Part A
ADS7822U
Texas Instruments
- Lifecycle
- Active
- Stock
- 7079 PCS
- Package
- SOIC-8
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Not a drop-in replacement
The ADS7822U and ADS7804UB/1K are not drop-in replacements for one another. The ADS7822U is a 12-bit micropower SAR ADC in a small SOIC-8 package with a serial SPI interface, while the ADS7804UB/1K is a 12-bit sampling ADC in a wider SOIC-28 package with a parallel byte interface and a different analog input range and reference architecture. Designers must account for differences in package footprint, digital interface, input configuration, and power/throughput characteristics before considering any substitution.
Different package footprint
Different digital interface
Different input configuration
Different power and throughput
Parts at a glance
Part B
ADS7804UB/1K
Texas Instruments
- Lifecycle
- Active
- Stock
- 4479 PCS
- Package
- SOIC-28
- 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 | ADS7822U | ADS7804UB/1K | Why it matters |
|---|---|---|---|
| Resolution | 12 bit | 12 bit | Both are 12-bit ADCs, so they offer the same nominal quantization step and are interchangeable in terms of resolution. |
| Sampling Rate | 75 kSPS | 100 kSPS | The maximum throughput differs; the ADS7804UB can sample faster, which matters for higher-bandwidth signal acquisition. |
| Input Type | Single-ended | Single-ended | Both accept single-ended analog inputs, so the signal conditioning topology can remain the same. |
| Number of Input Channels | 1 | 1 | Both are single-channel devices, so multiplexing requirements are identical. |
| Interface | SPI / Microwire (serial) | Parallel | The digital interface differs fundamentally; a serial SPI host cannot directly drive the parallel ADS7804UB without glue logic or a different MCU port. |
| Supply Voltage | 2.7 V to 5.25 V | 5 V (single supply) | The ADS7822U supports lower supply rails, enabling 3.3 V systems, while the ADS7804UB requires a 5 V rail. |
| Package | SOIC-8 | SOIC-28 | Different package footprints and pin counts mean the boards are not drop-in compatible and require layout changes. |
| Reference | External | Internal | The ADS7804UB includes an on-chip reference, simplifying design, while the ADS7822U needs an external reference for accurate conversions. |
| Operating Temperature Range | -40 °C to +85 °C | -40 °C to +85 °C | Both cover the industrial temperature range, so environmental compatibility is equivalent. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS7822U | ADS7804UB/1K |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Active | Obsolete |
| Number of Bits | 12 | 12 |
| Sampling Rate(Per Second) | 200k | 100k |
| Number of Inputs | 1 | 1 |
| Input Type | Pseudo-Differential | Single Ended |
| Data Interface | SPI | Parallel |
| Configuration | S/H-ADC | S/H-ADC |
| Ratio - S / H: ADC | 1:1 | 1:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | SAR | SAR |
| Reference Type | External | External, Internal |
| Voltage - Supply, Analog | 2.7V ~ 3.6V, 5V | 5V |
| Voltage - Supply, Digital | 2.7V ~ 3.6V, 5V | 5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Series | microPOWER™ | - |
Frequently asked questions
What are the key architectural differences between the ADS7822U and the ADS7804UB/1K?
The ADS7822U is a 12-bit, micropower, successive-approximation register (SAR) analog-to-digital converter that operates from a single 2.7 V to 5.25 V supply and communicates via a serial (SPI-compatible) interface. The ADS7804UB/1K is a 12-bit SAR ADC that operates from a single 5 V supply and provides a parallel 8-bit/12-bit data bus interface. The ADS7822U is offered in an SOIC-8 package, while the ADS7804UB/1K is offered in a 28-pin SOIC package.
Can the ADS7822U and ADS7804UB/1K be used interchangeably in an existing design?
No. The two devices differ in package footprint, pin count, supply voltage range, and digital interface type (serial versus parallel). The ADS7822U uses an 8-pin SOIC package with a serial interface, whereas the ADS7804UB/1K uses a 28-pin SOIC package with a parallel interface. A direct drop-in replacement is not possible without PCB redesign and interface logic changes.
How do the sampling rates of the ADS7822U and ADS7804UB/1K compare?
The ADS7822U offers a throughput rate of up to 75 kSPS at a 5 V supply (and up to 75 kSPS at 2.7 V). The ADS7804UB/1K provides a throughput rate of up to 100 kSPS. Designers requiring higher sampling throughput should verify the timing specifications in the respective manufacturer datasheets for the exact operating conditions.
What are the power consumption characteristics of each device?
The ADS7822U is designed for micropower operation, drawing approximately 1.6 mW at 75 kSPS with a 5 V supply, and it features a power-down mode that reduces consumption to typically 3 µW. The ADS7804UB/1K typically dissipates 100 mW from a 5 V supply. The ADS7822U is therefore better suited to battery-powered or low-power applications, while the ADS7804UB/1K targets higher-throughput systems where power is less critical.
What input voltage ranges do the ADS7822U and ADS7804UB/1K support?
The ADS7822U provides a pseudo-differential input with a unipolar input range of 0 V to VREF, where VREF can be externally set (commonly 2.5 V or 5 V). The ADS7804UB/1K provides a bipolar input range of ±10 V (with a 5 V reference) and includes an internal reference and input scaling. The input signal conditioning requirements therefore differ significantly between the two parts.
Which device is more suitable for space-constrained or portable designs?
The ADS7822U is more suitable for space-constrained and portable designs. It is housed in an 8-pin SOIC package, operates from a single supply as low as 2.7 V, and consumes significantly less power than the ADS7804UB/1K, which is packaged in a 28-pin SOIC and requires a 5 V supply with higher power dissipation.
Do both devices include an internal voltage reference?
No. The ADS7822U requires an external reference voltage applied to the VREF pin and does not include an internal reference. The ADS7804UB/1K includes an internal 5 V reference (with the option to use an external reference). This difference affects system-level component count and reference accuracy budgeting.
What digital interface does each converter use, and how does that affect system integration?
The ADS7822U uses a serial, SPI/QSPI/MICROWIRE-compatible interface requiring few I/O lines, which simplifies isolation and reduces pin count on the host controller. The ADS7804UB/1K uses a parallel interface with a 12-bit data bus (configurable for 8-bit or 12-bit reads), which requires more host I/O pins but can simplify interfacing to parallel-bus microcontrollers and DSPs. Interface selection should be matched to the host processor's available peripherals.