12v boost regulator circuit diagram

12v boost regulator circuit diagram (1)

The LM2698 is a general purpose boost converter with 18V, 1.35A current . 0.2 ohm internal switch. This results in high-efficiency power conversion to an output of 2.2V to 17V DC . The input supply voltage range is 2.2V to 17VDC. This IC features excellent line and load regulation and frequency compensation over the entire input voltage range.

In the circuit diagram given here, the IC is wired to produce an output voltage of 5V from a 12V input. The circuit works as follows. The input voltage is fed to the IC's analog power input (pin 6). In the first phase, the internal switch is closed and diode D1 is reverse biased. Energy will be stored in inductor L1 and the load current is provided by capacitor C3. During the second phase, the internal switch will be closed and diode D1 will be forward biased. The energy stored in inductor L1 is transferred to output capacitor C3 and the load. The IC's switching frequency can be selected using the IC's FSLCT (pin 7). If pin 3 is connected to the supply voltage, the switching frequency will be 1.25Mhz, if pin 3 is connected to ground, the switching frequency will be 600Khz. Resistors R2 and R3 form a feedback network , and R1 and C1 form a compensation network. Input capacitor C2 prevents the circuit from interacting with the impedance of the supply voltage source.

Assemble the circuit on a high quality PCB .

The input power can be any voltage between 4.5 and 5.5VDC.

Do not connect a load that consumes more than 400mA.

At 12V output, the IC can only provide up to 400mA.

C2 and C3 must be low ESR multilayer ceramic capacitors.

D1 can be a low forward voltage drop Schottky diode (such as Motorola's 0MQ040N).

Pin 3 (SHDN) connected to ground will close the circuit.

12v boost regulator circuit diagram (2)

12V DC regulated power supply circuit diagram produced by LM2576 , separate an example of DC regulated power supply circuit diagram, 12V DC regulated power supply circuit produced by LM2576, as shown below:

After the AC 14V voltage output by the secondary output of the power transformer (not shown in the figure) is rectified by a rectifier bridge composed of four 1N5401 diodes and filtered by capacitor C1, an unstable DC voltage is generated and sent to the input terminal ① of LM2576T-12. , after being stabilized by LM2576T-12, the output is a stable 12V DC voltage.

The output voltage of LM2576T-12 is a fixed 12V voltage, and the maximum output current is 3A.

There are various output voltages of LM2576. The output voltage of the above-mentioned LM2576T-12 is a fixed 12V. If you choose LM2576 ad j, you can form a regulated power supply with adjustable output voltage.

12v boost regulator circuit diagram (3)

This circuit mainly uses TWH8778 as the control chip . First, I will introduce to you the TWH8778 integrated circuit . TWH8778 is a high-speed integrated electronic switch that can be used in various automatic control circuits. It has a simple appearance, simple peripheral circuit, and internal overheating and overvoltage protection circuits . It has internal overvoltage, overcurrent, and overheating protection functions, and can be suitable for applications in the field of driving switches with high current. It is widely used in practical circuits such as timers and alarms.

TWH8778 has a total of 5 pins. The pin arrangement from left to right is: 1 pin (input terminal) 2, 3 pin (output terminal) 4 pin (ground) and 5 pin (control pole).

When the switch S is closed, the 220V AC voltage is rectified by VD1~VD4 and filtered by the capacitor C1, and then divided into two channels. output. One channel is added to pin 1 of the IC integrated circuit, and the other channel is added to the emitter terminal of the transistor VT through resistors R1 and R3, so that the transistor VT is in a saturated conduction state. At this time, the voltage of the collector (above 1.6V) is output to pin 5 of the IC integrated circuit, causing the internal electronic switch of the IC to be turned on, and then pins 2 and 3 output voltage, which increases the current in the inductor and supplies it to the load.

When the output voltage reaches 6V, the voltage regulator tube VS breaks down, and the current on the resistor R3 increases, causing the voltage on R3 to increase. When the output voltage reaches 12V, the transistor VT changes from the saturated state to the amplified state. When the output voltage exceeds 12V, the emitter junction voltage of the transistor VT decreases, causing the collector output voltage to drop. When it drops to 1.6V (that is, the potential of pin 5 of the IC integrated circuit drops to 1.6V), the IC switch integrated circuit is disconnected. The current of the inductor L decreases, and the output voltage also decreases. When it drops to 12V, the collector potential of the transistor VT rises to above 1.6V, and the IC integrated circuit is turned on again, so that the output voltage is always stable at 12V.

In the selection of components , IC uses TWH8778 electronic switch integrated circuit; R1~R5 uses RTX-1/4W carbon film resistors; C1 uses aluminum electrolytic capacitors with a withstand voltage of 25V, and C2 and C4 use CD11-16V. For electrolytic capacitors, C4 uses CT1 type high-frequency ceramic capacitors; VD1~VD5 uses IN4004 silicon type rectifier diodes , VD6 uses IN4148 silicon type switching diodes ; VS uses IN4106 or 2CW60 silicon voltage regulator diodes; RP can use WSW type organic solid trimmer variable Resistors; other components can be marked on the diagram. In addition, the structure of this circuit is simple. As long as it is welded according to the circuit diagram and the components selected are correct, it can work normally without debugging. The output voltage of the regulated power supply is 12V and the current is 1A.