THe Rev. 1.2 12/95 LINFINITY @ MICROELECTRONICS INFINITE POWER OF INNOVATION DESCRIPTION The UC184xA family of control ICs provides all the necessary features to implement off-line fixed-frequency, current-mode switching power supplies with a minimum of external compo- nents. The current mode architecture demonstrates improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supply output switch. The IC includes: A bandgap reference trimmed to +1% accuracy, an error amplifier, a current sense comparator with internal clamp to 1V, a high current totem pole output stage for fast switching of power MOSFETs, and an externally program- mable oscillator to set frequency and maximum duty cycle. The under voltage lock-out is designed to operate with 250pA typ. start-up current, allowing an efficient bootstrap supply voltage design. Available options for this family of products, such as start-up voltage hysteresis and duty cycle, are summarized below in the Available Options section. The UC184xA family of control ICs is also available in 14-pin SOIC package which makes the Power Output Stage Collector and Ground pins available. PRODUCT HIGHLIGHT COMPARISON OF UC384xA vs. SG384x DiscHARGE CURRENT UC384xA SG384x Min. Limit T= SG384x Max. Limit ee wD) Ss & SS AN PRODUCTION Oo Oo LIN Doc #: 1840 ve ee oS ee AS vs GSA CURRENT Move PWM ConrTRoOLLerR DATA SHEET LOW START-UP CURRENT. (0.5mA max.) TRIMMED OSCILLATOR DISCHARGE CURRENT. (See Product Highlight) OPTIMIZED FOR OFF-LINE AND DC-TO-DC CONVERTERS. AUTOMATIC FEED FORWARD COMPENSATION. PULSE-BY-PULSE CURRENT LIMITING. ENHANCED LOAD RESPONSE CHARACTERISTICS. UNDER-VOLTAGE LOCKOUT WITH HYSTERESIS. DOUBLE PULSE SUPPRESSION. HIGH-CURRENT TOTEM POLE OUTPUT. INTERNALLY TRIMMED BANDGAP REFERENCE. 500KHZ OPERATION. LOW R, ERROR AMPLIFIER. APPLICATIONS ECONOMICAL OFF-LINE FLYBACK OR FORWARD CONVERTERS. DC-DC BUCK OR BOOST CONVERTERS. LOW COST DC MOTOR CONTROL. AVAILABLE OPTIONS Start-Up | Hysteresis | Max. Duty Me) toler ea UCx842A| 16V 6V <100% I t ' + UCx843A | 8.4V 0.8V | <100% 7.5 7.8 8.3 8.8 3 ee Re? UCx844A| 16V | 6V_ | <50% Discharge Current Distribution - mA UCx845A| 8.4V 0.8V <50% PACKAGE ORDER INFORMATION T, (C) Plastic DIP Plastic SOIC Plastic SOIC Mae Ceramic DIP A 8-pin 8-pin 14-pin 8-pin Oto 70 UC384xAM UC384xADM UC384xAD _ -40 to 85 UC284xAM UC284xADM UC284xAD UC284xAY -55 to 125 _ _ _ UC184xAY Note: All surface-mount packages are available in Tape & Reel. Append the letter "T" to part number. (ie. UC3842ADMT) Oe ae 11861 Western AveNuE, GARDEN Grove, CA. 92841 1we HE Mh LD GTS as Gee a a cee PRODUCTION DATA SHEET PUT ITO LY ee Dee Rae Supply Voltage (Low Impedance Source) CV.) cies 30V Supply Voltage (j.