调节脉冲宽度调制器 REGULATING PULSE WIDTH MODULATORS
DESCRIPON
The UC1525A/1527A series of pulse width modulator integrated circuits are designed to offer improved performance and lowered external parts count when used in designing all types of switching power supplies. The on-chip +5.1-V reference is trimmed to 1% and the input common-mode range of the error amplifier includes the reference voltage, eliminating external resistors. A sync input to the oscillator allows multiple units to be slaved or a single unit to be synchronized to an external system clock. A single resistor between the CT and the discharge terminals provides a wide range of dead-time adjustment. These devices also feature built-in soft-start circuitry with only an external timing capacitor required. A shutdown terminal controls both the soft-start circuitry and the output stages, providing instantaneous turn off through the PWM latch with pulsed shutdown, as well as soft-start recycle with longer shutdown commands.
1FEATURES
• 8-V to 35-V Operation
• 5.1-V Reference Trimmed to 1%
• 100-Hz to 500-kHz Oscillator Range
• Separate Oscillator Sync Terminal
• Adjustable Deadtime Control
• Internal Soft-Start
• Pulse-by-Pulse Shutdown
• Input Undervoltage Lockout With Hysteresis
• Latching PWM to Prevent Multiple Pulses
• Dual Source/Sink Output Drivers