AP3842

AP3842 ANACHIP | Alldatasheet

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High Performance Current Mode PWM Controller AP3842/3/4/5 This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product. Rev.1.0 Oct.11, 2004 „ Features

• Optimized for Off-Line and DC to DC Converters
• Low Start-Up Current ( ≦0.5mA)
• Automatic Feed Forward Compensation
• Pulse-by-Pulse Current Limiting
• Enhanced Load Response Characteristics
• Under-Voltage Lockout (UVLO) with Hysteresis
• Double Pulse Suppression
• High Current Totem Pole Output
• Internally Trimmed Bandgap Reference
• Current Mode Operation to 500KHZ
• Low Ro Error Amplifier „ Pin Connections PDIP-8L, SOP-8L COMP. VFB VREF ISENSE RT/CT OUTPUT GROUND VI Top View „ General Description The AP3842/3/4/5 family of control ICs provides the necessary features to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. Internally implemented circuits include under voltage lockout featuring start-up current less than 0.5 mA, a precision reference trimmed for accuracy at the error amp input, logic to insure latched operation, a PWM comparator which also provides current limit control, and a totem pole output stage designed to source or sink high peak current. The output stage, suitable for driving N-Chan nel MOSFETs, is low in the off-state. Differences between members of this family are the under-voltage lockout thresholds and maximum duty cycle ranges. The AP3842 and AP3844 have UVLO thresholds of 16V(on) and 10V(off), ideally suited for off-line applications. The corresponding thresholds for the AP3843 and AP3845 are 8.5V and 7.6V. The AP3842 and AP3843 can operate to duty cycles approaching 100%. A range of the zero to < 50% is obtained by the AP3844 and AP3845 by the addition of an internal toggle flip flop which blanks the output off every other clock cycle. „ Ordering Information AP 384X X X X Package S8:SOP-8L N8:PDIP-8L Packing Blank: Tube Part No. 2:3842 3:3843 4:3844 5:3845 Lead Free Blank : Normal L : Lead Free Package A : Taping

High Performance Current Mode PWM Controller AP3842/3/4/5 Anachip Corp. „ Block Diagram ( toggle flip flop used only in AP3844 and AP3845 ) S/R 5V REF T S RR 1V CURRENT SENSE COMPARATOR PWM LATCH OUTPUT VREF 5V 50mA INTERNAL BIAS VREF GOOD LOGIC 2.50V OSC. ERROR AMP. Vi GROUND RT/CT VFB COMP CURRENT SENSE 16V AP384X UVLO36V „ Absolute Maximum Ratings Symbol Parameter Value Unit Vi Supply Voltage (low impedance source) 36 V Vi Supply Voltage (li < 30mA) Self Limiting Io Output Current ±0.7 A Eo Output Energy (capacitive load) 5 µJ Analog Inputs (pins2,3) -0.3 to 5.5 V Error Amplifier Output Sink Current 10 mA Ptot Power Dissipation at T amb ≦500C (PDIP8) 1.25 W Ptot Power Dissipation at T amb ≦250C (SOP8) 800 mW Tstg Storage Temperature Range -65 to 150 oC TL Lead Temperature (soldering 10s) 260 oC *Notes: 1. All voltages are with respect to pin 5, all currents are positive into the specified terminal. „ Electrical Characteristics (Unless otherwise stated, these specifications apply for 0 ≦Tamb≦70 o C for AP384X ; Vi = 15V(note 5); RT = 10KΩ;CT = 3.3nF) AP384X Symbol Parameter Test Conditions Min. Typ. Max. Unit REFERENCE SECTION VREF Output Voltage Tj = 25 0C I 0=1mA 4.90 5.00 5.10 V ∆VREF Line Regulation 12V ≦Vi≦25V 2 20 mV ∆VREF Load Regulation 1mA ≦Io≦20mA 3 25 mV ∆VREF/∆T Temperature Stability (Notes 2) 0.2 0.4 mV/ 0C Total Output Variation Line, Load, Temperature (Notes 2) 4.82 5.18 V eN Output Noise Voltage 10Hz≦f≦10KHz Tj=25 0C (Notes 2) 50 µV Long Term Stability T amb=1250C, 1000Hrs (Notes 2) 5 25 mV ISC Output Short Circuit current -85 -120 mA