< 30MA) .occccccceeeecseseeees Self Limiting COMP Cf 7 8D Vue OULPUE CUITON i EEC EEE EEE S ee cede Eerie aeaeeeaeeeeE +1A ; Ve 4; 4 a Output Energy (Capacitive Load) in nr ineri etree Sp R/C, das GND Analog Inputs CV, & Ljpucp) ceietenecens -0.3V to +6.3V Error Amp Output Sink Current wee .. LOMA M & Y PACKAGE Power Dissipation at T, = 25C (M Package) icici 1Ww (Top View) Storage Temperature Range wien ii iii -65C to +150C Lead Temperature (Soldering, 10 Seconds) oie ie eee eet ener nnienes 300C comP CO]' LD V,,, Note 1. Exceeding these ratings could cause damage to the device. All voltages are with respect V,, CO |2 77 Ve to Ground. Currents are positive into, negative out of the specified terminal. Pin leevse CL |S 61] OUTPUT numbers refer to DIL packages only. R/c, C1] |4 51 GND DM PACKAGE Ty ey. (Top View) M PACKAGE: THERMAL RESISTANCE-JUNCTION TO AMBIENT, @,, CMe ls comp CH]] = 14 v,,, DM PACKAGE: Nc. [1]|2 13[7T] N.C. V., CL] 3 12ET] Vy THERMAL RESISTANCE-JUNCTION TO AMBIENT, 0, nef Nc. Col 4 nfo v, D PACKAGE: leenyse CL] 5 10[1] OUTPUT 5 N.c. CT]} 6 9{1] GND THERMAL RESISTANCE-JUNCTION TO AMBIENT, 0 abies R/c, C7 3{C] PWRGND Y PACKAGE: D PACKAGE THERMAL RESISTANCE-JUNCTION TO AMBIENT, 0, 130C/]W (Top View) Junction Temperature Calculation: T, =T,+(P,x 0,,). The @, numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow = Cc ight 1995 3 LINFINI (mG opright 1995 MICROM ELECTRONICSGS a Gee ee a hae ce PRODUCTION DATA SHEET oe or ee oe (Unless otherwise specified, these specifications apply over the operating ambient temperatures for UC384xA with 0C <T, $70C, UC284xA with -40C < T, $ 85C, UC184xA with -55C T, $ 125C; V_.=15V; R.=10K; C_=3.3nF. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature.) ee a cc nos Oca Min. | Typ. | Max.| Min. [Typ. | Max. > Reference Section Output Voltage Veer T, = 25C, | =1mA 4.95 | 5.00 | 5.05 | 4.90 | 5.00 | 5.10 Vv Line Regulation 12 <V,, < Q5V 6 20 6 20 mV Load Regulation 1<1,<20mA 6 95 6 95 mv Temperature Stability (Note 2 & 7) 0.2 | 0.4 0.2 | 0.4 | mvc Total Output Variation Over Line, Load, and Temperature 49 5.1 | 4.82 5.18 Vv Output Noise Voltage (Note 2) Ww 10Hz <f < 10kHz, T, = 25C 50 50 Lv Long Term Stability (Note 2) T, = 125C, t = 1000hrs 5 25 5 25 mV Output Short Circuit Current Ise -30 | -100] -180 | -30 | -100] -180 | mA > Oscillator Section Initial Accuracy (Note 6) T, = 25C 47 | 52 | 57 | 47 | 52 | 57 kHz Voltage Stability 12<V,. < 95V 02 | 1 02 | 1 % Temperature Stability (Note 2) Tan S Ta S Trax 5 5 % Amplitude (Note 2) 1.7 1.7 Vv Discharge Current T,= 25C, Vong = 2V 7.8 | 33 | 838 [7.8 | 83 [38 | mA Vos = 2, Tran S Ta S Trax 75 8.8 | 7.6 8.8 mA > Error Amp Section Input Voltage Von 1 = 2-5V 9.45|9.50/2.55]9.49/950]9.58| V Input Bias Current I, 0.3} -1 0.3} -2 LA Open Loop Gain Avo. | 25 Vos 4V 65 | 90 65 | 90 dB Unity Gain Bandwidth (Note 2) UGBW | T, = 25C 0.7 1 0.7 1 MHz Power Supply Rejection Ratio (Note 3) | PSRR | 12<V,, < 25V 60 70 60 70 cB Output Sink Current lor | Vee = 2:7) Vow, = 1-1 2 6 2 6 mA Output Source Current lon | Vene = 2-3, Von = SV -0.5 | -0.8 -0.5 | -0.8 mA Output Voltage High Level Vou | Ves = 2-3V, R, = 15K to ground 5 6 5 6 Vv Output Voltage Low Level Vor | Voenwe = 2-7V, R, = 15K to Voce 0.7 | 1.1 0.7 | 1.1 v > Current Sense Section Gain (Note 3 & 4) Avo. 285) 3 |3.15]285] 3 |3.15] VV Maximum Input Signal (Note 3) Von 7 = OY 0.9 1 1.1 | 0.9 1 1.1 V Power Supply Rejection Ratio (Note 3) | PSRR | 12<V,,<25V 70 70 cB Input Bias Current I, -2 | -10 -2 | -10 LA Delay to Output (Note 2) Toa | Vom 