Part A
AD7708BRU
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 2125 個数
- Package
- TSSOP-28
- Series
- データ取得 - アナログ/デジタルコンバータ (ADC)
Replacement verdict
Compatible functional replacement candidate
The AD7706BRU-REEL is a functional replacement candidate for the AD7708BRU, sharing the same TSSOP-28 package, 16-bit sigma-delta architecture, and serial interface, but it provides 3 differential input channels instead of 8, so system channel count requirements must be validated before substitution.
Package Type
High match
Resolution
High match
Input Channel Count
Not compatible
Supply Voltage Range
Validation required
Parts at a glance
Part B
AD7706BRU-REEL
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 2708 個数
- Package
- TSSOP-16
- Series
- データ取得 - アナログ/デジタルコンバータ (ADC)
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7708BRU | AD7706BRU-REEL | Why it matters |
|---|---|---|---|
| Number of Input Channels | 8 (4 differential / 8 pseudo-differential) | 3 (2 differential / 3 pseudo-differential) | Channel count determines how many sensor signals can be measured; the AD7708 supports more inputs, so it is not a drop-in substitute where more than 3 channels are needed. |
| Resolution | 16-bit (sigma-delta) | 16-bit (sigma-delta) | Both provide 16-bit resolution, so measurement precision is comparable and resolution alone does not distinguish them. |
| Package / Pin Count | 28-lead TSSOP | 16-lead TSSOP | Different package sizes and pinouts mean the two parts are not footprint-compatible; a board redesign is required to swap them. |
| Supply Voltage Range | 2.7 V to 3.3 V (VDD), 2.7 V to 5.25 V (AVDD) | 2.7 V to 3.3 V (VDD), 2.7 V to 5.25 V (AVDD) | Identical supply requirements allow either part to operate from the same rails, simplifying power-supply design. |
| Interface | SPI / 3-wire serial | SPI / 3-wire serial | Both use the same serial interface, so firmware protocol is compatible even though the register map and channel count differ. |
| On-Chip PGA Gain Range | 1 to 128 | 1 to 128 | Matching programmable gain ranges allow both parts to handle small sensor signals with the same front-end configuration. |
| Output Data Rate | Up to 1.365 kSPS (programmable) | Up to 1.365 kSPS (programmable) | Equivalent maximum throughput means neither part limits system sampling speed relative to the other. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings make both suitable for the same industrial environments. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7708BRU | AD7706BRU-REEL |
|---|---|---|
| Supplier | - | Rochester Electronics, LLC |
| Part Status | Obsolete | Obsolete |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | 1.37k | 500 |
| Number of Inputs | 4, 8 | 3 |
| Input Type | Differential, Pseudo-Differential, Single Ended | Pseudo-Differential |
| 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 key differences between the AD7708BRU and the AD7706BRU-REEL?
The AD7708BRU is a 16-bit, 8-channel (4 differential) sigma-delta ADC, while the AD7706BRU-REEL is a 16-bit, 3-channel (2 differential) sigma-delta ADC. Both are pin-compatible in the same 28-lead TSSOP package, but the AD7708 provides more input channels. The "-REEL" suffix indicates tape-and-reel packaging for the AD7706.
Are the AD7708BRU and AD7706BRU-REEL pin-compatible?
Yes. Both devices are offered in the same 28-lead TSSOP (RU) package and share a common pinout, allowing the AD7706 to be used as a lower-channel-count drop-in alternative to the AD7708 on the same PCB footprint.
What is the resolution and architecture of these ADCs?
Both the AD7708BRU and AD7706BRU-REEL are 16-bit sigma-delta (Σ-Δ) analog-to-digital converters with on-chip programmable gain amplifiers (PGA) and digital filtering, intended for low-frequency, high-resolution measurement applications.
How many analog input channels does each device support?
The AD7708BRU supports 8 single-ended or 4 fully differential input channels. The AD7706BRU-REEL supports 3 single-ended or 2 fully differential input channels. Both include additional configuration for pseudo-differential and input-buffer options per the datasheet.
Do both parts support the same serial interface and supply voltage?
Yes. Both devices use a 3-wire SPI-compatible serial interface and operate from a single 2.7 V to 5.25 V supply (AVDD/DVDD), with a separate reference input, making them interchangeable at the interface and power level.
What does the "-REEL" suffix on the AD7706BRU-REEL indicate?
The "-REEL" suffix denotes tape-and-reel packaging for automated SMT assembly. It does not change the electrical specifications of the AD7706; the device remains a 16-bit, 3-channel sigma-delta ADC in a 28-lead TSSOP.
Can the AD7706BRU-REEL directly replace the AD7708BRU in an existing design?
Only if the design uses no more than 3 single-ended (or 2 differential) input channels, since the AD7706 has fewer input channels than the AD7708. Pinout, package, interface, and supply are compatible, but unused channel-related register settings and channel-count assumptions in firmware must be validated against the AD7706 datasheet.