UC28023
UC28025
SLUS557F -- MARCH 2003 -- REVISED AUGUST 2010
ECONOMY HIGH-SPEED PWM CONTROLLER
FEATURES
DESCRIPTION
D
Peak Current Mode, Average Current Mode,
or Voltage Mode (with Feed-Forward) Control
Methods
The UC28023 and UC28025 are fixed-frequency
PWM controllers optimized for high-frequency
switched-mode power supply applications. The
UC28023 is a single output PWM for single-ended
topologies while the UC28025 offers dual
alternating outputs for double-ended and full
bridge topologies.
D
D
D
D
Practical Operation Up to 1 MHz
50-ns Propagation Delay to Output
±1.5-A Peak Totem Pole Outputs
9-V to 30-V Nominal Operational Voltage
Range
Targeted for cost effective solutions with minimal
external components, UC2802x include an
oscillator, a temperature compensated reference,
a wide band width error amplifier, a high-speed
current-sense comparator and high-current
active-high totem-pole outputs to directly drive
external MOSFETs.
D
D
Wide Bandwidth Error Amplifier
Fully Latched Logic with Double Pulse
Suppression
D
D
D
D
D
Pulse-by-Pulse Current Limiting
Programmable Maximum Duty Cycle Control
Under--Voltage Lockout with Hysteresis
Trimmed 5.1-V Reference with UVLO
Same Functionality as UC3823 and UC3825
Protection circuitry includes a current limit
comparator with
a 1-V threshold, a TTL
compatible shutdown port, and a soft-start pin
which will double as a maximum duty cycle clamp.
The logic is fully latched to provide jitter free
operation and prohibit multiple pulses at an
output. An undervoltage lockout section with
800 mV of hysteresis assures low start-up
current. During undervoltage lockout, the outputs
are high impedance. Particular care was given to
minimizing propagation delays through the
comparators and logic circuitry while maximizing
bandwidth and slew rate of the error amplifier.
APPLICATIONS
D
D
Off-Line and DC/DC Power Supplies
Converters Using Voltage Mode, Peak
Current Mode, or Average Current Mode
Control Methods
D
Single-Ended or Two-Switch Topology
Designs
Devices areavailableintheindustrialtemperature
range of --40°C to 105°C. Package offerings are
16-pin SOICW (DW), or 16-pin PDIP (N)
packages.
ORDERING INFORMATION
PACKAGED DEVICES
OUTPUT
CONFIGURATION
EXTERNAL CURRENT
LIMIT REFERENCE
T
T
J
A =
PDIP-16 (N)
SOICW--16 (DW)
UC28023DW
Single
Yes
No
UC28023N
UC28025N
-- 4 0 °C to 105°C
Dual Alternating
UC28025DW
(1)
The DW package are also available taped and reeled. Add an R suffix to the device type (i.e., UC28023DWR (2,000 devices per reel).
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
Copyright © 2005 -- 2010, Texas Instruments Incorporated
1
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