3 = 0 to 2V 150 | 300 150 | 300 | ns Output Section Output Low Level V lone = 2ZOMA 0.1 | 0.4 0.1 | 0.4 Vv | Longe = ZOOMA 15 | 29 15 | 29 Vv Output High Level V Iource = 2ZOMA 13 | 13.5 13 | 13.5 Vv | Leource = ZOOMA 12 | 13.5 12 | 13.5 Vv Rise Time (Note 2) Ta T, = 25C, C, = 1nF 50 | 150 50 | 150 | ns Fall Time (Note 2) T. | 1, = 25C, G = 1nF 50 | 150 50 | 150] ns UVLO Saturation Vear | Vee = BY, bony = TOMA 0.7 | 1.2 0.7 | 1.2 Vv Copyright 1995 Rev. 1.2 12/95 (Electrical Characteristics continue next page.) MICRQMELECTRONICSHy GB i a GTS as Gee a a cee PRODUCTION DATA SHEET ee oe ee on oe ce) Tene Min. | Typ. | Max.] Min. | Typ. | Max. | Parmeter symbol Under-Voltage Lockout Section Start Threshold xB42A/4A 15 | 16 | 17 [14.5] 16 | 17.5 Vv x843A/5A 78 | 84 | 9.0 | 7.8 | 84 | 9.0 V Min. Operation Voltage After Turn-On xB49A/4A 9 10 11 | 85 | 10 | 11.5 Vv x843A/5A 7.0 | 7.6 | 82 | 7.0 | 7.6 | 82 V > PWM Section Maximum Duty Cycle xXB842A/3A 94 | 96 | 100 | 94 | 96 | 100 % x844A/5A 47 | 48 | 50 | 47 | 48 | 50 % Minimum Duty Cycle 0 0 % > Total Standby Section Start-Up Current 0.3 | 0.5 0.3 | 0.5 mA Operating Supply Current lee 11 17 11 17 mA Zener Voltage Vv, lee = 25MA 30 | 35 30 | 35 V Notes: 2. These parameters, although guaranteed, are not 100% tested in 7. "Temperature stability, sometimes referred to as average temperature production. coefficient, is described by the equation: .P d i int of latch with V_. = 0. ; 3. Parameter measured at me point of latch with V_.. Temp Stability ~ Veup (max.) - V,_, (min.) Vv ooo 4, Gain defined as: Aya, = FT 5 0S Visesse $ 0-8V. T, max.) -'T, Gmin.) ISENSE Vere (max.) & V,,, (min.) are the maximum & minimum reference 5. Adjust V. above the start threshold before setting at 15V. voltage measured over the appropriate temperature range. Note that 6. Output frequency equals oscillator frequency for the UC1842A the extremes in voltage do not necessarily occur at the extremes in and UC1843A. Output frequency is one half oscillator frequency temperature." for the UC1844A and UC1845A. BLOCK DIAGRAM Vee O 34V x Veer a _ >} S/R | a 5.0V sf GROUND Ale nq T8aDA/ 4A, Le 50mA 16V (18424/4A) 0.8V (1843A/5A) 8.4V (18434/5A) Internal Bias 2.5V . Voce . Ve Good Logic |g R/C, O Oscillator -4 RK --4 T a r OUTPUT Error Amp S Vig R PWM Latch 5 we COMP Current Sense POWER GROUND Comparator CURRENT SENSE () *- Vand V. are internally connected for 8 pin packages. x - POWER GROUND and GROUND are internally connected for 8 pin packages. xxx - Toggle flip flop used only in x844A and x845A series. Copyright 1995 Rev. 1.2 12/95 MICROM ELECTRONICS weGS a Gee ee a hae ce PRODUCTION DATA SHEET CHARACTERISTIC CURVES FIGURE 1. OSCILLATOR FREQUENCY vs. TIMING RESISTOR = IM o < y = & 100k irs 3 & 3 B 10k 1.72 For R, > 5k, f RC, Note: Output drive frequency is half the oscillator frequency for 300 1.0k 3.0k 10.0k 30.0k 100k the UCx844A/5A devices. R, - (ohms) FIGURE 2. MAXIMUM DUTY CYCLE vs. TIMING RESISTOR 100.0 80.0 60.0 40.0 Maximum Duty Cycle - (%) 20.0 300 1.0k 3.0k 10.0k 30.0k = 100k R, - (ohms) Ce ight 1995 = somata LINFINITY MICRQMELECTRONICSS _ HE Mh