MT9126AS1

As of now the CH340g is the cheapest USB to TTL IC in the market with very easy to solder foot print it has solder pitch of 1.27mm and SOIC16 package.

The?CH340 IC?does exactly what you would expect them to do: a full-speed USB device that emulates a standard serial interface, with speeds from 50bps to 2Mpbs. The chip supports 5V and 3.3V, and all the weird modem lines are supported.

Now a days lots of Node MCU, Arduino Nano and USB to TTL Converter Modules have been using this IC.

The CM8870PI provides full DTMF receiver capability by integrating both the bandsplit filter and digital decoder functions into a single 18-pin DIP. The filter section uses a switched capacitor technique for both high and low group filters and dial tone rejection. The CM8870 decoder uses digital counting techniques for the detection and decoding of all 16 DTMF tone pairs into a 4-bit code. This DTMF receiver minimizes external component count by providing an on-chip differential input ampli-fier, clock generator, and a latched three state interface bus. The on-chip clock generator requires only a low cost TV crystal or ceramic resonator as an external component.

Features of FT232

• Single chip USB to asynchronous serial data transfer interface.

• Entire USB protocol handled on the chip. No USB specific firmware programming required.

• Fully integrated 1024 bit EEPROM storing device descriptors and CBUS I/O configuration.

• Fully integrated USB termination resistors.

• Fully integrated clock generation with no external crystal required plus optional clock output selection enabling a glue-less interface to external MCU or FPGA.

• Data transfer rates from 300 baud to 3 Mbaud (RS422, RS485, RS232) at TTL levels.

• 128 byte receive buffer and 256 byte transmit buffer utilising buffer smoothing technology to allow for high data throughput.

MAX232 is a communication IC. It is used to convert TTL Signals to RS232 Signal and vice versa.?MAX232?provides RS-232 voltage level outputs (approx. ? 7.5 V) from a single 5 V supply via on-chip charge pumps and external capacitors. This makes it useful for implementing RS-232 in devices that otherwise do not need any voltages outside the 0 V to 5 V range, as power supply design does not need to be made more complicated just for driving the RS-232 in this case.

The receivers reduce RS-232 inputs (which may be as high as ? 25 V), to standard 5 V TTL levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V.