PULSE-WIDTH-MODULATION CONTROL CIRCUITS

Transcription

1 PULSEWIDTHMODULATION CONTROL CIRCUITS DESCRIPTION The incorporates on a single monolithic chip all the functions required in the construction of a pulsewidthmodulation control circuit. Designed primarily for power supply control, the contains an onchip 5volt regulator, two error amplifiers, adjustable oscillator, deadtime control comparator, pulsesteering flipflop, and outputcontrol circuitry. The uncommitted output transistors provide either commonemitter or emitterfollower output capability. Pushpull or singleended output operation may be selected through the outputcontrol function. The architecture of the prohibits the possibility of either output being pulsed twice during pushpull operation. PIN CONFIGURATION NONINV.INPUT INV.INPUT FEEDBACK DEAD TIME CONTROL CT RT GND D OR N PACKAGE (TOP VIEW) NONINV.INPUT INV.INPUT REFOUT OUTPUT CONTROL E E FEATURES Complete PWM Power Control Circuitry Uncommitted Outputs for 00mA Sink or Source Current Output Control Selects SingleEnded or PushPull Operation Internal Circuitry Prohibits Double Pulse at Either Output Internal Regulator Provides a Stable 5V Reference Supply Variable DeadTime Over Total Range ORDERING INFORMATION Temperature Range 0 C to 85 C Package Orderable Device Package Qty D Units /Tube SOP6L PbFree DR 3000 Units /R&T DIP6L N 5 Units/ Tube FUNCTION TABLE Output Control Pin Grounded Vref Output Function Singleended or Parallel Output Normal PushPull Operation

2 SCHEMATIC DIAGRAM RT CT OSCILLATOR PULSE STEERING FLIP FLOP OUTPUT CONTROL (See Function Table) (3) Q DEAD TIME CONTROL NONINVERTING INPUT =0.V (4) =0.7V ERROR AMPLIFIERS () PWM COMPARATOR T Q E(9) (8) INVERTING INPUT NONINVERTING INPUT INVERTING INPUT FEEDBACK () (6) () (3) ERROR AMP ERROR AMP 0.7mA REFERENCE REGULATOR () REF OUT (4) GND (7) E() () Figure. Representative Block Diagram ABSOLUTE MAXIMUM RATINGS (over operating freeair temperature range, unless otherwise noted) Parameter Symbol Min Max Unit Supply Voltage (Note) Amplifier Input Voltage Collector Output Voltage Collector Output Current Storage Temperature Range VI VO IO Tstg 65 0 Note : All voltages are with respect to the network ground terminal. RECOMMENDED OPERATING CONDITIONS 4 V 0.3 V 4 V ma Parameter Symbol Min Max Unit Supply Voltage Amplifier Input Voltage Collector Output Voltage Collector Output Current(each transistor) Current Into Feedback Terminal Oscillator Frequency Timing Capacitor Timing Resistor Operating Freeair Temperature VI VO IC IF FOSC CT RT TA C 7 40 V 0.3 V 40 V 00 ma 0.3 ma 300 khz nf.8 0 kω 0 85 C

3 ELECTRICAL CHARACTERISTICS (TA = 0 C to 85 C, = V, f = khz, unless otherwise noted) Reference Section Output Voltage Io = ma V Input Regulation Output Regulation Output Voltage Change with Temperature Vcc = 7V to 40V Io = ma to ma TA = 0 to 85 C 5 mv mv % Shortcircuit Output Current (Note ) Vref = 0V ma Note : Duration of short circuit should not exceed one second. Oscillator Section Frequency CT = 0.0uF, RT = kω 6 4 khz Standard Deviation of Frequency (Note3) All values of, CT, RT and TA constant % Frequency Change with Voltage Frequency Change with Temperature = 7 V to 40 V, TA = 5 C CT = 0.0uF, RT = kω TA = 0 C to 85 C % % Note 3: Standard deviation is a measure of the statistical distribution about the mean as derived from the formula. (XnX)² n= N DeadTime Control Section Input Bias Current (pin4) VI = 0 to 5.5 V μa Maximum Duty Cycle, Each Output VI (pin4) = 0V 45 % Input Threshold Voltage (pin4) Zero Duty Cycle 3.3 Maximum Duty Cycle 0 V σ = N 3

4 ErrorAmplifier Section Input Offset Voltage Input Offset Current Input Bias Current VO (pin3) =.5V VO (pin3) =.5V VO (pin3) =.5V mv na μa Commonmode Input Voltage Range Openloop Voltage Amplification Unitygain Bandwidth Commonmode Rejection Ratio Output Sink Current (pin3) = 7V to 40V Low High ΔVO = 3V, VO = 0.5V to 3.5V VO = 0.5V to 3.5V, RL = kω = 40 V, TA = 5 C VID = mv to 5 V V(pin3)=0.7V V db khz db ma Output Source Current (pin3) VID=mV to 5V, V(pin3) = 3.5 V ma PWM Comparator Section Input Threshold Voltage (pin3) Zero Duty Cycle 4.5 V Input Sink Current (pin3) VO (pin3) = 0.7V 0.3 ma Switching Characteristics (TA = 5ºC) Output Voltage Rise Time 00 ns Commonemitter Configuration Output Voltage Fall Time 0 ns Output Voltage Rise Time 00 ns Emitterfollower Configuration Output Voltage Fall Time 0 ns Output Section Collector Offstate Current Emitter Offstate Current VCE = 40 V, = 40 V = VC = 40 V, VE = μa μa Collectoremitter Common Emitter VE = 0, IC = 00 ma.3 Saturation Voltage Emitter Follower VO= V, IE = 00 ma.5 V Output Control Input Current VI = Vref 3.5 ma 4

