Part A
ADS1255IDBR
Texas Instruments
- Lifecycle
- Active
- Stock
- 2109 Stückzahl
- Package
- SSOP-20
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Compatible functional replacement candidate
The ADS1255IDBR and ADS1240E/1KG4 are both 24-bit delta-sigma ADCs from Texas Instruments sharing a comparable serial interface and supply architecture, making the ADS1240E/1KG4 a viable functional candidate in applications where its lower channel count and reduced feature set are acceptable. Designers should validate channel count requirements, package footprint, and missing on-chip features such as the input buffer and PGA before committing to a direct substitution.
Resolution and Architecture
Validation required
Channel Count
Not compatible
Package Type
Validation required
Integrated Features
Validation required
Parts at a glance
Part B
ADS1240E/1KG4
Texas Instruments
- Lifecycle
- Active
- Stock
- 7122 Stückzahl
- Package
- SSOP-24
- Series
- Datenerfassung mit Analog to Digital Converters (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 | ADS1240E/1KG4 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit delta-sigma ADCs, so resolution alone does not differentiate them for substitutability. |
| Number of input channels | 2 (differential) | 4 (differential) | Channel count determines how many signal sources can be measured; the ADS1240 offers more inputs, affecting system architecture. |
| Maximum sample rate (SPS) | 30k | 15 | Sample rate sets the achievable signal bandwidth; the ADS1255 is far faster, so it suits higher-speed acquisition than the ADS1240. |
| Programmable gain amplifier (PGA) range | 1 to 64 | 1 to 128 | PGA gain range determines the smallest input signal that can be resolved; the ADS1240 supports higher gain for lower-level sensors. |
| Supply voltage (analog) | 5 V | 2.7 V to 5.25 V | Supply range affects compatibility with the system power rail; the ADS1240 is more flexible for low-voltage designs. |
| Digital interface | SPI | SPI | Both use SPI, so the host microcontroller interface is compatible between the two parts. |
| Package | SSOP-20 | SSOP-20 | Matching package and footprint allows a drop-in board replacement without layout changes. |
| Operating temperature range | -40°C to +85°C | -40°C to +85°C | Identical temperature ratings mean both suit the same industrial environments. |
| Input type | Differential | Differential | Both accept differential inputs, preserving common-mode rejection behavior when substituting. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS1255IDBR | ADS1240E/1KG4 |
|---|---|---|
| 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 ADS1240E/1KG4?
The ADS1255IDBR is a 24-bit delta-sigma ADC with a maximum data rate of 30 kSPS, featuring a programmable gain amplifier (PGA) with gains from 1 to 64, and is supplied in a 20-pin SSOP package. The ADS1240E/1KG4 is a 24-bit delta-sigma ADC with a maximum data rate of 15 kSPS, offering a PGA with gains from 1 to 128, and is supplied in a 28-pin SSOP package. The ADS1255IDBR provides a higher maximum data rate, while the ADS1240E/1KG4 offers a higher maximum PGA gain and a different pin count and package size.
Are the ADS1255IDBR and ADS1240E/1KG4 pin-to-pin compatible?
No. The ADS1255IDBR is packaged in a 20-pin SSOP, whereas the ADS1240E/1KG4 is packaged in a 28-pin SSOP. The different pin counts and pin functions mean the two devices are not pin-to-pin compatible and cannot be interchanged on the same PCB footprint without redesign.
Can the ADS1255IDBR and ADS1240E/1KG4 operate from the same supply voltage?
Both devices support a single analog supply voltage of 5 V and a digital supply voltage of 1.8 V to 3.6 V, per their respective manufacturer datasheets. However, the ADS1240E/1KG4 also supports a 3 V analog supply option, which the ADS1255IDBR does not. Designers should verify the exact supply configuration against the latest datasheet before substitution.
Which device offers a higher maximum data output rate?
The ADS1255IDBR offers a higher maximum data rate of 30 kSPS, compared to 15 kSPS for the ADS1240E/1KG4. This makes the ADS1255IDBR more suitable for applications requiring faster sampling, while the ADS1240E/1KG4 may be preferred for lower-speed, higher-resolution gain applications.
Do both ADCs include a programmable gain amplifier (PGA)?
Yes. Both the ADS1255IDBR and the ADS1240E/1KG4 integrate a PGA. The ADS1255IDBR provides selectable gains from 1 to 64, while the ADS1240E/1KG4 provides selectable gains from 1 to 128. The higher gain range of the ADS1240E/1KG4 can be advantageous for low-level signal conditioning.
What are the package and pin count differences that affect PCB layout?
The ADS1255IDBR uses a 20-pin SSOP package, and the ADS1240E/1KG4 uses a 28-pin SSOP package. The differing pin counts, pin assignments, and package body widths require distinct PCB land patterns and routing, so a board designed for one device cannot directly accept the other without layout changes.
Are both devices suitable for precision sensor measurement applications?
Yes. Both are 24-bit delta-sigma ADCs with integrated PGAs, making them suitable for precision sensor measurement. The ADS1255IDBR's higher 30 kSPS rate suits faster acquisition, while the ADS1240E/1KG4's gain up to 128 and 15 kSPS rate suit lower-speed, high-gain sensor interfaces. Selection should be based on the required sample rate, gain range, and package constraints verified in the manufacturer datasheets.