AMC3843B

Features:

  Low Start-Up current ( typ. 200µA)
  Optimized for Off-Line and DC-to-DC Converters
  Maximum Duty Cycle
  U.V.L.O. with Hysteresis
  Operating Frequency Up to 500KHz
  Internal Trimmed Bandgap Reference
  High Current Totem Pole Output
  Error Amplifier With Low Output Resistance
  Available in 8-Pin Plastic DIP and Surface Mount 14-Pin S.O.I.C.
  Identical pin assignment to earlier UC384X series.


Application

  Off-line flyback or forward converters.
  DC-to-DC buck or boost converter.
  Monitor Power Supply


Specifications

ABSOLUTE MAXIMUM RATINGS (Note 1)
Supply voltage, VCC	35V
Output current, IO	± 1A
Analog inputs, VI	-0.3V to 6.3V
Error amp output sink current, ISINK(EA)	10mA
Power dissipation (TA = 25 ), PD	1W
Maximum juncture temperature, TJ	150
Storage temperature range	-65 to 150
Lead temperature (soldiering, 10 seconds)	260
Note 1: Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal.

Description

The AMC3842B/43B are fixed frequency current-mode PWM controllers specially designed for OFF-Line switching power supply and DC-to-DC converters with a minimum number of external components. These devices feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem pole output which is suitable for driving MOSFETs.

The under voltage lock-out (U.V.L.O.) is designed to operated with 200µA typ. start-up current, allowing an efficient bootstrap supply voltage design. The U.V.L.O. thresholds for the AMC3842B are 16V (on) and 10V (off) which are ideal for off-line applications. The corresponding typical threshold for the AMC3843B are 8.4V (on) and 7.6V (off). The AMC3842B/43B can operated within 100% duty cycle.