MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP M62281P/FP GENERALGENERAL PURPOSE PURPOSE CURRENT CURRENT MODE MODE PWM PWM CONTROL CONTROL IC IC PIN CONFIGURATION (TOP VIEW) DESCRIPTION M62281P/FP is designed as a high speed current mode PWM control IC. This small10 pin package contains many functions and protection circuits allowing simpler peripheral circuit and compact set design. This IC can operate high speed switching (700kHz max.) with high speed current sense comparator and current limiting circuit. FEATURES 10 Vcc VOUT 1 GND 2 9 EA IN CLM 3 8 EA OUT CURRENT 4 SENSE 7 CT CF 6 SOFT 5 700kHz applicable to MOS-FET • Output current Io(peak) = ±1A OUTLINE 10P2N-A • Totem pole output VOUT 1 14 CURRENT SENSE terminal separate form CLM terminal makes SMPS strong in noise. 13 EMIT 2 High speed pulse-by-pulse current limiting GND 3 12 Timer type latch protection circuit with OVP(external reset is possible) Soft start operation is possible (with dead time control) 11 CLM 4 Built-in OPAmp for feedback control (photo coupler can be driven) CURRENT 5 10 Small start-up current 180µA SENSE Start-up voltage 12.5V, Stop voltage 8.3V CF 6 9 APPLICATION N.C • Switching Regulator • DC-DC converter 7 COLLECT Vcc EA IN EA OUT CT SOFT 8 N.C OUTLINE 14P4 Vcc CLM UVLO CLM COMP CT (OVP) TIMER LATCH 0.2V CS COMP EA IN S CLM LATCH R :note COLLECT VOUT R PWM LATCH S :note EMIT GND 2.5V OSC. EA OUT SOFT DUTY SET-UP CURRENT CF SENSE (1/9) note: GND terminal is connected to emitter terminal as M62281FP in IC inside. And Vcc terminal is connected to collector terminal as M62281FP in IC inside. MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC ABSOLUTE MAXIMUM RATINGS (Ta=25˚C, unless otherwise noted) Symbol Parameter Vcc Condition Supply voltage Continuous Peak IOUT Output current VCT VEA IN VCLM VCS CT terminal Supply voltage EA IN terminal Supply voltage CLM terminal Supply voltage Pd Power dissipation Ktheta Thermal derating Topr Tstg Operating temperature Storage temperature CURENT SENSE terminal Supply voltage Ta≥25˚C P FP P FP Rating Unit 36 150 1.0 36 10 - 0.3 ~ + 4.0 - 0.3 ~ + 5.8 1500 440 12 3.52 - 20 ~ + 85 - 40 ~ + 150 V mA A V V V V mW mW/˚C ˚C ˚C ELECTRICAL CHARACTERISTICS (Ta=25˚C, Vcc=14V, unless otherwise noted) Block CT Symbol Parameter Test condition Min Limits Typ Vcc (STOP) Vcc Supply voltage range Vcc(START) Operation start-up voltage 11.5 Vcc(STOP) Operation stop voltage Max Unit 35 V 12.5 13.5 V 7.6 8.3 9.0 V 3.5 4.2 5.1 V 90 180 270 µA 7.5 13 19 mA 0.9 0.8 2.0 1.8 3.0 2.7 mA mA ∆Vcc Start-up and stop voltage difference IccL Stand-by current IccO Operating current IccOFF Timer latch circuit current VTHCTH CT term."H" threshold voltage 3.5 4.0 4.5 V VTHCTL CT term."L" threshold voltage 0.4 0.7 1.0 V 70 115 165 µA -33 -14 -5 µA Vcc=Vcc(START) - 0.5V Vcc=14V Vcc=Vcc(STOP) + 0.2V CT term. input current ITIMEOFFIN (timer off mode) CT term. output current ITIMEOFFOUT (timer on mode) VB Reference voltage 2.4 2.5 2.6 V IB Input bias current -300 -100 0 nA AVO Open loop gain 70 dB fT Unity gain bandwidth 1 MHz IOS Output source current -460 -370 -240 µA VOm + Output voltage (High) 5.3 5.8 6.25 V VOm - Output voltage (Low) 0 0.2 0.35 V AVCS CS term. input voltage gain IB Input bias burrent TPDCS CS term. delay time -5 Delay time to output (2/9) 3.0 V/V -1 µA 150 nS MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC ELECTRICAL CHARACTERISTICS (Ta=25˚C, Vcc=14V, unless otherwise noted) Block C L M S O F T Symbol Parameter Test condition Min Limits Typ Max 180 200 220 mV -270 -200 -140 µA VTHCLM CLM term. threshold voltage IOUTCLM CLM term. output current VCLM=0V TPDCLM CLM term. delay time Delay time to output VSOFT(0%) Soft term. input voltage range to set 0% duty VSOFT(50%) Soft term. input voltage range to set 0% duty Soft term. voltage when 50% duty Duty Max Maximum duty 83 90 97 ISOFT Soft term. input current -50 -43 -36 foscmax Maximum oscillation frequency 100 0 Unit nS 1.0 2.7 V V % 700 KHz fosc OSC. VOSCH Oscillation frequency CF= 270pF 130 180 230 KHz Oscillation upper limit voltage CF= 270pF 3.2 3.6 4.0 V VOSCL Oscillation