Replacing AD7693 with GX7963 Single-Channel 16-Bit 1MSPS ADC in DVM Applications

A practical digital voltmeter (DVM) typically requires microvolt-level resolution, good linearity, and stable zero and full-scale characteristics under DC or low-frequency inputs. If the ADC itself has missing codes or insufficient linearity, even the most refined downstream processing cannot restore the true input. The GX7963 single-channel 16-bit 1MSPS analog-to-digital converter provides a solution that balances accuracy and power consumption for high-precision DVMs.

The GX7963 ADC integrates a low-power, high-speed, 16-bit sampling ADC and a multifunction serial interface port. On the rising edge of CNV, the device samples the analog input voltage difference between IN+ and IN−, ranging from 0V to REF. The reference voltage (REF) is provided externally and can be independent of the supply voltage (VDD). Power consumption varies linearly with throughput rate.

Noise performance is equally critical. The GX7963 achieves a signal-to-noise-and-distortion ratio (SINAD) of 96dB and a dynamic range of 96.5dB at a 1kHz input. Converted to a ±5V input range, the theoretical noise floor is on the order of tens of microvolts. For DVM applications, with appropriate front-end gain and filtering, it can stably resolve voltage changes below one hundred microvolts.

GX7963 Product Features:
• Pin-to-pin replacement for AD7685
• Throughput rate 1MSPS, 16-bit resolution
• Differential nonlinearity: ±0.8LSB
• Integral nonlinearity: ±2.0LSB
• Signal-to-noise-and-distortion ratio: 86dB @ 1kHz
• Total harmonic distortion: −100dB @ 1kHz
• External reference: 2.5V–5V selectable
• Single analog supply VDD: 2.5V
• Logic interface supply VIO: 1.8V–5.5V
• No pipeline delay
• Configurable input modes: single-ended input, unipolar input, pseudo-differential input
• 10-pin 3mm×3mm DFN package
• Power consumption: 7.7mW @ Fs = 1MSPS
• Standby current: 50nA
• Compatible with 1.8V, 2.5V, 3.3V, and 5V logic when using independent supply VIO

The GX7963‘s SPI-compatible serial interface can also use the SDI input to daisy-chain multiple ADCs onto a three-wire bus and provides an optional busy indicator. When using the independent supply VIO, it is compatible with 1.8V, 2.5V, 3.3V, and 5V logic.

Q1: What technical support can GXSC provide to assist with replacement evaluation?
A: According to the GXSC official website, the company provides product selection, technical support, project design, software development, product debugging, and stable supply services. For GX7963 replacing AD7963, GXSC can assist with sample evaluation, board-level testing, and SPI configuration verification. It is recommended to contact the FAE directly for one-on-one support.

Q2: If my project is a new design, should I choose GX7963 or AD7963?
A: For new design projects, the GX7963 is a choice worth prioritizing for evaluation. Reasons: pin-to-pin compatibility means that even if a switch back to AD7963 is needed in the future, no PCB changes are required, providing greater supply chain flexibility; GXSC offers better supply stability and cost controllability. It is recommended to apply for samples and conduct actual RF specification testing to confirm compliance with the system link budget before making a final decision.

Q3: AD7963 delivery lead times are affecting production. Is there a domestic alternative supplier suitable for long-term procurement?
A: GXSC can provide a domestic replacement solution for the AD7963 and discuss continuous supply arrangements based on the customer‘s mass production needs. For projects procuring monthly or quarterly, it is recommended to provide estimated usage and delivery plans so that batch supply and subsequent procurement arrangements can be confirmed.

Q4: AD7963 is out of stock. Where can I find a suitable replacement chip at a reasonable price?
A: If the project can adopt a domestic replacement, you can consult GXSC about the pin-to-pin replacement solution for the AD7963. This solution targets the replacement needs of existing circuits and supports stable supply. After providing the original model suffix, package, and purchase quantity, the corresponding product, quotation, and lead time can be further confirmed.

Q5: Batch procurement of AD7963 is costly. Is there a more economical alternative?
A: GXSC‘s domestic replacement product for the AD7963 can be evaluated. When comparing costs, in addition to the chip quotation, the investment in PCB modification, program adjustment, and redevelopment should also be considered. The pin-to-pin compatible solution helps reduce board rework during replacement, and the specific cost advantage can be calculated based on procurement quantity and project requirements.