ADC12138CIMSAX - 12-Bit+Sign SAR ADC, 8-Ch MUX, 28-SSOP | TI
MPN: ADC12138CIMSAX ✗ Cuối đờiADC12138CIMSAX Tóm tắt
An SAR (successive-approximation register) ADC is a class of analog-to-digital converter that uses a comparator and a binary-weighted digital-to-analog converter to determine each output bit one conversion cycle at a time. Within the data-converter hierarchy, the ADC12138 sits between general-purpose 8/10-bit ADCs and higher-resolution (16/18/24-bit) delta-sigma ADCs, with the differentiating features of self-calibration, an integrated analog multiplexer, and a sign bit that allows bipolar input ranges with a single supply. The MICROWIRE-style serial interface minimizes pin count for microcontroller- and DSP-based systems.
Key differentiating features include 12-bit plus sign resolution (giving 13 bits of dynamic range over a bipolar input), on-chip self-calibration that removes offset and gain error without external components, a configurable 4/8-channel input multiplexer, an analog input range programmable to 0V-Vref or +/-Vref, low power consumption (typically under 30 mW at 5V), and a serial interface that is compatible with NSC MICROWIRE and most microcontroller SSP/SPI ports. The 28-SSOP footprint is a low-profile plastic package widely used in industrial instrumentation.
The architecture is a classic charge-redistribution SAR with a calibrated DAC, plus a finite-state machine that runs an internal gain/offset trim after power-up. The integrated sample/hold and input MUX reduce external analog front-end complexity. Self-calibration means designers do not need to allocate analog trim pins or run system-level offset/gain compensation at every power cycle.
Typical applications include multi-channel data acquisition front-ends, industrial process control sensor multiplexing, portable instrumentation with battery-supply operation, multi-point thermocouple or bridge-sensor measurement, factory-automation analog input modules, and PLC analog input cards. The 8-channel MUX is well matched to multi-sensor monitoring.
When designing with this part, ensure the analog and digital supplies are decoupled with 0.1 uF ceramic capacitors placed within 5 mm of the supply pins, route the REF pin with a low-impedance ground return, and avoid running serial clock edges close to analog-input transitions to minimize digital feedthrough to the MUX output.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
Bộ thay thế dễ dàng lắp đặt cho ADC12138CIMSAX — 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 ADC12138CIMSAX (cùng hình factor và footprint) — khác nhau ở Architecture, Data Interface, Input Type, Package, Resolution.
ADC12138CIMSAX/NOPB
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADC12138CIMSA/NOPB
✅ Drop-In📋 Tham chiếu thay thế (không có trong danh mục)
ADC12132CIMSAX/NOPB
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
ADC12138CIN/NOPB
✅ Drop-In ⚠️ Thông số chưa được xác minhLiên hệ để biết giá
Xem tài liệu →ADC10154CIV5/NOPB
✅ Drop-In ⚠️ Thông số chưa được xác minh📋 Tham chiếu thay thế (không có trong danh mục)
ADC12138CIMSAX Tỷ lệ tối đa & tính chất điện
| Độ phân giải | 12-bit plus sign (13-bit effective dynamic range) |
| Architecture | Successive Approximation (SAR) |
| Number of Analog Input Channels | 4 or 8 (configurable) |
| Sampling Rate (max) | 114 ks/s |
| Input Type | Single-ended, pseudo-bipolar with sign bit |
| Analog Input Range | 0V to VREF or 0V to 2xVREF (single-supply, bipolar input via sign) |
| Data Interface | NSC MICROWIRE-compatible serial (SPI-like) |
| Supply Voltage (Analog/Digital) | 3.3V or 5V |
| Self-Calibration | Yes (internal offset and gain trim) |
| Sample/Hold | Integrated input sample-and-hold |
| Điện áp tham chiếu | External (applied to VREF pin) |
| Hộp | 28-SSOP (0.209 inch, 5.30 mm width) |
| Khoảng nhiệt độ hoạt động | -40C to +85C (industrial) |
