ADS7834P - 12-Bit 500 kSPS SAR ADC with 2.5V Reference | Texas Instruments
부품 번호: ADS7834P ✓ 활성ADS7834P 개요
A SAR ADC is a class of analog-to-digital converter that compares the unknown input voltage against an internal DAC and a comparator, bit by bit, on each clock cycle. Unlike a sigma-delta or pipeline converter, a SAR converter needs no continuous internal oscillator and no oversampling, which makes its behaviour deterministic and its digital output easy to filter in the time domain. In the hierarchy of signal-chain devices, the ADS7834P sits under ADC, then data converter, then signal-chain IC, then semiconductor.
Key features of the ADS7834P include 12-bit resolution with a 500 kSPS sampling rate, a fully differential-free unipolar 0 V to VREF input range, an on-chip 2.5 V reference that can be bypassed or used to drive external circuitry, a low-power shutdown mode, and a simple synchronous serial (SPI-compatible) data interface with a chip-select line that holds the output in a high-impedance state. The internal reference eliminates the need for an external reference IC in most designs, reducing board area and cost.
The device uses a charge-redistribution DAC array and a comparator-based SAR control loop, so each conversion is a fixed sequence of clock cycles and the acquisition time is deterministic. Because the reference voltage defines the full-scale range, accuracy is directly tied to the reference quality: the 2.5 V internal reference tolerance and temperature drift set the absolute accuracy of every converted code. Because the analog front end is a switched-capacitor network, the source impedance at the AIN pin must be kept low enough for the sampling capacitor to settle within the acquisition window.
Typical applications include industrial process monitoring, thermocouple and RTD signal conditioning front ends, battery and power-supply telemetry, portable instrumentation, and low-cost data acquisition systems where a serial interface and through-hole package simplify assembly and prototyping.
When designing around the ADS7834P, keep the analog trace from the sensor to the AIN pin short and shield it from digital switching lines, place the reference bypass capacitor close to the REFOUT pin, and treat the analog and digital return currents as separate paths that join only at the device ground pin. If higher resolution is required, more channels are needed, or the design cannot accept a serial interface, a different converter family will be a better fit than this part.
This page combines manufacturer specifications, drop-in replacement options, parameter-by-parameter comparisons, and practical PCB and signal-integrity guidance that engineers can apply directly when qualifying the ADS7834P for a new design.
드롭인 대체품: ADS7834P — 동일 패키지, 핀 호환. PCB 재작업이 필요한 다른 패키지 부품은 제외됩니다.
ADS7822IP
✅ 드롭인 ⚠️ 사양 미검증📋 참조 대체품 (카탈로그에 없음)
ADS7834P 최대 정격 & 전기적 특성
| 분해능 | 12 bit |
| 샘플링 속도 | 500 kSPS |
| Converter Architecture | Successive-approximation (SAR), single channel |
| Input Range | 0 V to VREF (unipolar) |
| Internal Reference Voltage | 2.5 V |
| External Reference Option | Yes, internal reference can be bypassed |
| 인터페이스 | Synchronous serial (SPI-compatible), with chip select |
| Power Dissipation | 11 mW typical at 500 kSPS throughput |
| Power-Down Dissipation | 2.5 mW typical |
| 패키지 | 8-pin PDIP, through-hole, rectangular DIP |
| Number of Terminals | 8 |
| 실장 유형 | Through-hole |
| Input Type | Single-ended analog input |
| Sample-and-Hold | Internal sample-and-hold |
| Temperature Grade | Industrial |
ADS7834P 핀 구성
| 핀 1 | CS — Active-low chip select; serial data output is high impedance when deasserted |
| 핀 2 | SCLK — Serial clock input for the synchronous serial interface |
| 핀 3 | SDI — Serial data input |
| 핀 4 | GND — Ground reference for analog and digital circuits |
| 핀 5 | DOUT — Serial data output, conversion result |
| 핀 6 | REFOUT — 2.5 V internal reference output, can be bypassed or used externally |
| 핀 7 | AIN — Analog input, unipolar 0 V to VREF range |
| 핀 8 | V+ — Positive analog supply voltage |
일반적인 애플리케이션
ADS7834P 적합 용도: 6 애플리케이션s: Industrial Process and Sensor Monitoring, Battery-Powered Data Acquisition, Motor, Vibration and Ripple Waveform Capture, Thermocouple and RTD Front Ends, Automated Test and Measurement Equipment, Power Supply and Battery Telemetry.
Industrial Process and Sensor Monitoring
The ADS7834P suits process-control front ends that must digitise a 0 V to 2.5 V sensor signal at a few hundred samples per second. The 12-bit resolution provides roughly 1/4096 of full-scale steps, and the internal 2.5 V reference makes the conversion ratiometric without an external reference IC. Because the converter resolves in a fixed 2 microsecond cycle at the full 500 kSPS rate, a control loop can oversample the sensor and average codes to suppress noise without adding latency. The 8-pin PDIP package is through-hole, which makes it convenient for prototype and instrument builds where reworkability and inspection matter more than board area.
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Battery-Powered Data Acquisition
For portable loggers and handheld meters, the ADS7834P draws about 11 mW at the full 500 kSPS rate and drops to roughly 2.5 mW in power-down, which lets a microcontroller duty-cycle the converter between bursts of samples. The serial interface needs only a few I/O lines from the host MCU, and the internal reference removes the quiescent current burden of a separate reference device. Through-hole PDIP construction suits a compact handheld board built for serviceability. Choose a lower sampling rate part only if the recorded signal bandwidth allows it, since the 2 microsecond conversion time is a key reason to keep this device on duty.
