Green Mode PWM Controller

Transcription

1 电动车充电方案 NCN5201DX,MAX:70V3A, 无风扇设计, 外壳不需要开散热孔, 效率 90, 咨询 GENERAL DESCRIPTION The series are high performance fixed frequency for Off-Line and DC-to-DC converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparable, and a high current totem pole output ideally suited for driving a power MOSFET. Also included are protective features consisting of input and reference under voltage lockouts each with hysteria, cycle-by-cycle current limiting, programmable output dead time, and a latch for single pulse metering. Difference between members of this series is the under-voltage lockout thresholds. The has UVLO thresholds of 16 V (on) and 10 V (off), ideally suited for off-line converters. The is offered in SOP-8 and DIP-8packages. FEATURE Proprietary frequency shuffling technology for improved EMI performance Leading edge Blanking on current sense input. Internal synchronized slope compensation. Extended burst mode control for improved efficiency and minimum standby power design Low VDD start up current and low operating current. Cycle-by-Cycle Current Limiting Power on Soft-start, Programmable CV and CC Regulation VDD under Voltage Lockout with Hysteresis (UVLO), OVP, OCP, OLP, Clamp VDD Trimmed Oscillator Discharge Current for Precise Duty Cycle Control Adjustable Switching Frequency up to 500 khz Internally Trimmed Reference with under voltage Lockout High Current Totem Pole Output Under voltage Lockout with hysteresis Low Start-Up and Operating Current Up to 28V VCC Operation +500 ma/ 800 ma Source / Sink Capability TYPICAL APPLICATIONS Power Supplies for PC Silver Boxes TV/Set-Top Box Power Supplies Battery Charger Flyback and Forward Converter 1 OFFLINE CONTROLLER 1 8 PIN CONNECTIONS MARKING DIAGRAM Specific Device Code DX: Assembly Location XX: Year XX: Work Week ORDERING INFORMATION Part Number Package Type Production Flow. DX SOP-08L -40 C to +85 C* *Design Guarantee: The device is guaranteed to meet the specifications from 0 C to 70 C. Specifications over the 40 C to 85 C operating temperature range are assured by design, characterization and correlation with the statistical process controls - 1 -

2 TYPICAL APPLICATION SCHEMATIC BLOCK DIAGRAM - 2 -

3 PIN FUNCTION DESCRIPTION Pin No. Function Description 1 GND Connect this pin to the pre converter ground. 2 CS 3 RT Monitors the primary current and allows the selection of the ramp compensation amplitude. A resistor connected to ground fixes the switching frequency.500 khz is possible. 4 DRV This pin connects to the MOSFET gate 5 GND The controller ground pin 6 VCC DC power supply pin 7 PG_OK/REF5V 8 FB The Pin voltage is high (5 V) when the PWM stage is in a normal, steady state situation and low otherwise. This signal serves to inform the downstream converter that the PFC stage is ready and that hence, it can start operation. Feedback input pin. PWM duty cycle is determined by voltage level into this pin and current-sense signal level at Pin 2. ABSOLUTE MAXIMUM RATINGS Rating Total Power Supply and Zenger Current Symbol Value Unit (I CC +I Z ) 30 ma Power Supply voltage, VCC pin voltage Vcc 28 V Output Current, Source or Sink (Note 1) I O 1 A Output Energy (Capacitive Load per Cycle) w 5 u Current Sense and Voltage Feedback Inputs V in -0.3 to +5.5 V Maximum Power TA=25 C P D 862 mw Thermal Resistance Junction to Air R JA 1 C/ Maximum Power TA=25 C P D 1.25 W Thermal Resistance Junction to Air R JA 1 C/ Operating Junction Temperature T J +150 C Lead Temperature (Soldering, 10sec) TLEAD +300 C Storage Temperature Range T stg -65 to C ELECTRICAL CHARACTERISTICS (VCC=15V, RT=10k, CT=3.3nF, TA=TLOW to THIGH Parameter Symbol Conditions Min. Typ. Max. Unit FEEDBACK SECTION Open loop feedback voltage FB pin=open VFBOL V FB pin maximum current FB Pin= GND IFB 1 ma ZFB_IN -- Input Impedance 10 K Internal Diode forward voltage -- Vf 0.75 V - 3 -

