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Texas Instruments AFEx81H1 Low-Power Digital-to-Analog Converters

Texas Instruments AFEx81H1 Low-Power Digital-to-Analog Converters (DACs) are highly integrated, high-accuracy, extremely low-power DACs with voltage outputs designed for HART-enabled sensor-transmitter applications. The AFEx81H1 devices include most components required to create a 4mA to 20mA, 2-wire (loop-powered) sensor transmitter. With the highly accurate DAC, these parts include a HART-certified FSK modem, 10ppm/°C voltage reference, and a diagnostic analog-to-digital converter (ADC). An external voltage-to-current conversion and power regulation are required to accommodate intrinsic and functional safety concerns.

The internal diagnostic of ADC is multiplexed to several internal nodes, enabling an automatic self-health check. If any fault is detected from the diagnostic ADC, windowed watchdog timer, or CRC frame-error checking, the devices can optionally issue an interrupt, enter a fail-safe state corresponding to a standard NAMUR output value or user-specified custom value, or both. The Texas Instruments AFEx81H1 devices operate from supplies as low as 1.71V with a maximum quiescent current of 220µA. The devices are specified over the temperature range of –40°C to +125°C but are functional from –55°C to +125°C.

Features

  • Functional Safety-Capable
    • Documentation available to aid functional safety system design: AFE881H1, AFE781H1
  • Low quiescent current: 180µA (typical)
  • HART-compliant physical layer modem
  • 16-bit (AFE881H1) or 14-bit (AFE781H1) monotonic high-performance DAC
    • 1.8V supply: 0.15V to 1.25V, 0.2V to 1.0V
    • 5V supply: 0.3V to 2.5V, 0.4V to 2.0V
    • 4LSB INL at 16 bits
    • 0.07% FSR (max) TUE from –40°C to +125°C
  • 12-bit 3.84kSPS ADC for advanced diagnostics
  • Integrated 1.25V reference at 10ppm/°C (max)
  • Internal 1.2288MHz oscillator with clock output
  • Digital interface
    • Serial peripheral interface (SPI): Shared bus for both DAC and HART
    • Universal asynchronous receiver-transmitter (UART): Shared bus for both DAC and HART
    • Both SPI for DAC and UART for HART
  • Fault detection: CRC bit error checking, windowed watchdog timer, diagnostic ADC
  • Digital DAC slew-rate control
  • –55°C to +125°C wide operating temperature

Applications

  • 2-wire, 4mA to 20mA loop-powered transmitters
  • Process control and industrial automation
  • Smart transmitters

Functional Block Diagram

Block Diagram - Texas Instruments AFEx81H1 Low-Power Digital-to-Analog Converters

Related Development Tool

AFE881H1EVM Evaluation Module (EVM)

Texas Instruments AFE881H1EVM Evaluation Module (EVM)

Module tests and evaluates the AFE811H1, a highly integrated, high-accuracy 16-bit DAC.

Learn Moreabout Texas Instruments AFE881H1EVM Evaluation Module (EVM) View Productsrelated to Texas Instruments AFE881H1EVM Evaluation Module (EVM)
Published: 2024-04-10 | Updated: 2024-06-07