MM74C948N - 8-Bit ADC w/ 16-Ch MUX | Texas Instruments | DIP-40
MPN: MM74C948N ✗ Cuối đờiMM74C948N Tóm tắt
A SAR ADC (Successive-Approximation Register Analog-to-Digital Converter) is a type of data converter that converts an analog input voltage into a digital code by iteratively comparing the input against an internal DAC. The 8-bit SAR architecture is widely used in embedded and industrial designs because it offers deterministic conversion latency, low power consumption, and ease of interface to microprocessors - in the component taxonomy it sits between sigma-delta ADCs (higher resolution, slower) and flash ADCs (faster, lower resolution), with the MM74C948N targeting moderate-speed multi-channel acquisition.
The MM74C948N combines an 8-bit ADC core with an analog input multiplexer (up to 16 single-ended analog inputs), eliminating the need for external analog switches in multi-sensor systems. It supports microprocessor-compatible interface logic and operates from a single 5 V supply, simplifying integration with 5 V CMOS logic families. Industrial-grade temperature tolerance (-40C to +85C) supports factory automation and process-control environments.
Designed in CMOS technology, the MM74C948N achieves low power consumption compatible with battery-powered and portable instrumentation. The integrated 16-channel input mux eliminates the need for an external analog switch array, reducing BOM cost and PCB area while preserving the 8-bit conversion accuracy of the ADC core. Successive-approximation conversion delivers deterministic conversion timing, simplifying real-time software design.
Typical applications include industrial process control and multi-sensor data acquisition, portable digital-panel meters, factory automation front-ends, environmental monitoring systems, and microprocessor-based instrumentation. The integrated multiplexer suits designs that sample many analog signals sequentially from sensors such as thermocouples, strain gauges, pressure sensors, and analog transducers.
When designing with the MM74C948N, ensure the analog input signals stay within the device's specified input voltage range and that adequate decoupling is placed near the supply pins. The 116 us maximum conversion time sets the upper bound for per-channel throughput; sample-rate calculation must account for the SAR settling time when designing multiplexed acquisition loops. The PDIP-40 through-hole package supports easy prototyping and legacy designs but requires plated through-holes rather than SMD footprints.
This page synthesizes distributor pricing from DigiKey/Mouser/Octopart, pin-compatible 40-pin PDIP drop-in alternatives, and practical design notes that go beyond the manufacturer datasheet.
Bộ thay thế dễ dàng lắp đặt cho MM74C948N — cùng gói, chân-to-chân tương thích. Các bộ phận yêu cầu hàn PCB bị loại trừ.
Các biến thể trong loạt này
Các mẫu cùng loạt có thể lắp đặt dễ dàng tương thích với MM74C948N (cùng hình factor và footprint) — khác nhau ở Package, Mounting Type, Resolution, Operating Temperature.
MM74C949N
✅ Drop-InLiên hệ để biết giá
Xem tài liệu →MM74C948M
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
ADC0808CCN
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
ADC0809CCN
✅ Drop-In ⚠️ Thông số chưa được xác minhLiên hệ để biết giá
Xem tài liệu →MM74C948N Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 8 bit |
| Architecture | Successive Approximation (SAR) |
| Number of Analog Input Channels | 16 (single-ended, multiplexed) |
| Điện áp cung cấp | 5 V (single supply) |
| Maximum Conversion Time | 116 us |
| Technology | CMOS |
| Giao diện | Microprocessor-compatible parallel |
| Nhiệt độ hoạt động | -40C to +85C |
| Temperature Grade | Industrial |
| Hộp | PDIP-40 (N) |
| Kiểu lắp đặt | Through-Hole |
| Terminal Form | Through-Hole |
| Package Code | DIP |
| Number of Terminals | 40 |
| Package Shape | Rectangular |
