Part A
AD7705BRZ-REEL
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 7181 個数
- Package
- SOIC-16
- Series
- データ取得 - アナログ/デジタルコンバータ (ADC)
Replacement verdict
Not a drop-in replacement
The AD7705BRZ-REEL and AD7707BR are not drop-in replacements for one another. Although both are 16-bit sigma-delta ADCs from Analog Devices, they differ in input channel configuration, analog input range and front-end architecture, package and pinout, and supply voltage requirements. Each of these differences affects board-level compatibility, so the AD7707BR cannot be substituted directly for the AD7705BRZ-REEL without design validation and layout changes.
Different input channel configuration
Different analog input range
Different package and pinout
Different supply voltage requirements
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7705BRZ-REEL | AD7707BR | Why it matters |
|---|---|---|---|
| Number of Input Channels | 2 differential | 3 (2 differential + 1 single-ended high-level) | Channel count determines how many signal sources can be connected; the AD7707 adds a high-level input path not present on the AD7705. |
| Input Type / Signal Range | Low-level differential (analog front end for small signals) | Low-level differential plus high-level single-ended input | The AD7707 can directly accept larger single-ended signals, while the AD7705 is limited to low-level differential inputs, affecting sensor interface flexibility. |
| Resolution | 16-bit | 16-bit | Both provide 16-bit resolution, so precision is comparable; resolution alone does not differentiate them. |
| Package | 16-lead SOIC | 20-lead SOIC | Different package footprints and pin counts mean the parts are not drop-in replacements on an existing PCB. |
| Supply Voltage | 2.7 V to 3.3 V (single supply) | 2.7 V to 3.3 V (single supply) | Matching supply requirements allow both to operate from the same low-voltage rail, simplifying power design. |
| Interface | SPI-compatible serial (3-wire) | SPI-compatible serial (3-wire) | Identical serial interface protocol enables similar microcontroller firmware and bus connections. |
| PGA / Gain | On-chip PGA, gain 1 to 128 | On-chip PGA, gain 1 to 128 | Programmable gain allows both to amplify small sensor signals, supporting similar low-level measurement applications. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Equivalent industrial temperature range means both suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7705BRZ-REEL | AD7707BR |
|---|---|---|
| Supplier | - | Analog Devices Inc.,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 500 | 500 |
| Number of Inputs | 2 | 1, 2 |
| Input Type | Differential | Pseudo-Differential, Single Ended |
| Data Interface | SPI, DSP | SPI, DSP |
| Configuration | MUX-PGA-ADC | MUX-PGA-ADC |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 2.7V ~ 3.3V, 5V | 2.7V ~ 3.3V, 5V |
| Voltage - Supply, Digital | 2.7V ~ 3.3V, 5V | 2.7V ~ 3.3V, 5V |
| Features | PGA | PGA |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the primary functional differences between the AD7705BRZ-REEL and the AD7707BR?
The AD7705BRZ-REEL is a 2-channel, 16-bit sigma-delta ADC with a programmable gain amplifier (PGA) and an SPI-compatible serial interface. The AD7707BR is a 3-channel, 16-bit sigma-delta ADC that includes a high-level input channel (for ±10 V or ±20 mA signals) in addition to two low-level input channels, and it also provides an SPI-compatible serial interface. The AD7707BR is therefore suited to applications requiring a high-voltage input channel, while the AD7705BRZ-REEL is a two-channel low-level input device.
Are the AD7705BRZ-REEL and AD7707BR pin-compatible?
No. The AD7705BRZ-REEL is supplied in a 16-lead SOIC package, while the AD7707BR is supplied in a 20-lead SOIC package. The different package sizes and pin counts mean the two devices are not pin-compatible and cannot be interchanged on the same PCB land pattern without redesign.
Do both devices support the same supply voltage ranges?
Both devices operate from a single 2.7 V to 3.3 V or 4.75 V to 5.25 V supply for the digital and low-level analog sections, and both provide a separate AVDD supply for the analog front end. The AD7707BR additionally requires a high-voltage supply (AVDD) of 5 V to 12 V to support its high-level input channel, which the AD7705BRZ-REEL does not have.
What is the resolution and output data rate of each device?
Both the AD7705BRZ-REEL and the AD7707BR are 16-bit sigma-delta ADCs. Both offer programmable output update rates from 20 Hz to 500 Hz, with corresponding trade-offs in resolution and noise performance as documented in the respective manufacturer datasheets.
Can the AD7707BR replace the AD7705BRZ-REEL in an existing design?
Not as a direct drop-in replacement. Although both are 16-bit sigma-delta ADCs with SPI-compatible interfaces, the AD7707BR has a different package (20-lead vs 16-lead SOIC), an additional high-level input channel, and different supply requirements. Any substitution requires PCB redesign and validation against the target design requirements.
What input signal types does each device support?
The AD7705BRZ-REEL provides two differential low-level analog input channels with a programmable gain amplifier, suitable for direct connection to low-level sensors. The AD7707BR provides two low-level differential input channels plus one high-level input channel that can accept ±10 V or ±20 mA signals, making it suitable for industrial interfaces that require a high-voltage or current-loop input.
Do both parts share the same serial interface and register set?
Both devices use an SPI-compatible serial interface and a similar register structure (communication register, setup register, clock register, data register), which allows similar firmware architecture. However, the AD7707BR includes additional configuration for its high-level input channel, so register settings and channel selection logic are not identical between the two devices.