GTS as Gee a a cee PRODUCTION DATA SHEET TYPICAL APPLICATION CIRCUITS FIGURE 3. CURRENT SENSE SPIKE SUPPRESSION FIGURE 4. MOSFET PARASITIC OSCILLATIONS Vec DC BUS Vee DC BUS Ql R, Ql UCx84xA UCx84xA [2 6 5 et < 3 | _ 1LOV PKIMAX) = T " The RC low pass filter will eliminate the leading edge current spike A resistor (R,) in series with the MOSFET gate will reduce overshoot caused by parasitics of Power MOSFET. & ringing caused by the MOSFET input capacitance and any inductance in series with the gate drive. (Note: It is very important to have a low inductance ground path to insure correct operation of the LC. This can be done by making the ground paths as short and as wide as possible.) FIGURE 5. EXTERNAL DUTY CYCLE CLAMP AND MULTI-UNIT SYNCHRONIZATION P WW Co -C}-_ nN C4 L ZI UCx84xA Ry $ 6 555 3 4 Toml? 2 + 001 = 5 7 | To other fe 1.44 = UCx84xA devices (Ry + 2R,)C f= R, Precision duty cycle limiting as well as synchronizing several parts is R, + ZR, possible with the above circuitry. Copyright 1995 Rev. 1.2 12/95 MICROM ELECTRONICSCopyright 1995 Rev. 1.2 TYPICAL GS a Gee ee a hae ce PRODUCTION APPLICATION CIRCUITS DATA SHEET (continued) a eS SS XA ET A FIGURE 6. SLOPE COMPENSATION UCx84xA 712) >< 5V 8(14) UVLO / 5V = + R REF Sk | INTERNAL . BIAS 2.5V 2N222A Vacr GOOD LOGIC A(7) OSCILLATOR t From V5 | PWM LATCH aM) aw 6{10) 5(8) an 3(5) 650 oi = DC BUS O Ql TfL # Due to inherent instability of current mode converters running above 50% duty cycle, slope compensation should be added to either the current sense pin or the error amplifier. Figure 6 shows a typical slope compensation technique. FIGURE 7. OPEN LOOP LABORATORY FIXTURE 2N2222 4.7K . 100K 1K ERROR AMP ADJUST 5K 47K lense ADJUST High peak currents associated with capacitive loads necessitate careful grounding techniques. 0.1 pF Veer CQ OUTPUT ) GROUND Timing and bypass capacitors should be connected to pin 5 ina single point ground. The transistor and 5k potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3. 12/95 MICRQMELECTRONICSS Hi Mh y GTS as Gee a a cee PRODUCTION DATA SHEET TYPICAL APPLICATION CIRCUITS (continued) FIGURE 8. OFF-LINE FLYBACK REGULATOR ak Ww Tl MBR735 I I eT 1N4004 1N4004 2500 an ol = A7OOpF -L. SV = $140k lov J~ 2:54 21/2W 1N4935 AC 1N4004 ~ 1N4004 . _ INPUT Oo a 1N4935 oS 16V | UC3844A_ a LF FL goo 0.01pF 20V a & = - 3 2.5k . k Ke 3 = 8 = = 3.6k ie 1k 3 AAA | To 0.85k 0.01pF = is = = ISOLATION BOUNDARY SPECIFICATIONS Input line voltage: 9OVAC to 130VAC * This circuit uses a low-cost feedback scheme in which the DC Input frequency: 50 or 60Hz voltage developed from the primary-side control winding is Switching frequency: 40KHz +10% sensed by the UC3844A error amplifier. Load regulation is Output power: Q95W maximum therefore dependent on the coupling between secondary and Output voltage: 5V +5% control windings, and on transformer leakage inductance. Output current: 9to 5A Line regulation: 0.01 %/V Load regulation: 8%/A* Efficiency @ 25 Watts, Vy = GOVAC: 70% Vy = 130VAC: 65% Output short-circuit current: 9.5Amp average & TINFINITY Copyright 1995 Rev. 1.2 12/95 MICROM ELECTRONICS