MC33364

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4

PIN DESCRIPTION

Pin

Function

Description

1(1)

Zero Current Detect

The ZCD Pin ensures critical conduction mode. ZCD monitors the voltage on the auxiliary winding,

during the demagnetization phase of the transformer, comparing it to an internal reference. The

ZCD sets the latch for the output driver.

3(2)

Current Sense

The Current Sense Pin monitors the current in the power switch by measuring the voltage across

a resistor. Leading Edge Blanking is utilized to prevent false triggering. The voltage is compared to

a resistor divider connected to the Voltage Feedback Pin. A 110 mV voltage off--set is applied to

compensate the natural optocoupler saturation voltage.

4(3)

Voltage Feedback

The Voltage Feedback Pin is typically connected to the collector of the optocoupler for feedback

providing bias for the external optocoupler.

6(4)

8(NA)

Frequency Clamp

The Frequency Clamp Pin ensures a minimum off--time value, typically 6.9 ms. It prevents the

MOSFET from restarting within a fixed (33364D1) or adjustable (33364D) delay. The minimum

off--time is disabled in the 33364D2. Therefore the maximum switching frequency cannot exceed

9(5)

AGND

This pin is the ground for the internal circuitry excluding the gate drive stage.

10 (5)

PGND

This pin is the ground for the gate drive stage.

11 (6)

Gate Drive

The gate drive is the output to drive the gate of the power MOSFET.

12 (7)

Undervoltage Lockout with hysteresis.

16 (8)

Line

current source, eliminating the need for an external startup network.

NOTE: For further information please refer to the following Application Notes;

AN1594: Critical Conduction Mode, Flyback Switching Power Supply Using the MC33364.

AN1681: How to keep a Flyback Switch--Mode Power Supply Stable with a Critical--Mode Controller.

Rating

Symbol

Value

Unit

Power Supply Voltage (Operating)

16

V

Line Voltage

700

V

Current Sense, Compensation,

Voltage Feedback, Restart Delay and Zero Current Input Voltage

--1.0to+10

V

Zero Current Detect Input

5.0

mA

Restart Diode Current

5.0

mA

Power Dissipation and Thermal Characteristics

D1 and D2 Suffix, Plastic Package Case 751

450

mW

Thermal Resistance, Junction--to--Air

178

C/W

D Suffix, Plastic Package Case 751B--05

550

mW

Thermal Resistance, Junction--to--Air

145

C/W

Operating Junction Temperature

150

C

Operating Ambient Temperature

--25 to +125

C

Storage Temperature Range

--55 to +150

C

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

NOTE: ESD data available upon request.