Order this document by MC34025/D
High Speed Double-Ended
PWM Controller
The MC34025 series are high speed, fixed frequency, double–ended
pulse width modulator controllers optimized for high frequency operation.
They are specifically designed for Off–Line and DC–to–DC converter
applications offering the designer a cost effective solution with minimal
external components. These integrated circuits feature an oscillator, a
temperature compensated reference, a wide bandwidth error amplifier, a
high speed current sensing comparator, steering flip–flop, and dual high
current totem pole outputs ideally suited for driving power MOSFETs.
Also included are protective features consisting of input and reference
undervoltage lockouts each with hysteresis, cycle–by–cycle current limiting,
and a latch for single pulse metering.
The flexibility of this series allows it to be easily configured for either
current mode or voltage mode control.
•
50 ns Propagation Delay to Outputs
MC34025
MC33025
16
1
P SUFFIX
PLASTIC PACKAGE
CASE 648
16
1
•
•
•
•
•
•
•
•
•
•
•
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Dual High Current Totem Pole Outputs
Wide Bandwidth Error Amplifier
Fully–Latched Logic with Double Pulse Suppression
Latching PWM for Cycle–By–Cycle Current Limiting
Soft–Start Control with Latched Overcurrent Reset
Input Undervoltage Lockout with Hysteresis
Low Start–Up Current (500
µA
Typ)
Internally Trimmed Reference with Undervoltage Lockout
90% Maximum Duty Cycle (Externally Adjustable)
Precision Trimmed Oscillator
Voltage or Current Mode Operation to 1.0 MHz
Functionally Similar to the UC3825
Error Amp
Inverting Input
Error Amp
Noninverting Input
Error Amp Output
Clock
16
Vref
Clock
RT
CT
4
5
Oscillator
6
7
Latching
PWM and
Steering
Flip Flop
5.1V
Reference
UVLO
13
14
VC
Output B
15
VCC
RT
CT
Ramp
Soft–Start
1
2
3
4
5
6
7
8
DW SUFFIX
PLASTIC PACKAGE
CASE 751G
(SO–16L)
PIN CONNECTIONS
16
15
14
13
12
11
10
9
Vref
VCC
Output B
VC
Power Ground
Output A
Ground
Current Limit/
Shutdown
Simplified Application
(Top View)
Ramp
Error Amp 3
Output
Noninverting 2
Input
Inverting
Input 1
8
Soft–Start
Error
Amp
11
Output A
Power
12 Ground
9
Current
Limit/
Shutdown
ORDERING INFORMATION
Device
MC33025DW
MC33025P
MC34025DW
MC34025P
TA = 0° to +70°C
Operating
Temperature Range
TA = – 40° to +105°C
Package
SO–16L
Plastic DIP
SO–16L
Plastic DIP
Soft–Star
t
10
Ground
This device contains 227 active transistors.
©
Motorola, Inc. 1996
Rev 1
MOTOROLA ANALOG IC DEVICE DATA
1
MOTOROLA [ MOTOROLA, INC ]
