Part A
AD7789BRMZ
テキサス・インスツルメンツ
- Lifecycle
- Active
- Stock
- 4316 個数
- Package
- TFSOP-10
- 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 AD7787BRM is a functional replacement candidate for the AD7789BRMZ, sharing the same 24-bit sigma-delta architecture, 2-wire serial interface, and MSOP-10 package, but it is not a drop-in replacement due to differences in channel count, input configuration, and supply voltage range that require validation against the target application.
Channel Count
Validation required
Input Configuration
Validation required
Package Type
High match
Supply Voltage Range
Validation required
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | AD7789BRMZ | AD7787BRM | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit ADCs, so resolution is equivalent for high-precision measurement applications. |
| Number of input channels | 1 (single-ended/pseudo-differential) | 2 (differential) | Channel count determines how many signals can be measured; the AD7787 supports two differential inputs while the AD7789 is a single-channel device. |
| Input type | Pseudo-differential | Differential | Differential inputs offer better common-mode noise rejection, which is important for low-level signal measurement. |
| Package | 10-lead MSOP | 10-lead MSOP | Package compatibility affects PCB footprint and drop-in substitutability; both use the same 10-lead MSOP. |
| Interface | SPI-compatible (3-wire serial) | SPI-compatible (3-wire serial) | A matching serial interface simplifies firmware and hardware reuse between designs. |
| Supply voltage | 2.7 V to 5.25 V | 2.7 V to 5.25 V | Identical supply range allows operation from the same power rails in low-power systems. |
| On-chip PGA | No | No | Neither device includes a programmable gain amplifier, so external signal conditioning is required for small signals. |
| Output data rate | 4.17 Hz to 120 Hz (selectable) | 4.17 Hz to 120 Hz (selectable) | Matching update rates suit similar low-frequency precision measurement applications. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | AD7789BRMZ | AD7787BRM |
|---|---|---|
| Supplier | - | Analog Devices Inc. |
| Part Status | Active | Obsolete |
| Number of Bits | 24 | 24 |
| Sampling Rate(Per Second) | 16.6 | 120 |
| Number of Inputs | 1 | 2 |
| Input Type | Differential | Differential, Single Ended |
| Data Interface | SPI, DSP | SPI, DSP |
| Configuration | ADC | MUX-ADC |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 2.5V ~ 5.25V | 2.5V ~ 5.25V |
| Voltage - Supply, Digital | 2.5V ~ 5.25V | 2.5V ~ 5.25V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 105°C |
Frequently asked questions
What are the key differences between the AD7789BRMZ and the AD7787BRM?
The AD7789BRMZ is a single-channel, 24-bit sigma-delta ADC with a maximum output rate of 16.7 Hz, while the AD7787BRM is a dual-channel, 24-bit sigma-delta ADC with a maximum output rate of 16.7 Hz per channel. The AD7787BRM includes two differential input channels and a programmable gain amplifier (PGA) with gains of 1, 2, 4, 8, 16, 32, 64, and 128, whereas the AD7789BRMZ has a fixed gain of 1 and a single differential input channel. Both devices operate from a 2.7 V to 5.25 V supply and are packaged in a 10-lead MSOP.
Are the AD7789BRMZ and AD7787BRM pin-compatible?
No, the AD7789BRMZ and AD7787BRM are not pin-compatible. Both are offered in a 10-lead MSOP package, but the pin functions differ: the AD7787BRM provides two differential input channel pairs (AIN1 and AIN2) plus a PGA, while the AD7789BRMZ provides a single differential input pair. The digital interface pins (CS, SCLK, DIN, DOUT/RDY) are similar, but the analog input and reference pin assignments differ, so a direct drop-in replacement is not possible without PCB modification.
Can the AD7789BRMZ be used as a direct replacement for the AD7787BRM in an existing design?
No. Although both are 24-bit sigma-delta ADCs in 10-lead MSOP packages, the AD7787BRM has two differential input channels and an on-chip PGA, while the AD7789BRMZ has one differential input channel and no PGA. The pin assignments for the analog inputs and reference differ, and the register map and configuration options are not identical. A direct replacement would require PCB and firmware changes, and the reduced channel count and lack of PGA must be validated against the application requirements.
What is the resolution and output data rate of each device?
Both the AD7789BRMZ and AD7787BRM are 24-bit sigma-delta ADCs. The AD7789BRMZ offers output data rates of 16.7 Hz and 9.5 Hz (depending on the update rate setting), while the AD7787BRM offers output data rates of 16.7 Hz and 9.5 Hz per channel. Both devices provide 24-bit resolution with no missing codes. The AD7787BRM's PGA allows smaller input signals to be amplified before conversion, effectively improving resolution for low-level signals.
Do both parts support a programmable gain amplifier (PGA)?
No. Only the AD7787BRM includes a programmable gain amplifier with selectable gains of 1, 2, 4, 8, 16, 32, 64, and 128. The AD7789BRMZ does not have a PGA; it provides a fixed gain of 1. This difference is significant for applications measuring low-level sensor outputs, where the AD7787BRM's PGA can improve effective resolution without external amplification.
What are the supply voltage and power consumption specifications for these ADCs?
Both the AD7789BRMZ and AD7787BRM operate from a single supply voltage of 2.7 V to 5.25 V. The AD7789BRMZ typically consumes about 225 µA in normal mode, while the AD7787BRM typically consumes about 300 µA in normal mode (both figures are typical at 3 V supply). Both devices offer power-down modes to reduce current consumption when not converting. Designers should consult the respective datasheets for exact supply current versus temperature and supply voltage.
Which device is better suited for multi-channel sensor applications?
The AD7787BRM is better suited for multi-channel sensor applications because it provides two differential input channels and a PGA, allowing two sensors to be interfaced without an external multiplexer and enabling amplification of low-level signals. The AD7789BRMZ, with a single differential input channel and no PGA, is better suited to single-channel, low-power measurement applications where only one sensor input is required.
Are the AD7789BRMZ and AD7787BRM RoHS compliant?
Yes. Both the AD7789BRMZ and AD7787BRM are available in RoHS-compliant packages. The "Z" suffix in AD7789BRMZ denotes a RoHS-compliant lead-free package per Analog Devices' part numbering convention. The AD7787BRM is also offered in a RoHS-compliant version; designers should confirm the specific ordering code (e.g., AD7787BRMZ) with the manufacturer or authorized distributor to ensure RoHS compliance for the exact part ordered.