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Texas Instruments DAC8740HRGER
- Part No.:
- DAC8740HRGER
- Manufacturer:
- Texas Instruments
- Category:
- Specialized
- Package:
- 24-VFQFN Exposed Pad
- Datasheet:
-
DAC8740HRGER.pdf
- Description:
- IC INTERFACE SPECIALIZED 24VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,501
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Product details
Overview
DAC8740HRGER from Texas Instruments is a HART® and FOUNDATION Fieldbus™/PROFIBUS PA dual-mode physical layer modem IC designed for industrial field transmitters and I/O modules. It integrates UART digital interface, 1200/2200-Hz FSK modulation/demodulation, internal 1.5-V reference, integrated band-pass filter, and operates from –40°C to +105°C with ≤180 µA quiescent current in HART mode.
For engineers reviewing the DAC8740HRGER datasheet, DAC8740HRGER pinout, DAC8740HRGER application, or DAC8740HRGER equivalent, this page delivers verified functional role, exact pin functions, real-world timing behavior (e.g., carrier detect on/off, TX start/stop), supply current under defined modes, and validated alternative options for fieldbus modem selection.
Technical Context
The DAC8740HRGER implements a half-duplex HART physical layer using sinusoidal 1200-Hz mark and 2200-Hz space FSK signaling, with programmable transmit amplitude control and carrier detect (CD) output. Its internal band-pass filter (BPF_EN enabled) and demodulator require only 680-pF capacitor on MOD_INF for HART operation.
In FOUNDATION Fieldbus/PROFIBUS PA mode, it functions as an H1 controller and MAU, supporting 31.25 kbit/s Manchester-coded bus-powered communication with integrated encoder/decoder, 8-µs rise/fall time, and ±0.8-µs transmit jitter - all synchronized to a 4-MHz external clock or internal oscillator.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| HART FSK Frequencies | 1200 Hz (mark) and 2200 Hz (space); frequency error ≤±1% over –40°C to +105°C ensures reliable protocol compliance |
| Quiescent Current (HART) | ≤180 µA at –40°C to +85°C with external clock; enables ultra-low-power loop-powered transmitter designs |
| Internal Reference | 1.5 V ±20 mV (1.47–1.53 V); load regulation 1.3 V/mA supports stable biasing of analog front-end circuitry |
| MOD_OUT Output (HART) | 460 mVPP ±10 mVPP into 160-Ω AC-coupled load; meets HART physical layer amplitude requirements |
| Receiver Sensitivity | 100 mVPP typical for carrier detection/demodulation with internal filter; allows robust operation in noisy industrial environments |
| Digital Interface | UART-only (RX/TX/RTS/CD pins); no SPI support - distinct from DAC8741H variant |
| Operating Temperature | –40°C to +105°C ambient; qualified for harsh industrial process control environments |
Pinout & Package
Package: 24-pin VQFN (RGE), 4 mm × 4 mm, 0.5-mm pitch, exposed thermal pad (connected to GND).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| XEN | Clock enable input | Logic low enables crystal oscillator; high disables it and selects internal/external CMOS clock - critical for clock source selection |
| UART_IN | UART data input | Receives HART/FF command stream from host MCU; must not float - requires pull-up/down per system logic levels |
| UART_RTS | Modem direction control | High enables demodulator (RX), low enables modulator (TX); defines half-duplex state transition timing |
| CD | Carrier detect output | Logic high indicates valid incoming carrier (HART) or jabber trigger (FF/PA); used for automatic RX/TX handshaking |
| MOD_OUT | Analog modem output | FSK sinusoid (HART) or Manchester stream (FF/PA); requires 5–22 nF parallel capacitance in HART mode for stability |
| REF_EN | Reference enable input | Logic high activates internal 1.5-V reference; eliminates need for external reference in cost-sensitive designs |
| BPF_EN | Band-pass filter enable | High enables internal filter; reduces external component count - 680-pF cap required on MOD_INF for HART |
Key Features
| Feature | Design Value |
|---|---|
