MC34025, MC33025
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.
Features
http://onsemi.com
MARKING
DIAGRAMS
16
PDIP−16
P SUFFIX
CASE 648
1
1
16
16
1
1
x
A
WL
YY
WW
G
= 3 or 4
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
SO−16WB
DW SUFFIX
CASE 751G
MC3x025DW
AWLYYWWG
MC3x025P
AWLYYWWG
16
•
•
•
•
•
•
•
•
•
•
•
•
•
•
50 ns Propagation Delay to Outputs
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 Startup Current (500
mA
Typ)
Internally Trimmed Reference with Undervoltage Lockout
45% Maximum Duty Cycle (Externally Adjustable)
Precision Trimmed Oscillator
Voltage or Current Mode Operation to 1.0 MHz
Functionally Similar to the UC3825
Pb−Free Packages are Available*
16
V
ref
Clock
R
T
C
T
6
7
Latching
PWM and
Steering
Flip Flop
4
5
Oscillator
5.1V
Reference
UVLO
13
14
V
C
Output B
15
V
CC
PIN CONNECTIONS
Error Amp
Inverting Input
Error Amp
Noninverting Input
Error Amp Output
Clock
R
T
C
T
Ramp
Soft−Start
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
ref
V
CC
Output B
V
C
Power Ground
Output A
Ground
Current Limit/
Shutdown
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
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 18 of this data sheet.
Soft−Start
10 Ground
This device contains 227 active transistors.
Figure 1. Simplified Application
*For additional information on our Pb−Free strategy
and soldering details, please download the
ON Semiconductor Soldering and Mounting
Techniques Reference Manual, SOLDERRM/D.
©
Semiconductor Components Industries, LLC, 2005
1
October, 2005 − Rev. 7
Publication Order Number:
MC34025/D
ONSEMI [ ON SEMICONDUCTOR ]
