MC44605P 데이터 시트보기 (PDF) - ON Semiconductor

부품명

상세내역

제조사

MC44605P

High Safety, Latched Mode, GreenLine PWM Controller for (Multi) Synchronized Applications

ON Semiconductor 

MC44605

Pin

Name

Pin Description

1

VCC

This pin is the positive supply of the IC.

2

VC

The output high state, VOH, is set by the voltage applied to this pin. With a separate

connection to the power source, it gives the possibility to set by means of an external

resistor the output source current at a different value than the sink current.

3

Output

The output current capability is suited for driving a power MOSFET.

4

GND

The ground pin is a single return typically connected back to the power source. It is used as

control and power ground.

5

Maximum Power Limitation This block enables to estimate the input power. When this calculated power is detected as

too high, a fault information is sent to the disabling block in order to definitively disable the

circuit.

6

Over−Heating Detection

This block estimates the MOSFET heating. When this calculated heating is too high, the

device gets definitively disabled (disabling block action).

7

Current Sense Input

A voltage proportional to the current flowing into the power switch is connected to this input.

The PWM latch uses this information to terminate the conduction of the output buffer. A

maximum level of 1 V allows to limit the inductor current.

8

Demagnetization Detection A voltage delivered by an auxiliary transformer winding provides to the demagnetization pin

an indication of the magnetization state of the flyback energy reservoir. A zero voltage

detection corresponds to a complete core demagnetization. The demagnetization detection

prevents the oscillator from a re−start and so the circuit from a new conduction phase, if the

fly−back is not in a dead−time state. This function can be inhibited by connecting Pin 8 to

GND but in this case, there is a minimum off−time typically equal to 3 ms.

9

Synchronization and

Activating the synchronization input pin with a pulse higher or equal to the negative

E.H.T.OVP Input

threshold (typically −200 mV) allows the next switching period to be reinitialized. The

oscillator is free when connecting Pin 9 to GND.

When the E.H.T.OVP pin receives a voltage that is greater than 7.5 V, the disabling block

Cext capacitor is charged so that the circuit gets definitively disabled if the Cext voltage

becomes higher than Vref. This block is incorporated to detect and disable the device when

the synchronization pulses are too high.

10

Oscillator Capacitor CT

The free mode oscillator frequency is programmed by the capacitor CT choice together with

the Rref resistance value. CT, connected between pin 10 and GND, generates the oscillator

sawtooth.

11

Soft−Start

A capacitor connected to this pin can temporary reduce the maximum inductor peak

current. By this way, a soft−start can be performed. By connecting pin 11 to Ground, the

MC44605 is shutdown.

12

Cext (Disabling Block)

When a too high synchronization pulse voltage (E.H.T.OVP) or a winding short circuit

(WSCD) is detected, the capacitor Cext is charged using a current source IDis− H. In the

case of a MPL or OHD fault detection, Cext is charged using IDis−L. If the Cext capacitor

voltage gets higher than Vref, the circuit is definitively disabled. Then, to re−start, the

converter must be switched off in order to make VCC decrease down to about 0 V.

13

E/A Output

The error amplifier output is made available for loop compensation.

14

Voltage Feedback

This is the inverting input of the Error Amplifier. It can be connected to the Switching Mode

Power Supply output through an optical (or else) feedback loop or to the subdivided VCC

voltage in case of primary sensing technic.

15

Winding Short Circuit

The W.S.C.D. block is incorporated to detect the transformer Winding Short Circuits. This

Detection Programmation function is performed by detecting the inductor overcurrents thanks to a comparator which

threshold is programmable to be well adapted to any application.

16

Rref

The Rref value fixes the internal reference current that is particularly used to perform the

precise oscillator waveform. The current range goes from 100 mA up to 500 mA.

http://onsemi.com

7

Share Link: