The MC44605 is a high performance current mode controller that is specifically designed for off−line converters. This circuit has several distinguishing features that make it particularly suitable for multisynchronized monitor applications.

The MC44605 synchronization arrangement enables operation from 16 kHz up to 130 kHz. This product was optimized to operate with universal mains voltage, i.e., from 80 V to 280 V, and its high current totem pole output makes it ideally suited for driving a power MOSFET.

The MC44605 protections enable a well−controlled and safe power management. Four major faults while detected, activate the analogic counter of a disabling block designed to perform a latched circuit output inhibition.

Features

• Pb−Free Package is Available*

Current Mode Controller

• Current Mode Operation up to 250 kHz Output Switching Frequency

• Inherent Feed Forward Compensation

• Latching PWM for Cycle−by−Cycle Current Limiting

• Oscillator with Precise Frequency Control

• Externally Programmable Reference Current

• Secondary or Primary Sensing (Availability of Error Amplifier Output)

• Synchronization Facility

• High Current Totem Pole Output

• Vcc Undervoltage Lockout with Hysteresis

• Low Output dV/dT for Low EMI Radiations

• Low Startup and Operating Current

Safety/Protection Features

• Soft−Start Feature

• Demagnetization (Zero Current Detection) Protection

• Overvoltage Protection Facility against Open Loop

• EHT Overvoltage Protection (E.H.T.OVP): Detection of too High Synchronization Pulses

• Winding Short Circuit Detection (W.S.C.D.)

• Limitation of the Maximum Input Power (M.P.L.): Calculation of Input Power for Overload Protection

• Overheating Detection (O.H.D.): to Prevent the Power Switch from an Excessive Heating

Latched Disabling Mode

• When one of the following faults is detected: EHT overvoltage,

Winding Short Circuit (WSCD), a too high input power (M.P.L.),

power switch overheating (O.H.D.), an analogic counter is activated

• If the counter is activated for a time that is long enough, the circuit

gets definitively disabled. The latch can only be reset by making

decrease the Vcc down to about 3.0 V, i.e., practically by unplugging

or turning off the SMPS.