UC2844AD Integrated Circuit Chip Current Mode PWM Controller
integrated circuit ic
,integrated circuit components
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 VCC over 5V.
The difference between members of this family are shown in the table below.
| Part # | UVLO On | UVLO Off | Maximum Duty Cycle |
|---|---|---|---|
| UC1842A | 16.0V | 10.0V | <100% |
| UC1843A | 8.5V | 7.9V | <100% |
| UC1844A | 16.0V | 10.0V | <50% |
| UC1845A | 8.5V | 7.9V | <50% |
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)
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