Analog Devices Inc./Maxim Integrated MAX145BCPA+

Overview

MAX145BCPA+ from Maxim Integrated is a 12-bit pseudo-differential successive-approximation analog-to-digital converter (ADC) operating from +2.7V to +5.25V, delivering 108ksps sampling rate, ±1 LSB INL, and 0.2µA shutdown current in an 8-pin plastic DIP package. It integrates track/hold, on-chip clock, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface for compact, low-power data acquisition.

For engineers reviewing the MAX145BCPA+ datasheet, MAX145BCPA+ pinout, MAX145BCPA+ application, or MAX145BCPA+ equivalent, this page delivers verified electrical specs, real-world timing behavior, package-specific thermal derating, true pseudo-differential input constraints, and validated alternative options for battery-powered instrumentation and isolated sensing systems.

Technical Context

The MAX145BCPA+ implements a SAR architecture with integrated track-and-hold, where CH0 serves as pseudo-differential positive input (CH+) and CH1 as negative input (CH−), requiring CH− stability within ±0.5 LSB relative to GND during conversion. Its internal clock operates at ~2MHz (±20%), enabling external clock-free operation below 100kHz or above 2.17MHz.

Conversion is initiated by CS/SHDN falling edge, with acquisition time tACQ = 7.4µs and wake-up latency of 2.5µs from shutdown. The 3-wire serial interface outputs 16-bit frames - three leading '1's, channel ID bit, then 12 MSB-first data bits - with DOUT valid on SCLK falling edge and high-impedance when CS/SHDN is high.

Key Specifications

Pinout & Package

MAX145BCPA+ is housed in an 8-pin plastic DIP (dual in-line package) with 0.3-inch body width and through-hole mounting. Thermal derating is 9.09mW/°C above +70°C; max continuous power dissipation at TA = +70°C is 727mW.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit pseudo-differential SAR ADC applications.

Compared with ADS7816U and AD7476AARMZ, the MAX145BCPA+ uniquely combines pseudo-differential input capability, integrated track/hold, automatic shutdown, and DIP packaging-making it the only option among the three suitable for legacy-replacement, isolated, or battery-operated dual-input sensing without redesigning signal chain or layout.

Availability

MAX145BCPA+ is available at Aetrix Electronics and suitable for battery-powered data loggers, isolated industrial sensors, portable medical instrumentation, and process-control monitoring systems requiring stable component supply, long-lifecycle support, and through-hole manufacturability.

Supply support for MAX145BCPA+ 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 high-performance analog, mixed-signal, and power-management ICs for industrial, medical, and communications applications.

The MAX144/MAX145 product line was designed for ultra-low-power, space-constrained data acquisition systems requiring 12-bit accuracy, serial interface simplicity, and robust operation across extended temperature ranges.

FAQ

What is the input configuration supported by the MAX145BCPA+?

The MAX145BCPA+ supports pseudo-differential analog input: CH0 functions as CH+ (positive input) and CH1 as CH− (negative input). During conversion, only the voltage at CH+ is sampled, but CH− must remain stable within ±0.5 LSB relative to GND. This differs from true differential ADCs and requires careful grounding and decoupling of CH−, typically with a 0.1µF capacitor to GND.

Does the MAX145BCPA+ include an internal reference voltage?

No, the MAX145BCPA+ does not include an internal reference. It requires an external reference voltage applied to the REF pin, which sets the full-scale input range (0 to VREF). The device specifies minimum REF input resistance of 18kΩ and recommends a low-impedance (<10Ω) reference source capable of supplying 250µA during conversion, with a 0.1µF bypass capacitor placed directly at the REF pin.

How does the MAX145BCPA+ enter and exit shutdown mode?

The MAX145BCPA+ enters shutdown automatically when CS/SHDN is driven high (to VDD), reducing supply current to ≤0.2µA. It exits shutdown on the falling edge of CS/SHDN, with a guaranteed wake-up time of 2.5µs - provided the external reference is stable to within 1 LSB. If the reference is unstable, additional delay must be added before initiating conversion to allow reference settling.

What serial interface standards is the MAX145BCPA+ compatible with?

The MAX145BCPA+ is fully compatible with SPI, QSPI, and MICROWIRE serial interfaces. It operates with CPOL = 0 and CPHA = 0, outputs data on the SCLK falling edge, and expects input sampling on the rising edge. The 16-bit frame format includes three leading '1's, a channel ID bit, and 12 MSB-first data bits - matching standard microcontroller SPI peripheral timing requirements without modification.

Can the MAX145BCPA+ operate with a 3.3V supply and still achieve full 12-bit performance?

Yes, the MAX145BCPA+ is fully specified from +2.7V to +5.25V. At +3.3V supply, it maintains ±1 LSB INL, 108ksps sampling rate, and all dynamic specifications (SINAD = 70dB, SFDR = 80dB at 10kHz) per the datasheet. Power consumption scales linearly: typical IDD is 1.1mA at 108ksps and +3.3V, and shutdown current remains ≤0.2µA regardless of supply voltage.