Oscillators Circuit Diagrams

Simple Digital Signal Inverter Project Schematic Circuit Diagram

Digital Signal Inverter: There are situations where it becomes necessary to generate the inverse of a digital signal. Accomplishing this using discrete components can be quite challenging, especially when working with limited space constraints. Fortunately, there exist fully integrated circuits that, with the addition of a few passive components, can be transformed into a relatively straightforward afternoon project.

One of the most versatile chips for this particular application comes from the IR215x product family, and it is the IR2153 self-oscillating control chip developed by International Rectifier. According to the datasheet, the IR2153 serves as a high-voltage, high-speed, self-oscillating power MOSFET and IGBT driver, featuring both high- and low-side referenced output channels. Its front end incorporates a programmable oscillator, while the output drivers include a high-pulse-current buffer stage and an internal dead-time of 1.2 µS, carefully designed to minimize driver cross-conduction. To simplify its use in 50% duty cycle applications, the propagation delays for the two channels are matched. Furthermore, the floating channel can be effectively employed to drive an N-channel power MOSFET or IGBT in the high-side configuration, operating from a high-voltage rail of up to 600 V.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 1

IR2153 & IR2153D

Now I can see two popular versions: IR2153 and IR2153D. Below is the functional block diagram of the IR2153 series.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 2

In IR2153D, a bootstrap diode (D1) is included (it’s a separate dye). Also note that both ICs contain a Zener clamp structure between the chip VCC and COM, which has a nominal breakdown voltage of 15.6 V.

Inverter card & power drive

Were you aware that by using a few inexpensive electronic components, it’s entirely possible to construct a compact yet efficient inverter card? This card enables the creation of a mini power inverter that converts direct current (DC) into alternating current (AC). Here’s the fundamental circuit concept for a 12-V DC-powered universal inverter driver card (based on the IR2153) designed to simplify the construction of a 50-/60-Hz power inverter with remarkable ease.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 3

The inverter transformer driver, employing a half-bridge topology, generates a square wave output. Thanks to the integrated features of the IR2153 (IC1), which serves as a MOSFET driver encompassing an oscillator, undervoltage lockout, dead-time circuitry, and a Zener diode, only three external components are needed in this configuration (P1, R2, C5). IC1 receives power via an optional 1N5817 diode (D1). Capacitors C1, C2, C3, and C4 function for filtering, while the second (optional) 1N5817 diode (D2) serves as a safeguard for input supply polarity protection.

The operating frequency is set to 50/60 Hz and can be adjusted using the 22K multiturn trimpot (P1). Alternatively, the circuit can operate at higher frequencies by modifying the RT-CT components.

A vital element in the final output stage, serving as the power driver, is a standard power transformer equipped with two secondary windings selected to meet the required maximum load.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 4

For lighter loads, you can utilize MOSFETs like the IRFZ44, provided they are equipped with appropriate heat sinks. To accommodate higher output load requirements, you can also combine multiple MOSFETs in parallel. Keep in mind that the provided power inverter design generates an unstabilized square wave output voltage. The DC supply input should fall within the range of 9 to 14 V, as the circuit will deactivate if the input voltage drops below 9 V.

Additionally, it’s worth noting that the same circuit can be adapted for use in various other “high-frequency-drive” applications. These applications include fluorescent ballasts, mains-powered high-voltage transformers, spark gap Tesla coils, and induction heaters.

Regarding the recommendations from the IR2153 datasheet, the application example includes gate drive resistors. In certain scenarios, I have also incorporated gate-source resistors (R5–R6) to serve specific purposes. You can refer to the IO timing diagram of the IR2153, which has been extracted from the datasheet:

Simple Digital Signal Inverter Project Schematic Circuit Diagram 5

The provided schematic(s) displayed above doesn’t introduce any novel concepts; in fact, numerous versions of it can be found online. It was at this juncture that I began contemplating ways to enhance the design with additional components. I had an inkling that the shutdown feature of the IR2153 could be effectively harnessed using an optocoupler to either deactivate the circuit or regulate the output voltage. The subsequent image illustrates an isolated shutdown interface designed around a straightforward 4N35 optocoupler. In the context of a DC/DC converter design, this interface can be employed to fine-tune the output voltage with the assistance of a precise shunt regulator like the TL431, which is integrated into the feedback path as well.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 6

Please take note that the trigger thresholds for the oscillator are contingent upon Vcc referenced to the COM pin. In other words, the switching thresholds for Ct are established as a fixed fraction of Vcc and are determined by a ratio metric divider network integrated within the chip. It’s imperative to recognize that the Ct pin is susceptible to noise, which necessitates that all circuits connected directly or indirectly to the Ct pin be grounded to either the Vcc or COM node within the IC.

Moving on to another intriguing discovery I encountered in the design tip published by International Rectifier, there’s a mention of variable frequency control techniques. The initial method involves the utilization of a parallel capacitor switch, providing a convenient means to select one or more operational frequencies for the IR2153.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 7

In the provided circuit, when Q1 is in the “off” state, D1 blocks, and C2 is not part of the circuit, resulting in a high oscillator frequency. However, when Q1 is switched on and reaches saturation, it carries the charging current for C1, and diode D1 offers a discharge path. This essentially introduces C2 in parallel with C1, increasing the effective capacitance observed at the Ct node and consequently reducing the switching frequency. Additionally, both the diode and the small-signal bipolar transistor can be replaced with a single N-channel MOSFET since its internal body drain diode serves the same purpose as D1. In this scenario, it’s important to consider the output capacitance (Coss) of the MOSFET switch when it’s in the “off” state. It’s worth noting that the output capacitance is highest when the drain-to-source voltage is low, so it’s preferable to select the smallest available device.

Device in Action

Finally, some random snapshots from the author’s lab:

Simple Digital Signal Inverter Project Schematic Circuit Diagram 8

Scope traces

Simple Digital Signal Inverter Project Schematic Circuit Diagram 9

Quick experiments on breadboard

Simple Digital Signal Inverter Project Schematic Circuit Diagram 10

Beginning of the basic prototype build

Courtesy Note

This article is prepared with the help of snippets collected from various datasheets, design tips, and application notes published by International Rectifier (www.irf.com).

Disclaimer

Use this article as a foundation for developing a range of pulsed power supply circuits. Understand that the fundamental schematic provided here may not perform optimally in every scenario, and be ready to conduct your own experiments to achieve the desired outcomes. Keep in mind that experiments involving high voltage can be hazardous, so exercise caution.

Update

I hadn’t noticed at first, but there are new versions of IR2153 and IR2153D from International Rectifier. It’s based on the same core design and is pin-to-pin compatible, allowing minor changes to the previous design.

Furthermore, in the new IRS2153D (https://static.chipdip.ru/lib/285/DOC000285673.pdf ), there’s an internal FET in lieu of the internal bootstrap diode, which was a separate dye in the good old IR2153D (see next figure). The integrated bootstrap MOSFET is turned on only during the time when LO is high and has a limited source current due to RDSON.

Simple Digital Signal Inverter Project Sch

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