Texas Instruments ADS7958SDBT

Overview

ADS7958SDBT from Texas Instruments is a 8-bit, 4-channel, single-ended SAR analog-to-digital converter with 1-MSPS sample rate, zero-latency operation, and 20-MHz SPI-compatible serial interface. It features two software-selectable unipolar input ranges (0 to VREF and 0 to 2×VREF), programmable per-channel high/low alarm thresholds, and operates from 2.7–5.25 V analog supply and 1.7–5.25 V I/O supply. It is used in multi-channel signal monitoring within PLCs and digital power supplies.

For engineers reviewing the ADS7958SDBT datasheet, ADS7958SDBT pinout, ADS7958SDBT application, or ADS7958SDBT equivalent, key selection considerations include its 4-channel count, 8-bit resolution, TSSOP-30 package footprint, GPIO0–GPIO3 configurability (four pins in TSSOP), and alarm-triggered interrupt capability for real-time fault detection in industrial sensing systems.

Technical Context

The ADS7958SDBT implements a capacitor-based SAR architecture with integrated sample-and-hold, accepting analog inputs via a 4-channel single-ended multiplexer with MXO output. Its conversion timing is synchronized to CS falling edge and SCLK, supporting both auto-sequencing and manual channel selection modes.

It integrates dual programmable alarm comparators per channel referenced to REFP/REFM, with alarm outputs routed to GPIO0–GPIO3 (configured as Alarm, Low-alarm, Range select, or PD). The device supports glueless interfacing to microcontrollers via 3-wire SPI (CS, SCLK, SDI/SDO) and offers power-down mode drawing only 1 µA.

Key Specifications

Pinout & Package

The ADS7958SDBT is housed in a 30-pin TSSOP (DBT) package measuring 7.80 mm × 4.40 mm, with exposed thermal pad (not electrically connected). All pins are validated per TI SLAS605C Rev C (July 2018) Pin Functions table for ADS7950/54/58 variants.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multichannel SAR ADC applications.

Compared with ADS7954SDBT, the ADS7958SDBT trades 2 bits of resolution for lower cost and reduced data throughput; versus ADS8664IPWR, it sacrifices integrated signal conditioning and reference to retain flexible alarm-driven responsiveness in resource-constrained systems.

Availability

ADS7958SDBT is available at Aetrix Electronics and suitable for PLC analog input modules, digital power supply monitoring, optical line card supervision, and medical patient monitor sensor interfaces requiring stable component supply across long production lifecycles.

Supply support for ADS7958SDBT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company specializing in analog and embedded processing technologies, with leadership in precision data converters and industrial interface solutions.

The ADS79xx family-including ADS7958SDBT-is designed for high-speed, multi-channel data acquisition in industrial automation, where pin compatibility across resolutions (8/10/12-bit) simplifies platform scalability and reduces qualification overhead.

FAQ

What is the maximum input frequency the ADS7958SDBT can accurately digitize?

The ADS7958SDBT has a 47 MHz (3 dB) input bandwidth and 1-MSPS sample rate. Per Nyquist–Shannon theorem, it reliably captures baseband signals up to 500 kHz. For accurate representation of fast edges (e.g., switching noise), the 47 MHz bandwidth ensures minimal attenuation of harmonics up to the 5th–7th order. The ADS7958SDBT achieves this using a capacitor-based SAR architecture with integrated sample-and-hold, avoiding aliasing when anti-alias filtering is applied.

Does the ADS7958SDBT require an external reference voltage?

Yes, the ADS7958SDBT requires an external reference applied to REFP and REFM pins. It does not include an internal reference. Common choices include the REF5025 (2.5 V) or REF5045 (4.5 V), which connect directly to REFP/REFM. The device supports two input ranges: 0 to VREF and 0 to 2×VREF, selected via GPIO2. The ADS7958SDBT's reference input resistance is specified to ensure stable operation with standard reference ICs.

How many GPIOs does the ADS7958SDBT provide, and what functions do they serve?

The ADS7958SDBT provides four GPIOs (GPIO0–GPIO3) in its TSSOP-30 (DBT) package. Their default configured roles are: GPIO0 = active-high alarm output, GPIO1 = active-high low-alarm output, GPIO2 = input selecting 0–VREF (low) or 0–2×VREF (high) range, and GPIO3 = active-low power-down input. All are programmable via internal registers. The ADS7958SDBT documentation confirms these assignments in the Pin Functions table for ADS7950/54/58 variants.

Is the ADS7958SDBT pin-compatible with other devices in the ADS79xx family?

Yes, the ADS7958SDBT shares identical pinout and footprint with ADS7950SDBT (8-bit, 4-channel) and ADS7954SDBT (10-bit, 4-channel) in the 30-pin TSSOP package. This pin compatibility extends to power, analog input, reference, and digital interface pins. The ADS7958SDBT maintains register-level compatibility for core functions (channel selection, alarm setup, range control), enabling resolution upgrades without PCB revision.

What is the purpose of the MXO pin on the ADS7958SDBT?

The MXO (Multiplexer Output) pin provides buffered access to the analog signal currently selected by the internal multiplexer-whether from CH0–CH3, AINP/AINM, or internal test nodes. It allows external circuitry (e.g., oscilloscope probe, secondary ADC, or analog comparator) to monitor the active channel in real time without loading the input source. The ADS7958SDBT datasheet specifies MXO as an analog output with rail-to-rail swing and low output impedance, making it suitable for debugging and calibration workflows.