Part A
ADS1240E
德州儀器
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- 資料獲取-模數轉換器（ADC）
Replacement verdict
Not a drop-in replacement
The ADS1254E and ADS1240E are both 24-bit delta-sigma ADCs from Texas Instruments, but they differ in resolution architecture, input configuration, package footprint, and interface timing, so the ADS1240E cannot be treated as a direct drop-in substitute for the ADS1254E without design validation.
Different input configuration
Different package footprint
Different data rate
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 | ADS1254E | ADS1240E | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit delta-sigma ADCs, so resolution alone does not distinguish them for substitutability. |
| Number of input channels | 4 (differential) | 4 (differential) | Channel count determines how many sensor signals can be measured; matching counts supports direct functional replacement. |
| Maximum sample rate (SPS) | 20k | 15 | The ADS1254E supports much higher throughput, so it can replace the slower ADS1240E only if the application does not require the higher rate or if firmware timing is adjusted. |
| Interface | SPI (serial) | SPI (serial) | Both use a serial SPI-compatible interface, simplifying digital-side substitution in existing designs. |
| Supply voltage (analog) | 5 V | 2.7 V to 5.25 V | The wider analog supply range of the ADS1240E allows lower-voltage operation, while the ADS1254E requires a 5 V analog rail. |
| Package | SSOP-20 | SSOP-20 | Identical package and pin count support drop-in board-level replacement without layout changes. |
| PGA / gain stages | No integrated PGA | Integrated PGA (gain 1 to 128) | The ADS1240E's programmable gain amplifier enables direct connection of low-level sensors, whereas the ADS1254E requires external signal conditioning. |
| Input type | Differential | Differential | Both accept differential inputs, preserving common-mode rejection behavior for sensor interfaces. |
| Operating temperature range | -40°C to +85°C | -40°C to +85°C | Matching industrial temperature ranges ensure both parts are suitable for the same environmental conditions. |
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 | ADS1240E | ADS1254E |
|---|---|---|
| Part Status | Active | Active |
| Base Product Number | ADS1240 | - |
| Number of Bits | 24 | 24 |
| Sampling Rate (Per Second) | 15 | - |
| Number of Inputs | 4 | 4 |
| Input Type | Differential, Single Ended | Differential |
| Data Interface | SPI | SPI |
| Configuration | MUX-PGA-ADC | MUX-ADC |
| Number of A / D Converters | 1 | - |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 2.7V ~ 3.3V, 5V | 5V |
| Voltage - Supply, Digital | 2.7V ~ 5.25V | 1.8V ~ 3.6V |
| Features | PGA | - |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | - |
| Packaging | Tube | - |
| Sampling Rate(Per Second) | - | 20k |
| Number of A/D Converters | - | 1 |
Frequently asked questions
What are the key architectural differences between the ADS1254E and ADS1240E?
The ADS1254E is a 24-bit delta-sigma ADC with a fixed data rate of 20.8 kSPS and a 4-channel differential input multiplexer, while the ADS1240E is a 24-bit delta-sigma ADC with a programmable data rate from 15 SPS to 1 kSPS and a 4-channel differential input multiplexer with PGA. The ADS1254E targets higher-speed applications, whereas the ADS1240E targets higher-resolution, lower-speed precision measurement applications.
Do the ADS1254E and ADS1240E have the same package and pinout?
Both devices are offered in a 24-pin SSOP package, but their pin functions and internal register maps differ. The ADS1254E and ADS1240E are not pin-for-pin drop-in replacements, so PCB layout and firmware must be reviewed before substitution.
What are the maximum data rates of the ADS1254E and ADS1240E?
The ADS1254E provides a fixed 20.8 kSPS output data rate. The ADS1240E provides a programmable output data rate up to 1 kSPS. The ADS1254E is therefore better suited for higher-speed signal acquisition, while the ADS1240E is intended for lower-speed precision measurements.
Do both devices include a programmable gain amplifier (PGA)?
The ADS1240E includes a programmable gain amplifier with selectable gains of 1, 2, 4, 8, 16, 32, 64, and 128. The ADS1254E does not include an integrated PGA; its input range is fixed. Designs requiring small-signal amplification should account for this difference.
How do the supply voltage and reference requirements compare?
Both the ADS1254E and ADS1240E operate from a single 5 V analog supply and a 2.7 V to 5.25 V digital supply, and both require an external voltage reference. The reference input range and recommended reference values should be verified against the respective manufacturer datasheets for the target design.
Can the ADS1254E and ADS1240E be used interchangeably in an existing design?
No. Although both are 24-bit delta-sigma ADCs in 24-pin SSOP packages, they differ in data rate, PGA availability, register set, and pin functions. A direct substitution is not supported without schematic, layout, and firmware changes validated against the manufacturer datasheets.
Which device is better suited for high-speed multi-channel data acquisition?
The ADS1254E is better suited for higher-speed multi-channel acquisition because it offers a fixed 20.8 kSPS data rate with a 4-channel differential multiplexer. The ADS1240E, with a maximum 1 kSPS data rate, is intended for lower-speed precision measurement rather than high-speed acquisition.
Which device is better suited for low-level sensor signals requiring gain?
The ADS1240E is better suited for low-level sensor signals because it integrates a PGA with gains up to 128, allowing direct amplification of small differential signals. The ADS1254E lacks an integrated PGA, so external amplification would be required for similar low-level signal conditioning.