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MC34025_12 Datasheet, PDF (1/20 Pages) ON Semiconductor – High Speed Double-Ended PWM Controller | |||
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MC34025, MC33025
High Speed Double-Ended
PWM Controller
The MC34025 series are high speed, fixed frequency, doubleâended
pulse width modulator controllers optimized for high frequency
operation. They are specifically designed for OffâLine and
DCâtoâDC 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 flipâflop, 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, cycleâbyâcycle
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
⢠50 ns Propagation Delay to Outputs
⢠Dual High Current Totem Pole Outputs
⢠Wide Bandwidth Error Amplifier
⢠FullyâLatched Logic with Double Pulse Suppression
⢠Latching PWM for CycleâByâCycle Current Limiting
⢠SoftâStart 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
⢠These Devices are PbâFree, Halogen Free/BFR Free and are RoHS
Compliant
16
Vref
4
Clock
5
RT
CT
6
7
Ramp
Error Amp 3
Output
Noninverting 2
Input
Inverting
Input 1
8
Soft-Start
Oscillator
Error
Amp
5.1V
Reference
UVLO
Latching
PWM and
Steering
Flip Flop
Soft-Start
10 Ground
This device contains 227 active transistors.
Figure 1. Simplified Application
15
VCC
13
VC
14
Output B
11
Output A
Power
12 Ground
9
Current
Limit/
Shutdown
http://onsemi.com
16
1
16
1
PDIPâ16
P SUFFIX
CASE 648
MARKING
DIAGRAMS
16
MC3x025P
AWLYYWWG
1
16
SOâ16WB
DW SUFFIX
CASE 751G
MC3x025DW
AWLYYWWG
1
x
= 3 or 4
A
= Assembly Location
WL
= Wafer Lot
YY
= Year
WW
= Work Week
G
= PbâFree Package
PIN CONNECTIONS
Error Amp
Inverting Input 1
Error Amp 2
Noninverting Input
Error Amp Output 3
16 Vref
15 VCC
14 Output B
Clock
RT
CT
Ramp
Soft-Start
4
13 VC
5
12 Power Ground
6
11 Output A
7
10 Ground
8
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.
*For additional information on our PbâFree strategy
and soldering details, please download the
ON Semiconductor Soldering and Mounting
Techniques Reference Manual, SOLDERRM/D.
© Semiconductor Components Industries, LLC, 2012
1
October, 2012 â Rev. 9
Publication Order Number:
MC34025/D
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