Part A
ADS7846E
STマイクロエレクトロニクス
- Lifecycle
- Active
- Stock
- 5291 個数
- Package
- SSOP-16
- Series
- データ取得 - タッチスクリーンコントローラ
Replacement verdict
Compatible functional replacement candidate
The ADS7844N and ADS7846E are both 12-bit SAR analog-to-digital converters from Texas Instruments sharing a compatible serial control interface and similar supply requirements, making the ADS7846E a viable functional replacement candidate for the ADS7844N in many designs. However, the two devices differ in channel configuration, on-chip reference and temperature-sensing features, and package footprint, so the replacement is not a direct drop-in and requires validation against the target application's input topology and board layout.
Channel Configuration
Validation required
Resolution and Interface
High match
On-Chip Reference and Sensor Features
Validation required
Package and Footprint
Not compatible
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADS7844N | ADS7846E | Why it matters |
|---|---|---|---|
| Resolution | 12 bit | 12 bit | Both converters provide 12-bit resolution, so measurement granularity is equivalent for substitutability. |
| Number of Input Channels | 8 single-ended / 4 differential | 8 single-ended / 4 differential | Channel count and configuration determine how many analog signals can be monitored without external multiplexing. |
| Sampling Rate | 200 kSPS | 125 kSPS | A higher sampling rate supports faster signal acquisition; the ADS7844N can sample faster than the ADS7846E. |
| Interface | SPI-compatible serial | SPI-compatible serial | Both use a serial SPI interface, simplifying drop-in replacement in systems with an existing SPI bus. |
| Supply Voltage | 2.7 V to 5.25 V | 2.2 V to 5.25 V | The wider supply range of the ADS7846E allows operation at lower system voltages, affecting compatibility with low-voltage rails. |
| On-chip Reference | No (external reference required) | Yes (internal 2.5 V reference) | An internal reference reduces external component count and board space; the ADS7844N requires an external reference. |
| On-chip Temperature Sensor | No | Yes | The ADS7846E includes a temperature sensor for system-level thermal monitoring, which the ADS7844N lacks. |
| Touch Screen Controller Function | No | Yes (4-wire touch screen) | The ADS7846E integrates touch screen control, making it suitable for display applications where the ADS7844N would need additional circuitry. |
| Package | 20-pin SSOP | 16-pin SSOP | Different package pin counts and footprints affect PCB layout and mechanical compatibility for substitution. |
| Power Consumption | Approx. 1.5 mW at 5 V, 200 kSPS | Approx. 1.0 mW at 5 V, 125 kSPS | Lower power consumption benefits battery-powered and portable designs; the ADS7846E draws less power at its rated throughput. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS7846E | ADS7844N |
|---|---|---|
| Part Status | Active | Active |
| Touchscreen | 4 Wire Resistive | - |
| Resolution(Bits) | 12 b | - |
| Interface | SPI | - |
| Voltage Reference | External, Internal | - |
| Voltage - Supply | 2.2V ~ 5.25V | - |
| Supply Current | 500 µA | - |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | Surface Mount | - |
| Number of Bits | - | 12 |
| Sampling Rate(Per Second) | - | 200k |
| Number of Inputs | - | 4, 8 |
| Input Type | - | Differential, Single Ended |
| Data Interface | - | 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 |
Frequently asked questions
What are the key architectural differences between the ADS7844N and ADS7846E?
The ADS7844N is an 8-channel, 12-bit successive-approximation ADC with a serial SPI/QSPI/Microwire interface, housed in a 20-pin SSOP package. The ADS7846E is a 4-wire touch screen controller that integrates a 12-bit ADC with an on-chip temperature sensor, internal reference, and touch-pressure measurement capability, housed in a 16-pin SSOP package. The ADS7846E includes dedicated touch-screen control functions (pen-down detection, X/Y position measurement) that the ADS7844N does not provide.
Can the ADS7844N be used as a direct drop-in replacement for the ADS7846E?
No. The two devices differ in pin count (20-pin vs 16-pin SSOP), pin functions, and feature sets. The ADS7846E integrates touch-screen control logic and an internal reference, while the ADS7844N is a general-purpose 8-channel ADC. A direct PCB replacement is not possible without redesigning the layout and validating the interface and control logic against the respective datasheets.
What is the resolution and sampling rate of each device?
Both the ADS7844N and ADS7846E provide 12-bit resolution. The ADS7844N supports a throughput rate of up to 200 kSPS. The ADS7846E is specified for a throughput rate of up to 125 kSPS. Designers should verify the exact timing and throughput specifications in the respective manufacturer datasheets for their operating conditions.
How do the input configurations differ between the ADS7844N and ADS7846E?
The ADS7844N offers 8 input channels that can be configured as single-ended or differential pairs, making it suitable for multi-channel data acquisition. The ADS7846E provides a 4-wire touch-screen interface with X/Y position measurement and also supports auxiliary input channels for functions such as temperature sensing. The input multiplexing and control registers differ between the two devices.
Do both devices include an internal voltage reference?
The ADS7846E integrates an on-chip reference, which simplifies touch-screen controller designs by reducing external component count. The ADS7844N requires an external reference voltage applied to its VREF pin. Designers must account for this difference in the analog front-end and decoupling strategy when comparing the two parts.
What are the typical applications for each device?
The ADS7844N is typically used in multi-channel data acquisition systems, industrial process control, and portable instrumentation where 8 single-ended or 4 differential inputs are needed. The ADS7846E is designed primarily for 4-wire resistive touch-screen systems in portable devices, point-of-sale terminals, and handheld instruments, where its integrated touch control and reference reduce board space and component count.
What supply voltage and interface do the ADS7844N and ADS7846E support?
Both devices operate from a single supply in the 2.7 V to 5.25 V range and use a serial SPI-compatible interface. The ADS7846E additionally supports a programmable resolution mode and includes touch-screen control signals such as PENIRQ. Designers should confirm the exact supply range and digital interface timing from the official manufacturer datasheets for each part.