Part A
AD5420AREZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 2718 Stückzahl
- Package
- TSSOP-24
- Series
- Data Acquisition von Digital to Analog Converters (DAC)
Replacement verdict
Not a drop-in replacement
The AD5420AREZ and AD5421BREZ are not drop-in replacements for each other. Although both are single-channel 16-bit 4-20 mA loop-powered DACs from Analog Devices, they differ in output configuration, supply and compliance voltage range, package and thermal characteristics, and HART signal interface support. The AD5420AREZ provides a current-mode output with a regulated 4-20 mA loop and is specified for operation from a 10.8 V to 40 V supply, while the AD5421BREZ integrates a loop-powered regulator with a wider compliance voltage range and additional diagnostic features. These differences in output architecture, supply and compliance requirements, package footprint, and HART interface capability mean that a direct board-level substitution is not possible without circuit redesign and revalidation.
Different output architecture
Different supply range
Different package footprint
Different HART interface
Parts at a glance
Part B
AD5421BREZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 7775 Stückzahl
- Package
- TSSOP-28
- Series
- Data Acquisition von Digital to Analog Converters (DAC)
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD5420AREZ | AD5421BREZ | Why it matters |
|---|---|---|---|
| Resolution | 16 bit | 16 bit | Both are 16-bit DACs, so they offer the same output resolution and quantization step size. |
| Number of DAC Channels | 1 | 1 | Single-channel architecture means both devices serve one analog output loop each. |
| Output Current Range | 4 mA to 20 mA, 0 mA to 20 mA, 0 mA to 24 mA | 4 mA to 20 mA | The AD5420 supports additional current ranges, giving more flexibility for different loop configurations. |
| Supply Voltage (AVDD) | 10.8 V to 40 V | 5.5 V to 52 V | Different supply ranges affect compatibility with the available power rail in the target system. |
| Interface Type | SPI | SPI | Both use a serial SPI interface, so the host controller connection scheme is similar. |
| Operating Temperature Range | -40°C to +85°C | -40°C to +105°C | The wider temperature range of the AD5421BREZ suits more demanding industrial environments. |
| Package / Mounting Type | 24-TSSOP, Surface Mount | 28-TSSOP, Surface Mount | Different package sizes and pin counts affect PCB layout and drop-in substitutability. |
| Internal Reference | Yes | Yes | Both integrate a voltage reference, reducing external component count and simplifying design. |
| HART Compatibility | Yes | Yes | HART capability allows digital communication over the analog current loop in industrial systems. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD5420AREZ | AD5421BREZ |
|---|---|---|
| Series | - | AD5421 |
| Part Status | Active | Active |
| Number of Bits | 16 | 16 |
| Number of D/A Converters | 1 | 1 |
| Settling Time | 40µs | 50µs (Typ) |
| Output Type | Current - Buffered | Current - Buffered |
| Differential Output | No | No |
| Data Interface | SPI, DSP | SPI, DSP |
| Reference Type | External, Internal | External, Internal |
| Voltage - Supply, Analog | 10.8V ~ 40V | 1.71V ~ 5.5V |
| Voltage - Supply, Digital | 2.7V ~ 5.5V | 3.17V ~ 3.48V |
| INL / DNL(LSB) | -, ±1 (Max) | -, ±1 (Max) |
| Architecture | R-2R | Cyclic Serial |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 105°C |
Frequently asked questions
What are the primary functional differences between the AD5420AREZ and AD5421BREZ?
The AD5420AREZ is a single-channel, 16-bit, serial input, 4 mA to 20 mA, current source DAC with HART connectivity. The AD5421BREZ is a single-channel, 16-bit, serial input, 4 mA to 20 mA, current source DAC with HART connectivity and an integrated voltage regulator. The AD5421BREZ includes a regulated 5 V or 3.3 V output to power additional circuitry, while the AD5420AREZ does not.
Are the AD5420AREZ and AD5421BREZ pin-compatible?
No. The AD5420AREZ is available in a 24-lead TSSOP package, while the AD5421BREZ is available in a 28-lead TSSOP package. The different pin counts and pin functions prevent direct PCB footprint compatibility.
Can the AD5420AREZ and AD5421BREZ be used interchangeably in a loop-powered transmitter design?
No, not without design changes. The AD5421BREZ integrates a voltage regulator that can supply power to other components in a loop-powered transmitter, whereas the AD5420AREZ requires an external regulator or power source for auxiliary circuitry. The pinout and package differences also require a different PCB layout.
Do both the AD5420AREZ and AD5421BREZ support HART communication?
Yes. Both devices provide a HART connectivity interface, allowing a HART signal to be superimposed on the 4 mA to 20 mA current loop.
What are the operating temperature ranges for the AD5420AREZ and AD5421BREZ?
Both the AD5420AREZ and AD5421BREZ are specified for operation over the industrial temperature range of −40°C to +105°C.
What is the resolution and accuracy specification of the AD5420AREZ and AD5421BREZ?
Both devices are 16-bit DACs. The AD5420AREZ offers typical integral nonlinearity (INL) of ±0.01% of FSR and typical total unadjusted error (TUE) of ±0.05% of FSR. The AD5421BREZ offers typical INL of ±0.01% of FSR and typical TUE of ±0.05% of FSR. Exact specifications should be verified from the respective manufacturer datasheets.
Which device is better suited for a compact loop-powered field instrument?
The AD5421BREZ is generally better suited for compact loop-powered instruments because its integrated voltage regulator reduces external component count and board space. The AD5420AREZ requires an external regulator for auxiliary power, which may increase solution size.
What are the supply voltage requirements for the AD5420AREZ and AD5421BREZ?
The AD5420AREZ operates from a single supply of 10.8 V to 40 V. The AD5421BREZ operates from a single supply of 5.5 V to 52 V. The AD5421BREZ also provides a regulated output of 5 V or 3.3 V for auxiliary circuits.