UC1844A

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
· High Current Totem Pole Output
· Internally Trimmed Bandgap Reference
· 500kHz Operation
· Low RO Error Amp


Pinout




Specifications

Supply Voltage (Low Impedance Source) . . . . . . . . . . . . . . 30V
Supply Voltage (I_CC mA). . . . . . . . . . . . . . . . . . . . . Self Limiting
Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1A
Output Energy (Capacitive Load) . . . . . . . . . . . . . . . . . . . . . 5J
Analog Inputs (Pins 2, 3) . . . . . . . . . . . . . . . . . . -0.3V to +6.3V
Error Amp Output Sink Current . . . . . . . . . . . . . . . . . . . . 10mA
Power Dissipation at T_A  25°C (DIL-8) . . . . . . . . . . . . . . . . 1W
Storage Temperature Range . . . . . . . . . . . . . -65°C to +150°C
Lead Temperature (Soldering, 10 Seconds) . . . . . . . . . . 300°C

Note 1. All voltages are with respect to Ground, Pin 5. Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. Pin numbers refer to DIL package only.


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.