MAX942CUA+T - 80ns High-Speed 3V/5V Comparator | Maxim
부품 번호: MAX942CUA+T ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $3.43 | $3.43 |
| 10 | $3.08 | $30.80 |
| 100 | $2.74 | $274.00 |
| 500 | $2.46 | $1,230.00 |
| 1,000 | $2.19 | $2,190.00 |
MAX942CUA+T 개요
A comparator is an analog decision-making element that compares two input voltages and drives its output to one of two saturated states; it is the 1-bit ADC of the analog domain, often used to translate an analog level into a digital logic edge for a microcontroller, ASIC, or FPGA. Comparators sit in the broader linear IC hierarchy: analog building block -> op-amp/comparator -> high-speed comparator -> rail-to-rail input comparator -> single-supply part. The MAX941/MAX942/MAX944 family from Maxim occupies the 3V/5V rail-to-rail comparator node of that hierarchy and is widely cited as the reference for low-power, fast-responding comparators in commercial-grade designs.
Key features of the MAX942 include a 3 mV typical input offset voltage, 150 nA typical input bias current, 80 ns propagation delay, 3 mA supply current per comparator, push-pull CMOS/TTL-compatible output, and operation from 2.7 V to 5.5 V. It is specified over the 0 °C to +70 °C commercial temperature range in the MAX942CUA+T (uSOP-8) variant and is offered in tape-and-reel packaging with the +T suffix.
The MAX942 uses a standard high-speed comparator architecture with input ESD-protection diodes, a low-offset input stage, and a CMOS push-pull output driver. The rail-to-rail input stage uses an N-channel / P-channel complementary differential pair that switches automatically as the common-mode voltage crosses the mid-supply region, preserving low distortion across the entire input range including 200 mV beyond VCC and GND. The push-pull output swings within millivolts of both rails for direct interfacing to 3V/5V CMOS logic.
Typical applications include window detectors, threshold detectors, zero-crossing detectors, A/D front-ends, and line receivers in portable, industrial, and instrumentation equipment. Because the inputs remain linear 200 mV beyond both rails, the MAX942 is well suited to monitor a 5 V rail with a 5.5 V reference or to sense signals near ground with a single-supply design.
When designing with this part, observe the absolute-maximum input current limit on the input ESD diodes and add a series resistor if a large overdrive is expected. The push-pull output cannot be wire-ORed with other open-drain outputs - if a shared interrupt line is needed, choose the open-drain MAX941 instead.
드롭인 대체품: MAX942CUA+T — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
MAX942CUA+
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX942ESA+
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX941EUA+T
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX943EUA+T
✅ 드롭인 ⚠️ 사양 미검증📋 참조 대체품 (카탈로그에 없음)
TLV3201AIDCKT
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
TS331ILT
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX942CUA+T 최대 정격 & 전기적 특성
| Number of Comparators | 1 |
| Comparator Type | General Purpose |
| 출력 유형 | CMOS, Push-Pull, TTL |
| Propagation Delay | 80 ns |
| Input Offset Voltage (typical) | 3 mV |
| Input Bias Current (typical) | 150 nA |
| Supply Current per Comparator | 3 mA |
| Supply Voltage Range | 2.7 V to 5.5 V |
| Input Common-Mode Range | Rail-to-rail (extends 200 mV beyond rails) |
| 동작 온도 범위 | 0 C to +70 C |
| 패키지 | uMAX / uSOP-8 |
| 실장 유형 | Surface Mount |
| Packaging | Tape & Reel |
| RoHS 상태 | Compliant |
| 핀 수 | 8 |
MAX942CUA+T 핀 구성
| 핀 1 | OUT — Comparator output (push-pull CMOS/TTL) |
| 핀 2 | IN1- — Inverting input |
| 핀 3 | IN1+ — Non-inverting input |
| 핀 4 | VEE — Negative supply (ground) |
| 핀 5 | NC — Not connected (per datasheet) |
| 핀 6 | VCC — Positive supply (2.7 V to 5.5 V) |
| 핀 7 | NC — Not connected (per datasheet) |
| 핀 8 | NC — Not connected (per datasheet) |
일반적인 애플리케이션
MAX942CUA+T 적합 용도: 7 애플리케이션s: Threshold / Window Detector, Zero-Crossing Detector, A/D Converter Front-End, Line Receiver / Signal Conditioning, Battery Voltage Monitor, Oscillator / Crystal-Less Clock Source, Industrial Sensor Interface.
