The LM338 and LM118 are both voltage regulator integrated circuits (ICs), but they have different functionalities:
LM338:
Type: Adjustable positive voltage regulator
Function: Regulates the output voltage to a user-defined positive value (relative to ground) by adjusting external resistors.
Key Features:
Adjustable output voltage: Typically from 1.2V to 32V (check datasheet for specifics).
High output current: Up to 5A (depending on the version).
Internal protections: Current limiting, thermal overload protection.
Simple to use: Requires few external components.
Applications: Adjustable power supplies, constant current regulators, various electronic circuits requiring regulated positive voltage.
LM118 (Obsolete):
Type: Positive voltage regulator (fixed voltage)
Function: Provides a fixed positive output voltage (typically 5V or 12V options).
Key Features:
Fixed output voltage options (limited variety).
High output current: Up to 1A (depending on the version).
Internal short-circuit protection.
Applications: Limited use in older circuits requiring a fixed 5V or 12V supply (consider alternatives for new designs due to obsolescence).
Key Differences:
Adjustability: LM338 is adjustable, LM118 is fixed voltage.
Availability: LM338 is widely available, LM118 is obsolete.
Voltage range: LM338 offers a wider output voltage range.
Choosing the Right One:
If you need an adjustable positive voltage regulator with a wide range and high current capability, the LM338 is the better choice.
If you specifically need a fixed 5V or 12V positive voltage supply and can find an LM118, it might work in older designs. However, for new designs, consider readily available adjustable regulators like the LM338 or more modern alternatives that might offer better efficiency or features.