High Performance Current Mode PWM Controller AP3842/3/4/5 Anachip Corp. „ Electrical Characteristics(Continued) (Unless otherwise stated, these specifications apply for 0 ≦Tamb≦70 o C for AP384X ; Vi = 15V(note 5); RT = 10KΩ;CT = 3.3nF) AP384X Symbol Parameter Test Conditions Min. Typ. Max. Unit OSCILLATOR SECTION fs Oscillator Frequency Tj=25 0C (Notes 6, 7) 49 52 55 KHz Voltage Stability 12V ≦Vi≦25V 0.2 1 % Temperature Stability T MIN≦Tamb≦TMAX (Notes 2) 0.5 % V4 Amplitude V PIN4 Peak to Peak 1.6 V Discharge Current Tj=25 0C V PIN4=2V 7.8 8.3 8.8 mA ERROR AMP SECTION V2 Feedback Input Voltage V PIN1=2.5V 2.42 2.50 2.58 V Ib Input Bias Current V FB=5V -0.1 -2 µA A VOL 0V ≦V0≦4V 65 90 dB B Unity Gain Bandwidth Tj=25 oC 0.7 1 MHz SVRR Supply Voltage Rejection Ratio 12V≦Vi≦25V 60 70 dB IO Output Sink Current V PIN2=2.7V V PIN1=1.1V 2 6 mA IO Output Source Current V PIN2=2.3V V PIN1=5V -0.5 -0.8 mA V OUT High V PIN2=2.3V; RL=15KΩ to ground 5 7 V V OUT Low V PIN2=2.7V; RL=15KΩ to pin 8 0.8 1.1 V CURRENT SENSE SECTION Gv Gain (Notes3&Notes4) 2.85 3 3.15 V/V V3 Maximum Input Signal V PIN1=5V (Notes3) 0.9 1 1.1 V SVRR Supply Voltage Rejection Ratio 12≦Vi≦25V (Notes3) 70 dB Ib Input Bias Current -2 -10 µA Delay to Output 150 300 ns OUTPUT SECTION ISINK= 20mA 0.1 0.4 V VOL Output Low Level ISINK= 200mA 1.6 2.2 V ISOURCE= 20mA 13 13.5 V VOH Output High Level ISOURCE= 200mA 12 13.5 V Tr Rise Time Tj=25 0C C L=1nF (Notes2) 50 150 ns Tf Fall Time Tj=25 0C C L=1nF (Notes2) 50 150 ns VOLS UVLO Saturation Vcc = 6V ; Isink = 1mA 0.1 1.1 V UNDER-VOLTAGE LOCKOUT SECTION 3842/4 14.5 16 17.5 V Start Threshold 3843/5 7.8 8.4 9 V 3842/4 8.5 10 11.5 V Min Operating Voltage After Turn-on 3843/5 7.0 7.6 8.2 V PWM SECTION 3842/3 94 96 % Maximum Duty Cycle 3844/5 47 48 50 % Minimum Duty Cycle 0 % TOTAL STANDBY CURRENT Ist Start-up Current Vi=14V,3842/4 ; Vi=6.5V 3843/5 0.3 0.5 mA Ii Operating Supply Current V PIN2=VPIN3=0V 12 17 mA Viz Zener Voltage I i=25mA 30 36 V

High Performance Current Mode PWM Controller AP3842/3/4/5 Anachip Corp. Peak current(is) is determined by the formula 1.0V IS max ≈ RS A small RC filter may be required to suppress switch transients. Figure 4. RT CT VREF RT/CT GROUND for RT > 5KΩ f= 1.72 RTCT Figure 5 : Open Loop Test Circuit. 4 5 8COMP. VFB VREF ISENSE RT/CT OUTPUT GROUND Vi AP3842 A GROUND OUTPUT Vi VREF TW 0.1 uF 0.1 uF CT 4.7K 4.7K 100K ISENSE ADJUST ERROR AMP. ADJUST RT 2N2222 High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and bypass apacitors should be connected close to pin 5 in a single point ground. The transistor and 5 K Ω potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3. Figure 6 : Shutdown Techniques. B

1 COMP

High Performance Current Mode PWM Controller AP3842/3/4/5 Anachip Corp. Shutdown of the AP3842 can be accomplished in two ways; either raise pin 3 above 1V or pull pin 1 below a voltage two diode drops above ground. Either one of them causes the output of the PWM comparator to be high (refer to block diagram). The PW M latch is reset dominant so that the output will rema in low until the next clock cycle after the shutdown condition at pins 1 and/or 3 is removed. In one example, an externally latched shutdown may be accomplished by adding an SCR that will be reset by cycling V i below the lower UVLO threshold. At this point the reference turns off, allowing the SCR to reset. Figure 7 : Slope Compensation. Uref RT/CT Isense CT RT C Rsense Isense 0.1uF AP3842/3 A fraction of the oscillato r ramp can be resistively summed with th e current sense signal to provide slope compensation for converters requiring duty cycles over 50%. Note that capacitor, C, forms a filter with R 2 to suppress the leading edge switch spikes.

High Performance Current Mode PWM Controller AP3842/3/4/5 Anachip Corp. „ Package Diagrams (1) PDIP-8L (Plastic Dual-in-line Package) D 7 (4X) AL A2A1 B2B1 B eS 15 (4X) E C eB E-PIN O0.118 inch PIN #1 INDENT O0.025 DEEP 0.006-0.008 inch

High Performance Current Mode PWM Controller AP3842/3/4/5 Anachip Corp. (2) SOP-8L (JEDEC Small Outline Package) VIEW "A" L C VIEW "A" H E A A2A1Be D 7 (4X) 0.015x45 7 (4X) y A1 0.10 - 0.25 0.040 - 0.100 θ 0O - 8 O 0 O - 8 O „ Marking Information AP384XB YYWW X X 2,3,4,5 Year : "01"=2001 "02"=2002 Xth Week : 01~52 ID code: internal Logo Part No. Blank: normal L: Lead Free Package