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MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC >
M62281P/FP M62281P/FP
GENERAL PURPOSE CURRENT MODE PWM CONTROL IC GENERAL PURPOSE CURRENT MODE PWM CONTROL IC 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.
PIN CONFIGURATION (TOP VIEW)
VOUT 1 GND CLM 2 3
10 Vcc 9 8 7 EA IN EA OUT CT
FEATURES
CURRENT 4 SENSE CF 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 180A SENSE Start-up voltage 12.5V, Stop voltage 8.3V CF 6 9
6 SOFT
COLLECT
Vcc EA IN EA OUT CT SOFT
APPLICATION
* Switching Regulator * DC-DC converter
N.C
7
OUTLINE 14P4
8 N.C
Vcc
CLM
UVLO
CLM COMP
CT (OVP)
TIMER LATCH
0.2V
S CLM LATCH R
:note COLLECT
CS COMP
VOUT
R PWM LATCH S :note
EA IN
EMIT
2.5V OSC.
GND
EA OUT
SOFT
DUTY SET-UP
CURRENT CF SENSE
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.
(1/9)
MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC >
M62281P/FP
GENERAL PURPOSE CURRENT MODE PWM CONTROL IC
ABSOLUTE MAXIMUM RATINGS (Ta=25C, unless otherwise noted) Symbol
Vcc IOUT VCT VEA IN VCLM VCS Pd Ktheta Topr Tstg
Parameter
Supply voltage Output current CT terminal Supply voltage EA IN terminal Supply voltage CLM terminal Supply voltage
CURENT SENSE terminal Supply voltage
Condition
Continuous Peak
Rating
36 150 1.0 36 10 - 0.3 ~ + 4.0 - 0.3 ~ + 5.8 1500 440 12 3.52 - 20 ~ + 85 - 40 ~ + 150
Unit
V mA A V V V V mW mW/C C C
Power dissipation Thermal derating Operating temperature Storage temperature Ta25C
P FP P FP
ELECTRICAL CHARACTERISTICS (Ta=25C, Vcc=14V, unless otherwise noted)
Block
Symbol
Vcc Vcc(START) Vcc(STOP) Vcc IccL IccO IccOFF VTHCTH
Parameter
Supply voltage range Operation start-up voltage Operation stop voltage
Start-up and stop voltage difference
Test condition
Min
Vcc (STOP)
Limits Typ
12.5 8.3 4.2 180 13 2.0 1.8 4.0 0.7 115 -14 2.5 -100 70 1
Max
35 13.5 9.0 5.1 270 19 3.0 2.7 4.5 1.0 165 -5 2.6 0
Unit
V V V V A mA mA mA V V A A V nA dB MHz
11.5 7.6 3.5 Vcc=Vcc(START) - 0.5V Vcc=14V Vcc=Vcc(STOP) + 0.2V 90 7.5 0.9 0.8 3.5 0.4 70 -33 2.4 -300
Stand-by current Operating current Timer latch circuit current
CT term."H" threshold voltage CT term."L" threshold voltage
CT term. input current (timer off mode) CT term. output current (timer on mode)
CT
VTHCTL ITIMEOFFIN ITIMEOFFOUT VB IB AVO fT IOS VOm + VOm AVCS IB TPDCS
Reference voltage Input bias current Open loop gain Unity gain bandwidth Output source current Output voltage (High) Output voltage (Low) CS term. input voltage gain Input bias burrent CS term. delay time Delay time to output
-460 5.3 0 -5
-370 5.8 0.2 3.0 -1 150
-240 6.25 0.35
A V V V/V A nS
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MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC >
M62281P/FP
GENERAL PURPOSE CURRENT MODE PWM CONTROL IC
ELECTRICAL CHARACTERISTICS (Ta=25C, Vcc=14V, unless otherwise noted)
Block C L M S O F T
Symbol
VTHCLM IOUTCLM TPDCLM VSOFT(0%) VSOFT(50%) Duty Max ISOFT foscmax
Parameter
CLM term. threshold voltage
Test condition
Min
180 -270
Limits Typ
200 -200 100
Max
220 -140
Unit
mV A nS
CLM term. output current CLM term. delay time
Soft term. input voltage range to set 0% duty Soft term. voltage when 50% duty
VCLM=0V Delay time to output
Soft term. input voltage range to set 0% duty
0 2.7 83 -50 130 3.2 1.2 1.9 90 -43 180 3.6 1.4 2.2 0.04 0.3 12.0 11.5 12.7 12.5 50 35
1.0
V V
Maximum duty Soft term. input current
Maximum oscillation frequency
97 -36 700
% KHz KHz V V V V V V V nS nS
fosc OSC. VOSCH VOSCL VOSC VOL1 VOL2 VOH1 VOH2 TRISE TFALL
Oscillation frequency
Oscillation upper limit voltage Oscillation lower limit voltage
CF= 270pF CF= 270pF CF= 270pF CF= 270pF Vcc=14V, Io=10mA
230 4.0 1.6 2.5 0.4 1.4
Oscillation voltage Output low voltage Output high voltage Output voltage rise time Output voltage fall time
Vcc=14V, Io=100mA Vcc=14V, Io=-10mA Vcc=14V, Io=-100mA No load No load
(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(370A typ.) shown in Fig.1. Output voltage of error amp. is controlled by the output transistor to provide currentsense comp. with the controlled voltage. 370A 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
R1 EA IN R2 RF EA OUT
Reference voltage(2.5V)
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
R1
Reference voltage(2.5V)
Reference voltage(2.5V)
EA IN RIN EA IN R2 RF EA OUT EAOUT
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 52K 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 2.0 1.5 1.0 0.5 0
5 10 15 20 25 30 35 Latch reset 8.3V
Supply voltage : Vcc (V) Fig.4 Supply current/voltage chracteristics (at timer latch)
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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.
CT
OVP function operates when photo-coupler is ON.
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
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: Duty(max.) (42 * VSOFT) - 59 (%) ,where VSOFT=ISOFT * RSOFT (V), ISOFT=43A(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.
SOFT
CSOFT
VSOFT
Fig.6 Method to set up duty and SOFT start function.
(6/9)
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 OUT
RNF CNF RCS CNF
RNF1 RNF2 RCS
Fig.7-1 peripheral circuit of CLM
Fig. 7-2 peripheral circuit of CLM when the detected voltage is high.
1000pF to 22000pF is recommended for CNF. Be sure to use 100 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 85C, 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 30C 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 100C with adequate margin considering the absolute maximum rating of junction temperature is 150C.
(8/9)
MITSUBISHI SEMICONDUCTOR < STANDERD LINEAR IC >
M62281P/FP
GENERAL PURPOSE CURRENT MODE PWM CONTROL IC
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