The DS8500 is a single-chip modem with Highway Addressable Remote Transducer (HART) capabilities and satisfies the HART physical layer requirements.
The device integrates the modulation and demodulation of the 1200Hz/2200Hz FSK signal, has very low power consumption, and needs only a few external components due to the integrated digital signal processing.
The input signal is sampled by an analog-to-digital converter (ADC), followed by a digital filter/demodulator.
This architecture ensures reliable signal detection in noisy environments. The output digital-to-analog converter (DAC) generates a sine wave and provides a clean signal with phase-continuous switching between 1200Hz and 2200Hz. Low power is achieved by disabling the receive circuits during transmit and vice versa. The DS8500 is ideal for low-power process control transmitters .
Main features of Ds8500 chip are : 1200bps FSK Modulation and Demodulation , Digital Signal Processing Provides Reliable Input Signal Detection in Noisy Conditions , Sinusoidal Output Signal with Lowest Harmonic Distortion , Few External Components Enable a Space-Saving Solution , Standard Component 3.6864MHz Crystal , Complies to HART Physical Layer Requirements , 2.7V to 3.6V Operating Voltage , 285μA (max) Current Consumption
The DS8500 modem chip consists of a demodulator, carrier detect, digital filter, ADC for input signal conversion, a modulator and DAC for output signal generation, and receive and transmit state machine blocks to perform the HART communication.
The input HART signal’s noise interference is attenuated by a one-pole highpass filter that is external to the chip; the attenuated signal is digitized by the ADC and filtered by the receive state machine. The transmit state machine modulates the input to the HART-compliant signal with the help of the modulator and the DAC.
The DS8500 chip can be used in applications like : 4–20mA Loop-Powered Transmitters for Temperature, Pressure, Flow, and Level Measurement ; HART Multiplexers ; HART Modem Interface Connectivity
Maxim introduce 80V, 300mW Boost Converter and current Monitor for APD Bias Applications . The MAX15031 consists of a constant-frequency pulsewidth modulating (PWM) step-up DC-DC converter with an internal switch and a high-side current monitor with high-speed adjustable current limiting.
This device can generate output voltages up to 76V and provides current monitoring up to 4mA (up to 300mW) and can be used in for a wide variety of applications such as avalanche photodiode biasing, PIN biasing, or varactor biasing, and LCD displays and operates from 2.7V to 11V.
The MAX15031 includes a current monitor with more than three decades of dynamic range and monitors current ranging from 500nA to 2mA with high accuracy.
The MAX15031 is available in a thermally enhanced 4mm x 4mm, 16-pin TQFN package and operates over the -40°C to +125°C automotive temperature range.
Main features of MAX15031 are : Input Voltage Range +2.7V to +5.5V (Using Internal Charge Pump) or +5.5V to +11V , Wide Output-Voltage Range from (VIN + 1V) to 76V , Internal 1Ω (typ) 80V Switch , 300mW Boost Converter Output Power , Accurate ±10% (500nA to 1mA) and ±3.5% (1mA to 4mA) High-Side Current Monitor , Resistor-Adjustable Ultra-Fast APD Current Limit (1μs Response Time) , Open-Drain Current-Limit Indicator Flag , 400kHz Fixed Switching Frequency , Constant PWM Frequency Provides Easy Filtering in Low-Noise Applications , Internal Soft-Start , 2μA (max) Shutdown Current .