MC33364
http://onsemi.com
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
from the isolated secondary output. The Feedback is connected to the V
ref
Pinviaa5kresistor
providing bias for the external optocoupler.
6(4) V
ref
The V
ref
Pin is a buffered internal 5.0 V reference with Undervoltage Lockout.
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--t ime is disabled in the 33364D2. Therefore the maximum switching frequency cannot exceed
1/(T
ON
+T
OFFmin
).
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) V
CC
Provides the voltage for all internal circuitry including the gate drive stage and V
ref
. This pin has
Undervoltage Lockout with hysteresis.
16 (8) Line The Line Pin provides the initial power to the V
CC
pins. Internally the line pin is a high voltage
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.
MAXIMUM RATINGS (T
A
=25C, unless otherwise noted.)
Rating
Symbol Value Unit
Power Supply Voltage (Operating) V
CC
16 V
Line Voltage V
Line
700 V
Current Sense, Compensation,
Voltage Feedback, Restart Delay and Zero Current Input Voltage
V
in1
--1.0to+10 V
Zero Current Detect Input I
in
5.0 mA
Restart Diode Current I
in
5.0 mA
Power Dissipation and Thermal Characteristics
D1 and D2 Suffix, Plastic Package Case 751
Maximum Power Dissipation @ T
A
=70C P
D
450 mW
Thermal Resistance, Junction--to--Air
R
θ
JA
178 C/W
D S uffix, Plastic Package Case 751B--05
Maximum Power Dissipation @ T
A
=70C P
D
550 mW
Thermal Resistance, Junction--to--Air
R
θ
JA
145 C/W
Operating Junction Temperature T
J
150 C
Operating Ambient Temperature T
A
--25 to +125 C
Storage Temperature Range T
stg
--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.