Threshold / Window Detector
The MAX942CUA+T is well suited as a single-channel threshold or window detector in 3.3V / 5V supervisory circuits. Its 80 ns propagation delay allows detection of fast transients on power rails, and the rail-to-rail input that extends 200 mV beyond the rails simplifies over-voltage sensing on a 5 V rail without a precision attenuator. Two MAX942s can be wired as a window comparator to assert a fault when a monitored supply drifts outside a programmed band. Place the device close to the sense node, use 100 nF ceramic bypass on VCC, and add a small hysteresis resistor (typically 100 kohm to 1 Mohm) to prevent output chatter near the threshold.
추천
Zero-Crossing Detector
The MAX942CUA+T's 80 ns propagation delay and rail-to-rail inputs make it appropriate for zero-crossing detection on AC mains or audio signals after attenuation. With the input biased at VCC/2 by a resistor divider, the comparator switches as the AC signal crosses mid-supply and produces a clean 0 V / 5 V logic edge for a microcontroller timer capture or TRIAC firing circuit. The push-pull output drives a CMOS logic input directly without a pull-up resistor. Add a series resistor at the input (typically 10 kohm) to limit fault current if the AC signal source exceeds VCC by more than 200 mV.
추천
A/D Converter Front-End
In a successive-approximation A/D converter front-end, the MAX942CUA+T acts as a fast pre-comparator that resolves a coarse bit before the precision SAR comparator latches the final value. The 80 ns delay limits the maximum input slew to a few V/us, but for low-frequency industrial sensors (RTD, strain gauge, thermocouple excitation) this is far above the signal bandwidth. The push-pull CMOS output can drive the SAR latch directly without an external buffer. Power the MAX942 from the same 5 V analog rail as the A/D converter and decouple VCC with 100 nF + 10 uF ceramic capacitors.
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Line Receiver / Signal Conditioning
The MAX942CUA+T functions as a single-ended line receiver that converts a small differential or attenuated analog signal into a clean logic-level edge for a UART, RS-232, or RS-485 transceiver. The 3 mV typical input offset and rail-to-rail input range allow direct interfacing to 0 V to 5 V analog signals without pre-conditioning. The 80 ns propagation delay is sufficient for signaling rates up to several megabaud. Use a 100 kohm feedback resistor for hysteresis to prevent output chatter on slow rising signals.
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Battery Voltage Monitor
In portable battery-powered equipment (single-cell Li-ion, 2x AA, USB-powered), the MAX942CUA+T operates from 2.7 V to 5.5 V and consumes only 3 mA, making it practical for periodic battery-voltage checks invoked by a microcontroller. Its rail-to-rail input allows direct sensing of a battery voltage up to VCC plus 200 mV, useful for over-voltage detection on charging rails. The push-pull output drives an MCU interrupt or GPIO directly. Use a low-power variant such as MAX9028 for always-on monitoring and reserve the MAX942 for active-mode sampling.
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Oscillator / Crystal-Less Clock Source
The MAX942CUA+T can be wired as a relaxation oscillator using its open-loop comparator behavior with an RC network, providing a low-cost clock source for microcontrollers or timers where crystal accuracy is not required. The 80 ns propagation delay and 3 mA supply current set the upper frequency around 1 MHz for typical RC values. The push-pull output drives a CMOS logic clock input directly. For applications requiring tighter frequency tolerance, replace the RC network with a ceramic resonator or external crystal oscillator.
추천
Industrial Sensor Interface
In industrial 4-20 mA loop and 0-10 V sensor interfaces, the MAX942CUA+T detects when an analog sensor signal crosses a programmed threshold (over-range, under-range, or fault condition) and drives a logic-level interrupt to a PLC or MCU. The 0 C to +70 C commercial temperature range suits indoor cabinet installations; for outdoor or extended-temperature deployments, use the MAX942MJA (CERDIP, military temp) or upgrade to the automotive MAX9032. The push-pull CMOS output interfaces directly to 3.3V / 5V PLC digital inputs. Add a TVS diode at the input for surge protection on long sensor cables.
