AD7858LARS-REEL - 12-bit 100kSPS 8-Ch SAR ADC | Analog Devices
MPN: AD7858LARS-REEL ✓ فعالAD7858LARS-REEL جائزہ
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.
کے لیے ڈراپ اِن متبادل AD7858LARS-REEL — یکساں پیکیج، پن سے پن مطابقت پذیر۔ مختلف پیکیج والے پرزے جن کے لیے PCB دوبارہ کام درکار ہو، شامل نہیں ہیں۔
اس سیریز میں مختلف ورژن
اسی سیریز کے ماڈلز جو ڈراپ اِن مطابقت رکھتے ہیں AD7858LARS-REEL (یکساں فارم فیکٹر اور فٹ پرنٹ) — میں مختلف Package, RoHS Status.
AD7858LARZ-REEL
✅ ڈراپ-اِن📋 حوالہ جاتی متبادل (کیٹلاگ میں نہیں)
AD7858LARS
✅ ڈراپ-اِن ⚠️ تفصیلات غیر تصدیق شدہ📋 حوالہ جاتی متبادل (کیٹلاگ میں نہیں)
AD7858ARS
✅ ڈراپ-اِن ⚠️ تفصیلات غیر تصدیق شدہ📋 حوالہ جاتی متبادل (کیٹلاگ میں نہیں)
AD7858ARZ-REEL
✅ ڈراپ-اِن ⚠️ تفصیلات غیر تصدیق شدہ📋 حوالہ جاتی متبادل (کیٹلاگ میں نہیں)
AD7265BCPZ-REEL
✅ ڈراپ-اِنقیمت کے لیے رابطہ کریں
ڈیٹا شیٹ دیکھیں →AD7858LARS-REEL زیادہ سے زیادہ ریٹنگز اور برقی خصوصیات
| Manufacturer | Analog Devices Inc. |
| Part Number | AD7858LARS-REEL |
| Part Status | Active |
| Product Type | SAR Analog-to-Digital Converter (ADC) |
| ریزولوشن | 12 bit |
| Number of Input Channels | 8 single-ended / 4 pseudo-differential |
| سیمپلنگ ریٹ | 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 |
| پیکیج | 24-SSOP (5.30 mm width, 0.65 mm pitch) |
| آپریٹنگ درجہ حرارت رینج | -40 C to +85 C |
| ماؤنٹنگ ٹائپ | Surface Mount |
| Packaging | Tape & Reel |
| RoHS اسٹیٹس | Compliant (REEL suffix; LARS body is lead-free; older reels may be non-compliant - check lot) |
AD7858LARS-REEL پن کنفیگریشن
| پن 1 | AGND — Analog ground |
| پن 2 | AIN0 — Analog input channel 0 |
| پن 3 | AIN1 — Analog input channel 1 |
| پن 4 | AIN2 — Analog input channel 2 |
| پن 5 | AIN3 — Analog input channel 3 |
| پن 6 | AIN4 — Analog input channel 4 |
| پن 7 | AIN5 — Analog input channel 5 |
| پن 8 | AIN6 — Analog input channel 6 |
| پن 9 | AIN7 — Analog input channel 7 |
| پن 10 | VDD — +3V to +5.5V analog/digital supply |
| پن 11 | VREF — Reference voltage output (decouple to AGND) |
| پن 12 | REFIN — Reference voltage input |
| پن 13 | SCLK — Serial clock input |
| پن 14 | DOUT — Serial data output |
| پن 15 | CONVST — Conversion start input (active high) |
| پن 16 | CAL — Calibration enable input |
| پن 17 | RESET — Reset input (active low) |
| پن 18 | PD — Power-down input |
| پن 19 | BUSY — Busy output (active high during conversion) |
| پن 20 | DGND — Digital ground |
| پن 21 | MODE — Mode select (single-ended / pseudo-differential) |
| پن 22 | NC — Not connected (per datasheet) |
| پن 23 | NC — Not connected (per datasheet) |
| پن 24 | NC — Not connected (per datasheet) |
عام استعمالات
AD7858LARS-REEL کے لیے موزوں ہے 6 ایپلیکیشنs: 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.
تجویز کردہ
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.
تجویز کردہ
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.
تجویز کردہ
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.
تجویز کردہ
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.
تجویز کردہ
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.
تجویز کردہ
تجویز کردہ پروڈکٹس کا خلاصہ
کے لیے انجینئرنگ ریفرنس ڈیٹا AD7858LARS-REEL — موازنہ، ڈیزائن رہنمائی، اور تعمیل کی معلومات۔
انتخاب کی گائیڈ
متبادلات کے ساتھ موازنہ
| پیرامیٹر | یہ پروڈکٹ | 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) |
اہم امتیازی خصوصیات
- Lowest-power 12-bit 8-channel SAR in 24-SSOP (بمقابلہAD7858ARS)
- Lead-free RoHS drop-in variant available (بمقابلہAD7858LARS)
- Single-rail 3V to 5.5V supply simplifies power tree (بمقابلہAD7265BCPZ-REEL)
ڈیزائن نوٹس
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.
تعمیل کی معلومات
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.