lower limit voltage CF= 270pF 1.2 1.4 1.6 V Oscillation voltage CF= 270pF 1.9 2.2 2.5 V Vcc=14V, Io=10mA 0.04 0.4 V Vcc=14V, Io=100mA 0.3 1.4 V ∆VOSC VOL1 VOL2 VOH1 VOH2 Output low voltage Output high voltage Vcc=14V, Io=-10mA 12.0 12.7 V Vcc=14V, Io=-100mA 11.5 12.5 V TRISE Output voltage rise time No load 50 nS TFALL Output voltage fall time No load 35 nS (3/9) MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC FUNCTION DESCRIPTION AND APPLICATION (1) EA IN, EA OUT TERMINAL Circuit for EAOUT terminal is connected to constant current load(370µA typ.) shown in Fig.1. Output voltage of error amp. is controlled by the output transistor to provide currentsense comp. with the controlled voltage. 370µA EA OUT To current -sense comp. Fig.1 Circuit diagram of EAOUT terminal Peripheral circuit of Error Amp Detected voltage devided by R1 and R2 is input to EAIN terminal in such case as fly-back system where VCC line voltage is proportional to output voltage, or in the case that the voltage detection is made on the primary side. In this case operating region is set by R1 and R2, and AC gain by R1// R2, RF. From detecting voltage Reference voltage(2.5V) R1 EA IN R2 EA OUT RF Fig.2 Method to detect the voltage on the primary side In the case that feedforward system by photo-coupler is applied, following two methods are available. One is the method by error amp. as in Fig.3-1, the other is by the direct connection to photo-coupler as in Fig.3-2. When photo-coupler is directly connected to EAOUT terminal, input terminal of error amp. is connected to GND, photo-coupler is connected directly to EAOUT terminal. Vcc Reference voltage(2.5V) R1 Reference voltage(2.5V) EA IN EAOUT RIN EA IN R2 EA OUT RF Fig.3-1 Method to use photo-coupler (1) Fig.3-2 Method to use photo-coupler (2) (4/9) MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC In Fig. 3-1, AC gain is represented as: | Av | = | RF/ RIN | Proper gain setting is about 40dB. RF should be 52KΩ or more due to the current source capability of error amp. R1, R2 should meet the condition as below so that the voltage of EAIN terminal should not be over 5V. R2 * Vcc/ (R1 + R2) ≤ 5V Due to the input impedance of EAIN terminal, the current in R1, R2 should be less than several mA. (2) CT(OVP) TERMINAL Timer type latch circuit works as follows. Constant charge current flows out from CT terminal to the external capacitor when CLM is operative. When the voltage of CT terminal rises up to over 4.0V(typ.), the latch circuit operates to make functions of this IC inoperative. Inoperative status is sustained until supply voltage becomes less than stop voltage. The value for start-up register has to be set so that the current over 1.8mA(typ.) can flow the resistor because the stop status has to be kept by the current in start-up resistor R1 shown in application circuit. When timer latch circuit is operative, supply current increases at high voltage as shown in Fig.4 to avoid the damage caused by unnecessarily increased supply voltage. Inoperative status goes back to operation by forcibly decreasing the voltage of CT terminal to less than 0.7V. 3.0 2.5 Latch reset 8.3V 2.0 1.5 1.0 0.5 0 5 10 15 20 25 30 35 Supply voltage : Vcc (V) Fig.4 Supply current/voltage chracteristics (at timer latch) (5/9) MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC Even if the timer function is not needed, latch function operates, that is, IC becomes inoperative when the voltage of CT terminal is forced to be high voltage. Therefore, CT terminal can also be used for OVP(over voltage protection). When only OVP function is needed(timer latch function is not necessary), connect the resistor between CT terminal and GND. In this case, the above mentioned charge current cannot make the voltage of CT terminal rise up to "H" threshold, thus latch function does not operate. (Refer to Fig.5-1, 5-2) Vcc Vcc OVP function operates when photo-coupler is ON. OVP function operates when photo-coupler is ON. CT CT Fig.5-1 Method to use timer type latch and OVP Fig.5-2 Method to use only OVP (3) SOFT(DUTY SET-UP) TERMINAL SOFT The voltage of SOFT terminal determines the maximum duty. Maximum duty can be set by connecting the resistor as in Fig.6 because the constant current compensated for temperature flows out of this terminal. And by connecting the capacitor between the terminal and GND, soft start function operates. That is, we can get the gradual increase of maximum duty at start-up. Maximum duty is represented as: CSOFT Duty(max.) ≈ (42 * VSOFT) - 59 (%) ,where VSOFT=ISOFT * RSOFT (V), ISOFT=43µA(typ.) If the voltage of SOFT terminal is higher than 3.53V(typ.)