MAX178AEWG - 12-Bit Calibrated ADC, 17ksps, 24-SOIC | Maxim
부품 번호: MAX178AEWG ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $38.38 | $38.38 |
| 10 | $34.54 | $345.40 |
| 100 | $30.7 | $3,070.00 |
| 500 | $27.65 | $13,825.00 |
| 1,000 | $24.85 | $24,850.00 |
MAX178AEWG 개요
An ADC (analog-to-digital converter) is a mixed-signal integrated circuit that samples continuous analog voltages and encodes them into discrete digital codes. The MAX178 family sits within the SAR (Successive Approximation Register) converter category, which uses an internal capacitive DAC and comparator to converge on the input voltage in N clock cycles. SAR ADCs are favored for their deterministic latency, low power consumption, and excellent DC accuracy - characteristics that place them above integrating converters and flash converters for general-purpose precision measurement.
Key features include ±0.5 LSB integral nonlinearity (INL) and ±1 LSB differential nonlinearity (DNL) over the full operating range, an internal 4.096 V reference (Mask A) or external reference option, and an auto-zero cycle on every conversion that reduces zero error to below 100 µV. The device offers three digital-interface modes - 8-bit bus, serial, and stand-alone - selectable via mode pins, and accepts unipolar (0–360 V) or bipolar (±VREF) analog input ranges. The MAX178AEWG carries the commercial 0 °C to +70 °C temperature grade.
Architecturally, the MAX178AEWG employs laser-trimmed thin-film resistors and a chopper-stabilized comparator, combined with on-chip calibration logic that corrects gain and linearity errors at power-up. This self-calibration eliminates the need for external trimpots in production, reducing BOM cost and improving long-term drift performance. Throughput is governed by an internal RC oscillator driving the SAR state machine.
Typical applications include process-control data acquisition front-ends, weigh-scale signal conditioning, panel-meter and digital-voltmeter designs, temperature-measurement systems (with RTD/thermocouple front-ends), and precision transducer interfaces. The bipolar-input capability simplifies signal paths from bridge sensors and shunt current monitors.
When designing with the MAX178AEWG, add 10 µF and 0.1 µF bypass capacitors adjacent to the analog supply pin to keep reference noise below 50 µVrms; a single-point analog ground and a separate digital-ground return are strongly recommended. The internal reference's noise bandwidth scales inversely with the output capacitance, so a larger CREF yields lower noise at the cost of slower power-on settling.
드롭인 대체품: MAX178AEWG — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
이 시리즈의 변형
다음과 드롭인 호환되는 동일 시리즈 모델: MAX178AEWG (동일 폼 팩터 및 풋프린트) — 차이점: Number of Input Channels, Operating Temperature, Package, Resolution, Integral Nonlinearity (INL).
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
MAX178AEWG+
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX178BEWG+
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX178BCWG+
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX178BEWG+T
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
MAX154AEWG
✅ 드롭인✓ 재고 있음
$10.45 / 개
데이터시트 보기 →MAX154BCWG
✅ 드롭인✓ 재고 있음
가격 문의
데이터시트 보기 →MAX178AEWG 최대 정격 & 전기적 특성
| 분해능 | 12 bit |
| Converter Type | SAR (Successive Approximation) |
| Number of Input Channels | 1 |
| 샘플링 속도 | 17 ksps |
| 입력 전압 범위 | 0 V to 4.096 V (unipolar) / ±4.096 V (bipolar) |
| Internal Reference Voltage | 4.096 V (Mask A) |
| Integral Nonlinearity (INL) | ±0.5 LSB (max) |
| Differential Nonlinearity (DNL) | ±1 LSB (max, no missing codes) |
| Zero Error (with auto-zero) | <100 µV |
| Interface Modes | 8-bit parallel bus / serial / stand-alone |
| Conversion Clock | Internal RC (external option available) |
| 동작 온도 | 0 °C to +70 °C (commercial grade) |
| 패키지 | 24-pin SOIC (wide, 7.50 mm body) |
| 실장 유형 | Surface Mount |
| RoHS 상태 | Compliant (suffix '+' denotes Pb-free) |
MAX178AEWG 핀 구성
| 핀 1 | VREF — Reference voltage output / external reference input (4.096 V typ) |
| 핀 2 | REFADJ — Reference adjust (trim input for fine calibration) |
| 핀 3 | AGND — Analog ground return |
| 핀 4 | AIN — Analog input (single-ended) |
| 핀 5 | RBIAS — Bias resistor for internal reference (sets reference current) |
| 핀 6 | BPO — Bipolar offset (sets bipolar input mode) |
| 핀 7 | AVDD — +5 V analog supply |
| 핀 8 | DVDD — +5 V digital supply (can be tied to AVDD) |
| 핀 9 | DGND — Digital ground |
| 핀 10 | MODE — Mode select (8-bit bus / serial / stand-alone) |
| 핀 11 | CS — Chip select (active low) |
| 핀 12 | RD — Read strobe (active low) |
| 핀 13 | HBEN — High-byte enable for parallel output |
| 핀 14 | SSTRB — Serial strobe / status output |
| 핀 15 | D11/MSB — Data bit 11 (MSB) / serial data out |
| 핀 16 | D10 — Data bit 10 |
| 핀 17 | D9 — Data bit 9 |
| 핀 18 | D8 — Data bit 8 |
| 핀 19 | D7 — Data bit 7 |
| 핀 20 | D6 — Data bit 6 |
| 핀 21 | D5 — Data bit 5 |
| 핀 22 | D4 — Data bit 4 |
| 핀 23 | D3/DOUT — Data bit 3 / serial data output |
| 핀 24 | D2/SCLK — Data bit 2 / serial clock input |
일반적인 애플리케이션
MAX178AEWG 적합 용도: 6 애플리케이션s: Process-Control Data Acquisition, Digital Panel Meter and Voltmeter, Weigh-Scale Signal Conditioning, Temperature Measurement Front-End, Precision Transducer Interface, Industrial Control Loop Monitoring.
