Part A
ADS7870EA
Texas Dụng cụ
- Lifecycle
- Active
- Stock
- 3964 PCS
- Package
- SSOP-28
- Series
- Data Acquisition - ADCs-DACs - Special Purpose
Replacement verdict
Not a drop-in replacement
The ADS7870EA and ADS7844NBG4 are not functionally interchangeable despite sharing a similar analog-to-digital converter role. The ADS7870EA integrates a programmable-gain instrumentation amplifier, an on-chip voltage reference, and a serial control interface with a different command structure, while the ADS7844NBG4 is a 12-bit successive-approximation ADC with a 4-wire touch-screen-oriented serial interface and no integrated PGA or reference. Their package footprints, channel configurations, and interface protocols differ, so a direct board-level substitution is not possible without redesign.
Different interface protocol
Different channel configuration
Different package footprint
Different integrated features
Parts at a glance
Part B
ADS7844NBG4
Texas Dụng cụ
- Lifecycle
- Active
- Stock
- 2245 PCS
- Package
- SSOP-20
- Series
- Data Acquisition - 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 | ADS7870EA | ADS7844NBG4 | Why it matters |
|---|---|---|---|
| Resolution | 12 bit | 12 bit | Both are 12-bit ADCs, so nominal conversion resolution is equivalent for substitutability. |
| Number of ADC Inputs / Channels | 8 single-ended / 4 differential (with on-chip MUX) | 8 single-ended / 4 differential | Channel count and configuration determine how many signals can be multiplexed into the converter. |
| Sampling Rate | 52 kSPS | 200 kSPS | Maximum throughput affects whether the part can keep up with faster signal acquisition requirements. |
| Interface | SPI / QSPI / Microwire compatible serial | SPI / QSPI / Microwire compatible serial | Serial interface compatibility ensures the part can be connected to the same host controller bus. |
| Supply Voltage | 2.7 V to 5.5 V | 2.7 V to 5.25 V | Operating supply range must cover the system rail to guarantee correct operation and signal swing. |
| On-chip Programmable Gain Amplifier | Yes (PGA with gain settings) | No | A PGA allows direct amplification of small signals, which affects front-end design and external component count. |
| On-chip Voltage Reference | Yes (internal reference) | No (external reference required) | An internal reference simplifies the design and reduces external components; absence requires an external reference. |
| Package | SSOP-28 | SSOP-20 | Package footprint and pin count affect PCB layout and whether a drop-in replacement is possible. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Temperature range must match the application environment for reliable operation. |
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 | ADS7870EA | ADS7844NBG4 |
|---|---|---|
| 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 primary functional differences between the ADS7870EA and ADS7844NBG4?
The ADS7870EA is a 12-bit data acquisition system (DAS) integrating a 12-bit SAR ADC, an 8-channel multiplexer, a programmable gain amplifier, and a precision voltage reference in a single package. The ADS7844NBG4 is a 12-bit SAR ADC with an 8-channel multiplexer but does not integrate a programmable gain amplifier or a precision reference; it requires external signal conditioning and reference circuitry.
Do the ADS7870EA and ADS7844NBG4 have the same package and pinout?
No. The ADS7870EA is offered in a 28-pin SSOP package, while the ADS7844NBG4 is offered in a 20-pin SSOP package. The pin counts and pin functions differ, so the two devices are not pin-compatible and cannot be interchanged on the same PCB land pattern without redesign.
What are the supply voltage requirements for each device?
The ADS7870EA operates from a single 5 V analog supply (with a separate digital supply range of 2.7 V to 5.5 V). The ADS7844NBG4 operates from a single 2.7 V to 5.25 V supply. Designers should verify the exact supply rail requirements against the respective manufacturer datasheets before selecting a replacement.
How do the serial interfaces of the ADS7870EA and ADS7844NBG4 compare?
Both devices provide a serial interface for communication with a host controller. The ADS7870EA supports a serial interface compatible with SPI, QSPI, and Microwire protocols. The ADS7844NBG4 also provides an SPI-compatible serial interface. The exact timing, word length, and control register formats differ between the two devices and must be reviewed in the datasheets.
Can the ADS7870EA be used as a drop-in replacement for the ADS7844NBG4?
No. The devices differ in package pin count, integrated functionality (the ADS7870EA includes a PGA and reference), and supply requirements. A drop-in replacement is not possible; any substitution requires a full review of schematic, layout, and firmware changes against both datasheets.
What is the maximum sampling rate of each device?
The ADS7870EA supports a maximum throughput of 52 kSPS. The ADS7844NBG4 supports a maximum throughput of 200 kSPS. System designers should confirm these rates under their specific operating conditions using the manufacturer datasheets.
Which device is better suited for applications requiring integrated signal conditioning?
The ADS7870EA is better suited for applications requiring integrated signal conditioning because it includes an on-chip programmable gain amplifier and a precision voltage reference, reducing external component count. The ADS7844NBG4 requires external signal conditioning and reference circuitry, making it more suitable where those functions are provided elsewhere in the system.