| HART-compliant physical layer | Fully integrates FSK modulator/demodulator, carrier detect, and band-pass filtering - eliminates discrete analog front-end design effort |
| FOUNDATION Fieldbus H1 MAU | Meets IEC 61158-2 for 31.25 kbit/s Manchester encoding/decoding and bus power management - certified for FF system integration |
| Low-power operation | 180 µA max quiescent current in HART mode enables 4–20 mA loop-powered devices without compromising battery life or thermal budget |
| Flexible clock architecture | Supports internal oscillator, external crystal (X1/X2), or CMOS clock (CLKO) - simplifies BOM and layout across diverse field device platforms |
| Integrated 1.5-V reference | Stable, factory-trimmed reference with <±20 mV tolerance - removes external voltage reference IC and associated calibration overhead |
Applications
| Smart Pressure Transmitter | PLC Analog Output Module |
|---|---|
Use Scenario: 4–20 mA loop-powered pressure sensor with HART digital communication for configuration and diagnostics. IC Role / Device Role / Timing Role: DAC8740HRGER serves as the HART physical layer modem, handling FSK modulation/demodulation and carrier detection while interfacing via UART to the host microcontroller. Use Value: Enables bidirectional digital communication over legacy analog wiring without increasing loop power consumption beyond 4 mA. |
Use Scenario: Industrial PLC module providing 4–20 mA analog outputs with HART-enabled calibration and fault reporting. IC Role / Device Role / Timing Role: DAC8740HRGER acts as the HART modem, receiving commands from control system and transmitting device status via UART-linked MCU. Use Value: Delivers protocol-compliant HART response within <6 bit-times carrier detect on time, ensuring deterministic communication in real-time control loops. |
| Fieldbus Foundation H1 Device | PROFIBUS PA Segment Coupler |
Use Scenario: Smart valve positioner implementing FOUNDATION Fieldbus H1 communication for distributed control in process plants. IC Role / Device Role / Timing Role: DAC8740HRGER functions as H1 controller and MAU, performing Manchester encoding/decoding and bus power conditioning at 31.25 kbit/s. Use Value: Achieves ±0.8 µs transmit jitter and 8-µs rise/fall time - meets IEC 61158-2 timing tolerances for reliable multi-drop network operation. |
Use Scenario: Segment coupler linking PROFIBUS PA field devices to higher-level DCS networks in hazardous areas. IC Role / Device Role / Timing Role: DAC8740HRGER provides PA-compliant physical layer signaling, including Manchester coding and bus-powered interface compliance. Use Value: Supports interoperability with PROFIBUS PA infrastructure through identical electrical characteristics and timing behavior as certified PA devices. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar HART and Fieldbus modem applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DAC8741HRGER | SPI interface instead of UART; adds CRC error checking and watchdog timer; same pinout but different digital I/O mapping (SDI/SDO/SCLK/IRQ vs UART_IN/UART_OUT/UART_RTS/CD) | Required when host MCU uses SPI peripherals exclusively; unsuitable for UART-only systems without level-shifting or protocol translation | Select DAC8741HRGER only if SPI interface and enhanced reliability features (CRC, watchdog) are needed - not a drop-in replacement |
| AD5700-1ACPZ-RL7 | HART-only modem (no Fieldbus support); uses external reference; lacks integrated band-pass filter - requires additional RC components for filtering | Limited to HART applications only; cannot replace DAC8740HRGER in FOUNDATION Fieldbus or PROFIBUS PA systems | Choose AD5700-1ACPZ-RL7 only for cost-optimized, HART-only designs where Fieldbus compatibility is unnecessary |
Compared with DAC8740HRGER, DAC8741HRGER offers SPI flexibility and enhanced diagnostics but requires firmware redesign, while AD5700-1ACPZ-RL7 reduces feature set and increases external component count - making DAC8740HRGER optimal for dual-protocol, UART-based, low-component-count field devices.