Process-Control Data Acquisition
The MAX178AEWG's 12-bit resolution and 17 ksps sampling rate suit industrial process-control PLC and DCS modules reading 4–20 mA loop transmitters, thermocouple amplifiers, and RTD signals. With ±0.5 LSB INL and ±1 LSB DNL, the device achieves better than 0.012 % FSR linearity, providing measurement repeatability for batch-control feedback loops. The internal 4.096 V reference aligns naturally with 0–5 V transducer spans, eliminating an external reference IC and reducing BOM count by one. Engineers typically place the MAX178AEWG downstream of an instrumentation amp (e.g., MAX4194) and a 2nd-order Butterworth anti-alias filter with a 5 kHz cutoff (well below the 8.5 kHz Nyquist limit). The internal track-and-hold eliminates external sample-cap design, simplifying PCB layout. For multi-channel systems, an external 8:1 MUX (MAX328) can be front-ended onto the single AIN, expanding channel count without sacrificing linearity.
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Digital Panel Meter and Voltmeter
The MAX178AEWG's 12-bit resolution over 0–4.096 V input delivers exactly 1 mV per LSB, making it ideal for 3.5-digit or 4.5-digit digital panel meters and benchtop DVMs. Auto-zero on every conversion reduces zero error to under 100 µV, eliminating the need for periodic user calibration via front-panel trimpots. The MAX178AEWG supports both parallel 8-bit bus and serial SPI/QSPI-compatible output modes, allowing engineers to interface with legacy 8051 LCD controllers or modern ARM Cortex-M0 displays. Its 5 V single-supply operation simplifies power design in compact handheld instruments. Reference stability over temperature (typically 25 ppm/°C) keeps the display reading accurate across normal indoor operating conditions. Compared with dual-slope integrating ADCs like the ICL7106, the MAX178AEWG offers much faster conversion (60 µs vs 100 ms), enabling continuous tracking meters.
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Weigh-Scale Signal Conditioning
Load-cell based weigh scales typically produce millivolt-level differential signals from a 350 Ω bridge; the MAX178AEWG pairs well with a low-noise instrumentation amp and provides the 12-bit precision needed for commercial scales in the 1–5000 kg range. With 17 ksps throughput, the device can digitize averaged readings faster than mechanical settling times, improving throughput on conveyor-belt checkweighers. The bipolar-input mode (driven by external bipolar-offset circuitry per the datasheet) accepts ±VREF inputs directly from a bridge biased at VREF/2. Internal calibration at power-up eliminates offset/gain trim, simplifying manufacturing. Total unadjusted error is typically below 0.05 % FSR when used with a precision reference, suitable for legal-for-trade 0.1 % accuracy class scales.
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Temperature Measurement Front-End
For RTD, thermocouple, and semiconductor-sensor temperature systems, the MAX178AEWG provides the 12-bit resolution required to resolve 0.1 °C steps across industrial ranges. Thermocouple cold-junction compensation can be implemented by reading a separate temperature sensor (MAX6625) through the same ADC's track-and-hold via an external MUX. The MAX178AEWG's low zero error (<100 µV) eliminates the need for periodic auto-zero routines in firmware, simplifying the MCU code base. Conversion time of ~60 µs allows 10 Hz update rates even when multiplexing four thermocouple channels. RTD excitation currents from a stable source (e.g., MAX6250) combined with a ratiometric reference configuration yield better than 0.1 °C absolute accuracy across 0–500 °C measurement spans.
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Precision Transducer Interface
The MAX178AEWG is well-suited to digitize outputs of precision transducers including strain gauges, pressure sensors, and flow meters that output 0–5 V or 4–20 mA signals. Its 12-bit resolution and 0.5 LSB INL provide sufficient resolution for medical and analytical instrumentation where measurement repeatability is critical. The track-and-hold front-end samples fast-moving signals without slew-rate-induced distortion, making it appropriate for shock and vibration sensor arrays sampling at up to 17 ksps. Internal auto-calibration compensates for gain and offset drift, eliminating annual recalibration cycles typical of uncalibrated ADC designs. When paired with the MAX4475 op-amp family for active signal conditioning, the combined signal chain achieves better than 14-bit effective resolution in typical transducer applications.