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Motor, Vibration and Ripple Waveform Capture
The 500 kSPS sampling rate of the ADS7834P captures motor-commutation ripple, switching-node ringing and vibration envelopes that would alias into nonsense with a 100 kSPS-class converter. Because the SAR conversion is deterministic, successive samples land on evenly spaced time points, so a host MCU can compute peak, RMS and crest factor values directly from the code stream. Keep the analog front end short: an RC filter at the analog input pin, an input buffer for high-impedance accelerometers, and a separate return path keep switching noise out of the sampled waveform.
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Thermocouple and RTD Front Ends
In a thermocouple or RTD signal chain, the ADS7834P performs the analogue-to-digital stage after amplification, with the internal 2.5 V reference defining the conversion scale. Cold-junction compensation for thermocouples is handled by the host MCU, which uses its own temperature sensor and applies the offset before scaling the digital code. Because the reference is internal, the ADC contribution to absolute error is small compared with the millivolt-level sensor signal, but the front-end amplifier and reference bypass capacitor still dominate the error budget. Anti-alias filtering and a slow, low-drift reference arrangement are essential in this application.
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Automated Test and Measurement Equipment
Test equipment that measures slow or burst signals benefits from the ADS7834P because the converter can be clocked on demand from the fixture controller, producing a deterministic result in 2 microseconds at maximum rate. The synchronous serial interface with chip select lets several converters share a bus, and the chip-select line can place the output in a high-impedance state between conversions. In a rack instrument the analog input routing and relay contacts are the noisy elements, so isolate the ADC analog ground and bypass the supply locally at the device pins.
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Power Supply and Battery Telemetry
The ADS7834P is a natural fit for supervisory telemetry that reports rail voltage, current sense output or battery voltage to a system controller. The 2.5 V internal reference and 12-bit resolution give roughly 610 microvolts per code, which is sufficient for rail-level monitoring, and the low 11 mW operating dissipation keeps it from adding meaningful loss in a high-efficiency supply. For cell-level monitoring in a battery pack, scale the sense output into the 0 V to 2.5 V input range and keep the trace away from the switching node, since common-mode coupling through the input is the dominant error source in this topology.
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추천 제품 요약
엔지니어링 참조 데이터: ADS7834P — 비교, 설계 지침 및 규정 준수 정보.
선택 가이드
대체품과의 비교
| 파라미터 | 이 제품 | ADS7822IP |
|---|---|---|
| Package | PDIP-8 (through-hole) | PDIP-8 (through-hole) - same |
| Brand | Texas Instruments | Texas Instruments |
| Resolution | 12 bit | 12 bit |
| Sampling Rate | 500 kSPS | 200 kSPS (-60%) |
| Converter Architecture | Single-channel SAR | Single-channel SAR |
| Input Range | 0 V to VREF (unipolar) | 0 V to VREF (unipolar) |
| Internal Reference | 2.5 V | 2.5 V |
| Interface | Synchronous serial (SPI-compatible) | Synchronous serial (SPI-compatible) |
| Mounting Type | Through-hole | Through-hole |
주요 차별점
- Higher conversion throughput in the same PDIP-8 footprint (vs ADS7822IP)
- Integrated 2.5 V reference removes an external component (vs ADS7822IP)
- Deterministic SAR conversion and low shutdown power (vs ADS7822IP)
설계 노트
Keep the analog input trace from the sensor to the AIN pin as short and direct as possible, and place the anti-alias RC filter immediately at the ADS7834P analog input pin rather than at the connector. The switched-capacitor input of a SAR converter needs to settle within the acquisition window, so a long trace adds parasitic capacitance and source impedance that slow settling and show up as gain error. Route the trace away from the serial clock and data lines, and keep the digital return path separate from the analog return so they meet only at the device ground pin.
Place the supply bypass capacitor directly at the supply pin with a minimal loop area, and add a local bulk capacitor if the supply trace reaches the ADC across more than a few centimetres. The ADS7834P dissipates about 11 mW at the full 500 kSPS rate and 2.5 mW in power-down, so supply noise is rarely a thermal problem, but a switching converter upstream can inject ripple that is indistinguishable from a real input change. Verify that the bypass capacitor voltage rating and X7R temperature characteristic hold across the full industrial temperature range.
Decouple the reference section exactly as shown in the typical application circuit in the manufacturer datasheet, with a small ceramic capacitor at REFOUT. Because the internal 2.5 V reference defines the full-scale range, reference noise appears directly as input-referred noise and gain error. If a system already carries a higher-precision reference, the internal reference can be bypassed, but then the accuracy budget must include the external reference error, drift and its own bypass network.
Two mistakes dominate ADS7834P bring-up failures. First, driving the analog input above the 2.5 V reference range causes incorrect codes and can stress the input network; add clamping if the source can overshoot. Second, assuming the first conversion after power-up is valid wastes a reading, because the sample-and-hold network needs a settling conversion after the supply ramps or after a power-down cycle. Discard the first sample after any supply or reference disturbance and use the chip-select line to guarantee a clean, isolated output when multiple converters share a bus.
규정 준수 정보
The ADS7834P is an industrial-temperature-grade Texas Instruments analog-to-digital converter in an 8-pin PDIP package. RoHS, REACH, lead-free and halogen-free status were not stated for this specific MPN and should be confirmed on the manufacturer product page.
