Overview
The AD421BN, manufactured by Analog Devices Inc., is a loop-powered, digital to 4 mA to 20 mA converter designed to meet the needs of smart transmitter manufacturers in the industrial control industry. This single-chip solution provides a high-performance, low-cost alternative for generating 4 mA to 20 mA signals. The AD421BN is fully integrated, including a DAC, current amplifier, and voltage regulator, making it an ideal component for extending the resolution of smart transmitters at a very low cost.
Key Specifications
| Parameter | Value |
|---|---|
| Resolution | 16 bits |
| Current Output Range | 4 mA to 20 mA |
| Integral Nonlinearity | ±0.01% |
| Zero Scale Offset Error | ±0.1% |
| Full-Scale Gain Error | ±0.2% |
| Regulator Output Voltage | +3 V, +3.3 V, or +5 V (pin selectable) |
| Precision Reference Voltages | +1.25 V and +2.5 V |
| Quiescent Current | 750 µA max |
| Operating Temperature Range | –40°C to +85°C |
| Package Type | 16-lead SOIC and PDIP |
| Data Interface | High speed serial interface (MICROWIRE, Serial) |
Key Features
- HART® compatible and supports other similar FSK protocols.
- Programmable alarm current capability to indicate transducer faults.
- High speed serial interface capable of operating at 10 Mbps.
- Includes a selectable regulator to power itself and other devices in the transmitter.
- Precision reference voltages (+1.25 V and +2.5 V) available.
- Loop-powered design, eliminating the need for an external power source.
- Compact 16-lead package (SOIC and PDIP).
Applications
The AD421BN is primarily used in smart industrial control transmitters, particularly in applications requiring high precision and reliability. It is suitable for:
- Smart transmitter systems in industrial control.
- Loop-powered 4 mA to 20 mA current output applications.
- Systems requiring HART or similar FSK protocol communication.
- Industrial automation and process control.
Q & A
- What is the primary function of the AD421BN?
The AD421BN is a digital to 4 mA to 20 mA converter designed for use in smart transmitter applications, converting digital data to analog current signals.
- What are the available regulator output voltages for the AD421BN?
The AD421BN provides pin-selectable regulator output voltages of +3 V, +3.3 V, or +5 V.
- What precision reference voltages are available on the AD421BN?
The AD421BN offers precision reference voltages of +1.25 V and +2.5 V.
- Is the AD421BN compatible with HART protocol?
Yes, the AD421BN is fully compatible with standard HART circuitry and other similar FSK protocols.
- What is the resolution of the AD421BN's DAC?
The AD421BN has a 16-bit resolution DAC.
- What is the operating temperature range of the AD421BN?
The AD421BN operates over an industrial temperature range of –40°C to +85°C.
- What type of packages is the AD421BN available in?
The AD421BN is available in 16-lead SOIC and PDIP packages.
- Does the AD421BN support high-speed serial communication?
Yes, the AD421BN features a high-speed serial interface capable of operating at 10 Mbps.
- Can the AD421BN be used to indicate transducer faults?
Yes, the AD421BN has a programmable alarm current capability to indicate out-of-range conditions or transducer faults.
- What is the quiescent current of the AD421BN?
The quiescent current of the AD421BN is 750 µA max.