4 CURRENT SENSE SECTION Gain GV V/V Current Sense Voltage Threshold VI(MAX) VILIM V Power Supply Rejection Ratio PSRR 25V db Input Bias Current IBIAS A Propagation Delay (Current Sense Input to gate turned off) - tilim ns OSCILLATOR SECTION Oscillator Frequency f TJ = 25 C khz Frequency Change with Voltage 25V % Oscillator Amplitude VOSC 1.6 VP-P Maximum operating frequency f 500 khz PWM SECTION D(Max) % PGOK/REF5V Line Regulation PG 25V mv VPG OKH PG VREF TJ = 25 C, IREF = 1mA V Icap_ref ma DRIVE OUTPUT VOL Low Output Voltage ISINK = 20mA V ISINK = 200mA V High Output Voltage VOH ISOURCE = 20mA V ISOURCE = 200mA V Rise Time tr TJ = 25 C, CL= 1nF ns Fall Time tf TJ = 25 C, CL= 1nF ns DRV Source resistance RSRC DRV Sink resistance RSINK 6 19 SUPPLY SECTION AND VCC MANAGEMENT Startup threshold at which driving VCC pulses are authorized increasing VCC(on) V Min. Operating Voltage (After Turn On) Hysteresis between VCC(on) and VCC(min) VCC decreasing VCC(off) V VCC(HYS) V TOTAL STANDBY CURRENT Start-Up Current IST ma Operating Supply Current ICC(OPR) Vpin3=Vpin2=ON ma Tthat is synchronized with the PWM clock to the control voltage, the I perturbation will decrease to zero on succeeding cycles. This compensation ramp(m3) must have a slope equal to or slightly greater than m2/2 for stability. With m2/2 slope compensation, the average inductor current follows the control voltage yielding true current mode operation. The compensating ramp can be derived from the oscillator and add to either the Voltage Feedback or Current Sense inputs

5 APPLICATION INFORMATION Introduction The hosts a high performance current mode controller specifically developed to drive power supplies designed for the ATX and the adapter market: Current Mode operation: implementing peak current mode control topology, the circuit offers supplies. Adjustable switching frequency: a resistor to ground precisely sets the switching frequency between 50 khz and a maximum of 500 khz. There is no synchronization capability. Internal frequency jittering: Frequency jittering softens the EMI signature by spreading out peak energy within a band 5% from the center frequency. Wide Vcc excursion: the controller allows operation up to 28 V continuously and accepts transient voltage up to 30 V during 10 ms with IVCC < 20 ma. standby power represents a difficult exercise when the controller requires an external, lossy, resistor connected to the bulk capacitor. The to be less than 100 _A maximum, helping the designer to reach a low standby power level. Shutdown: if an external transistor brings the FB pin down, the controller is shut down, but all internal biasing circuits are alive. When the pin is released, a Internal ramp compensation: a simple resistor connected from the CS pin to the sense resistor allows the designer to inject ramp compensation inside his design. PG_ OK REF: the circuit detects when the circuit it is in a startup or fault condition. In the first case, Pin7 is in high state and lowotherwise. Pin7 serves to control the downstream converter operation in response to the PFC state. Current Sensing and leading edge blanking Cycle-by-Cycle current limiting is offered in current mode PWM control. The switch current is detected by a sense resistor into the sense pin. An internal leading edge blanking circuit chops off the sense voltage spike at initial MOSFET on state due to snubber diode reverse recovery so that the external RC filtering on sense input is no longer required. The current limit comparator is disabled and thus cannot turn off the external MOSFET during the blanking period. PWM duty cycle is determined by the current sense input voltage and the FB input voltage. : The high to permit a large energy storage in a small VCC capacitor value. This helps to operate with a together with a small VCC capacitor, will not hamper the To further reduce the standby power, the current of the controller is extremely low, below 15 m refore beconnected to the bulk capacitor or directly to the mains input voltage to further reduce the power dissipation. The first step starts with the calculation of the VCC capacitor which will supply the controller when it operates until the auxiliary winding takes over. Experience shows that this time t1 can be between 5 ms and 20 ms. If we consider we need at least an energy reservoir for a t1 time of 10 ms, the VCC capacitor must be larger than: Let us select a 4.7 _F capacitor at first and we were too optimistic for the time t1. The VCC capacitor being known, we can now evaluate the charging current we need to bring the VCC voltage from 0 to - 5 -

