Oscillators Circuit Diagrams

Simple Digital Signal Inverter Project Schematic Circuit Diagram

There are times when one needs to take an digital signal and create the inverse of this signal.  Doing this in discrete components can be challenging to fit into a small space.  Lucky for us there are fully integrated circuits, that with a few passives can be turned into a quick afternoon project.

One of the most broadly applicable chip to be used for this application is in the IR215x product family is the IR2153 self-oscillating control chip from International Rectifier. The IR2153, according to the datasheet, is, in fact, a high-voltage, high-speed, self-oscillating power MOSFET and IGBT driver with both high- and low-side referenced output channels. Its front end features a programmable oscillator, and the output drivers feature a high-pulse-current buffer stage and an internal dead-time (1.2 µS) designed for minimum driver cross-conduction. Propagation delays for the two channels are matched to simplify use in 50% duty cycle applications. The floating channel can be used to drive an N-channel power MOSFET or IGBT in the high-side configuration that operates off of a high-voltage rail 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

Did you know that, with just a handful of cheap electronic components, you can build a little yet effective inverter card for making your own mini power inverter that converts direct current (DC) into alternating current (AC)? Here’s the basic circuit idea of such a 12-V DC-powered universal inverter driver card (centered on IR2153) to build a simplified 50-/60-Hz power inverter very easily.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 3

The output of this inverter transformer driver with a half-bridge topology is square wave. Because the IR2153 (IC1) is a MOSFET driver, which contains an oscillator, undervoltage lockout, dead-time circuitry, and a Zener diode, only three external components are required here (P1, R2, C5). IC1 is powered through an optional 1N5817 diode (D1). Capacitors C1, C2, C3, and C4 are used for filtering, and the second (optional) 1N5817 diode (D2) works as an input supply polarity protection guard. The operating frequency should be 50/60 Hz and can be set by the 22K multiturn trimpot (P1). It’s also possible to run the circuit at higher frequencies by changing the RT-CT components.

A key component in the final output stage (power driver) is a standard power transformer with two secondary windings selected for the maximum load required.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 4

For smaller loads, the MOSFETs can be the type IRFZ44 fitted with proper heat sinks, and we can combine multiple MOSFETs (in parallel) for handling higher output load requirements. Remember, the given power inverter design gives non-stabilized square wave output voltage. The DC supply input must be in the range of 9 to 14 V because if it’s below 9 V, the circuit is turned off. Another noteworthy fact is that the same circuit can be modified to use in other distinct “high-frequency-drive” applications as well — fluorescent ballasts, mains-powered high-voltage transformers, spark gap tesla coils, and/or induction heaters.

The IR2153 datasheet’s recommendations in the application example has gate drive resistors. I also put gate-source resistors (R5–R6) in to serve a purpose in certain situations. See the IO timing diagram of IR2153 traced from the datasheet:

Simple Digital Signal Inverter Project Schematic Circuit Diagram 5

The schematic(s) shown above has nothing new; actually, many editions are available online. At this point, I started thinking about techniques to improve the design by add-ons and got a clue that the shutdown feature on IR2153 can be exploited with the help of an optocoupler to shut down the circuit and/or regulate the output voltage. The next image illustrates an isolated shutdown interface wired around the simple 4N35 optocoupler. In case of a DC/DC converter design, we can use this interface to regulate the output voltage with the support of a precision shunt regulator like TL431, introduced in the feedback path as well.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 6

Note that oscillator trigger thresholds are a function of Vcc referenced to the COM pin; i.e., the Ct switching thresholds are set at a fixed proportion of Vcc and derived from a ratio metric divider network within the chip. Because the Ct pin is noise-sensitive, all circuits connected directly or indirectly to the Ct pin MUST be returned to either the Vcc or COM node at the IC.

Now to another interesting thing I found in the design tip published by International Rectifier, which is a note about variable frequency control techniques. The first trick is the use of a parallel capacitor switch at ease to select one or more running frequencies of IR2153.

Simple Digital Signal Inverter Project Schematic Circuit Diagram 7

In the above circuit, if Q1 is in an “off” state, D1 is blocking and C2 is out of circuit, so the oscillator frequency is high. However, when Q1 is turned on (in saturation), it carries charging current for C1 and the diode D1 provides a discharge path. This effectively adds C2 in parallel with C1, increasing the capacitance seen at the Ct node and reducing switch frequency. Besides, both the diode and the small-signal bipolar transistor may be replaced with a single, N-channel MOSFET because its internal body drain diode will serve the function of D1. Here, it may be necessary to account for output capacitance (Coss) of the MOSFET switch when in the “off” sate (the output capacitance is highest when drain-to-source voltage is low and, therefore, it is preferable to select the smallest device available).

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

Consider this article as a basis for the construction of various pulsed power supply circuits. The basic schematic rendered here cannot hope to work well in all situations, and for this reason, be prepared to do your own experiments to get the desired results. High-voltage experiments are dangerous, so beware!

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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