OPA828 - 45MHz 36V JFET Op Amp, 4nV Noise | TI
MPN： OPA828 ✓ 啟用中OPA828 概覽
A JFET-input operational amplifier is a linear amplifier IC whose input stage uses junction field-effect transistors, giving it extremely low input bias current (picoampere level) while preserving the voltage-noise performance of a bipolar front end. Within the power management and signal-chain hierarchy, op amps form the core of analog signal conditioning between sensors and data converters.
Key features include 4 nV/Hz input voltage noise density at 1 kHz, only 60 nVRMS of noise from 0.1 Hz to 10 Hz, 50 uV input offset voltage, and 0.45 uV/C offset drift. JFET inputs draw just 1 pA typical bias current, and MUX-friendly inputs simplify multiplexed signal chains. The wide supply range of +/-4 V and above supports 36 V single-supply operation.
Architecturally, the OPA828 pairs a precision JFET input stage with a rail-to-rail output stage, enabling maximum output swing into ADCs and loads on low supply rails. Compared with the OPA627, TI documents wider bandwidth, higher slew rate, and rail-to-rail output as the key upgrade paths (per the TI comparison tool).
Typical applications include photodiode transimpedance amplifiers, precision ADC driver front ends, high-fidelity audio stages, and test-and-measurement signal conditioning where low bias current, low noise, and high speed must coexist.
Design consideration: ensure headroom for the JFET common-mode input range, and decouple supply pins with 0.1 uF ceramics placed within 2 mm; for TIA use, compensate feedback capacitance against input capacitance to preserve phase margin.
直接替換替代品，適用於 OPA828 — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： OPA828 （相同外形與佔位） — 差異在於 Slew Rate, Amplifier Type, Gain Bandwidth Product, Input Bias Current, Input Type.
OPA827
✅ 直接替換聯絡詢價
查看資料表 →OPA627
✅ 直接替換聯絡詢價
查看資料表 →OPA2828
⚡ 相同封裝📋 參考替代品（不在目錄中）
AD8610
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
OPA828 最大額定值與電氣特性
| Amplifier Type | JFET-Input Operational Amplifier (RRO) |
| 通道數 | 1 |
| Gain Bandwidth Product | 45 MHz |
| Slew Rate | 150 V/us |
| Supply Voltage Range | +/-4 V to 36 V (8 V to 36 V single supply) |
| Input Voltage Noise Density | 4 nV/Hz at 1 kHz |
| Input Voltage Noise (0.1 Hz to 10 Hz) | 60 nVRMS |
| Input Bias Current | 1 pA (typical) |
| Input Offset Voltage | 50 uV |
| Input Offset Drift | 0.45 uV/C |
| 輸出類型 | Rail-to-Rail Output (RRO) |
| Input Type | MUX-friendly JFET inputs |
| 封裝 | SOIC-8 (D) / HVSSOP-8 (DGN) |
| 安裝類型 | Surface Mount |
| 工作溫度 | -40C to +125C |
| RoHS 狀態 | Compliant |
| Successor To | OPA627 / OPA827 |
OPA828 腳位配置
| 腳位 1 | TRIM — Offset trim (optional, per package variant) |
| 腳位 2 | IN- — Inverting input |
| 腳位 3 | IN+ — Non-inverting input |
| 腳位 4 | V- — Negative supply |
| 腳位 5 | NC/TRIM — No connect / offset trim per package variant |
| 腳位 6 | OUT — Rail-to-rail output |
| 腳位 7 | V+ — Positive supply |
| 腳位 8 | NC — No connect (DGN: thermal pad under package) |
典型應用
OPA828 適用於 6 應用s: Photodiode Transimpedance Amplifier, Precision ADC Driver, High-Fidelity Audio Signal Chain, Test and Measurement Signal Conditioning, Sensor Interface for Industrial Automation, Active Filter and Buffer Circuits.
Photodiode Transimpedance Amplifier
The OPA828s 1 pA input bias current and 4 nV/Hz noise make it ideal for photodiode TIA front ends, where input current error and voltage noise directly set sensitivity. A feedback resistor (e.g., 1 Mohm) with a small compensation capacitor across Rf maintains phase margin against photodiode junction capacitance. Its 45 MHz bandwidth enables MHz-range optical signal detection; keep feedback node leakage guarded on the PCB.