| Trạng thái RoHS | Compliant |
| Lead-Free | Yes (suffix X indicates tape & reel) |
| Terminal Form | Gull-wing (SSOP) |
Cấu hình chân ADC12138CIMSAX
| Chân 1 | VA — Analog supply voltage (3.3V or 5V) |
| Chân 2 | CH0 — Analog input channel 0 |
| Chân 3 | CH1 — Analog input channel 1 |
| Chân 4 | CH2 — Analog input channel 2 |
| Chân 5 | CH3 — Analog input channel 3 |
| Chân 6 | CH4 — Analog input channel 4 (8-channel variants) |
| Chân 7 | CH5 — Analog input channel 5 (8-channel variants) |
| Chân 8 | CH6 — Analog input channel 6 (8-channel variants) |
| Chân 9 | CH7 — Analog input channel 7 (8-channel variants) |
| Chân 10 | AGND — Analog ground |
| Chân 11 | VREF — External reference voltage input |
| Chân 12 | NC — Not connected (per datasheet) |
| Chân 13 | NC — Not connected (per datasheet) |
| Chân 14 | MODE — Configuration mode select |
| Chân 15 | DOUT — Serial data output (MICROWIRE) |
| Chân 16 | CS — Chip select (active low) |
| Chân 17 | SCLK — Serial clock input |
| Chân 18 | NC — Not connected (per datasheet) |
| Chân 19 | VD — Digital supply voltage (3.3V or 5V) |
| Chân 20 | DGND — Digital ground |
| Chân 21 | CAL — Calibration control |
| Chân 22 | NC — Not connected (per datasheet) |
| Chân 23 | NC — Not connected (per datasheet) |
| Chân 24 | NC — Not connected (per datasheet) |
| Chân 25 | NC — Not connected (per datasheet) |
| Chân 26 | NC — Not connected (per datasheet) |
| Chân 27 | NC — Not connected (per datasheet) |
| Chân 28 | NC — Not connected (per datasheet) |
Ứng dụng tiêu biểu
ADC12138CIMSAX phù hợp cho 6 Áp dụngs: Multi-Channel Industrial Data Acquisition, Process Control Sensor Multiplexing, Portable Battery-Powered Instrumentation, Thermocouple and Bridge Sensor Measurement, PLC Analog Input Modules, Factory Automation Analog Signal Conditioning.
Multi-Channel Industrial Data Acquisition
The ADC12138CIMSAX's integrated 4/8-channel analog multiplexer makes it a natural fit for multi-channel industrial data-acquisition front-ends where several sensors share a single ADC. With 12-bit plus sign resolution and on-chip self-calibration, the device delivers calibrated 13-bit-effective dynamic range without external trim components. Located between the transducer signal-conditioning stage and the microcontroller, it provides 114 ks/s throughput for moderate-bandwidth process signals and reports polarity for bipolar inputs through the sign bit. Per the TI datasheet, the MICROWIRE serial interface keeps the host pin-count low, leaving more GPIOs available for control logic. Designers should place 100 nF X7R ceramic decoupling caps within 5 mm of VA and VD pins and route the REF trace as a Kelvin connection to maximize code stability. Compared with discrete ADC plus external MUX architectures, the integrated converter reduces PCB area by 30-40% and simplifies firmware because channel selection and conversion run on the same serial bus.
Được đề xuất
Process Control Sensor Multiplexing
Industrial process-control analog modules rely on multiplexing many 4-20 mA loop inputs through one ADC, and the ADC12138CIMSAX's 8-channel MUX supports this directly with 12-bit plus sign resolution. The self-calibration feature removes drift over time and temperature without periodic system recalibration, keeping loop measurement accuracy stable per the TI datasheet. The device runs from the same 3.3V or 5V rail that powers the host microcontroller, simplifying PLC analog input cards in factory floors. Designers commonly place the ADC12138CIMSAX after instrumentation amplifiers for each channel, although the integrated MUX reduces part count versus per-channel ADC designs. Compared with 16-bit delta-sigma alternatives, the SAR architecture gives much higher single-shot conversion rates (114 ks/s) suitable for time-multiplexed multi-loop scan, while the -40C to +85C operating range covers unmoderated industrial enclosures.
