo=40V,TA = 25 C VID= -15Mv TO -5v V(PIN3) =0.7v VID= -15mV TO -5V V(PIN3) =3.5v MIN TYP MAX 2 25 0.2 10 250 1 Unit mV nA A -0.3 to Vcc-2 V 70 95 DB 800 kHZ 65 80 dB 0.3 0.7 mA -2 mA *For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions. ** All typical values except for parameter changes with temperature are at TA =25 C ***Duration of the short-circuit should not exceed one second. ****Standard deviation is a measure of the statistical distribution about the mean as derived from the formula. 1/2 = [ N ( xn - x )2 N-1 n=1 ] ******Temperature coefficient of timing capacitor and timing resistor not taken into account Output Section Parameter Collector off-state current Emitter off-state current Collector-emitter saturation Voltage Common-Emitter Emitter-Follower Output control input current Test conditions Vce=40V Vcc =40 V MIN Value TYP* MAX 2 100 A -100 % Vce=Vcc=40V Ve=0 Unit V Ve=0,Ic=200mA Vc=15V, Ie=-200mA VI=Vref 1.1 1.5 1.3 2.5 3.5 mA * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com * LND494 Dead-Time Control Section (See figure 1) Parameter Test conditions Input Bias current (pin4) Maximum Duty Cycle,Each output VI=0 to 5.25V VI(pin 4)=0,CT =0.1F, RT =12K Zero duty cycle Maximum Duty Cycle Input Threshold Voltage (pin4) MIN Value TYP* -2 Unit MAX -10 A 45 3 % 3.3 V 0 PWM comparator section (see figure 1) Parameter Test Conditions Input threshold voltage (pin 3) Input sink current (pin 3) Zero duty cycle V(pin3)= 0.7V MIN 0.3 Value TYP* 4 Unit MAX 4.5 V 0.7 mA Total Device Parameter Test Conditions Standby supply current Average supply current Pin 6 at Vref, all other Vcc=15V inputs and outputs open Vcc=40V VI ( pin 4) =2V, See figure 1 MIN Value TYP 6 9 7.5 MAX 10 15 Unit mA Switching characteristics, Ta=25C PARAMETER TEST CONDITIONS Output voltage rise time Common-emitter configuration See figure 3 Output voltage fall time Output voltage rise time Emitter-follower configuration See Figure 4 Output voltage fall time *All typical values except for temperature coefficient at TA= 25C MIN VALUE TYP* 100 25 100 40 MAX 200 100 200 100 UNIT nS * Linear Dimensions, Inc. * 445 East Ohio Street, Chicago IL 60611 USA * tel 312.321.1810 * fax 312.321.1830 * www.lineardimensions.com *