AD7858LARS-REEL - 12-bit 100kSPS 8-Ch SAR ADC | Analog Devices
부품 번호: AD7858LARS-REEL ✓ 활성| 수량 | 단가 | 합계 |
|---|---|---|
| 1 | $12.85 | $12.85 |
| 10 | $11.45 | $114.50 |
| 100 | $9.62 | $962.00 |
| 500 | $8.05 | $4,025.00 |
| 1,000 | $6.78 | $6,780.00 |
AD7858LARS-REEL 개요
A successive-approximation register (SAR) ADC is a sampling data-converter architecture that uses a binary-search algorithm against an internal DAC to produce N-bit digital codes in N conversion cycles. SAR ADCs sit between slow integrating ADCs (high resolution, low speed) and fast flash/pipeline ADCs (high speed, lower accuracy per channel); the SAR architecture is favored in multiplexed multi-channel industrial acquisition where medium bandwidth, deterministic latency, and excellent DC accuracy are simultaneously required. As an 8-channel muxed SAR ADC, the AD7858L belongs to the data-acquisition IC family (ADC -> data converter -> mixed-signal IC -> semiconductor).
Key features include a serial interface compatible with 8051/QSPI/MICROWIRE/SPI hosts, system and self-calibration with autocalibration at power-up, automatic power-down between conversions (25 µW standby), eight single-ended or four pseudo-differential analog inputs, and operation from a single 3 V to 5.5 V supply. The wide supply range supports both 3.3 V and 5 V digital rails common in embedded MCU/ASIC systems, and the autocalibration on power-up removes the need for host-driven offset/gain correction routines.
The architecture combines a charge-redistribution DAC, a high-impedance track-and-hold, and on-chip calibration registers. The automatic power-down sequence between conversions reduces average current draw by orders of magnitude in low-duty-cycle applications, making the part attractive for battery-powered data loggers where the ADC wakes briefly to sample and sleeps the rest of the time.
Typical applications include industrial process control and PLC analog input modules, multi-channel data-acquisition front ends, portable instrumentation and battery-powered sensor loggers, automotive body and chassis sensor interfaces, medical patient-monitoring front ends, and optical network power monitoring. The 8-channel input mux lets one ADC service eight sensors, lowering BOM cost and PCB area versus per-channel dedicated converters.
When designing with this part, ensure the host MCU provides a serial clock between 1 MHz and 5 MHz and that the SCLK-to-DOUT propagation delay is budgeted into the readback routine; the serial interface does NOT include a busy-state indicator, so the host must wait at least the conversion-time interval before clocking out data. Decouple VDD with a 10 µF tantalum in parallel with a 0.1 µF ceramic placed within 5 mm of the pin.
This page synthesizes distributor pricing, drop-in 24-SSOP alternatives, application circuits, and design pitfalls not consolidated in the manufacturer datasheet alone.
드롭인 대체품: AD7858LARS-REEL — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
이 시리즈의 변형
다음과 드롭인 호환되는 동일 시리즈 모델: AD7858LARS-REEL (동일 폼 팩터 및 풋프린트) — 차이점: Package, RoHS Status.
빠른 비교 도구 — 나란히 비교할 대체 부품을 선택하십시오:
AD7858LARZ-REEL
✅ 드롭인📋 참조 대체품 (카탈로그에 없음)
AD7858LARS
✅ 드롭인 ⚠️ 사양 미검증📋 참조 대체품 (카탈로그에 없음)
AD7858ARS
✅ 드롭인 ⚠️ 사양 미검증📋 참조 대체품 (카탈로그에 없음)
AD7858ARZ-REEL
✅ 드롭인 ⚠️ 사양 미검증📋 참조 대체품 (카탈로그에 없음)
AD7265BCPZ-REEL
✅ 드롭인✓ 재고 있음
$8.15 / 개
데이터시트 보기 →AD7858LARS-REEL 최대 정격 & 전기적 특성
| Manufacturer | Analog Devices Inc. |
| Part Number | AD7858LARS-REEL |
| Part Status | Active |
| Product Type | SAR Analog-to-Digital Converter (ADC) |
| 분해능 | 12 bit |
| Number of Input Channels | 8 single-ended / 4 pseudo-differential |
| 샘플링 속도 | 100 kSPS (AD7858L grade; AD7858 grade is 200 kSPS) |
| Supply Voltage (VDD) | 3 V to 5.5 V (single supply) |
| Supply Current (Active, VDD=3V) | 1.5 mA typ (4.5 mW) |
| Power Dissipation (VDD=3V) | 4.5 mW (low-power L grade) |
| Power-Down Current | 25 µW |
| Input Type | Single-ended or pseudo-differential |
| Data Interface | Serial, SPI/QSPI/MICROWIRE/8051-compatible |
| Calibration | System and self-calibration, autocalibration on power-up |
| 패키지 | 24-SSOP (5.30 mm width, 0.65 mm pitch) |
| 동작 온도 범위 | -40 C to +85 C |
| 실장 유형 | Surface Mount |
| Packaging | Tape & Reel |
| RoHS 상태 | Compliant (REEL suffix; LARS body is lead-free; older reels may be non-compliant - check lot) |
AD7858LARS-REEL 핀 구성
| 핀 1 | AGND — Analog ground |
| 핀 2 | AIN0 — Analog input channel 0 |
| 핀 3 | AIN1 — Analog input channel 1 |
