Part A
AD7849BRZ
Công ty Analog Devices Inc.
- Lifecycle
- Active
- Stock
- 5626 PCS
- Package
- SOIC-20
- Series
- Data Acquisition - Digital to Analog Converters (DAC)
Replacement verdict
Not a drop-in replacement
The AD7849BRZ and AD7845AR are not drop-in replacements for one another. Although both are Analog Devices digital-to-analog converters, they differ in resolution, output configuration, and package, so a direct board-level substitution is not possible without design changes.
Different resolution
Different output configuration
Different package
Different interface timing
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 | AD7845AR | Why it matters |
|---|---|---|---|
| Resolution | 16 bit | 12 bit | Higher resolution provides finer output steps and lower quantization error, which directly affects achievable accuracy in the application. |
| Number of DAC Channels | 1 | 1 | Channel count determines how many independent analog outputs the device can drive; both are single-channel parts. |
| Output Type | Voltage output | Voltage output | Voltage-output DACs can drive loads directly without an external I/V converter, simplifying the signal chain. |
| Digital Interface | Serial (SPI-compatible) | Parallel | The interface type dictates the host connection, pin count, and firmware; serial and parallel parts are not drop-in interchangeable. |
| Supply Voltage | ±12 V to ±15 V (dual) | ±12 V to ±15 V (dual) | Supply requirements must match the board's available rails for the device to operate within specification. |
| Reference | External | External | An external reference allows the user to set the output span and accuracy; both parts require an external reference. |
| Package | 20-lead SOIC (R-20) | 24-lead PDIP (N-24) | Package footprint and pinout must match the PCB layout; different packages require board redesign. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | The temperature range must cover the application's environment to guarantee specified performance. |
| Integral Nonlinearity (INL) | ±1 LSB (max) | ±1/2 LSB (max) | INL defines deviation from an ideal transfer function and bounds the achievable absolute accuracy of the DAC. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7849BRZ | AD7845AR |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | - |
| Number of D/A Converters | 1 | - |
| Settling Time | 10µs (Typ) | - |
| Output Type | Voltage - Buffered | - |
| Differential Output | No | - |
| Data Interface | SPI | - |
| Reference Type | External | - |
| Voltage - Supply, Analog | ±14.25V ~ 15.75V | - |
| Voltage - Supply, Digital | 5V | - |
| INL / DNL(LSB) | ±16 (Max), ±0.9 (Max) | - |
| Architecture | String DAC | - |
| Operating Temperature | -40°C ~ 85°C | - |
Frequently asked questions
What are the primary functional differences between the AD7849BRZ and the AD7845AR?
The AD7849BRZ is a 16-bit voltage-output DAC with a serial interface, while the AD7845AR is a 12-bit multiplying DAC with a parallel interface. The AD7849BRZ offers higher resolution and a serial control bus, whereas the AD7845AR provides a faster parallel interface and a current output for multiplying applications.
Are the AD7849BRZ and AD7845AR pin-compatible?
No. The AD7849BRZ is supplied in a 20-lead SOIC (R-20) package, and the AD7845AR is supplied in a 24-lead SOIC (R-24) package. The different package sizes and pin counts mean they are not pin-compatible and cannot be interchanged on the same PCB footprint without redesign.
What are the resolution and accuracy specifications for each device?
The AD7849BRZ provides 16-bit resolution with a relative accuracy (INL) of ±2 LSB maximum. The AD7845AR provides 12-bit resolution with a relative accuracy of ±1/2 LSB maximum. The AD7849BRZ therefore offers four times the resolution of the AD7845AR.
How do the digital interfaces of the AD7849BRZ and AD7845AR differ?
The AD7849BRZ uses a serial interface compatible with SPI, QSPI, and MICROWIRE, requiring fewer microcontroller I/O pins. The AD7845AR uses a 12-bit parallel interface with standard data, address, and control lines, which allows higher update rates but requires more board routing and I/O pins.
What are the output configurations of the AD7849BRZ and AD7845AR?
The AD7849BRZ provides a buffered voltage output that can be configured for unipolar or bipolar ranges. The AD7845AR provides a current output (IOUT) intended for multiplying applications, typically used with an external op-amp to convert the current to a voltage.
Can the AD7849BRZ and AD7845AR operate from the same supply voltages?
No. The AD7849BRZ operates from a single +5 V supply or dual ±5 V supplies, depending on the output range configuration. The AD7845AR requires dual supplies of ±12 V to ±15 V for operation. The supply requirements are therefore not interchangeable.
Which device is better suited for high-resolution setpoint control versus multiplying applications?
The AD7849BRZ is better suited for high-resolution setpoint control because of its 16-bit resolution and buffered voltage output. The AD7845AR is better suited for multiplying applications, such as gain control and signal attenuation, because its current-output architecture and parallel interface support fast, ratiometric multiplication of an input signal.
Do the AD7849BRZ and AD7845AR share the same temperature range and package grade?
Both devices are specified for the industrial temperature range of −40 °C to +85 °C. However, the AD7849BRZ is offered in a 20-lead SOIC package, and the AD7845AR is offered in a 24-lead SOIC package, so the package grade and footprint differ even though the temperature ratings are the same.