MC33066P View Datasheet(PDF) - ON Semiconductor
Part Name
Description
Manufacturer
MC33066P Datasheet PDF : 11 Pages
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MC34066, MC33066
VCC
15
Enable/
UVLO Adjust 9
Osc Deadtime
ROSC
RDT 1
Osc RC
2
COSC
One−Shot RC
16
CT
RT Osc Control
Current
3
IOSC
RVFO
Error Amp 6
Output
Error Amp 7
Inverting Input
Error Amp
Noninverting Input
8
CSoft−Start
11
50k
7k
7k
+
50k −
8V VCC UVLO
VCC
Reference
Regulator
Q1
IOSC
Q2
5.1V
− Oscillator
+
4.9V/3.6V
One−Shot
−
+
5.1V
Vref UVLO
−
UVLO
+
4.2V/4V
Steering
Flip−Flop
Q
T
ton
Q
R
4.9V/3.6V
Current Mirror
+
Error Amp
−
Output Clamp
2.5V
EA Clamp
UVLO + Fault
R
Q
S
Fault
Latch
−
+
Error
Amplifier
Soft−Start
Buffer
9μA
5 Vref
Gnd
4
Drivers
Drive
14 Output A
Drive
12 Output B
Drive
13 Gnd
Fault
Comparator +
Fault
−
1.0V
Fault
10 Input
Figure 2. MC34066 Representative Block Diagram
OPERATING DESCRIPTION
Introduction
As power supply designers have strived to increase power
conversion efficiency and reduce passive component size, high
frequency resonant mode power converters have emerged as
attractive alternatives to conventional square−wave control.
When compared to square−wave converters, resonant mode
control offers several benefits including lower switching
losses, higher efficiency, lower EMI emission, and smaller
size. This integrated circuit has been developed to support new
trends in power supply design. The MC34066 Resonant Mode
Controller is a high performance bipolar IC dedicated to
variable frequency power control at frequencies exceeding
1.0 MHz. This integrated circuit provides the features,
performance and flexibility for a wide variety of resonant
mode power supply applications.
The primary purpose of the control chip is to supply
precise pulses to the gates of external power MOSFETs at a
repetition rate regulated by a feedback control loop. The
MC34066 can be operated in any of three modes as follows:
1) fixed on−time, variable frequency; 2) fixed off−time,
variable frequency; and 3) combinations of 1 and 2 that
change from fixed on−time to fixed off−time as the
frequency increases. Additional features of the IC ensure
that system startup and fault conditions are administered in
a safe, controlled manner.
A simplified block diagram of the IC is shown on the first
page of this data sheet, which identifies the main functional
blocks and the block−to−block interconnects. Figure 2 is a
detailed functional diagram which accurately represents the
internal circuitry. The various functions can be divided into
two sections. The first section includes the primary control
path which produces precise output pulses at the desired
frequency Oscillator, a One−Shot, a pulse Steering
Flip−Flop, a pair of power MOSFET Drivers, and a wide
bandwidth Error Amplifier. The second section provides
several peripheral support functions including a voltage
reference, undervoltage lockout, Soft−Start circuit, and a
fault detector.
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