UC2844AD Integrated Circuit Chip Current Mode PWM Controller

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

• High Current Totem Pole Output

• Internally Trimmed Bandgap Reference

• 500kHz Operation

• Low RO Error Amp

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 V_CC over 5V.

The difference between members of this family are shown in the table below.

ABSOLUTE MAXIMUM RATINGS (Note 1)

Supply Voltage (Low Impedance Source) . . . . . . . . . . . . . . 30V

Supply Voltage (ICC mA). . . . . . . . . . . . . . . . . . . . . Self Limiting

Output Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±1A

Output Energy (Capacitive Load) . . . . . . . . . . . . . . . . . . . . . 5µJ

Analog Inputs (Pins 2, 3) . . . . . . . . . . . . . . . . . . -0.3V to +6.3V

Error Amp Output Sink Current . . . . . . . . . . . . . . . . . . . . 10mA

Power Dissipation at TA ≤ 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.

BLOCK DIAGRAM

Stock Offer (Hot Sell)