Analog Devices Inc. AD7631BCPZ

Overview

AD7631BCPZ from Analog Devices is an 18-bit, 250 kSPS, fully differential successive approximation register (SAR) ADC with programmable input ranges (±10 V, ±5 V, 0–10 V, 0–5 V), internal 5 V reference (3 ppm/°C drift), and dual parallel/serial (SPI/QSPI/MICROWIRE/DSP-compatible) interfaces. It targets high-precision data acquisition in process control, spectrum analysis, and ATE systems where missing-code-free performance and low THD (−112 dB) are critical.

For engineers reviewing the AD7631BCPZ datasheet, AD7631BCPZ pinout, AD7631BCPZ application, or AD7631BCPZ equivalent, key selection criteria include its iCMOS® process enabling ±15 V analog supplies, no pipeline delay, 102.5 dB dynamic range, 73 mW power at full throughput, and 48-lead LFCSP (7 mm × 7 mm) package with exposed pad tied to VEE.

Technical Context

The AD7631BCPZ implements a charge redistribution SAR architecture with integrated error correction, eliminating pipeline latency and guaranteeing deterministic conversion timing (4.0 μs cycle). Its hardware- or serial-configurable input range selection supports four differential voltage spans via MODE[1:0], TEN, and BIPOLAR pins, while the internal reference buffer (REFBUFIN) and temperature sensor (TEMP pin, 1 mV/°C) enable self-calibrated system monitoring.

Dual interface flexibility is achieved through mode-selectable 18-/16-/8-bit parallel bus or master/slave serial operation-supporting both read-during-convert and read-after-convert modes-with configurable SDCLK division (DIVSCLK[1:0]), SYNC polarity (INVSYNC), and clock edge (INVSCLK) for timing robustness across host controllers.

Key Specifications

Pinout & Package

The AD7631BCPZ is housed in a Pb-free, 48-lead LFCSP (7 mm × 7 mm) with exposed thermal pad. The pad must be connected to VEE for optimal thermal performance and EMI suppression, per Analog Devices' layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-resolution SAR ADC applications.

Compared with AD7631BCPZ, AD7641BCPZ trades integrated reference/temperature sensing for 2 extra bits of resolution, while AD7621ASTZ sacrifices programmability and analog flexibility for raw speed-making AD7631BCPZ the balanced choice for mixed-signal systems needing configurability, precision, and embedded intelligence.

Availability

AD7631BCPZ is available at Aetrix Electronics and suitable for process control, high-speed data acquisition, and automated test equipment requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for AD7631BCPZ 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

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with R&D and manufacturing operations worldwide.

The AD7631BCPZ belongs to Analog Devices' PulSAR® family of precision SAR ADCs, designed specifically for applications demanding high DC accuracy, excellent AC performance, and flexible interface options in industrial, instrumentation, and communications infrastructure.

FAQ

What input voltage ranges does the AD7631BCPZ support, and how are they selected?

The AD7631BCPZ supports four differential input ranges: 0 V to 5 V, 0 V to 10 V, ±5 V, and ±10 V. Selection is performed using the hardware pins BIPOLAR and TEN in combination with MODE[1:0]-no software register write is needed. For example, BIPOLAR = high and TEN = high configures the ±10 V range. All ranges maintain full 18-bit resolution and no missing codes, as verified in the AD7631BCPZ datasheet Rev. B, Table 2.

Does the AD7631BCPZ require an external reference, or does it include an internal one?

The AD7631BCPZ includes a 5 V internal reference with typical drift of 3 ppm/°C and a buffered output at the REF pin. When PDREF and PDBUF are driven low, the internal reference and buffer are enabled. When both are high, the internal reference is disabled, allowing use of an external reference up to AVDD + 0.1 V. This dual-mode capability is confirmed in the AD7631BCPZ datasheet Section "INTERNAL REFERENCE" and Figure 1 block diagram.

What is the purpose of the TEMP pin on the AD7631BCPZ, and what is its output characteristic?

The TEMP pin on the AD7631BCPZ provides an analog voltage proportional to die temperature: 311 mV at 25°C with a sensitivity of 1 mV/°C and output resistance of 4.33 kΩ. It is internally calibrated and referenced to AGND, enabling real-time thermal monitoring for gain/offset compensation or system-level thermal management without adding discrete sensors. This specification is documented in the AD7631BCPZ datasheet Rev. B, page 4, "TEMPERATURE PIN" table.

Can the AD7631BCPZ operate in both parallel and serial interface modes simultaneously?

No-the AD7631BCPZ operates in only one interface mode at a time, selected by the MODE[1:0] pins. MODE[1:0] = 00 enables 18-bit parallel mode; 01 and 10 configure 16-bit and 8-bit parallel modes respectively; 11 selects serial mode (SPI/QSPI/MICROWIRE-compatible). Pin functions like D0/OB/2C and D1/A0 repurpose based on this setting, as defined in Table 6 of the AD7631BCPZ datasheet Rev. B.

What is the maximum throughput rate of the AD7631BCPZ, and what determines its minimum conversion time?

The AD7631BCPZ achieves a maximum throughput rate of 250 kSPS, corresponding to a minimum conversion cycle time of 4.0 μs. This timing is fixed by the internal conversion clock and SAR logic-no external clock is required for basic operation. The 4.0 μs value is specified in the AD7631BCPZ datasheet Rev. B, Table 3, "CONVERSION AND RESET" section, under "Time Between Conversions (t2)".