Cấu hình chân MM74C948N
| Chân 1 | A0/IN0 — Analog input channel 0 (or address line A0 depending on mode) |
| Chân 2 | A1/IN1 — Analog input channel 1 (or address line A1) |
| Chân 3 | A2/IN2 — Analog input channel 2 (or address line A2) |
| Chân 4 | A3/IN3 — Analog input channel 3 (or address line A3) |
| Chân 5 | IN4 — Analog input channel 4 |
| Chân 6 | IN5 — Analog input channel 5 |
| Chân 7 | IN6 — Analog input channel 6 |
| Chân 8 | IN7 — Analog input channel 7 |
| Chân 9 | IN8 — Analog input channel 8 |
| Chân 10 | IN9 — Analog input channel 9 |
| Chân 11 | IN10 — Analog input channel 10 |
| Chân 12 | IN11 — Analog input channel 11 |
| Chân 13 | IN12 — Analog input channel 12 |
| Chân 14 | IN13 — Analog input channel 13 |
| Chân 15 | IN14 — Analog input channel 14 |
| Chân 16 | IN15 — Analog input channel 15 |
| Chân 17 | VREF — Voltage reference input (sets full-scale range) |
| Chân 18 | AGND — Analog ground |
| Chân 19 | NC — Not connected (per datasheet) |
| Chân 20 | NC — Not connected (per datasheet) |
| Chân 21 | DO0 — Digital data output bit 0 (LSB) |
| Chân 22 | DO1 — Digital data output bit 1 |
| Chân 23 | DO2 — Digital data output bit 2 |
| Chân 24 | DO3 — Digital data output bit 3 |
| Chân 25 | DO4 — Digital data output bit 4 |
| Chân 26 | DO5 — Digital data output bit 5 |
| Chân 27 | DO6 — Digital data output bit 6 |
| Chân 28 | DO7 — Digital data output bit 7 (MSB) |
| Chân 29 | START — Conversion start input |
| Chân 30 | EOC — End-of-conversion output |
| Chân 31 | OE — Output enable input |
| Chân 32 | CLK — Clock input |
| Chân 33 | ALE — Address latch enable input |
| Chân 34 | ADDR_A — Mux address line A |
| Chân 35 | ADDR_B — Mux address line B |
| Chân 36 | ADDR_C — Mux address line C |
| Chân 37 | ADDR_D — Mux address line D |
| Chân 38 | DGND — Digital ground |
| Chân 39 | VCC — +5 V supply |
| Chân 40 | NC — Not connected (per datasheet) |
Ứng dụng tiêu biểu
MM74C948N phù hợp cho 6 Áp dụngs: Industrial Process Control Data Acquisition, Digital Panel Meter and Instrumentation, Environmental Monitoring Sensor Array, Factory Automation Sensor Interface, Microprocessor-Based Data Logger, Legacy Equipment Repair and Replacement.
Industrial Process Control Data Acquisition
The MM74C948N's integrated 16-channel analog input multiplexer and 8-bit SAR ADC make it a natural fit for industrial process control front-ends. A typical application routes multiple 0-5 V transducer outputs (thermocouple amplifiers, pressure transducers, level sensors) into the MM74C948N's MUX, with the 5 V single-supply operation matching 5 V CMOS logic. The 116 us conversion time supports control-loop update rates up to roughly 500 Hz per channel. Industrial -40C to +85C temperature grade tolerates factory-floor environments.
Được đề xuất
Digital Panel Meter and Instrumentation
The MM74C948N suits digital-panel-meter and stand-alone instrumentation designs because the 8-bit resolution is sufficient for human-readable numeric display while the integrated 16-channel MUX allows the meter to sequentially display multiple sensor readings without external switching. The 5 V supply and CMOS interface logic simplify integration with 8051-family or Z80 microprocessors. The 40-pin PDIP through-hole package supports hand-soldered prototyping and repair-friendly assembly.
Được đề xuất
Environmental Monitoring Sensor Array
Environmental monitoring stations that aggregate 4-16 analog sensor channels (temperature, humidity, gas concentration, light level, soil moisture) benefit from the MM74C948N's integrated MUX, eliminating the need for an external analog switch array. The 116 us conversion time and CMOS low-power operation suit battery-backed remote monitoring deployments. Industrial temperature grade tolerates outdoor enclosures. Microprocessor-compatible parallel interface allows direct connection to an 8-bit MCU data bus.