Availability
DAC8740HRGER is available at Aetrix Electronics and suitable for industrial process control, PLC I/O modules, and field transmitter designs requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for DAC8740HRGER includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and connectivity technologies for industrial, automotive, and communications markets.
The DAC8740HRGER belongs to TI's industrial communications modem product line, engineered specifically for seamless integration into 4–20 mA loop-powered field instruments supporting both HART and FOUNDATION Fieldbus/PROFIBUS PA protocols.
FAQ
What communication protocols does the DAC8740HRGER support?
The DAC8740HRGER supports HART (1200/2200-Hz FSK), FOUNDATION Fieldbus H1, and PROFIBUS PA protocols. It implements full physical layer functionality for all three standards - including modulation/demodulation, Manchester encoding/decoding, and bus power management - enabling single-chip dual-mode field device design. DAC8740HRGER does not support CAN, RS-485, or Modbus natively.
Does the DAC8740HRGER include an internal voltage reference?
Yes, the DAC8740HRGER integrates a factory-trimmed 1.5-V internal reference with ±20 mV tolerance (1.47–1.53 V) and 1.3 V/mA load regulation. The REF_EN pin controls activation, and the REF pin outputs the reference when enabled. This eliminates the need for an external reference in most HART/Fieldbus applications, reducing BOM cost and board area.
What is the function of the UART_RTS pin on the DAC8740HRGER?
On the DAC8740HRGER, UART_RTS is a digital input that controls modem direction: logic high enables the demodulator (RX mode), and logic low enables the modulator (TX mode). It directly gates the half-duplex signal path and determines whether MOD_OUT transmits or MOD_IN receives - critical for precise timing of HART carrier start/stop transitions.
Can the DAC8740HRGER operate with an external crystal oscillator?
Yes, the DAC8740HRGER supports external crystal oscillation via X1 and X2 pins with 16-pF or 36-pF load capacitors. XEN must be driven low to enable the crystal oscillator circuit. Crystal startup time is 25 ms (tcos1/tcos2), and the device supports 3.6864 MHz (HART) or 4 MHz (Fieldbus) crystals - matching standard protocol timing requirements.
How does the DAC8740HRGER handle carrier detection in HART mode?
In HART mode, the DAC8740HRGER asserts a logic-high CD (carrier detect) output within 6 bit-times of valid carrier presence on MOD_IN, and de-asserts it within 3 ms after carrier removal. This timing is specified in the datasheet (tcdeton/tcdetoff1) and enables fast, deterministic host MCU response to incoming HART messages - essential for real-time field device responsiveness.
DAC8740HRGER Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 24-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- -
- Interface:
- UART
- Voltage - Supply:
- 1.71V ~ 5.5V
- Supplier Device Package:
- 24-VQFN (4x4)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
DAC8740HRGER FAQ
1.How can I place an order for DAC8740HRGER through Aetrix?
Please submit a Request for Quotation (RFQ) for DAC8740HRGER on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for DAC8740HRGER reliable?
The price and inventory of DAC8740HRGER are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DAC8740HRGER is usually 5 days.
3.What payment methods are accepted for DAC8740HRGER?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DAC8740HRGER transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DAC8740HRGER?
DAC8740HRGER orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DAC8740HRGER order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for DAC8740HRGER?
For technical support, including DAC8740HRGER datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DAC8740HRGER requirements.
6.How does Aetrix verify that DAC8740HRGER is sourced from the original manufacturer or authorized distributors?
All DAC8740HRGER products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that DAC8740HRGER meets industry standards.
7.What is the process for return or replacement of DAC8740HRGER?
All DAC8740HRGER units undergo pre-shipment inspection (PSI). If there is an issue with DAC8740HRGER, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The DAC8740HRGER part is unused and in its original packaging.
Return procedure for DAC8740HRGER:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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