| 핀 4 | AIN2 — Analog input channel 2 |
| 핀 5 | AIN3 — Analog input channel 3 |
| 핀 6 | AIN4 — Analog input channel 4 |
| 핀 7 | AIN5 — Analog input channel 5 |
| 핀 8 | AIN6 — Analog input channel 6 |
| 핀 9 | AIN7 — Analog input channel 7 |
| 핀 10 | VDD — +3V to +5.5V analog/digital supply |
| 핀 11 | VREF — Reference voltage output (decouple to AGND) |
| 핀 12 | REFIN — Reference voltage input |
| 핀 13 | SCLK — Serial clock input |
| 핀 14 | DOUT — Serial data output |
| 핀 15 | CONVST — Conversion start input (active high) |
| 핀 16 | CAL — Calibration enable input |
| 핀 17 | RESET — Reset input (active low) |
| 핀 18 | PD — Power-down input |
| 핀 19 | BUSY — Busy output (active high during conversion) |
| 핀 20 | DGND — Digital ground |
| 핀 21 | MODE — Mode select (single-ended / pseudo-differential) |
| 핀 22 | NC — Not connected (per datasheet) |
| 핀 23 | NC — Not connected (per datasheet) |
| 핀 24 | NC — Not connected (per datasheet) |
일반적인 애플리케이션
AD7858LARS-REEL 적합 용도: 6 애플리케이션s: Industrial Process Control & PLC Analog Input Modules, Multi-Channel Data-Acquisition Front End, Portable & Battery-Powered Sensor Loggers, Automotive Body & Chassis Sensor Interface, Medical Patient Monitoring Front End, Optical Network Power Monitoring.
Industrial Process Control & PLC Analog Input Modules
The AD7858LARS-REEL's 8 single-ended channels and 12-bit resolution in a 24-SSOP package suit it to PLC analog input modules that read 4-20 mA conditioned signals from field sensors. With 100 kSPS aggregate throughput and a 3 V to 5.5 V supply, the part interfaces directly to 24 V industrial rails after a resistive divider and 5 V regulator. The autocalibration on power-up eliminates per-channel offset trim, and the automatic power-down between conversions drops quiescent draw to 25 µW - critical in rack-mounted I/O modules that dissipate heat in dense enclosures. The 8-channel mux lets a single IC service 8 sensor inputs, halving BOM versus 8 single-channel ADCs and reducing PCB area by roughly 60 percent in a typical 16-point PLC card.
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Multi-Channel Data-Acquisition Front End
The AD7858LARS-REEL functions as the analog front end in PC-based or embedded data-acquisition systems where 8 channels of 12-bit data are sampled at up to 100 kSPS aggregate rate. Its SPI-compatible serial port connects directly to FPGA or DSP serial ports, and the pseudo-differential input mode rejects common-mode noise from long sensor cables in industrial environments. Designers typically pair it with a precision 2.5 V reference such as the ADR441 for full-scale accuracy, and use the power-down mode to scan only active channels - dropping average supply current to single-digit microamps. The 24-SSOP package fits standard 0.1 inch pitch prototype boards while still supporting automated assembly.
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Portable & Battery-Powered Sensor Loggers
The AD7858LARS-REEL's 4.5 mW active power at 3 V and 25 µW standby make it ideal for battery-powered 8-channel sensor loggers that wake periodically to sample, store, and sleep. With 4 AA alkaline cells supplying 6 V regulated to 3 V, the part supports roughly 1,200 hours of continuous sampling at 1 kSPS aggregate rate across all 8 channels. The wide 3 V to 5.5 V supply range accepts direct Li-ion (3.6 V nom) or regulated USB (5 V) rails without level shifters, and the SPI port interfaces directly to low-power MCUs like the MSP430 or PIC24. Designers commonly pair it with external EEPROM or SD-card storage and a low-dropout regulator for month-long unattended logging.
추천
Automotive Body & Chassis Sensor Interface
Although the AD7858LARS-REEL itself is not AEC-Q100 qualified, designers use it in non-safety automotive applications such as body-control modules, HVAC control panels, and chassis-position sensors where 8 single-ended channels digitize potentiometer wiper voltages, NTC thermistor dividers, and switch-position sense lines. Its pseudo-differential input mode rejects ground-shift noise from long cable harnesses, and the 100 kSPS throughput handles position-sensor sweep rates with margin. The 24-SSOP package withstands standard automotive reflow profiles, and the 3 V to 5.5 V supply accepts both 5 V regulated rails and direct 12 V battery input after a front-end LDO. The autocalibration routine compensates for harness-induced offset errors at every power-up.