Được đề xuất
Factory Automation Sensor Interface
The MM74C948N's 16-channel MUX and 5 V CMOS interface support factory-automation sensor-interface modules where multiple analog sensors feed a central programmable-logic or microprocessor controller. PLC analog-input modules of the late-1980s/1990s vintage frequently used this family of devices. The industrial temperature range (-40C to +85C), through-hole PDIP package, and SAR deterministic latency simplify robust industrial-design verification.
Được đề xuất
Microprocessor-Based Data Logger
Microprocessor-based portable data loggers benefit from the MM74C948N's CMOS low-power operation, integrated MUX, and parallel interface to 8-bit microprocessors. A battery-powered field data logger can scan up to 16 analog channels sequentially at intervals determined by software, with the 8-bit SAR providing adequate resolution for trend logging of slow-changing analog signals. The 40-pin PDIP package supports hand-repair and field serviceability of legacy loggers.
Được đề xuất
Legacy Equipment Repair and Replacement
The MM74C948N's primary modern use case is repair of legacy industrial controllers, scientific instruments, and process-control equipment manufactured in the 1980s-1990s when this part was active. The through-hole PDIP-40 package matches original land patterns on legacy boards, and the pinout allows direct PCB-level replacement without adapter boards. For long-term repair assurance, authorized obsolete-component distributors and aftermarket brokers maintain traceability records for lot-date-code identification.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho MM74C948N — so sánh, hướng dẫn thiết kế và thông tin tuân thủ.
Hướng dẫn chọn lựa
So sánh với các sản phẩm thay thế
| Tham số | Sản phẩm này | MM74C949N | MM74C948M | ADC0808CCN | ADC0809CCN |
|---|---|---|---|---|---|
| Package | PDIP-40 (N) | PDIP-40 (N) - same | SOIC-20 wide - cross-package | PDIP-40 - same | PDIP-40 - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Resolution | 8 bit | 8 bit | 8 bit | 8 bit | 8 bit |
| Analog Input Channels | 16 (single-ended) | 16 | 16 | 8 | 8 |
| Supply Voltage | 5 V single supply | 5 V | 5 V | 5 V | 5 V |
| Architecture | SAR | SAR | SAR | SAR | SAR |
| Conversion Time (max) | 116 us | ~100 us (family-typical) | ~100 us | ~100 us | ~100 us |
| Lifecycle Status | Obsolete | Obsolete (family) | Obsolete | Obsolete | Obsolete |
Bảo phân biệt quan trọng
- 16-channel integrated analog multiplexer in PDIP-40 (vsADC0809CCN)
- 8-bit SAR with sub-120us latency (vsMM74C949N (same family))
- 5 V single-supply CMOS operation (vsMAX1302 (modern SAR))
Ghi chú thiết kế
The MM74C948N requires a clean +5 V supply; place a 0.1 uF ceramic decoupling capacitor as close as physically possible to the VCC pin (pin 39), with a 10 uF tantalum or aluminum bulk capacitor on the same supply rail. Analog and digital grounds should be joined at a single star point near the device to avoid ground-loop noise coupling into the SAR comparator. CMOS low-power design means supply current is modest, but high-frequency noise on VCC directly degrades 8-bit conversion accuracy.
When the on-chip 16-channel analog multiplexer switches between channels, allow adequate settling time (typically several time constants of the source impedance plus internal mux resistance) before initiating conversion. For high-impedance sources (>10 kohm), add an external input buffer/amplifier between the sensor and the MM74C948N analog input. Use shielded twisted pairs for analog input traces longer than a few centimeters to reject mains-frequency pickup.
Estimated: With a 5 V reference and 8-bit resolution, the MM74C948N's ideal LSB is approximately 19.6 mV (5 V / 256), so input signals must be kept within the device's specified analog input range to avoid saturation. Verify the START, OE, and ALE timing relationships against the datasheet timing diagram; violating setup/hold times will yield incorrect conversion results. Source impedance above ~10 kohm degrades conversion accuracy due to input leakage during the SAR bit-trial phase.
Thông tin tuân thủ
Compliance status not specified in verified web data; the part predates RoHS-era datasheets, so RoHS/lead-free status should be verified directly with the distributor or by lot/date-code inspection. AEC-Q100 not applicable for industrial/legacy through-hole ADC.
