
Semiconductor Components Industries, LLC, 2005
September, 2005 Rev. 8
1
Publication Order Number:
CS51221/D
CS51221
Enhanced Voltage Mode
PWM Controller
The CS51221 fixed frequency feed forward voltage mode PWM
controller contains all of the features necessary for basic voltage mode
operation. This PWM controller has been optimized for high
frequency primary side control operation. In addition, this device
includes such features as: SoftStart, accurate duty cycle limit control,
less than 50 A startup current, over and undervoltage protection, and
bidirectional synchronization. The CS51221 is available in a 16 lead
SOIC narrow surface mount package.
Features
1.0 MHz Frequency Capability
Fixed Frequency Voltage Mode Operation, with Feed Forward
Thermal Shutdown
Undervoltage LockOut
Accurate Programmable Max Duty Cycle Limit
1.0 A Sink/Source Gate Drive
Programmable PulseByPulse Overcurrent Protection
Leading Edge Current Sense Blanking
75 ns Shutdown Propagation Delay
Programmable SoftStart
Undervoltage Protection
Overvoltage Protection with Programmable Hysteresis
Bidirectional Synchronization
25 ns GATE Rise and Fall Time (1.0 nF Load)
3.3 V 3% Reference Voltage Output
PbFree Packages are Available*
*For additional information on our PbFree strategy and soldering details, please
download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
V
FB
I
SET
1
C
A
16
COMP
R
T
C
T
SS
OV
LGND
UV
V
REF
FF
V
CC
SYNC
PGND
I
SENSE
V
C
GATE
PIN CONNECTIONS AND
MARKING DIAGRAM
1
16
http://onsemi.com
Device
Package
Shipping
ORDERING INFORMATION
CS51221ED16
CS51221ED16G
SOIC16
SOIC16
(PbFree)
48 Units / Rail
48 Units / Rail
CS51221EDR16
CS51221EDR16G
SOIC16 2500 Tape & Reel
SOIC16
(PbFree)
TSSOP16
(PbFree)
2500 Tape & Reel
2500 Tape & Reel
For information on tape and reel specifications,
including part orientation and tape sizes, please
refer to our Tape and Reel Packaging Specifications
Brochure, BRD8011/D.
CS51221EDTB16G
96 Units / Rail
CS51221EDTB16R2G TSSOP16
(PbFree)
SOIC16
D SUFFIX
CASE 751B
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16
TSSOP16
DTB SUFFIX
CASE 948F
CS51221= Specific Device Code
A
= Assembly Location
WL, L
= Wafer Lot
YY, Y
= Year
WW, W = Work Week
= PbFree Package
C
A
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