Silicon Labs TSM971CSA+T

Overview

TSM971CSA+T from Silicon Labs is an ultra-low-power, single-channel analog comparator with integrated 1.182V ±1% reference, open-drain output, and adjustable hysteresis. It operates from +2.5V to +11V single supply or ±1.25V to ±5.5V dual supply, draws ≤4μA max supply current over temperature, and delivers 12μs propagation delay at 10mV overdrive - ideal for battery-powered threshold detection in portable instrumentation.

For engineers reviewing the TSM971CSA+T datasheet, TSM971CSA+T pinout, TSM971CSA+T application, or TSM971CSA+T equivalent, key selection factors include its GND-referenced open-drain output, internal reference accuracy over 0°C to +70°C, hysteresis programmability via HYST pin, and compatibility with MAX971 drop-in replacement requirements in space-constrained 8-pin SOIC layouts.

Technical Context

The TSM971CSA+T implements a micropower rail-to-rail input comparator core with input common-mode range extending from V− to (V+ − 1.3V), enabling direct sensing near ground in single-supply systems. Its open-drain output sinks to GND (not V−), supporting wired-OR logic and level translation between disparate voltage domains.

Internal 1.182V reference is buffered and referenced to V−, sourcing up to 25μA and sinking 15μA, with ±1% initial accuracy over 0°C to +70°C. Hysteresis is added externally using two resistors between REF and HYST pins, generating a user-defined band up to 100mV without requiring feedback across the comparator inputs.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (Small Outline Integrated Circuit), 3.99mm × 4.90mm body, JEDEC MS-012 compliant, lead-free.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX971CSA+, TSM971CSA+T offers identical performance in commercial-temperature applications with Silicon Labs' lead-free packaging assurance; versus TSM971ESA+, it trades extended temperature support for lower cost and qualification scope in consumer-grade portable electronics.

Availability

TSM971CSA+T is available at Aetrix Electronics and suitable for battery-powered instrumentation, portable medical devices, and industrial sensor interfaces requiring stable component supply, long-lifecycle availability, and tape-and-reel delivery for automated assembly.

Supply support for TSM971CSA+T 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

Silicon Labs is a fabless semiconductor company specializing in low-power, mixed-signal ICs for timing, MCU, wireless, and sensor applications.

The TSM971CSA+T belongs to Silicon Labs' TSM97x micropower comparator family, designed specifically for energy-constrained systems where supply current, reference stability, and small footprint are critical - such as wearables, remote sensors, and battery-backed security peripherals.

FAQ

What is the maximum supply voltage rating for TSM971CSA+T?

The absolute maximum supply voltage for TSM971CSA+T is +12V between V+ and V−, or +12V between V+ and GND in single-supply configuration. Operation above +11V is not recommended for reliable long-term performance, as the specified functional range is +2.5V to +11V. Exceeding +12V risks permanent damage per Absolute Maximum Ratings on page 2 of the datasheet. Always maintain ≥0.3V margin below absolute max in production designs using TSM971CSA+T.

Does TSM971CSA+T require an external bypass capacitor on the REF pin?

No, TSM971CSA+T does not require an external bypass capacitor on the REF pin. The internal reference is designed to operate stably without external capacitance, and the datasheet explicitly states "the REF pin is referenced to V− and it should not be bypassed." Adding capacitance may degrade transient response or cause instability. For optimal noise immunity, route the REF trace short and away from noisy signals - but do not add capacitors. This applies strictly to TSM971CSA+T and matches behavior documented in the Theory of Operation section.

Can TSM971CSA+T operate from a 1.8V supply?

No, TSM971CSA+T cannot operate reliably from a 1.8V supply. Its minimum specified supply voltage is +2.5V, and the datasheet confirms that TSM971/972/973/982 "cannot be used with a supply voltage much lower than 2.5V" due to degraded propagation delay and output drive. While TSM984 supports down to 1.5V, TSM971CSA+T lacks that low-voltage optimization. Using 1.8V will result in undefined behavior, including failure to assert output or reference regulation - verify all designs with TSM971CSA+T at ≥2.5V.

What is the purpose of the HYST pin on TSM971CSA+T?

The HYST pin on TSM971CSA+T enables user-programmable hysteresis without external feedback components. By connecting two resistors between REF and HYST (and HYST to V−), designers create a positive feedback path that sets distinct upper and lower trip thresholds - eliminating oscillation near the decision point. The HYST pin accepts voltages from REF down to REF−50mV, allowing hysteresis bands up to 100mV. This feature is exclusive to TSM971CSA+T, TSM973, and TSM982 - and is fully supported in all production revisions of TSM971CSA+T.

Is TSM971CSA+T pin-compatible with MAX971CSA+?

Yes, TSM971CSA+T is fully pin-compatible and functionally equivalent to MAX971CSA+. Both use identical 8-pin SOIC packaging, matching pinout (GND, V−, IN+, IN−, HYST, REF, V+, OUT), and share identical electrical specifications including supply current, propagation delay, reference accuracy, and input voltage range. Silicon Labs explicitly positions the TSM971 series as an "alternate source for MAX971," and the datasheet confirms form-factor and electrical identity - making TSM971CSA+T a verified drop-in replacement for MAX971CSA+ in existing PCB layouts.