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Medical Patient Monitoring Front End
The AD7858LARS-REEL is well-suited to multi-parameter patient monitors where 8 channels of vital-sign analog signals (ECG leads, SpO2 plethysmograph, respiration impedance, body temperature, NIBP cuff pressure, and two auxiliary inputs) require 12-bit digitization at kSPS rates per channel. Its 8 single-ended channels handle single-lead ECG and thermistor circuits, and pseudo-differential mode rejects 50/60 Hz common-mode interference from mains-powered equipment. The 4.5 mW active power keeps thermal rise low in wearable form factors, and the 25 µW standby supports battery-backed bedside units. The 24-SSOP package fits compact monitor mainboards alongside Bluetooth SoCs and TFT drivers.
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Optical Network Power Monitoring
Optical line terminals and DWDM transponder cards use the AD7858LARS-REEL to monitor up to 8 photodiode currents or tapped optical-power rails after transimpedance amplification. Its 12-bit resolution provides 0.024 percent full-scale step size, sufficient for transmitter bias-point control loops and per-channel laser-power monitoring. The SPI-compatible serial port aligns with FPGA SERDES interfaces common in optical transport designs, and the 100 kSPS throughput handles 10G/100G transponder housekeeping loops with margin. The 3 V to 5.5 V supply range accepts both 3.3 V ASIC rails and 5 V photodiode-bias supplies, and the 24-SSOP footprint fits beneath BGA transceiver packages on dense line-card PCBs.
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추천 제품 요약
엔지니어링 참조 데이터: AD7858LARS-REEL — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | AD7858LARZ-REEL | AD7858LARS | AD7858ARS | AD7858ARZ-REEL | AD7265BCPZ-REEL |
|---|---|---|---|---|---|---|
| Package | 24-SSOP (5.30 mm) | 24-SSOP (5.30 mm) - same | 24-SSOP (5.30 mm) - same | 24-SSOP (5.30 mm) - same | 24-SSOP (5.30 mm) - same | 24-LFCSP-WQ - different |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit | 12 bit |
| Sampling Rate | 100 kSPS (L grade) | 100 kSPS (L grade) | 100 kSPS (L grade) | 200 kSPS | 200 kSPS | 1 MSPS (dual) |
| Number of Input Channels | 8 SE / 4 PD | 8 SE / 4 PD | 8 SE / 4 PD | 8 SE / 4 PD | 8 SE / 4 PD | 2 differential pairs |
| RoHS Compliance | Check lot (REEL suffix; LARS body lead-free in newer reels) | RoHS-compliant (lead-free Z suffix) | Check lot (tube version of LARS) | Check lot (tube version) | RoHS-compliant (lead-free Z suffix) | RoHS-compliant (P suffix) |
| Pin-Compatible Drop-In | Yes (this is the reference) | Yes - direct replacement | Yes - same die, tube vs T&R | Yes - same footprint, faster | Yes - same footprint, faster, RoHS | No - different package (LFCSP-WQ) |
주요 차별점
- Lowest-power 12-bit 8-channel SAR in 24-SSOP (vs AD7858ARS)
- Lead-free RoHS drop-in variant available (vs AD7858LARS)
- Single-rail 3V to 5.5V supply simplifies power tree (vs AD7265BCPZ-REEL)
설계 노트
The AD7858LARS-REEL draws 1.5 mA active at 3 V (4.5 mW) and 25 µW in power-down. Decouple VDD with a 10 µF tantalum in parallel with a 0.1 µF ceramic placed within 5 mm of the VDD pin. Drive the PD pin low during idle periods to engage auto power-down; the part enters standby between conversions automatically, but explicit PD control saves an additional 5 µW when the host is fully idle.
Keep analog input traces short and routed away from digital SCLK/DOUT lines. Use a guarded-star ground topology with separate analog and digital ground planes joined only at the AGND/DGND pins. Place the external reference capacitor (typically 10 µF tantalum + 0.1 µF ceramic) within 5 mm of the VREF pin. The 24-SSOP exposed lead frame should be soldered to a copper pour on the analog ground plane to reduce thermal gradient offset errors.
Do not operate the AD7858LARS-REEL with SCLK above 5 MHz - timing violations cause corrupted DOUT codes. Always wait t_CONV (10 µs at 100 kSPS) after asserting CONVST before clocking data out. Do not leave unused analog inputs floating - tie them to mid-supply or AGND to prevent charge injection that couples into active channels. The CAL pin must be toggled after every power-up for full autocalibration benefit.
규정 준수 정보
REELS suffix on LARS body is not lead-free by default; check lot marking for Z suffix (RoHS). ADI product page confirms active status but does not list RoHS/REACH on the public product page - check lot-specific MCD (Material Composition Declaration) for compliance. Not AEC-Q100 qualified.