5 Total Device Parameter Test Conditions Min Max Unit Standby Supply Current Average Supply Current RT = Vref, All Other Inputs and Outputs Open VI (pin4) = V =V =40V TYPICAL PERFORMANCE CHARACTERISTICS 7 ma ma foscillator Frequency and Frequency VariationHz 0k 40k k 4k k % =V TA=5ºC 0.00μF % 0.0μF 0% 0.μF CT=μF Df =% k 4k k 40k 0k 400k M RTTiming ResistanceΩ Frequency variation(δf) is the change in oscillator frequency that occurs over the full temperature range. Figure. Oscillator Frequency and Frequency Variation vs. Timing Resistance AAmplifier Voltage AmplificationdB 0 90 =V VO=3V 80 TA=5ºC k k 0k M ffrequencyhz Figure 3. Amplifier Voltage Amplifcation vs. Frequency 5

6 TEST CIRCUITS VI _ Amplifier Under Test FEEDBACK Vref _ Other Amplifier Figure 4. Amplifier Characteristics V Each Output Circuit 68Ω W Output CL=pF (See Note A) tf tr 90% 90% % % NOTE A: CL Includes Probe and Jig Capacitance. Output Voltage Waveform Figure 5. CommonEmitter Configuration V Each Output Circuit CL=pF (See Note A) 68Ω W Output 90% 90% % % tr tf NOTE A: CL Includes Probe and Jig Capacitance. Output Voltage Waveform Figure 6. EmitterFollower Configuration 6

7 TEST CIRCUITS(CONTINUED) =V Test Input 4 3 DTC FEEDBACK E 8 9 0Ω W 0Ω W Output kω kω μF 6 3 RT CT IN IN IN IN Error Ampifiers OUTPUT CTRL GND 7 E 4 REF Output Figure 7. Deadtime and Feedback Control Circuit Voltage at Voltage at 0V 0V Voltage at CT DTC Threshold Voltage 0V Threshold Voltage FEEDBACK 0.7V Duty Cycle 0% MAX 0% VOLTAGE WAVEFORMS Figure 8. Operational Test Circuit and Waveforms 7

8 TYPICAL APPLICATION CIRCUITS Vin=8.0V to 0V M 33k Comp OC VREF DT CT RT Gnd E E Tip 3 Tip 3 5V T N4934 L N4934 k 35V 4.7k.0 VO=8V IO=0.A 35V 4.7k 4.7k k 0.00 k 40 All capacitors in μf L A T Primary: 0T C.T. #8 AWG Secondary: OT C.T. #36 AWG Core: Ferroxcube 408PL00 3CB Parameter Line Regulation Line Regulation Output Ripple Short Circuit Current Efficiency Test Conditions Vin = V to 40 V Vin = 8 V, IO =.0 ma to.0 A Vin = 8 V, IO =.0 A. Vin = 8 V, RL = 0.Ω Vin = 8 V, IO =.0 A Results 4 mv 0.8% 3.0 mv 0.06% 65 mvpp P.A.R.D.6 A 7% Figure 9. Pulse Width Modulated PushPull Converter 8

9 TYPICAL APPLICATION CIRCUITS(CONTINUED) Vin=V to 4V Tip VO=5.0V IO=.0A k V 8 Comp Vref CT RT D.T. O.C. Gnd E E M 5.k 5.k MR8 5.k 0 V V Parameter Line Regulation Line Regulation Output Ripple Short Circuit Current Efficiency Test Conditions Vin = 8.0 V to 40 V Vin =.6 V, IO = 0. ma to 00 ma Vin =.6 V, IO = 00 ma Vin =.6 V, RL = 0.Ω Vin =.6 V, IO = 00 ma Results 3.0 mv 0.0% 5.0 mv 0.0% 40 mvpp P.A.R.D. ma 7% Figure. Pulse Width Modulated PushDown Converter 9

10 B θ3 C4 PHYSICAL DIMENSIONS SOP6L A A A3 D D B B D θ A θ4 R θ C R C3 Symbol A A A A3 B B B C C3 Dimension(mm) Min Max (TYP) 0.35(TYP) (TYP) Symbol C4 D D D R R θ θ θ3 θ4 Dimension(mm) Min Max 0.0(TYP).05(TYP) (TYP) 0.(TYP) 8 (TYP) 8 (TYP) 4 (TYP) (TYP)

11 C4 C5 DIP6L D A θ B θ D D C3 A5 A A3 A A4 Symbol A A A A3 A4 A5 B Dimension(mm) Dimension(mm) Symbol Min Max Min Max (TYP) 0.46(TYP).54(TYP) 0.5(TYP) 0.99(TYP) (TYP) C3 C4 C5 D D D θ θ (TYP) (TYP) 8º (TYP) 5º (TYP)