Part A
ADS1255IDBR
Texas Instruments
- Lifecycle
- Active
- Stock
- 2109 PCS
- Package
- SSOP-20
- Series
- Acquisition de données - Convertisseur analogique - numérique (ADC)
Replacement verdict
Not a drop-in replacement
The ADS1255IDBR and ADS1240EG4 are both 24-bit delta-sigma ADCs from Texas Instruments, but they differ in resolution architecture, input channel configuration, package footprint, and interface timing, so the ADS1240EG4 cannot be treated as a direct drop-in substitute for the ADS1255IDBR without design validation.
Different input channel configuration
Different package footprint
Different data rate capability
Different interface timing
Parts at a glance
Part B
ADS1240EG4
Texas Instruments
- Lifecycle
- Active
- Stock
- 7995 PCS
- Package
- SSOP-24
- Series
- Acquisition de données - Convertisseur analogique - numérique (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 | ADS1255IDBR | ADS1240EG4 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit delta-sigma ADCs, so resolution alone does not differentiate them for high-precision measurement applications. |
| Number of input channels | 2 (differential) / 1 (differential) | 4 (differential) / 8 (single-ended) | Channel count determines how many sensors or signals can be multiplexed into a single ADC, directly affecting system architecture and board space. |
| Maximum data rate (SPS) | 30k | 15 | Higher sample rates enable faster signal acquisition and support wider signal bandwidths, which is critical for dynamic or multiplexed measurements. |
| PGA gain range | 1 to 64 | 1 to 128 | Programmable gain amplifies small sensor signals before conversion; a wider gain range allows direct interfacing with lower-level signals such as thermocouples or bridge sensors. |
| Supply voltage (analog) | 5 V (single 4.75–5.25 V) | 2.7–5.25 V | Supply voltage compatibility determines whether the part can operate directly from the system rail or requires additional regulation. |
| Interface | SPI (serial peripheral interface) | SPI (serial peripheral interface) | Both use SPI, so the host microcontroller interface is compatible, but firmware register maps and command sets differ and must be adapted. |
| Package | SSOP-20 | SSOP-28 | Different package footprints and pin counts prevent direct drop-in replacement and require PCB layout changes. |
| Operating temperature range | -40 to +85 °C | -40 to +85 °C | Identical temperature ratings mean both are suitable for the same industrial environments without derating concerns. |
| Input type | Differential only | Differential and single-ended | Single-ended capability in the ADS1240EG4 allows more flexible sensor connections, while the ADS1255IDBR is limited to differential inputs. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS1255IDBR | ADS1240EG4 |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Active | Discontinued at Digi-Key |
| Number of Bits | 24 | 24 |
| Sampling Rate(Per Second) | 30k | 15 |
| Number of Inputs | 1, 2 | 4 |
| Input Type | Differential, Single Ended | Differential, Single Ended |
| Data Interface | SPI | SPI |
| 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 | 5V | 2.7V ~ 3.3V, 5V |
| Voltage - Supply, Digital | 1.8V ~ 3.6V | 2.7V ~ 5.25V |
| Features | PGA | PGA |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the primary differences between the ADS1255IDBR and the ADS1240EG4?
The ADS1255IDBR is a 24-bit delta-sigma ADC with a maximum data rate of 30 kSPS, featuring a programmable gain amplifier and a serial SPI interface, housed in a 20-pin SSOP package. The ADS1240EG4 is a 24-bit delta-sigma ADC with a maximum data rate of 15 SPS, offering a lower-speed, lower-power solution in a 24-pin QSOP package. The ADS1255IDBR targets higher-speed precision applications, while the ADS1240EG4 suits low-frequency, low-power measurement systems.
Are the ADS1255IDBR and ADS1240EG4 pin-to-pin compatible?
No. The ADS1255IDBR uses a 20-pin SSOP package, while the ADS1240EG4 uses a 24-pin QSOP package. The pin counts and package footprints differ, so they are not directly interchangeable on the same PCB land pattern.
What are the maximum data rates of these two ADCs?
The ADS1255IDBR supports a maximum data rate of 30 kSPS (30,000 samples per second). The ADS1240EG4 supports a maximum data rate of 15 SPS (samples per second), making it suitable for slow, high-resolution measurements rather than high-speed acquisition.
Do both devices include a programmable gain amplifier (PGA)?
Yes. Both the ADS1255IDBR and the ADS1240EG4 integrate a programmable gain amplifier. The ADS1255IDBR offers selectable gains of 1, 2, 4, 8, 16, 32, and 64. The ADS1240EG4 provides selectable gains of 1, 2, 4, 8, 16, 32, 64, and 128, allowing direct interfacing with low-level sensors.
What digital interface do the ADS1255IDBR and ADS1240EG4 use?
Both devices use a serial peripheral interface (SPI)-compatible serial interface for communication with a host microcontroller. The ADS1255IDBR supports SPI with a maximum SCLK frequency of 1.92 MHz, while the ADS1240EG4 supports SPI-compatible serial communication suitable for its lower data rate operation.
How do the power consumption characteristics compare?
The ADS1255IDBR typically consumes approximately 38 mW at 5 V supply in normal operation. The ADS1240EG4 is designed for lower-power applications, typically consuming about 2.5 mW at 3 V supply. The ADS1240EG4 is therefore better suited to battery-powered or energy-sensitive designs, while the ADS1255IDBR prioritizes higher throughput.
Can the ADS1240EG4 be used as a drop-in replacement for the ADS1255IDBR in an existing design?
No. Beyond the package and pin count differences, the two devices differ in maximum data rate (30 kSPS vs. 15 SPS), supply voltage ranges, and register configurations. A direct drop-in replacement is not possible; the design would require schematic, layout, and firmware changes validated against the respective datasheets.