Share:
Specifications
SKU: 12426917
| Parameter | Symbol | Min | Typ | Max | Unit | Description |
|---|---|---|---|---|---|---|
| Supply Voltage | Vcc | 7.0 | - | 40.0 | V | Operating supply voltage range |
| Start-Up Current | Istart | - | 0.5 | - | mA | Typical start-up current |
| Operating Current | Icc | 2.0 | 3.5 | 5.0 | mA | Typical operating current |
| Oscillator Frequency | fosc | 100 | - | 500 | kHz | Range of oscillator frequency |
| Maximum Duty Cycle | Dmax | - | 50 | - | % | Maximum duty cycle limit |
| Minimum On-Time | ton(min) | - | 1.0 | - | μs | Minimum on-time for PWM operation |
| Minimum Off-Time | toff(min) | - | 1.9 | - | μs | Minimum off-time for PWM operation |
| Thermal Shutdown Temperature | Tsd | 160 | - | 180 | °C | Temperature at which thermal shutdown occurs |
| Storage Temperature | Tstg | -40 | - | 125 | °C | Operating temperature range for storage |
Instructions for Using UC2844
Power Supply:
- Ensure the supply voltage (Vcc) is within the range of 7.0V to 40.0V.
- Use a bypass capacitor (typically 0.1μF to 10μF) close to the Vcc pin to filter out noise.
Start-Up and Operating Current:
- The typical start-up current is 0.5mA, and the operating current ranges from 2.0mA to 5.0mA.
- Ensure the power supply can provide sufficient current to meet these requirements.
Oscillator Configuration:
- Set the oscillator frequency (fosc) between 100kHz and 500kHz using an external resistor (RT) and capacitor (CT).
- The formula for calculating the frequency is ( f_ = frac{1.8}{R_T cdot C_T} ).
Duty Cycle Control:
- The maximum duty cycle (Dmax) is 50%.
- Use the feedback (FB) pin to control the duty cycle and maintain stable output.
On-Time and Off-Time:
- The minimum on-time (ton(min)) is 1.0μs, and the minimum off-time (toff(min)) is 1.9μs.
- These parameters help prevent short-circuit conditions and ensure proper switching.
Thermal Management:
- The device will shut down if the junction temperature exceeds 160°C to 180°C.
- Ensure adequate heat dissipation and cooling to prevent thermal shutdown.
Storage and Operating Temperature:
- Store the device within the temperature range of -40°C to 125°C.
- Operate the device within the same temperature range to ensure reliable performance.
Protection Features:
- The UC2844 includes overcurrent protection and thermal shutdown to protect against faults.
- Monitor the output and input conditions to ensure they remain within safe limits.
Layout Considerations:
- Place the UC2844 and its associated components close together to minimize parasitic inductance and capacitance.
- Use wide, short traces for high-current paths to reduce resistance and inductance.
Testing and Debugging:
- Use an oscilloscope to monitor the signals at the FB, RT, and CT pins to verify correct operation.
- Check the supply voltage and current to ensure they are within the specified ranges.
By following these instructions, you can ensure that the UC2844 operates reliably and efficiently in your application.
(For reference only)Inquiry - UC2844