(upper limit voltage of the oscillation waveform), maximum duty is internally decided to be 90%. Soft start time (TSOFT) is represented as: TSOFT ≈ CSOFT * 31 * 103 (sec) TSOFT means the time from start-up until the voltage of SOFT terminal goes up to higher than 1.4V(typ.) (lower limit voltage of the oscillation waveform). Discharging circuit operative before start-up at Vcc is internally equipped so that the soft start never fail to operate at the restart of voltage supply. (6/9) VSOFT Fig.6 Method to set up duty and SOFT start function. MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC (4) CLM TERMINAL This terminal is for pulse-by-pulse current limiting. Current limiting circuit is almost the same as that of M51995. CLM terminal is separate from CURRENT SENSE terminal allowing the noise filter to be optimized and the high-speed over current protection. The voltage detected by the current detecting resistor can be directly input as shown in Fig.7-1, if the detected voltage is about the threshold voltage(200mV(typ.)), but if the voltage is larger than the threshold, the voltage has to be input divided by resistors as shown in Fig.7-2. CLM OUT CLM RNF CNF OUT RNF1 CNF RCS RNF2 RCS Fig. 7-2 peripheral circuit of CLM when the detected voltage is high. Fig.7-1 peripheral circuit of CLM 1000pF to 22000pF is recommended for CNF. Be sure to use 100Ω or less for RNF and RNF1// RNF2 (*)so that the detection sensitivity is not influenced by the current flown out from CLM terminal. Non-inductive resistor is recommended for current detecting resistor. * RNF1//RNF2 = (RNF1 * RNF2)/(RNF1 + RNF2) (5) CURRENT SENSE TERMINAL The voltage proportional to the switching current is supplied to this terminal. Output duty is controlled by comparing this voltage with the output of error amp.. CLM and CURRENT SENSE terminal is separate from each other, so various settings are available depending upon the application. CURRENT SENSE OUT RNF CNF RCS VCS Fig.8 peripheral circuit of CURRENT SENSE RCS is determined by: VCS = (VEAOUT - 1.3)/3 (V), where VEAOUT represents the voltage of EAOUT terminal. (7/9) MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC (6) CF TERMINAL Oscillation frequency is set by capacitor connected to CF terminal. The waveform of CF terminal is triangular one with the ratio of 9:1 for charge-discharge period. Oscillation frequency is represented as: fOSC = 1 (19.4 * 103 * COSC) + (0.4 * 10-6) (Hz) (7) Attention for heat generation Although the absolute maximum rating of ambient temperature is spelled out as 85˚C, it is always annoying to specify the location this temperature refers to because the power dissipation generated locally in switching regulator is fairly large and the temperature in the vicinity of the IC varies from place to place. One of the recommendable ways to solve this problem is to check the teperature on the surface of the IC. The difference in temperature between IC junction and the surface of IC package is 30˚C or less when IC junction temperature is measured by utilizing the temperature characteristics of p-n junction forward voltage, and the surface temperature by "thermo-viewer" on the condition that the IC is mounted on the "phenol-base" PC board in normal atomosphere. This concludes that maximum case temperature (surface temperature of IC package) rating is 100˚C with adequate margin considering the absolute maximum rating of junction temperature is 150˚C. (8/9) MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC > M62281P/FP GENERAL PURPOSE CURRENT MODE PWM CONTROL IC (9/9)