6 the VCCon of the IC, 18V typical. This current e lowest mains (85 V rms) to be less than 3 s (2.5 s for design margin): If we account for the 15uA that will flow inside the controller, then the total charging current delivered by the ua. network to the mains that the will be the smallest when VCC reaches the VCCon of the controller: To make sure this current is always greater than 49uA, be extracted: This calculation is purely theoretical, and assumes a constant charging current. In reality, the take over time can be shorter (or longer!) and it can lead to a reduction of the VCC capacitor. Hence, a decrease in charging current and an sistor, thus reducing the standby power. Laboratory experiments on the prototype are thus mandatory to fine tune the converter. If we chose the 413k resistor as suggested by Equation 4, the dissipated power at high line amounts to: Now that the first VCC capacitor has been selected, we not disappear when in deep that refreshing pulses are likely to be widely spaced, inducing a large ripple on the VCC capacitor. If this ripple is too large, chances exist to touch the VCC min and reset the sequence. A solution is to grow this capacitor but it will obviously be detrimental to the The option offered in Figure 1 elegantly solves this potential issue by adding an extra capacitor on the auxiliary winding. However, this component is separated from the VCC pin via a simple diode. You therefore have the ability to grow this capacitor as youneedtoensurethe controller without jeopardizing the and standby power. A capacitor ranging from 22 to 47uF is the typical value for this device. One note on thestart-upcurrent. If educingit helpsto improve the standby power, its value cannot fall below a certain level at the minimum input voltage. Failure to inject enough current (30uA) at low line will turn a converter in fault into an auto-recovery mode since the SCR won t remain latched. To build a sufficient design margin, we recommend to keep at least 60uA flowing at the lowest input line (80 Vrms for 85V minimum for instance). (eq.5) - 6 -

7 Figure 1. The Startup Resistor Can Be Connected to the Input Mains for Further Power Auto : supply experiences a severe overloading situation, an internal error flag is raised and starts a countdown timer. If the flag is asserted longer than 100ms, the driving pulses are stopped and the VCC pin slowly goes down to around 10V. At this point, the controller due to the resistive starting network. When VCC reaches VCCon, the controller attempts to absence of the fault. If the fault is still there, the supply enters another If the fault has cleared, normal operation. Figure 2. ated for Faults Longer than 100 ms Slope Compensation: The includes an internal ramp compensation signal. This is the buffered oscillator clock delivered only during the on time. Its amplitude is around 5V at the maximum means used to cure sub harmonic oscillations in Continuous Conduction Mode (CCM) operated signal will be disconnected from the CS pin, Current mode converters. These oscillations take place at half the switching frequency and occur only during CCM with a 50%. To lower the current loop gain, one usually injects between 50% and 100% of the inductor downslope. Figure 3 depicts how internally the ramp is generated. Please note that the ramp during the off time

8 Figure 3. Inserting a Resistor in Series with the Current Sense Information Brings Ramp Compensation and In the E controller, the oscillator ramp features a clock operates at a 65kHz frequency, then the available oscillator slope corresponds to: (eq.6) In our flyback design, let s assume that our primary inductance Lp is 770uH, and the SMPS delivers 19V with a Np:Ns ratio of 1:0.25. The Sp is thus given by: (eq.7) Given a sense resistor of 330m, the above current ramp turns into a voltage ramp of the following amplitude: Slope Compensation: Oscillator timing capacitor, CT, is chargedby (eq.8) If we select 50% of the downslope as the required amount of ramp compensation, then we shall inject a ramp whose slope is 17 mv/_s. Our internal compensation being of 208 mv/_s, the divider ratio (divratio) between Rcomp and the internal 20k resistor is: (eq.9) The series compensation resistor value is thus: (eq.10) A resistor of the above value will then be inserted from the sense resistor to the current sense pin. We recommend adding a small capacitor of 100 pf, from the current sense pin to the controller ground for an improved immunity to the noise. Please make sure both components are located very close to the controller

9 PG_Vref through RT and discharged by an internal current source. During the discharge time, the internal clock signal blanks the output to the low state. Selection of RT and CT therefore determines both oscillator frequency and maximum duty cycle. Charge and discharge times are determined by the formulas: tc = 0.55 RT CT Frequency, then, is: f=(tc + td)-1 (eq.11) (eq.12) Figure 4. Oscillator Dead Time & Frequency 电动车充电方案 NCN5201DX,MAX: 70V3A, 无风扇设计, 外壳不需要开散热孔, 效率 90 注 :MAX70V 10A 的即将上市, 敬请期待 - 9 -

