Overview
The AD421BRRL7, produced by Analog Devices Inc., is a high-performance, loop-powered 4 mA to 20 mA digital-to-analog converter (DAC) designed for smart industrial control transmitters. This single-chip solution integrates a DAC, a current amplifier, and a voltage regulator, making it a comprehensive and cost-effective option for industrial control applications. The AD421 is fully compatible with HART (Highway Addressable Remote Transducer) circuitry and other similar FSK protocols, enhancing its versatility in industrial settings.
Key Specifications
| Parameter | Conditions | Min | Max | Unit | |
|---|---|---|---|---|---|
| Current Output Range | 4 mA | 20 mA | |||
| Resolution | 16-bit | ||||
| Integral Nonlinearity | ±0.01% | ||||
| Full-Scale Settling Time | 8 ms (typ) | ||||
| Output Impedance | 25 MΩ (typ) | ||||
| Voltage Regulator Output | LV Pin Connected to VCC | 2.95 V / 3.05 V (3 V Mode) | 3 V | V | |
| Voltage Regulator Output | LV Pin Connected Through 0.01 µF to VCC | 3.25 V / 3.35 V (3.3 V Mode) | 3.3 V | V | |
| Voltage Regulator Output | 4.95 V / 5.05 V (5 V Mode) | 5 V | V | ||
| Quiescent Current | 750 µA (max) | ||||
| Precision Reference Voltages | 1.25 V, 2.5 V |
Key Features
- HART Compatibility: Fully compatible with standard HART circuitry and other similar FSK protocols.
- High Resolution: 16-bit resolution and monotonicity for precise current output.
- Voltage Regulator: Regulated supply voltage output selectable as +3 V, +3.3 V, or +5 V.
- Precision References: On-chip references providing +1.25 V and +2.5 V precision reference voltages.
- Programmable Alarm Current: Capability to send out-of-range currents to indicate transducer faults.
- High Speed Serial Interface: Flexible and high-speed serial interface for data communication.
- Low Quiescent Current: Maximum quiescent current of 750 µA.
- Loop-Powered Operation: Can operate from VCC + 2 V min to the breakdown voltage of the pass transistor.
Applications
The AD421BRRL7 is primarily used in smart industrial control transmitters, where precise and reliable current output is crucial. It is suitable for various industrial automation and control systems, including those requiring HART communication protocol. Other applications include process control instruments, field transmitters, and any system that requires a loop-powered DAC with high accuracy and reliability.
Q & A
- What is the primary function of the AD421BRRL7?
The AD421BRRL7 is a loop-powered 4 mA to 20 mA digital-to-analog converter (DAC) designed for smart industrial control transmitters. - What is the resolution of the AD421BRRL7?
The AD421BRRL7 has a 16-bit resolution. - Is the AD421BRRL7 compatible with HART protocol?
Yes, the AD421BRRL7 is fully compatible with standard HART circuitry and other similar FSK protocols. - What are the available voltage regulator output options for the AD421BRRL7?
The voltage regulator output can be set to +3 V, +3.3 V, or +5 V. - What is the maximum quiescent current of the AD421BRRL7?
The maximum quiescent current is 750 µA. - Can the AD421BRRL7 be used in loop-powered applications?
Yes, it can operate from VCC + 2 V min to the breakdown voltage of the pass transistor. - What is the settling time for full-scale output of the AD421BRRL7?
The full-scale settling time is typically 8 ms. - Does the AD421BRRL7 have programmable alarm current capability?
Yes, it can send out-of-range currents to indicate transducer faults. - What are the precision reference voltages provided by the AD421BRRL7?
The AD421BRRL7 provides +1.25 V and +2.5 V precision reference voltages. - What type of interface does the AD421BRRL7 use for data communication?
The AD421BRRL7 uses a high-speed serial interface for data communication.