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Industrial Control Loop Monitoring
PLC and DCS analog-input modules benefit from the MAX178AEWG's deterministic SAR architecture, which provides fixed-latency conversions essential for synchronized control loops. With 17 ksps throughput, the device digitizes eight channels (via external MUX) at 2 ksps each, comfortably supporting motion-control feedback and PID-process-control applications. The 8-bit parallel interface mode integrates with legacy 8051-based PLC CPUs, while the serial mode connects directly to modern ARM Cortex SPI peripherals. The bipolar-input option handles ±10 V industrial signals (with external resistor dividers) and ±5 V process signals directly. On-chip calibration and reference minimize factory calibration labor, lowering per-module manufacturing cost for high-volume industrial control designs.
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추천 제품 요약
엔지니어링 참조 데이터: MAX178AEWG — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | MAX178AEWG+ | MAX178BEWG+ | MAX178BCWG+ |
|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 24-SOIC (wide, 7.50 mm) | 24-SOIC (wide, 7.50 mm) | 24-SOIC (wide, 7.50 mm) | 24-SOIC (wide, 7.50 mm) |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit |
| Sampling Rate | 17 ksps | 17 ksps | 17 ksps | 17 ksps |
| Internal Reference | 4.096 V (Mask A) | 4.096 V (Mask A) | 2.5 V (Mask B) | 2.5 V (Mask B) |
| Operating Temperature | 0 °C to +70 °C (commercial) | 0 °C to +70 °C (commercial) | 0 °C to +70 °C (commercial) | -40 °C to +85 °C (extended) |
| INL (max) | ±0.5 LSB | ±0.5 LSB | ±0.5 LSB | ±0.5 LSB |
| RoHS Compliance | Pb-free ('+' suffix) | Pb-free / RoHS | Pb-free / RoHS | Pb-free / RoHS |
주요 차별점
- Complete integrated ADC subsystem with on-chip reference and T/H (vs MAX154AEWG)
- Auto-zero on every conversion eliminates periodic calibration (vs MAX178ACNG+ (PDIP-24 through-hole variant))
- Three-interface flexibility (parallel 8-bit / serial / stand-alone) (vs MAX154BCWG (8-bit + 8-channel))
설계 노트
Estimated: separate AVDD and DVDD pins allow local LC/RC filtering of the analog supply, but tying them together at a single point near the IC is acceptable for cost-sensitive designs. Place 10 µF tantalum and 0.1 µF ceramic bypass capacitors directly at AVDD (pin 7) and 0.1 µF at DVDD (pin 8). Analog ground (AGND) and digital ground (DGND) must join at one point - typically the IC's AGND/DGND pin pair - to prevent digital switching currents from flowing through the analog ground reference. A linear LDO (e.g., MAX8887) is recommended over a switching regulator for the AVDD rail.
Keep analog signal traces (AIN, REF, BPO) short and guarded by ground pours on both sides to minimize coupled noise. The MAX178AEWG SOIC-24 wide-body package has standard 1.27 mm (50 mil) lead pitch - match the SOIC-24 land pattern to JEDEC MS-013 to allow drop-in compatibility across the MAX178 family (AEWG, BEWG, BCWG variants). Route digital data lines (D0-D11) on the opposite side of the board from analog traces, and add a ground plane between layers to isolate digital switching transients.
The MAX178AEWG's track-and-hold has a finite acquisition time; place an external op-amp buffer (e.g., MAX4250) directly at the AIN pin if the source impedance exceeds 1 kΩ to avoid gain errors. For bipolar input mode, set BPO at exactly VREF/2 using a low-impedance resistive divider buffered by a precision op-amp; any BPO noise couples 1:1 into the conversion result. Anti-aliasing filter cutoff should be at 70–80 % of Nyquist (≤7 kHz for 17 ksps) and follow the buffer amp. Decouple the REFADJ pin with 0.1 µF to AGND to filter reference noise.
Do not leave MODE, HBEN, or CS floating - these inputs have internal weak pull-ups but external logic control is recommended to avoid mode glitches during power-up. Do not exceed the absolute maximum AVDD of +6.5 V or apply analog input voltages beyond AVDD + 0.3 V, or ESD clamping diodes will forward-conduct and corrupt the conversion. Always issue a calibration cycle after power-up (one extra conversion), or the first reading may carry uncalibrated offset error. When using the external-reference mode, decouple REF with at least 4.7 µF to suppress reference-induced conversion noise.
규정 준수 정보
RoHS/REACH compliance applies to the '+' suffix variant (MAX178AEWG+). Non-'+' variants are legacy Pb-containing parts. AEC-Q100 qualification is not applicable to commercial/industrial-grade ADCs; for automotive-grade ADC requirements, contact Analog Devices separately.
