PWM Controller. UCC2884 Datasheet

UCC2884 Controller. Datasheet pdf. Equivalent

Part UCC2884
Description Frequency Foldback Current Mode PWM Controller
Feature .
Manufacture etcTI
Datasheet
Download UCC2884 Datasheet




UCC2884
UCC2884
UCC3884
www.ti.com............................................................................................................................................. SLUS160C – AUGUST 1999 – REVISED NOVEMBER 2008
Frequency Foldback Current Mode PWM Controller
FEATURES
1
Frequency Foldback Reduces Operating
Frequency Under Fault Conditions
Accurate Programmable Volt-Second Clamp
Programmable Maximum Duty Cycle Clamp
Oscillator Synchronization
Overcurrent Protection
Shutdown With Full Soft Start
Wide Gain Bandwidth Amplifier (GBW > 2.5
MHz)
Current Mode Operation
Precision 5-V Reference
DESCRIPTION
The UCC3884 is a high performance current mode
PWM controller intended for single ended switch
mode power supplies. The chip implements a
frequency foldback scheme that decreases the
oscillator frequency as the output voltage falls below
a programmed value. This technique decreases the
average output current sourced into a low impedance
load which can occur during an output short circuit or
overload condition. Excessive short circuit current is
more prevalent in high frequency converters where
the propagation delay and switch turn-off time forces
a minimum attainable duty cycle. An accurate
volt-second clamp limits the duty cycle during line or
load transient conditions which could otherwise
saturate the transformer. The volt-second clamp may
also be used with an external overvoltage protection
circuit to handle fault conditions such as current
sense disconnect or current transformer saturation.
The frequency foldback, volt-second clamp,
cycle-by-cycle current limit, and overcurrent shutdown
provide a rich set of protection features for use in
peak current-mode pulse width modulators.
OSCILLATOR SYNCHRONIZATION
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 1999–2008, Texas Instruments Incorporated



UCC2884
UCC2884
UCC3884
SLUS160C – AUGUST 1999 – REVISED NOVEMBER 2008............................................................................................................................................. www.ti.com
ABSOLUTE MAXIMUM RATINGS(1)
Supply voltage
Output sink current
Output source current
All other pins
Storage temperature
Junction temperature
Lead temperature (soldering, 10 sec)
VALUE
15
1
0.5
6
–65 TO 150
–40 TO 150
300
UNIT
V
A
V
°C
(1) Currents are positive into, negative out of the specified terminal.
TJ
-40°C to 85°C
0°C to 70°C
ORDERING INFORMATION
PACKAGED DEVICES(1)
SOP (D)
PDIP(N)
UCC2884D (16)
UCC2884N (16)
UCC3884D (16)
UCC3884N (16)
(1) Both the D and N packages are available taped and reeled (indicated by the TR suffix on the device type e.g., UCC2884DTR)
CONNECTION DIAGRAMS
N or D Package (Top View)
2 Submit Documentation Feedback
Copyright © 1999–2008, Texas Instruments Incorporated
Product Folder Link(s): UCC2884 UCC3884







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