UC28023
UC28025
SLUS557B − MARCH 2003 − REVISED APRIL 2004
ECONOMY HIGH SPEED PWM CONTROLLER
FEATURES
D
Peak Current Mode, Average Current Mode,
D
D
D
D
D
D
D
D
D
D
D
or Voltage Mode (with Feed-Forward) Control
Methods
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
Wide Bandwidth Error Amplifier
Fully Latched Logic with Double Pulse
Suppression
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
DESCRIPTION
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.
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.
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.
Devices are available in the industrial temperature
range of −40°C to 105°C. Package offerings are
16-pin SOICW (DW), or 16-pin PDIP (N)
packages.
APPLICATIONS
D
Off-Line and DC/DC Power Supplies
D
Converters Using Voltage Mode, Peak
D
Current Mode, or Average Current Mode
Control Methods
Single-Ended or Two-Switch Topology
Designs
ORDERING INFORMATION
TA = TJ
−40°C to 105°C
OUTPUT
CONFIGURATION
Single
Dual Alternating
EXTERNAL CURRENT
LIMIT REFERENCE
Yes
No
PACKAGED DEVICES
PDIP-16 (N)
UC28023N
UC28025N
SOICW−16 (DW)
UC28023DW
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
2004, Texas Instruments Incorporated
www.ti.com
1
TI [ TEXAS INSTRUMENTS ]
