NTE7154 Integrated Circuit Control Circuit for Switch Mode Power Supplies using MOS Transistors Description: The NTE7154 is an integrated circuit in an 8–Lead DIP type package which controls the MOS power transistor and performs all necessary regulation and monitoring functions in free running flyback converters. Since good load regulation over a wide load range is attained, this device is particularly suitable for consumer as well as industrial power supplies. Features: D Fold–Back Characteristic Provides Overload Protection for External Diodes D Burst Operation Under Short–Circuit and No Load Conditions D Loop Error Protection D Switch–Off In Case of Too Low Line Voltage (Under Voltage Switch–Off) D Line Voltage Compensation of Overload Point D Soft–Start for Smooth Start–Up D Chip Over–Temperature Protection (Thermal Shutdown) D On–Chip Parasitic Transformer Oscillation Suppression Circuitry D Decrease of Regulated Voltage for Low Power Consumption Absolute Maximum Ratings: Supply Voltage (Pin1), V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 to +3.0V Supply Voltage (Pin2, Pin3, Pin4, Pin7), V2, V3, V4, V7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3V Supply Voltage (Pin6), V6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 to +20V Supply Current (Pin1, Pin2, Pin3, Pin7), I1, I2, I3, I7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3mA Supply Current (Pin4, Note 1), I4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –1.5A Supply Current (Pin5, Note 1), I5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.5 to +1.5A Supply Current (Pin6, Note 1), I6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5A Supply Current (Pin8), I8 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –3 to +3mA Operating Junction Temperature, TJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +125°C Ambient Temperature Range, TA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –20° to +85°C Storage Temperature Range, Tstg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –40° to +125°C Thermal Resistance, Junction–to–Ambient, RthJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85°C/W Thermal Resistance, Junction–to–Case, RthJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45°C/W Note 1. tp ≤ 50µs, V ≤ 0.1. Electrical Characteristics: (VCC = 10V, TA = +25°C unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit – 0.6 0.8 mA Start–Up Hysteresis Start–Up Current Drain I6E0 V6 = V6E Switch–On Voltage V6E 11 12 13 V Switch–Off Voltage V6A 4.5 5.0 5.5 V Switch–On Current I6E1 V6 = V6E – 11 – mA Switch–Off Current I6A1 V6 = V6A – 10 – mA At Pin2 (V6 < V6E) V2(Max) I2 = 1mA 5.6 6.6 9.0 V At Pin3 (V6 < V6E) V3(Max) I3 = 1mA 5.6 6.6 9.0 V 400 410 420 mV – 43 – dB Voltage Clamp (V6 = 10V, IC Switched Off) Control Range Control Input Voltage V1R Voltage Gain of the Control Circuit in the Control Range –VR VR = d(V2S – V2B)/dV1, f = 1kHz Primary Current Simulation Voltage Basic Value VsB 0.955 1.000 1.030 V Overload Range and Short Circuit Operation Peak Value in the Range of Secondary Overload V2O V1 = V1R = 10mV 2.80 2.95 3.10 V Maximum Ramp Amplitude DV2 V2O – V2B 1.82 1.95 2.08 V Peak value in the Range of Secondary Short–Circuit Operation V2S V1 = 0 2.3 2.5 2.7 V –I2 V3 = 3.7V 300 500 650 µA Foldback Point Correction Foldback Point Correction Current Generally Valid Data (V6 = 10V) Voltage of the Zero Transition Detector Positive Clamping Voltage V8P I8 = 1mA – 0.75 – V Negative Clamping Voltage V8N I8 = –1mA – –0.2 – V Threshold Voltage V8S 40 50 – mV Suppression of Transformer Ringing TUL 3.0 3.8 4.5 µs V8 = 0 0 – 4 µV Input Current –I8 Push–Pull Output Stage Saturation Voltages Pin5 Sourcing VSatU I5 = –0.1A – 1.5 2.0 V Pin5 Sinking VSatU I5 = +0.1A – 1.0 1.2 V I5 = +0.5A – 1.4 1.8 V Output Slow Rate Rising Edge +dV5/dt – 70 – V/µs Falling Edge –dV5/dt – 100 – V/µs – 50 – µA Reduction of Control Voltage Current to Reduce the Control Voltage –I1 V7 = 1V Electrical Characteristics (Cont’d): (VCC = 10V, TA = +25°C unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Protection Circuit Undervoltage Protection for V6: Voltage at Pin5 = V5(min) if V6 < V6(Min) V6(Min) 7.00 7.25 7.50 V Overvoltage Protection for V6: Voltage at Pin5 = V5(min) if V6 > V6(Min) V6(Max) 15.0 16.0 16.5 V 970 1005 1040 mV – 150 – °C I3 = 750µA – 0.4 0.8 V V3 = V2 = 0V – 8 – mA Undervoltage Protection for VAC: Voltage at Pin5 = V5(min) if V3 < V3A V3A Over Temperature: At the given chip temperature the IC will switch V5 to V5(Min) Voltage at Pin3 if one of the protection functions was triggered; (V3 will be clamped until V6 < V6A) Current Drain During Burst Operation V2 = 0V Oj V3Sat I6 Pin Connection Diagram Regulation Input 1 8 Zero Crossing Detector Input 7 Soft–Start 6 Supply Voltage Primary Current Simulation 2 Primary Voltage Monitoring 3 GND 4 8 5 Output 5 .260 (6.6) Max 1 4 .430 (10.92) Max .300 (7.62) .200 (5.08) .125 (3.18) Min .100 (2.54) .300 (7.62)