Current Mode PWM Controller 1.5A 16-Pin SOIC T/R

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.

Peak Current Mode, Average Current Mode, 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

APPLICATIONS

• Off-Line and DC/DC Power Supplies
• Converters Using Voltage Mode, Peak Current Mode,
  or Average Current Mode Control Methods
• Single-Ended or Two-Switch Topology Designs