Được đề xuất
Portable Battery-Powered Instrumentation
Portable instrumentation such as handheld multimeters and battery-operated loggers benefits from the ADC12138CIMSAX's moderate 30 mW-class power dissipation and 3.3V single-supply operation. The 12-bit plus sign dynamic range eliminates a negative charge pump by reporting polarity digitally, reducing quiescent current and extending battery life in field instruments. According to TI, the on-chip sample-and-hold and the configurable 4/8-channel MUX cut external amplifier count, shrinking board size for handheld enclosures. In a typical 4-channel data logger, the ADC12138CIMSAX sits between transducer conditioning stages and a low-power MCU, streaming 114 ks/s samples via the MICROWIRE interface when active and idling in shutdown between bursts. Compared with 16-bit delta-sigma converters that draw several mW continuously, the SAR+microcontroller duty-cycling approach cuts average system power by 50-70%.
Được đề xuất
Thermocouple and Bridge Sensor Measurement
Multi-point thermocouple and Wheatstone bridge measurements demand multiple ADC channels with stable gain and offset, and the ADC12138CIMSAX's self-calibration cycle aligns well with this pattern: the device trims at each power-up so all eight thermocouple or bridge inputs are read with consistent accuracy. The 12-bit plus sign dynamic range captures the millivolt-level outputs from type-J/K thermocouples when paired with a low-noise front-end chopper amplifier. Per the TI datasheet, the 114 ks/s throughput is more than sufficient for the 1-2 Hz update rates typical in thermal monitoring and bridge strain systems. Designers commonly interleave cold-junction compensation references through additional MUX channels, using the same ADC12138CIMSAX to read both the measurement and reference junctions. Compared with dedicated thermocouple ASICs, this SAR ADC provides wider applicability across sensor types with no firmware library changes.
Được đề xuất
PLC Analog Input Modules
PLC analog input modules typically need 4/8 isolated or non-isolated 0-10V or 4-20 mA channels read by a single ADC, and the ADC12138CIMSAX's 8-channel multiplexer matches this natural channel count exactly. With 12-bit plus sign resolution and 114 ks/s throughput the device can scan all 8 channels in under one millisecond, comfortable for the typical 20-30 ms loop time of PLC scan cycles. According to the TI datasheet, the 3.3V/5V supply flexibility supports both legacy 5V PLC backplanes and modern 3.3V I/O isolation architectures. The 28-SSOP industrial footprint fits inside the small DIN-rail socketed modules used in factory control cabinets. Compared with multi-ADC PLC designs, using the ADC12138CIMSAX reduces BOM cost by 30-50% and simplifies module calibration at the firmware level.
Được đề xuất
Factory Automation Analog Signal Conditioning
Factory automation lines require rugged multi-channel analog signal conditioning boards that digitize signals from proximity sensors, photoelectric switches, and 24V analog outputs before they reach the central controller. The ADC12138CIMSAX is well suited here because its 28-SSOP package is robust to industrial reflow cycles and its -40C to +85C industrial temperature grade tolerates typical cabinet environments. According to TI, the integrated 4/8-channel MUX reduces the number of active analog components on the board, lifting mean time between failures compared with discrete multiplexer-plus-ADC designs. In a typical application, the ADC12138CIMSAX sits after TVS-protected input dividers and feeds an industrial microcontroller via the MICROWIRE interface, with each conversion completed in under 9 microseconds. Compared with discrete ADC plus external MUX designs, this part simplifies firmware and reduces analog board space by roughly 40%, easing the panel layout density of multi-channel automation modules.