10 PACKAGE OUTLINES PACKAGE DIMENSIONS SOP 8 Small Outline Package UNIT : inch

11 Shipping packing SOP-8 tape & Reel: 1Pc / device 2500 devices / Reel 12 Reel / Carton (30,000Pcs / Carton) Label Label

12 EMBOSSED TAPE AND REEL DATA CARRIER TAPE SPECIFICATIONS DIMENSIONS Tape B 1 Max D D 1 E F K P 0 P 2 R Min T Max W Max (Note 1) 4.55 mm mm 1.0 Min mm mm 2.4 mm mm mm 25 mm 0.6 mm 8.3 mm 8 mm (0.179 ) 0.0 (0.039 ) (0.069 (0.138 Max (0.157 (0.079 (0.98 ) (0.024 ) (0.327 ) ( or ) ) (0.094 ) ) ) mm 0.0) Min (0.020 ) 8.2 mm 1.5 mm mm 6.4 mm 30 mm mm 12 mm (0.323 ) Min (0.217 Max (1.18 ) (0.470 (0.060 ) ) (0.252 ) ) 12.1 mm mm 7.9 mm 16.3 mm 16 mm (0.476 ) (0.295 Max (0.642 ) ) (0.311 ) 20.1 mm mm 11.9 mm 24.3 mm 24 mm (0.791) (0.453 Max (0.957 ) ) (0.468 )

13 REEL DIMENSIONS A B C Reel Tape D E Min Max Min Max Min Max (7.01) 16.0 (0.63) 50.0 (1.97) 6.5 (0.26) 7.5 (0.30) 16.4 (0.65) 18.4 (0.72) 22.4 (0.88) 19.4 (0.76) (12.99) 12.0 (0.47) (7.01) 4.5 (0.18) 5.5 (0.22) 12.4 (0.49) 14.4 (0.57) 18.4 (0.72) 15.4 (0.61) (12.99) (5.91) 10.0 (0.39) 11.0 (0.43) 56.4 (2.22) 58.4 (2.30) 62.4 (2.46) 59.4 (2.34) (12.99) 44.0 (1.73) (3.94) 10.0 (0.39) 11.0 (0.43) 44.4 (1.75) 46.4 (1.83) 62.4 (2.46) 47.4 (1.87) (12.99) 32.0 (1.26) (3.94) 10.0 (0.39) 11.0 (0.43) 32.4 (1.28) 34.4 (1.35) 38.4 (1.51) 35.4 (1.39) (12.99) 24.0 (0.94) 60.0 (2.36) 9.5 (0.37) 10.5 (0.41) 24.4 (0.96) 26.4 (1.04) 30.4 (1.51) 27.4 (1.08) (12.99) 16.0 (0.63) 6.5 (0.26) 7.5 (0.30) 16.4 (0.65) 18.4 (0.72) 22.4 (0.88) 19.4 (0.76) (12.99) 12.0 (0.47) 4.5 (0.18) 5.5 (0.22) 12.4 (0.49) 14.4 (0.57) 18.4 (0.72) 15.4 (0.61) (12.99) 8.0 (0.31) 50.0 (1.97) 2.5 (0.10) 3.5 (0.14) 8.4 (0.33) 9.9 (0.39) 14.4 (0.57) 10.9 (0.43) (7.01) 12.0 (0.47) 50.0 (1.97) 4.5 (0.18) 5.5 (0.22) 12.4 (0.49) 14.4 (0.57) 18.4 (0.72) 15.4 (0.61) (7.00) 8.0 (0.31) 50.0 (1.97) 2.5 (0.10) 3.5 (0.14) 8.4 (0.33) 9.9 (0.39) 14.4 (0.47) 10.9 (0.43) (12.99) 8.0 (0.31) 50.0 (1.97) 4.0 (0.16) 5.0 (0.20) 8.4 (0.33) 9.9 (0.39) 14.4 (0.57) 10.9 (0.43) (7.00) 8.0 (0.31) 50.0 (1.97) 4.0 (0.16) 5.0 (0.20) 8.4 (0.33) 9.9 (0.39) 14.4 (0.57) 10.9 (0.43)