MC33065P View Datasheet(PDF) - Motorola => Freescale
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MC33065P Datasheet PDF : 15 Pages
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MC34065 MC33065
PIN FUNCTION DESCRIPTION
Pin
Function
Description
1
Sync Input
A narrow rectangular waveform applied to this input will synchronize the oscillator. A dc voltage
within the range of 2.4 V to 5.5 V will inhibit the oscillator.
2
CT
Timing capacitor CT connects from this pin to ground setting the free–running oscillator frequency
range.
3
RT
Resistor RT connects from this pin to ground precisely setting the charge current for CT. RT must
be between 4.0 k and 16 k.
4
Voltage Feedback 1
This pin is the inverting input of Error Amplifier 1. It is normally connected to the switching power
supply output through a resistor divider.
5
Compensation 1
This pin is the output of Error Amplifier 1 and is made available for loop compensation.
6
Current Sense 1
A voltage proportional to the inductor current is connected to this input. PWM 1 uses this
information to terminate conduction of output switch Q1.
7
Drive Output 1
This pin directly drives the gate of a power MOSFET Q1. Peak currents up to 1.0 A are sourced
and sunk by this pin.
8
Gnd
This pin is the control circuitry ground return and is connected back to the source ground.
9
Drive Gnd
This pin is a separate power ground return that is connected back to the power source. It is used
to reduce the effects of switching transient noise on the control circuitry.
10
Drive Output 2
This pin directly drives the gate of a power MOSFET Q2. Peak currents up to 1.0 A are sourced
and sunk by this pin.
11
Current Sense 2
A voltage proportional to inductor current is connected to this input. PWM 2 uses this information
to terminate conduction of output switch Q2.
12
Compensation 2
This pin is the output of Error Amplifier 2 and is made available for loop compensation.
13
Voltage Feedback 2
This pin is the inverting input of Error Amplifier 2. It is normally connected to the switching power
supply output through a resistor divider.
14
Drive Output 2 Enable A logic low at this input disables Drive Output 2.
15
Vref
16
VCC
This is the 5.0 V reference output. It can provide bias for any additional system circuitry.
This pin is the positive supply of the control IC. The minimum operating voltage range after startup
is 11 V to 15.5 V.
16
14 3.3 nF
12
Figure 1. Timing Resistor versus
Oscillator Frequency
500 pF
1.0 nF
100 pF
220 pF
10
5.0 nF
330 pF
2.2 nF
8.0
CT =
10 nF
6.0
VCC = 15 V
4.0 TA = 25°C
10 k
30 k 50 k 100 k
300 k 500 k 1.0 M
fosc, OSCILLATOR FREQUENCY (Hz)
Figure 2. Maximum Output Duty Cycle
versus Oscillator Frequency
50
48
46
Output 2
44
Output 1
42 VCC = 15 V
RT = 4.0 k to 16 k
40
CL = 15 pF
TA = 25°
38
10 k
30 k 50 k 100 k
300 k 500 k
fosc, OSCILLATOR FREQUENCY (Hz)
1.0 M
4
MOTOROLA ANALOG IC DEVICE DATA
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