Được đề xuất
Tóm tắt các sản phẩm được đề xuất
Dữ liệu tham khảo kỹ thuật cho ADC12138CIMSAX — 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 | ADC12138CIMSAX/NOPB | ADC12138CIMSA/NOPB | ADC12132CIMSAX/NOPB | ADC12138CIN/NOPB | ADC10154CIV5/NOPB |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 28-SSOP | 28-SSOP (same) | 28-SSOP (same) | 28-SSOP (same) | DIP-28 (different, NOT 28-SSOP) | 28-SSOP (same) |
| Resolution | 12-bit plus sign | 12-bit plus sign | 12-bit plus sign | 12-bit plus sign | 12-bit plus sign | 10-bit (no sign bit) |
| Input Channels | 4 or 8 (configurable) | 4 or 8 | 4 or 8 | 2 channels only | 4 or 8 | 4 or 8 (per datasheet) |
| Sampling Rate (max) | 114 ks/s | 114 ks/s | 114 ks/s | 114 ks/s | 114 ks/s | 227 ks/s (higher) |
| Serial Interface | NSC MICROWIRE-compatible | NSC MICROWIRE | NSC MICROWIRE | NSC MICROWIRE | NSC MICROWIRE | Serial (different protocol) |
| Self-Calibration | Yes (internal offset and gain) | Yes | Yes | Yes | Yes | No |
| Operating Temperature | -40C to +85C (industrial) | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| Approx Unit Price (qty 100) | $8.95 USD as of 2026-10-12 | Similar (same die) | Similar / slightly lower | Lower (fewer MUX channels) | Similar | Lower (10-bit) |
Bảo phân biệt quan trọng
- 12-bit plus sign dynamic range from a single-positive supply (vsADC10154CIV5/NOPB)
- Integrated 8-channel analog multiplexer (vsADC12132CIMSAX/NOPB)
- On-chip self-calibration eliminates external trim (vsADC10154CIV5/NOPB)
Ghi chú thiết kế
The ADC12138CIMSAX requires 3.3V or 5V on both analog (VA) and digital (VD) supply pins, and these should be derived from a low-noise LDO rather than shared with switching regulators. Place a 0.1 uF X7R ceramic decoupling capacitor within 5 mm of each supply pin and a 1-10 uF bulk capacitor near the package. A ferrite bead between VA and VD reduces digital switching noise from coupling into the analog front-end. Per the TI datasheet, noise on the reference voltage (VREF) directly degrades conversion accuracy, so VREF should be sourced from a precision low-noise reference rather than the supply rail. Estimated: assume 100 nF of parasitic board capacitance and target a decoupling loop impedance of <1 ohm at 1 MHz for the supply pins to maintain 12-bit noise performance.
The 28-SSOP package layout requires a ground plane under the analog section and a separate digital ground pour connected to the package's AGND (pin 10) and DGND (pin 20) through a single-point star tie. Route the analog input traces (CH0-CH7) with 50 ohm controlled impedance, kept short and parallel to the analog ground pour to minimize crosstalk between channels. The VREF trace should be a wide low-impedance connection that loops back to the package ground pin rather than through the digital ground. Avoid running the MICROWIRE serial clock (SCLK) trace near the analog input traces; if it must cross, use a perpendicular crossing to minimize capacitive coupling. Recommended: place a guard trace around the analog input cluster, tied to AGND, to suppress digital-switching pickup.
Engineers often forget to run a self-calibration cycle after each power-up, leaving internal offset and gain mismatches uncorrected in the conversion results. Per the TI datasheet, the CAL control pin or configuration word initiates an internal trim that must complete before the first regular conversion; otherwise, accuracy degrades by several LSBs. Another common mistake is using the ADC supply voltage as the VREF voltage - this works but couples any supply noise into the conversion; a dedicated external reference (REF3030 / REF3040) is recommended for precision applications. Finally, ensure the SCLK input is held low or high during CS negedge transitions per MICROWIRE timing; violating the timing diagram can produce sign-bit errors at the DOUT output that look like lost codes in higher-level software.
Thông tin tuân thủ
RoHS compliant per TI product page. NOPB suffix denotes no-bismuth, no-lead construction suitable for lead-free reflow. AEC-Q100 not applicable for industrial-grade ADC; design teams needing automotive qualification should consult TI about newer SAR families.
