器件名称: UC1845A
功能描述: Current Mode PWM Controller
文件大小: 517.22KB 共11页
简 介:application INFO available
UC1842A/3A/4A/5A UC2842A/3A/4A/5A UC3842A/3A/4A/5A
Current Mode PWM Controller
FEATURES
Optimized for Off-line and DC to DC Converters Low Start Up Current (<0.5mA) Trimmed Oscillator Discharge Current Automatic Feed Forward Compensation Pulse-by-Pulse Current Limiting Enhanced Load Response Characteristics Under-Voltage Lockout With Hysteresis Double Pulse Suppression
Part # UVLO On 16.0V 8.5V 16.0V 8.5V UVLO Off 10.0V 7.9V 10.0V 7.9V Maximum Duty Cycle <100% <100% <50% <50%
DESCRIPTION
The UC1842A/3A/4A/5A family of control ICs is a pin for pin compatible improved version of the UC3842/3/4/5 family. Providing the necessary features to control current mode switched mode power supplies, this family has the following improved features. Start up current is guaranteed to be less than 0.5mA. Oscillator discharge is trimmed to 8.3mA. During under voltage lockout, the output stage can sink at least 10mA at less than 1.2V for VCC over 5V. The difference between members of this family are shown in the table below.
High Current Totem Pole Output
UC1842A
Internally Trimmed Bandgap Reference 500kHz Operation Low RO Error Amp
UC1843A UC1844A UC1845A
BLOCK DIAGRAM
Note 1: A/B A = DIL-8 Pin Number. B = SO-14 Pin Number. Note 2: Toggle flip flop used only in 1844A and 1845A.
SLUS224A - SEPTEMBER 1994 - REVISED APRIL 2002
CONNECTION DIAGRAMS ABSOLUTE MAXIMUM RATINGS (Note 1)
Supply Voltage (Low Impedance Source) . . . . . . . . . . . . . . 30……
