Part A
AD7849BRZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5626 PCS
- Package
- SOIC-20
- Series
- Acquisição de dados - Convertedores digitais para analógicos (DAC)
Replacement verdict
Not a drop-in replacement
The AD7849BRZ and AD7845ARZ are not functionally interchangeable. Although both are Analog Devices 12-bit voltage-output DACs in a 24-lead SOIC package, they differ in resolution architecture, reference configuration, interface timing, and output amplifier characteristics, so the AD7845ARZ cannot be substituted for the AD7849BRZ without a full design review and validation.
Different DAC architecture
Different reference configuration
Different interface timing
Different output amplifier
Parts at a glance
Part B
AD7845ARZ
Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 4216 PCS
- Package
- SOIC-24
- Series
- Acquisição de dados - Convertedores digitais para analógicos (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 | AD7849BRZ | AD7845ARZ | Why it matters |
|---|---|---|---|
| Resolution (bits) | 16 | 12 | Resolution determines the smallest output step and overall precision; a 16-bit DAC offers 16x finer granularity than a 12-bit DAC, which is critical for high-accuracy control loops. |
| Number of DAC channels | 1 | 1 | Channel count defines how many independent analog outputs are available; both are single-channel, so channel count is not a differentiator here. |
| DAC architecture | String DAC (segmented R-2R) | Multiplying R-2R ladder | Architecture affects settling behavior, glitch performance, and whether the DAC can be used in multiplying (AC reference) applications; the R-2R multiplying type supports four-quadrant multiplication. |
| Output type | Voltage output | Current output (multiplying) | Voltage-output DACs drive loads directly, while current-output multiplying DACs require an external op-amp; this fundamentally changes the external circuit design and substitutability. |
| Supply voltage | ±12 V to ±15 V (dual) | ±12 V to ±15 V (dual) | Supply requirements must match the host system rails; both parts operate on similar dual supplies, so power-rail compatibility is maintained. |
| Interface | Serial (SPI-compatible) | Parallel | Serial vs parallel interface dictates the digital bus, pin count, and microcontroller compatibility; this is a major factor preventing drop-in substitution. |
| Package | 20-lead SOIC (R-20) | 24-lead SOIC (R-24) | Package footprint and pin count must match the PCB layout; differing lead counts mean the parts are not footprint-compatible. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range confirms suitability for industrial environments; both share the same industrial range, so thermal compatibility is equivalent. |
| Integral nonlinearity (INL) | ±1 LSB (B grade) | ±1/2 LSB (A grade) | INL specifies worst-case deviation from an ideal transfer function; it directly bounds achievable accuracy and must be evaluated against system error budgets. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7849BRZ | AD7845ARZ |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC,Analog Devices Inc. |
| Part Status | Active | Active |
| Number of Bits | 16 | 12 |
| Number of D/A Converters | 1 | 1 |
| Settling Time | 10µs (Typ) | 5µs |
| Output Type | Voltage - Buffered | Voltage - Buffered |
| Differential Output | No | No |
| Data Interface | SPI | Parallel |
| Reference Type | External | External |
| Voltage - Supply, Analog | ±14.25V ~ 15.75V | ±14.25V ~ 15.75V |
| INL / DNL(LSB) | ±16 (Max), ±0.9 (Max) | ±1 (Max), ±1 (Max) |
| Architecture | String DAC | R-2R |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Voltage - Supply, Digital | 5V | - |
Frequently asked questions
What are the key architectural differences between the AD7849BRZ and AD7845ARZ?
The AD7849BRZ is a 16-bit voltage-output DAC with a serial interface, while the AD7845ARZ is a 12-bit multiplying DAC with a parallel interface. The AD7849BRZ integrates an output amplifier and reference, whereas the AD7845ARZ requires an external op-amp and reference for voltage-output operation.
Are the AD7849BRZ and AD7845ARZ pin-compatible?
No. The AD7849BRZ is offered in a 20-lead SOIC (R-20) package, and the AD7845ARZ is offered in a 24-lead SOIC (R-24) package. The pin counts and pin functions differ, so they are not drop-in replacements.
What are the resolution and accuracy specifications of each device?
The AD7849BRZ provides 16-bit resolution with ±1 LSB integral nonlinearity (INL) and ±1 LSB differential nonlinearity (DNL) at 25°C. The AD7845ARZ provides 12-bit resolution with ±1/2 LSB INL and ±1 LSB DNL at 25°C.
How do the digital interfaces of the AD7849BRZ and AD7845ARZ differ?
The AD7849BRZ uses a serial interface compatible with SPI, QSPI, and MICROWIRE, operating at clock rates up to 10 MHz. The AD7845ARZ uses a 12-bit parallel interface with standard CS, WR, and data bus control signals.
What are the output voltage ranges and reference requirements for each part?
The AD7849BRZ has a fixed output range of 0 V to VREF and requires an external reference; with a 2.5 V reference, the output spans 0 V to 2.5 V. The AD7845ARZ is a current-output multiplying DAC that requires an external op-amp and reference to produce a voltage output, with the output range set by the external components.
How do the supply voltage and power consumption compare?
The AD7849BRZ operates from a single +5 V supply (or ±5 V) and typically consumes 10 mW. The AD7845ARZ operates from ±15 V supplies and typically consumes 30 mW.
What are the operating temperature ranges for the AD7849BRZ and AD7845ARZ?
Both the AD7849BRZ and AD7845ARZ are specified for the industrial temperature range of −40°C to +85°C.
Can the AD7845ARZ be used as a direct replacement for the AD7849BRZ in an existing design?
No. The AD7845ARZ has a different package, pinout, resolution, interface type, and output configuration. A direct replacement is not possible without a PCB redesign and validation of the system requirements.