Analog Devices Inc./Maxim Integrated MX7705EPE+

Overview

MX7705EPE+ from Maxim Integrated is a 16-bit, low-power, 2-channel sigma-delta analog-to-digital converter with on-chip PGA (gain 1–128), internal input buffer, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface. It delivers ±0.003% FSR INL, 650nV RMS noise (typ), and 150dB common-mode 50/60Hz rejection - ideal for precision weigh scales and strain-gauge measurements in industrial instrumentation.

For engineers reviewing the MX7705EPE+ datasheet, MX7705EPE+ pinout, MX7705EPE+ application, or MX7705EPE+ equivalent, key selection criteria include its dual fully differential input channels, software- and pin-compatibility with AD7705, single-supply operation (2.7V–5.25V), 320µA typical supply current at 3V, and programmable digital filter notch frequencies (20Hz–500Hz) for high-rejection AC line noise suppression.

Technical Context

The MX7705EPE+ employs a second-order sigma-delta modulator followed by a programmable digital filter that sets output data rate and first-notch frequency (20Hz–500Hz), enabling precise rejection of 50Hz/60Hz interference in both common-mode (150dB) and normal-mode (98dB). Its on-chip PGA supports gain settings from 1 to 128, allowing direct digitization of low-level transducer outputs without external amplification.

Calibration is supported via self-calibration and system calibration modes, correcting gain and offset errors across temperature and supply voltage variations. The device operates in buffered or unbuffered analog input mode, with internal input buffers enabling use with high-impedance sensors (e.g., RTDs, thermocouples) while maintaining ±0.003% FSR integral nonlinearity and no missing codes.

Key Specifications

Pinout & Package

The MX7705EPE+ is housed in a 16-pin PDIP package (0.300" wide), suitable for through-hole prototyping and legacy industrial PCBs. Pin spacing is 0.1" (2.54mm), compatible with standard DIP sockets and breadboards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar sigma-delta ADC applications.

Compared with AD7705BNZ, MX7705EPE+ offers lower power and integrated buffering for high-impedance sensors; compared with ADS124S08IPWR, it provides drop-in AD7705 compatibility and simpler reference design at 16-bit resolution - making MX7705EPE+ optimal for cost-sensitive, power-constrained industrial upgrades.

Availability

MX7705EPE+ is available at Aetrix Electronics and suitable for industrial instrumentation, weigh scales, and loop-powered systems requiring stable component supply, RoHS-compliant through-hole packaging, and long-term obsolescence management.

Supply support for MX7705EPE+ 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

Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in precision analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.

The MX7705 product line targets low-power, high-accuracy measurement systems requiring integrated signal conditioning - designed specifically for industrial sensors, weigh scales, and portable instrumentation where size, power, and noise immunity are critical.

FAQ

What is the operating supply voltage range for the MX7705EPE+?

The MX7705EPE+ operates from a single supply voltage ranging from 2.7V to 5.25V. This dual-voltage capability supports both 3V and 5V system designs without level-shifting. At 3V, typical supply current is 320µA; at 5V, it rises to 450µA (typ) depending on PGA gain and clock configuration. Absolute maximum rating is 6V.

Does the MX7705EPE+ require an external crystal or can it use an external clock source?

Yes, the MX7705EPE+ supports both configurations: a 2.4576MHz crystal/resonator can be connected between CLKIN and CLKOUT, or an external CMOS-compatible clock signal can be applied directly to CLKIN with CLKOUT left unconnected. The device accepts clock frequencies from 400kHz to 2.5MHz, and the CLKDIV bit allows division for lower effective rates.

How does the MX7705EPE+ achieve 150dB rejection of 50Hz/60Hz noise?

The MX7705EPE+ achieves 150dB common-mode 50Hz/60Hz rejection through its programmable digital filter, which places the first notch frequency precisely at 25Hz (for 50Hz rejection) or 20Hz (for 60Hz rejection). This architecture suppresses line-frequency interference before digitization, eliminating the need for external analog notch filters or complex software post-processing in the MX7705EPE+ design.

Is the MX7705EPE+ pin-compatible with the AD7705, and what does that mean for my existing design?

Yes, the MX7705EPE+ is fully pin-compatible and software-compatible with the AD7705. That means the MX7705EPE+ can replace the AD7705 on the same PCB footprint with identical connections and register-level commands - no layout changes, firmware modifications, or timing adjustments are required. This enables seamless second-sourcing and obsolescence mitigation.

What is the purpose of the internal input buffer in the MX7705EPE+, and when should it be enabled?

The internal input buffer in the MX7705EPE+ isolates high-impedance analog sources (e.g., RTDs, thermocouples, or bridge sensors) from the sampling capacitor's capacitive load, preventing gain error and settling-time degradation. It should be enabled (via BUF bit in Setup Register) when source impedance exceeds ~1kΩ or when measuring low-level signals where signal integrity is critical - especially in buffered mode, INL remains ±0.003% FSR.