Texas Instruments ADS7861E/2K5G4

Overview

ADS7861E/2K5G4 from Texas Instruments is a dual, 12-bit, 500kSPS simultaneous-sampling SAR analog-to-digital converter with four fully differential input channels (A0/A1/B0/B1), 2.5V internal reference, 80dB CMRR at 50kHz, and SSI serial interface - designed for high-accuracy motor control and multi-axis positioning systems.

For engineers reviewing the ADS7861E/2K5G4 datasheet, ADS7861E/2K5G4 pinout, ADS7861E/2K5G4 application, or ADS7861E/2K5G4 equivalent, key selection criteria include simultaneous dual-channel acquisition timing (≤2µs per channel), bipolar ±2.5V input range referenced to internal 2.5V, 12-bit no-missing-codes performance, and operation across –40°C to +125°C industrial temperature range.

Technical Context

The ADS7861E/2K5G4 implements two independent successive approximation register (SAR) ADCs with matched sample-and-hold amplifiers, enabling true simultaneous sampling of two differential channel pairs (A0/A1 and B0/B1). Its fully differential analog front-end maintains signal integrity through 80dB common-mode rejection up to 50kHz.

Control logic uses three address pins (M0, M1, A0) to configure operation modes: two-channel (A0/B0 or A1/B1), four-channel sequential, and serial output routing (dual-port or single-port A-only). Conversion is initiated by CONVST edge, with BUSY indicating active conversion and RD synchronizing 16-cycle serial data transfer.

Key Specifications

Pinout & Package

ADS7861E/2K5G4 is packaged in SSOP-24 (2.2 mm × 7.9 mm body, 0.635 mm pitch) with exposed thermal pad connected internally to substrate; pin 1 = DGND, pin 12 = AGND, pin 13 = +VA, pin 24 = +VD.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel simultaneous-sampling ADC applications.

Compared with ADS8327IPW and AD7357BRUZ, the ADS7861E/2K5G4 uniquely delivers true simultaneous sampling across two differential pairs with guaranteed <100 ps aperture delay matching - a non-negotiable requirement for field-oriented motor control and multi-axis synchronization.

Availability

ADS7861E/2K5G4 is available at Aetrix Electronics and suitable for motor control, multi-axis positioning systems, and 3-phase power control requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADS7861E/2K5G4 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 leader specializing in analog and embedded processing technologies, with decades of expertise in precision data converters for industrial and automotive applications.

The ADS7861 product line was engineered specifically for high-fidelity, phase-coherent signal acquisition in real-time motion control systems - emphasizing simultaneous sampling, robust noise immunity, and extended temperature reliability.

FAQ

What is the maximum clock frequency required to achieve 500 kSPS operation for ADS7861E/2K5G4?

The ADS7861E/2K5G4 requires an 8 MHz external clock to sustain 500 kSPS per channel, as each 12-bit conversion consumes exactly 16 clock cycles (f_CLK = 16 × f_SAMPLE). Clock frequencies below 8 MHz reduce throughput proportionally; exceeding 8 MHz violates timing specifications and risks conversion errors due to insufficient setup/hold margins on internal logic paths.

Does ADS7861E/2K5G4 support external reference voltage, and what is the valid input range?

Yes, ADS7861E/2K5G4 accepts external reference voltages from 1.2 V to 2.6 V applied to the REFIN pin, scaling the full-scale input range linearly from ±1.2 V to ±2.6 V. When using external reference, the internal 2.5 V buffer is disabled, and REFIN must be low-noise (<10 µV_PP) with adequate current sourcing capability (>2 mA) to maintain 12-bit accuracy across temperature.

How does the M0/M1/A0 pin configuration affect channel selection and data output in ADS7861E/2K5G4?

In ADS7861E/2K5G4, M0=0 selects two-channel mode (A0/B0 or A1/B1 per A0 state); M0=1 enables four-channel sequential mode (A0→A1→B0→B1). M1=0 routes data to both SERIAL DATA A and B ports; M1=1 consolidates both channels onto SERIAL DATA A only, placing SERIAL DATA B in high-impedance state - reducing interface wiring at the cost of doubled serial clock cycles per conversion.

What is the significance of the 80 dB CMRR specification for ADS7861E/2K5G4 in motor control applications?

The 80 dB CMRR at 50 kHz allows ADS7861E/2K5G4 to reject high-frequency common-mode noise generated by IGBT/PWM switching in motor drives, ensuring accurate current sensing without additional isolation or filtering. This directly enables compact, cost-effective shunt-based current measurement in noisy inverter environments where op-amp-based solutions would require complex compensation networks.

Can ADS7861E/2K5G4 operate with a single 5 V supply, and how are analog and digital grounds handled?

Yes, ADS7861E/2K5G4 operates from a single +5 V supply (+VA and +VD both at 4.75–5.25 V). Analog ground (AGND, pin 12) and digital ground (DGND, pin 1) must be connected directly together at the device package - TI specifies ≤0.3 V ground potential difference - to prevent ground-loop induced offset errors while maintaining separation of analog/digital return paths on the PCB.