SNAS648C October 2014 – February 2023 TDC1000
PRODUCTION DATA
The main functional blocks of TDC1000 are the Transmit (TX) and the Receive (RX) Channels. The transmitter supports flexible settings for driving various ultrasonic transducers, and the receiver provides configurable blocks with a wide range of settings for signal conditioning in various applications. The receive signal chain consists of an LNA (Low Noise Amplifier), a PGA (Programmable Gain Amplifier), and two auto-zeroed comparators for echo qualification and STOP pulse generation.
The TDC1000 provides three modes of operation: Mode 0, Mode 1 and Mode 2. Each mode is intended for one or more applications such as flow/concentration measurement, container level measurement, proximity detection, distance measurement, and a range of other applications where a precision measurement of Time-of-Flight (TOF) is required.
A measurement cycle is initiated with a trigger signal on the TRIGGER pin of the device. After a trigger signal is asserted, an output pulse is generated on the START pin. This signal is used as the time reference to begin a TOF measurement. The transmitter generates programmable TX pulses, synchronous to the rising edge of the START pulse, to drive an ultrasonic transducer and generate an ultrasonic wave that is shot through an acoustic medium. The receiver detects the ultrasound wave that traveled through the medium and generates STOP signals. Whether the ultrasound wave is received directly or from a reflection will depend on the system configuration. The STOP signals are used by an external Time-to-Digital Converter (TDC), which functions as a very accurate stopwatch. The system must include a TDC to measure the TOF based on the interval between the START and STOP pulses. In some applications with medium-range accuracy requirements (ns range), a microcontroller can be used to measure the TOF duration. In applications with high-range accuracy requirements (ps range), TI recommends using the TDC7200 time-to-digital converter to measure the TOF duration.
In each application, the TDC1000 has to be configured by a serial interface (SPI) for one of the three modes of operation available. In addition, the device must be programmed to various application-specific parameters that are explained in the following sections.