推薦
Precision ADC Driver
Driving 16-24 bit SAR or delta-sigma ADCs demands fast settling, low noise, and low offset. The OPA828s 150 V/us slew rate and 45 MHz GBW settle quickly between ADC conversions, while 50 uV offset and 0.45 uV/C drift preserve DC accuracy. Its rail-to-rail output maximizes ADC input swing on low supply rails; add an RC filter (e.g., 10-100 ohm + 1 nF) between amplifier and ADC input to absorb charge kickback.
推薦
High-Fidelity Audio Signal Chain
The OPA828s 4 nV/Hz noise, 60 nVRMS 0.1-10 Hz noise, and 150 V/us slew rate deliver low THD+N and fast transient response for DAC I/V conversion, line gain, and headphone-driver gain stages. The wide +/-4 V to 36 V supply range fits standard +/-15 V audio rails. DIY and professional audio communities evaluate it against the OPA627, generally reporting similar tonal character with improved speed.
推薦
Test and Measurement Signal Conditioning
Bench instruments, oscilloscope front ends, and data acquisition systems need amplifiers combining low noise with bandwidth. The OPA828 provides 45 MHz of small-signal bandwidth and MUX-friendly inputs that tolerate fast-switched multiplexed channels without long settling artifacts. Its JFET inputs present high impedance to probes and sensors; ensure supply decoupling of 0.1 uF per pin for wideband stability.
推薦
Sensor Interface for Industrial Automation
High-impedance industrial sensors (piezoelectric, pH, photodetector arrays) benefit from the OPA828s 1 pA bias current and 50 uV offset. The 36 V supply range tolerates industrial supply rails, and MUX-friendly inputs allow several sensors to share one amplifier through an analog multiplexer. Design gain stages with 1% resistors and guard rings to preserve picoampere-level input accuracy in noisy environments.
推薦
Active Filter and Buffer Circuits
The OPA828 builds high-order active low-pass, band-pass, and Sallen-Key filters whose cutoffs reach the MHz range thanks to the 45 MHz GBW, preserving accurate Q at high frequencies. As a buffer, its rail-to-rail output swings close to the rails into ADCs and cables. Watch for unity-gain stability requirements and use the HVSSOP DGN thermal pad variant for lower thermal impedance in dense layouts.
推薦
推薦產品摘要
工程參考資料，適用於 OPA828 — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | OPA827 | OPA627 | AD8610 |
|---|---|---|---|---|
| Package | SOIC-8 (D) / HVSSOP-8 (DGN) | SOIC-8 (D) - same pinout | SOIC-8 (D) - same pinout | SOIC-8 (D) - similar pinout |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Analog Devices |
| Gain Bandwidth | 45 MHz | 22 MHz | 16 MHz | 25 MHz |
| Slew Rate | 150 V/us | ~30 V/us | ~55 V/us | 50 V/us |
| Input Voltage Noise | 4 nV/Hz | 3.8 nV/Hz | 4.5 nV/Hz | 6 nV/Hz |
| Input Bias Current | 1 pA | pA-level JFET | pA-level JFET | 1 pA |
| Input Offset Voltage | 50 uV | ~75 uV | ~100 uV | 100 uV |
| Output Stage | Rail-to-Rail Output | RRO | Non-RRO (EF output) | RRO |
主要差異化特點
- 2x+ bandwidth and 5x slew rate vs predecessor-generation parts (對比OPA827)
- Rail-to-rail output stage (對比OPA627)
- Lower noise than the leading cross-brand JFET alternative (對比AD8610)
設計說明
Decouple V+ and V- with 0.1 uF X7R ceramics placed within 2 mm of each supply pin, plus a 2.2-10 uF bulk capacitor per rail. Guard the inverting input node with a driven or grounded guard ring to preserve the 1 pA bias current advantage, especially on high-value TIA feedback resistors above 1 Mohm.
For transimpedance designs, calculate the feedback compensation capacitor Cf = sqrt(Cin / (2*pi*Rf*GBP)) to maintain 45 degrees of phase margin; with the OPA828s 45 MHz GBW, a 1 Mohm / 10 pF photodiode node typically needs a few tenths of a picofarad of Cf. Do not add stray capacitance at IN- via long traces.
When replacing OPA627 with OPA828, the rail-to-rail output changes output-stage behavior near the rails and the input common-mode range differs; TI E2E thread 1218326 documents a legacy TIA that failed after a simple swap. Validate DC operating point and compensation on the actual PCB, and check that no circuit node relies on the OPA627s emitter-follower output characteristics.
合規資訊
RoHS compliance per TI product page and DigiKey listings. AEC-Q100 status not stated in provided data; the OPA858-Q1 exists for automotive but OPA828 qualification is [DATA_NEEDED: AEC-Q100 qualification status].
