Details

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Parameter	Symbol	Conditions	Min	Typical	Max	Unit
Input Voltage	VIN		11.5		35	V
Output Voltage	VOUT			9.0		V
Output Current	IOUT	Continuous		1.5		A
Line Regulation		12V to 35V input		0.004		%
Load Regulation		0 to 1.5A output		0.01		%
Dropout Voltage	VDROPOUT	1.5A output		2.0		V
Thermal Shutdown	TSD			175		°C
Output Noise	VN	10Hz to 100kHz		45		μVrms
Ripple Rejection	RRR	120Hz, 50mV input		60		dB
Storage Temperature	TSTG		-65		150	°C
Operating Junction Temp	TJ		0		125	°C

Instructions for Using the LM7809:

1. Input Capacitor (Cin):

   • Place a 0.33 μF capacitor between the input and ground as close as possible to the regulator to ensure stability and reduce input ripple.

2. Output Capacitor (Cout):

   • Use a 0.1 μF capacitor between the output and ground to stabilize the output voltage and filter out high-frequency noise.
   • For better transient response, a larger capacitor (e.g., 10 μF) can be added in parallel with the 0.1 μF capacitor.

3. Heat Sink:

   • The LM7809 may require a heat sink if it is operating at high current levels or in high ambient temperatures.
   • Calculate the power dissipation (P = (VIN - VOUT) * IOUT) and use a heat sink to keep the junction temperature within safe limits.

4. Input Voltage Range:

   • Ensure the input voltage is within the specified range (11.5V to 35V) to avoid damage to the regulator.

5. Output Voltage Regulation:

   • The output voltage is fixed at 9V. If a different output voltage is required, consider using an adjustable regulator like the LM317.

6. Thermal Protection:

   • The LM7809 has built-in thermal shutdown to protect against overheating. However, it is still important to monitor the temperature and ensure adequate cooling.

7. Short-Circuit Protection:

   • The regulator includes internal short-circuit protection, but it is recommended to use external fuses or circuit breakers to prevent damage from prolonged short circuits.

8. Layout Considerations:

   • Keep the input and output capacitors as close as possible to the regulator to minimize inductive effects and improve performance.
   • Use wide traces for the input and output connections to reduce resistance and voltage drops.

By following these guidelines, you can ensure reliable and efficient operation of the LM7809 voltage regulator.

(For reference only)