The **FT240XS-R** is a compact USB-to-Parallel FIFO interface IC developed by FTDI Chip. It is part of the FT-X series, designed to reduce component count and PCB space by integrating many functions that previously required external components. --- ## 1. Key Technical Specifications The following table highlights the primary electrical and functional characteristics of the FT240XS-R: | Parameter | Specification | | :--- | :--- | | **Interface** | USB to 8-bit Parallel FIFO | | **USB Speed** | USB 2.0 Full Speed (12Mbps) | | **FIFO Buffer** | 512 Byte Receive / 512 Byte Transmit | | **Operating Voltage** | 3.3V to 5.25V | | **I/O Voltage** | 1.8V to 3.3V (Logic levels) | | **Package** | 24-pin SSOP | | **Internal Clock** | Integrated (No external crystal required) | | **MTP Memory** | 2048 Bytes (For storing USB descriptors) | --- ## 2. Core Electronic Components & Features ### A. Integrated Clock Circuit Unlike older USB-to-Serial chips, the FT240XS-R does not require an external crystal or ceramic resonator. It features an internal clock generation circuit, which reduces the BOM (Bill of Materials) cost and saves PCB space. ### B. Internal MTP Memory It includes 2048 bytes of Multi-Time Programmable (MTP) memory. This is used to store: * USB Vendor ID (VID) and Product ID (PID). * Device serial strings. * Power descriptor data (Bus-powered vs. Self-powered). ### C. Voltage Regulation The chip integrates a **+3.3V LDO regulator**. This allows the device to operate on a 5V USB bus while providing a regulated 3.3V output to power its own internal logic and potentially low-power external components. ### D. Battery Charger Detection One unique feature of the "X-series" is the ability to detect the presence of a USB Battery Charging (BC) compliant port. This allows a device to draw higher currents (up to 1.5A) for faster charging if connected to a dedicated charging port. --- ## 3. Pinout Functional Groups The FT240XS-R pins can be categorized into four functional groups: 1. **USB Interface:** `USBDP` and `USBDM` (Differential pair for data). 2. **FIFO Data Bus:** `D0` through `D7` (The 8-bit parallel data path). 3. **Control Lines:** * `RXF#`: Receiver Full (Data available to read). * `TXE#`: Transmitter Empty (Ready to accept data). * `RD#`: Read trigger. * `WR#`: Write trigger. 4. **CBUS Pins:** Configurable I/O pins that can be programmed for functions like LED drive, Clock output, or Sleep status. --- ## 4. Typical Application Circuitry To implement this chip, you typically only need a few passive components: * **Decoupling Capacitors:** 0.1μF and 4.7μF on the VCC and VCCIO pins. * **Pull-up Resistors:** Usually required on the `RESET#` line if not driven by a microcontroller. * **USB Connector:** Standard Type-C or Micro-B wired to the `USBDP/DM` lines.