Analog Devices Inc./Maxim Integrated MAX1135BCAP

Overview

The MAX1135BCAP from Maxim Integrated is a 16-bit, 150ksps successive-approximation analog-to-digital converter (ADC) with internal track/hold, input scaling network, and SPI/QSPI/MICROWIRE-compatible serial interface. It operates from a single 3.3V supply, accepts ±2.048V bipolar or 0 to +2.048V unipolar analog inputs, delivers −100dB THD, and features three user-programmable digital outputs for multiplexer or PGA control in industrial I/O modules.

For engineers reviewing the MAX1135BCAP datasheet, MAX1135BCAP pinout, MAX1135BCAP application, or MAX1135BCAP equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts with documented differences, and supply support for volume procurement and BOM continuity.

Technical Context

The MAX1135BCAP implements a capacitive DAC-based SAR architecture with integrated input scaling to map ±2.048V external signals to its internal ADC core while operating from a single 3.3V supply. Its internal track/hold and on-demand software calibration correct offset, gain, and INL errors-guaranteeing ±2.5 LSB INL over temperature.

It supports three serial clock modes: 24-clock short acquisition (150ksps bipolar), 32-clock long acquisition (112ksps), and internal clock mode (7µs conversion time, SSTRB-strobed readout). The device uses a configurable 8-bit control byte to select unipolar/bipolar range, internal/external clock, calibration, power-down, and P0–P2 output states.

Key Specifications

Pinout & Package

MAX1135BCAP is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm pitch, rated for 0°C to +70°C operation. Pin functions are validated per Maxim's official datasheet revision 0 (April 2002).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with ADS8325IPW and AD7682BCPZ, the MAX1135BCAP uniquely integrates input scaling for ±2.048V bipolar operation from a single 3.3V rail, reducing BOM cost and layout area-making it optimal for space- and supply-constrained industrial and portable instrumentation.

Availability

MAX1135BCAP is available at Aetrix Electronics and suitable for industrial process control, medical instrumentation, and portable test equipment requiring stable component supply across extended product lifecycles.

Supply support for MAX1135BCAP 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) designs precision analog and mixed-signal ICs for demanding industrial, medical, and communications applications.

The MAX1135BCAP belongs to Maxim's high-accuracy SAR ADC product line, engineered specifically for single-supply, low-power, high-linearity data acquisition in space-constrained embedded systems.

FAQ

What input voltage ranges does the MAX1135BCAP support?

The MAX1135BCAP supports 0 to +2.048V in unipolar mode and ±2.048V in bipolar mode. These ranges are software-selectable via the UNI/BIP bit in the 8-bit control byte. Unlike the MAX1134BCAP, the MAX1135BCAP is optimized for 2.048V reference systems-its internal scaler is fixed for this voltage, ensuring full-scale accuracy without external resistor networks. The device rejects common-mode noise effectively within these ranges due to its differential input structure and on-chip calibration.

Does the MAX1135BCAP require an external reference voltage?

Yes, the MAX1135BCAP requires an external 2.048V reference connected to the REF pin. The datasheet specifies that REF must be bypassed with a 4.7µF capacitor to AGND, and the reference source must deliver up to 150µA DC load current with ≤10Ω output impedance. Using a different reference voltage scales the full-scale input range proportionally-for example, a 2.5V reference yields ±2.5V bipolar input-but performance metrics like INL and THD are guaranteed only at the specified 2.048V reference per the MAX1135BCAP's characterization.

How does the MAX1135BCAP handle power-down and wake-up?

The MAX1135BCAP offers two power-down methods: hardware shutdown via the SHDN pin (active-low, <20µA current) and software power-down initiated by setting M1=1, M0=0 in the control byte (1.2µA typical). In both modes, register contents-including P0–P2 output states-are retained. Wake-up is immediate: releasing SHDN or issuing a new control byte restores full operation within one conversion cycle. No reset sequence or reinitialization is needed, enabling rapid duty-cycled sampling in battery-powered applications using the MAX1135BCAP.

Can the MAX1135BCAP interface directly with a TMS320 DSP?

Yes, the MAX1135BCAP interfaces directly with Texas Instruments TMS320 family DSPs via its SSTRB (serial strobe) output. In internal clock mode, SSTRB goes low at conversion start and high upon completion-providing a clean, synchronous ready signal for DMA-triggered data reads. In external clock mode, SSTRB pulses high for one SCLK period before MSB output, aligning with TMS320's strobe-synchronized serial port timing. No glue logic or timing adapters are required, and the MAX1135BCAP's 4MHz max SCLK rate meets standard DSP interface speeds.

What is the purpose of the P0, P1, and P2 pins on the MAX1135BCAP?

The P0, P1, and P2 pins on the MAX1135BCAP are user-programmable CMOS push-pull outputs controlled by bits 0–2 of the serial control byte. They retain their last written state-even during hardware or software shutdown-and are initialized to logic low at power-on reset. These outputs are designed to drive address/control lines of external 8-channel analog multiplexers (e.g., ADG708) or gain-setting inputs of programmable-gain amplifiers (e.g., PGA204), eliminating the need for discrete GPIO expanders. Their simultaneous update ensures glitch-free channel switching synchronized with ADC configuration changes.