Analog Devices Inc./Maxim Integrated MAX921CSA+

Overview

The MAX921CSA+ from Maxim Integrated is a single-channel, ultra-low-power comparator with integrated 1.182V ±1% bandgap reference, programmable hysteresis via HYST pin, and TTL/CMOS-compatible output capable of sourcing up to 40mA. It operates from +2.5V to +11V single supply (or ±1.25V to ±5.5V dual supply), features 4μA max quiescent current over 0°C to +70°C, and supports input common-mode range from V− to V+ − 1.3V - ideal for battery-powered threshold detection in portable instrumentation.

For engineers reviewing the MAX921CSA+ datasheet, MAX921CSA+ pinout, MAX921CSA+ application, or MAX921CSA+ equivalent, key selection criteria include its rail-to-rail input capability, internal reference accuracy, hysteresis configurability without external feedback, and guaranteed 12μs propagation delay at 10mV overdrive under 5V operation.

Technical Context

The MAX921CSA+ integrates a precision 1.182V reference referenced to V− (not GND), enabling accurate single-supply thresholding without external components. Its unique output stage eliminates crowbar current during transitions, suppressing supply-line parasitic feedback and improving stability in noisy layouts.

Input leakage is ≤±5nA over temperature, common-mode rejection exceeds 0.1mV/V, and the HYST pin accepts voltages from REF − 50mV to REF - allowing precise, resistor-programmed hysteresis bands up to 100mV. The device maintains functionality down to 2.5V supply but degrades below that voltage.

Key Specifications

Pinout & Package

MAX921CSA+ uses an 8-pin SO (Small Outline) package with exposed pad (RoHS-compliant, JEDEC MS-012AC). Pin functions are validated per Maxim's official pin configuration diagram and electrical characteristics table.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar comparator applications.

Compared with LM393DR and TLV3701IDBVR, the MAX921CSA+ uniquely combines internal 1.182V ±1% reference, HYST-pin hysteresis programming, and 40mA source capability - reducing BOM count and PCB area in space-constrained, battery-operated threshold detectors.

Availability

MAX921CSA+ is available at Aetrix Electronics and suitable for battery-powered systems, threshold detectors, window comparators, and oscillator circuits requiring stable component supply with long-term lifecycle support.

Supply support for MAX921CSA+ 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 power, sensing, and interface applications in industrial, medical, and portable electronics.

The MAX921CSA+ belongs to the MAX921–MAX924 micropower comparator family, engineered specifically for ultra-low-quiescent-current threshold detection in energy-constrained systems where internal reference accuracy and hysteresis simplicity are critical.

FAQ

What is the maximum supply voltage for MAX921CSA+ in single-supply operation?

The MAX921CSA+ supports a single-supply voltage range of +2.5V to +11V. Operation above +11V violates absolute maximum ratings and may cause permanent damage. At +11V, the device maintains specified performance including 4μA max quiescent current and 1.182V reference accuracy - confirmed in Electrical Characteristics tables for C-temp range.

Does MAX921CSA+ require external bypass capacitors on V+ and REF pins?

No external bypass capacitor is required on the REF pin - doing so degrades reference stability and is explicitly prohibited in the datasheet. A 100nF ceramic capacitor on V+ is recommended only if supply impedance is high or leads are long; low-impedance lab supplies typically operate reliably without it. MAX921CSA+'s crowbar-free output minimizes supply noise generation.

Can MAX921CSA+ operate from a ±5V dual supply?

Yes - MAX921CSA+ supports dual supplies from ±1.25V to ±5.5V. When configured with V+ = +5V and V− = −5V, the output swings from +5V to GND (not to −5V), and the internal 1.182V reference remains referenced to V− (−5V), yielding 1.182V above −5V (i.e., −3.818V). This enables bipolar input monitoring while maintaining TTL-compatible output levels.

How is hysteresis programmed on MAX921CSA+ using the HYST pin?

Hysteresis is programmed by connecting two resistors: R1 from REF to HYST, and R2 from HYST to V−. The voltage at HYST sets the hysteresis band (V_HB ≈ 2 × (V_REF − V_HYST)), with maximum V_HB = 100mV. For example, setting V_HYST = REF − 25mV yields ~50mV hysteresis. MAX921CSA+'s HYST pin draws <0.02nA, ensuring minimal loading on the resistor network.

What is the guaranteed input offset voltage for MAX921CSA+ over temperature?

The MAX921CSA+ has a guaranteed input offset voltage of ±10mV over the full 0°C to +70°C commercial temperature range. This specification is measured at V_CM = 2.5V and applies to both IN+ and IN− inputs. The offset contributes directly to threshold uncertainty in precision detection circuits, making it a key parameter for applications requiring sub-20mV accuracy.