Part A
ADS7870EA
Texas Instruments
- Lifecycle
- Active
- Stock
- 3964 PCS
- Package
- SSOP-28
- Series
- Acquisição de dados - ADCs-DACs - Objetivo Especial
Replacement verdict
Not a drop-in replacement
The ADS7870EA and ADS7844E/2K5G4 are not drop-in replacements for each other. Although both are 12-bit successive-approximation ADCs from Texas Instruments, they differ in resolution architecture, input channel configuration, serial interface protocol, and package footprint, so a direct board-level substitution is not possible without redesign.
Different input architecture
Different channel count
Different serial interface
Different package footprint
Parts at a glance
Part B
ADS7844E/2K5G4
Texas Instruments
- Lifecycle
- Active
- Stock
- 2200 PCS
- Package
- SSOP-20
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (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 | ADS7870EA | ADS7844E/2K5G4 | Why it matters |
|---|---|---|---|
| Resolution | 12 bit | 12 bit | Both are 12-bit converters, so resolution alone does not differentiate them for substitutability. |
| Number of ADC Inputs / Channels | 8 single-ended / 4 differential (with on-chip multiplexer) | 8 single-ended / 4 differential | Channel count and configuration determine how many signals can be measured without external multiplexing. |
| Sampling Rate | 52 kSPS | 200 kSPS | Maximum throughput affects whether the part can handle faster-changing signals or higher sample-rate requirements. |
| Interface Type | SPI / serial (with on-chip PGA and reference) | SPI / serial | Both use a serial interface, but the ADS7870 integrates additional signal-conditioning blocks that change system architecture. |
| On-chip Programmable Gain Amplifier (PGA) | Yes (gain 1 to 20) | No | An integrated PGA allows direct connection of low-level sensors without external amplification, a major functional difference. |
| On-chip Voltage Reference | Yes (internal reference) | No (external reference required) | An internal reference simplifies the design and reduces external component count; absence requires an external reference. |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.25 V | Supply range affects compatibility with the system power rail; slight differences can matter at the extremes. |
| Package | SSOP-28 | SSOP-20 | Different package pin counts and footprints prevent direct drop-in replacement on the same PCB. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Identical temperature ratings mean both suit the same industrial environments. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS7870EA | ADS7844E/2K5G4 |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Active | Discontinued at Digi-Key |
| Number of Bits | - | 12 |
| Sampling Rate(Per Second) | 52k | 200k |
| Number of Inputs | - | 4, 8 |
| Input Type | - | Differential, Single Ended |
| Data Interface | Serial | SPI |
| Configuration | - | MUX-S/H-ADC |
| Ratio - S / H: ADC | - | 1:1 |
| Number of A/D Converters | - | 1 |
| Architecture | - | SAR |
| Reference Type | - | External |
| Voltage - Supply, Analog | - | 2.7V ~ 3.6V, 5V |
| Voltage - Supply, Digital | - | 2.7V ~ 3.6V, 5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Type | Data Acquisition System (DAS) | - |
| Number of Channels | 8 | - |
| Resolution(Bits) | 12 b | - |
| Voltage Supply Source | Single Supply | - |
| Voltage - Supply | 2.7V ~ 5.5V | - |
| Mounting Type | Surface Mount | - |
Frequently asked questions
What are the key architectural differences between the ADS7870EA and the ADS7844E/2K5G4?
The ADS7870EA is a 12-bit data acquisition system (DAS) that integrates a 12-bit SAR ADC, an 8-channel multiplexer, a programmable gain amplifier (PGA), and a precision voltage reference in a single package. The ADS7844E/2K5G4 is a 12-bit SAR ADC with an 8-channel multiplexer but does not integrate a PGA or a precision reference; it requires external signal conditioning and reference circuitry. The ADS7870EA is therefore a more highly integrated solution for complete signal-chain applications, while the ADS7844E/2K5G4 is a simpler standalone ADC.
Do the ADS7870EA and ADS7844E/2K5G4 have the same package and pinout?
No. The ADS7870EA is offered in a 28-pin SSOP package, while the ADS7844E/2K5G4 is offered in a 20-pin SSOP package. Because the pin counts and pin functions differ, the two devices are not pin-compatible and cannot be dropped into the same PCB land pattern without redesign.
What are the maximum sampling rates of the ADS7870EA and ADS7844E/2K5G4?
The ADS7870EA supports a maximum throughput of 52 kSPS. The ADS7844E/2K5G4 supports a maximum throughput of 200 kSPS. The ADS7844E/2K5G4 is therefore better suited for higher-speed acquisition, while the ADS7870EA trades speed for integrated signal conditioning.
How do the input configurations differ between the ADS7870EA and ADS7844E/2K5G4?
Both devices provide an 8-channel input multiplexer that can be configured for single-ended or differential inputs. However, the ADS7870EA includes an on-chip PGA with selectable gains (1, 2, 4, 8, 16, 20, 32, and 64), allowing direct connection of low-level sensors. The ADS7844E/2K5G4 does not include a PGA, so low-level signals must be amplified externally before reaching the ADC inputs.
Do both devices include an on-chip voltage reference?
No. The ADS7870EA integrates a precision voltage reference on-chip, which simplifies the design and reduces external component count. The ADS7844E/2K5G4 does not include an internal reference and requires an external reference voltage to be supplied to its VREF pin for proper operation.
What are the supply voltage requirements for the ADS7870EA and ADS7844E/2K5G4?
Both devices operate from a single 5 V analog supply (typically 4.75 V to 5.25 V). The ADS7870EA also requires a digital supply (VDD) that can range from 2.7 V to 5.5 V, allowing direct interfacing to lower-voltage logic. The ADS7844E/2K5G4 operates with a single 5 V supply for both analog and digital functions and its digital interface levels are referenced to that supply.
What digital interfaces do the ADS7870EA and ADS7844E/2K5G4 support?
Both devices provide a serial digital interface compatible with SPI, QSPI, and Microwire protocols. The ADS7870EA supports both 3-wire and 4-wire serial interface modes and includes a dedicated interrupt output. The ADS7844E/2K5G4 uses a standard 3-wire serial interface (CS, DIN, DOUT, and DCLK) for communication with a host controller.
Which device is more suitable for portable or space-constrained designs?
The ADS7844E/2K5G4 is offered in a smaller 20-pin SSOP package and has lower integration, which can reduce board area when external signal conditioning is already present. The ADS7870EA, in a 28-pin SSOP, integrates the PGA and reference, which can reduce total system component count and board area in designs that would otherwise require those external blocks. The choice depends on whether integration or minimal package size is the priority.