Description:
The 7915 is a linear, three-terminal negative voltage regulator that provides a fixed output voltage of -15V. It is part of the 79xx series of integrated circuits, which are complementary to the 78xx series of positive voltage regulators.
Key specifications:
- Output Voltage: A steady and precise -15V.
- Output Current: Most standard versions, such as the LM7915 in a TO-220 package, can deliver up to 1.5A of output current, though smaller surface-mount versions (like the 79M15) have lower current ratings.
- Input Voltage: The input voltage must be more negative than the output voltage. For the 7915, this typically means a range from about -18V to -35V, depending on the load.
- Protection Features: Includes built-in thermal overload protection and short-circuit protection to prevent damage to the IC and the circuit.
Pinout :
The pin configuration for the 7915 is different from its positive counterpart, the 7815. While the 7815 has an input-ground-output pinout, the standard TO-220 package for the 7915 has a ground-input-output pinout.
- Pin 1: Ground
- Pin 2: Input Voltage (
VINcap V sub cap I cap N end-sub
𝑉𝐼𝑁
)
- Pin 3: Output Voltage (
VOUTcap V sub cap O cap U cap T end-sub
𝑉𝑂𝑈𝑇
)
Applications:
The 7915 regulator is primarily used in circuits that require a stable negative voltage supply, including:
- Split Power Supplies: Often used with a corresponding 7815 positive voltage regulator to create a dual-rail power supply, such as one with +15V, -15V, and a common ground. These are commonly required for powering operational amplifiers (op-amps) and other analog circuits.
- On-card Regulation: Can be used for local regulation on a printed circuit board (PCB) to eliminate noise and distribution problems from a central power supply.
- Power Supply Circuits: As a reliable, constant -15V source for various electronic applications.
Basic circuit diagram:
To create a stable -15V regulated power supply using a 7915, you need a few external components:
- Input Capacitor (
CINcap C sub cap I cap N end-sub
𝐶𝐼𝑁
): A capacitor (e.g., 2.2µF) placed between the input pin and ground helps to filter noise on the unregulated input voltage.
- Output Capacitor (
COUTcap C sub cap O cap U cap T end-sub
𝐶𝑂𝑈𝑇
): A capacitor (e.g., 1µF) placed between the output pin and ground improves the transient response of the regulator.
- Heat Sink: If the current draw is significant, a heat sink on the regulator is required to dissipate excess heat and ensure the IC operates within its safe temperature range.
The complete circuit will have the unregulated negative input voltage connected to the input pin, the ground reference connected to the ground pin, and the regulated -15V output taken from the output pin.
Reviews
There are no reviews yet.