추천
추천 제품 요약
엔지니어링 참조 데이터: MAX942CUA+T — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | MAX942CUA+ | MAX941EUA+T | MAX942ESA+ | TLV3201AIDCKT | TS331ILT |
|---|---|---|---|---|---|---|
| Package | uMAX-8 (uSOP) | uMAX-8 - same | uMAX-8 - same | SOIC-8 - different | uSOP-8 (DCK) - same | SOT-23-5 / uSOP-8 option |
| Brand | Analog Devices (formerly Maxim Integrated) | Analog Devices | Analog Devices | Analog Devices | Texas Instruments | STMicroelectronics |
| Number of Comparators | 1 | 1 | 1 | 1 | 1 | 1 |
| Propagation Delay | 80 ns | 80 ns | 80 ns | 80 ns | 40 ns (faster) | 500 ns (slower) |
| Input Offset Voltage (typ) | 3 mV | 3 mV | 3 mV | 3 mV | 1 mV (better) | 1.5 mV (better) |
| Supply Current per Comparator | 3 mA | 3 mA | 3 mA | 3 mA | 1.8 mA (lower) | 0.02 mA (much lower) |
| Supply Voltage Range | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2.7 V to 5.5 V | 2 V to 5.5 V |
| Output Type | CMOS push-pull / TTL | CMOS push-pull / TTL | Open-drain (requires pull-up) | CMOS push-pull / TTL | Push-pull CMOS | Push-pull CMOS |
| Rail-to-Rail Inputs | Yes (extends 200 mV beyond rails) | Yes | Yes | Yes | Yes | No (VCC - 1.5 V common-mode limit) |
| Operating Temperature | 0 C to +70 C | 0 C to +70 C | 0 C to +70 C | -40 C to +85 C | -40 C to +125 C | -40 C to +125 C |
주요 차별점
- Push-pull CMOS output eliminates the external pull-up resistor required by open-drain comparators like the MAX941 (vs MAX941EUA+T)
- Rail-to-rail inputs extend 200 mV beyond both rails, enabling direct sensing of voltages slightly above VCC or below GND (vs TS331ILT)
- Faster 80 ns propagation delay compared with general-purpose CMOS comparators in the same uSOP-8 footprint (vs TS331ILT)
- Wider 2.7 V to 5.5 V supply range supports both 3.3V and 5V systems from a single part number (vs TLV3201AIDCKT)
설계 노트
Bypass VCC (pin 4 in the uMAX package) with a 100 nF ceramic capacitor placed within 5 mm of the pin, plus a bulk 1 uF to 10 uF electrolytic or ceramic capacitor if the comparator shares a rail with noisy digital circuitry. The MAX942 draws 3 mA typical per comparator and additional dynamic current during output transitions; insufficient bypassing will manifest as output chatter or false triggering on the input. Estimated: dynamic current peaks of 5-10 mA during fast output edges can couple into VCC if bypass impedance exceeds 1 ohm at 10 MHz.
Keep input traces short and avoid routing them parallel to fast-switching digital traces or the comparator output pin. Add a 10 kohm series resistor at each input if the source can drive more than 200 mV beyond the rail, to limit fault current through the input ESD diodes (absolute maximum 20 mA). For high-impedance source designs, add a 10 Mohm bleed resistor from each input to ground to prevent charge accumulation when the source is high-impedance or floating.
Do not wire-OR the MAX942's push-pull output with another open-drain output - the two drivers will fight and draw large short-circuit currents. If a shared interrupt or comparator bus is required, use the open-drain MAX941EUA+T instead, or add a series resistor in the MAX942 output (typically 100 ohm to 1 kohm) to limit cross-conduction current. Also note: the MAX942 inputs extend 200 mV beyond the rails, but the ESD diodes clamp at roughly 0.7 V beyond the rail - always add a series resistor when overdrive exceeds this 200 mV linear range.
For sub-microsecond input edges, add 1 to 10 mV of hysteresis via a 1 Mohm to 10 Mohm positive-feedback resistor from the output to the non-inverting input. Without hysteresis, the MAX942's 3 mV typical input offset combined with board noise can cause output chatter on slow-moving signals near the threshold. Estimate: a 1 Mohm feedback resistor with a 100 kohm source impedance gives roughly 5 mV of hysteresis, enough to suppress 50 Hz / 60 Hz line noise pickup on threshold-detect inputs.
규정 준수 정보
RoHS compliant per DigiKey and Mouser product listings. Commercial-grade part (0 C to +70 C), not AEC-Q100 qualified - choose the MAX9032 for automotive applications. Lead-free reflow compatible. Halogen-free status not explicitly listed in the verified distributor data and is marked unknown.
