ICL7135CQI+ - 4.5-Digit Differential ADC | Analog Devices
MPN： ICL7135CQI+ ✓ 啟用中ICL7135CQI+ 概覽
A dual-slope ADC is a signal-conversion architecture that integrates an unknown input voltage over a defined interval and compares it with a reference-driven ramp. In a broader hierarchy, the ICL7135CQI+ is an ADC, a data-converter IC, and a precision measurement component. Its BCD outputs can reduce the display-processing burden in instruments, while differential input architecture helps reject common-mode disturbances when suitable source and reference arrangements are used.
Key characteristics include 4.5-digit resolution, differential analog inputs, multiplexed parallel BCD outputs, and dual output polarity. The Analog Devices product page identifies the ICL7135 as a high-precision monolithic converter with ±1 count in 20,000 accuracy. These attributes make it applicable to laboratory instruments, panel meters, weighing systems, temperature measurement, and other linear analog measurement products.
The converter architecture divides each measurement cycle into distinct phases controlled by internal counters, input interfaces, output interfaces, and control logic. Its differential input stage operates with high input impedance, which is useful when measuring slowly changing sensor signals and when the source impedance is not extremely low. The 2.0000 V full-scale reference requirement also places a clear constraint on analog front-end and reference design.
Typical applications include digital panel meters, laboratory measurement equipment, process monitoring, resistance and temperature measurement, and other display-oriented instruments. The multiplexed BCD outputs are particularly useful when the measured value must be presented directly through seven-segment display drivers without requiring a complex digital data bus.
For PCB implementation, place the input, reference, and bypass connections according to the manufacturer datasheet and keep sensitive analog routing compact. Designers should also verify timing, conversion-cycle behavior, display multiplexing requirements, and output logic levels against the target instrument rather than treating the converter as a generic modern high-speed ADC.
This product page organizes the verified technical characteristics, sourcing information, drop-in candidate assessment, application guidance, and design considerations around the ICL7135CQI+. It is intended to help engineers determine whether its dual-slope architecture, BCD interface, differential inputs, and 28-pin PLCC package fit a precision display-oriented measurement design.
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ICL7135CQI+T
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ICL7135CQI
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ICL7135CQI+ 最大額定值與電氣特性
| ADC Resolution | 4.5 digits |
| Architecture | Dual-slope ADC |
| Input Configuration | Differential |
| Full-Scale Input Range | 2.0000 V |
| Accuracy | ±1 count in 20,000 |
| Input Impedance | High impedance |
| Output Interface | Multiplexed parallel BCD |
| Output Polarity | Dual, ± |
| Device Type | Display-driver ADC |
| 封裝 | 28-pin PLCC (11.51 mm × 11.51 mm) |
| 腳位數 | 28 pins |
| 安裝類型 | Surface mount |
| 工作溫度 | 0 °C to 70 °C |
| Screening Level | Commercial |
| RoHS 狀態 | Compliant |
| Input Voltage | -2 V to 2 V |
| Manufacturer Product Family | ICL7135 |
ICL7135CQI+ 28-pin plcc (11.51 mm × 11.51 mm) 腳位配置指南
ICL7135CQI+（28-pin plcc (11.51 mm × 11.51 mm) 封裝）的腳位配置。 此類比元件具有輸入、輸出與電源腳位。偏移歸零、補償與致能腳位配置請參閱製造商資料表。適用於訊號調理與放大器電路。
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典型應用
ICL7135CQI+ 適用於 6 應用s: Digital Panel Meters, Laboratory Precision Measurement, Industrial Process Monitoring, Temperature Measurement Systems, Weighing and Load-cell Instruments, Resistance and Bridge Measurement.
Digital Panel Meters
The ICL7135CQI+ fits digital panel meters because its 4.5-digit multiplexed BCD output can drive seven-segment display decoding without requiring a complex serial data protocol. The differential input architecture supports measurement of slowly varying analog signals, while the documented accuracy of ±1 count in 20,000 is appropriate for readable laboratory and industrial indications. Its 2.0000 V full-scale capability gives the analog front end a defined reference point. The converter should be paired with stable references, appropriate input filtering, and display multiplexing arranged according to the manufacturer timing information.
推薦
Laboratory Precision Measurement
The ICL7135CQI+ is suited to laboratory instruments that measure slowly changing voltages and display the result directly. Its high-impedance differential inputs reduce loading sensitivity when connected to suitable sensors or buffered analog stages, while the 4.5-digit format provides finer display resolution than a basic three-and-a-half-digit meter. The 2.0000 V full-scale specification and ±1 count in 20,000 accuracy support precision-instrument architecture. Reference stability, input filtering, grounding, and calibration determine whether the theoretical converter accuracy is realized at the panel reading.
推薦
Industrial Process Monitoring
The ICL7135CQI+ can be used in industrial process-monitoring equipment when a slow sensor signal requires a stable numeric indication rather than rapid sampling. Differential inputs help reject common-mode voltage present in industrial environments, and the high input impedance accommodates higher source impedances better than a low-impedance ADC input. The 4.5-digit BCD interface simplifies connection to display and relay-threshold hardware. Isolation, surge protection, and sensor grounding must be handled separately, while the ADC input must remain within the documented -2 V to 2 V range.
推薦
Temperature Measurement Systems
The ICL7135CQI+ fits temperature-measurement instruments that convert a conditioned sensor voltage into a direct digital-panel reading. High-impedance differential inputs can work with appropriately buffered bridges or transducers, and the 4.5-digit resolution provides additional display detail beyond common 3.5-digit instruments. The dual-slope architecture favors stable measurements of slowly varying temperature rather than transient capture. For thermocouple or RTD systems, the analog front end must provide linearization, cold-junction compensation where applicable, and safe fault handling before the signal reaches the converter.
推薦
Weighing and Load-cell Instruments
The ICL7135CQI+ is applicable to bench-top scales and load-cell instruments that need a stable reading with direct BCD display support. The differential input arrangement is compatible with appropriately conditioned bridge signals, while the high-impedance input helps preserve small sensor outputs. Its 4.5-digit resolution and ±1 count in 20,000 accuracy specification support useful resolution when system noise, excitation stability, and mechanical performance are controlled. Excitation regulation, bridge excitation, input protection, calibration, and averaging strategy remain important because the converter cannot compensate for unstable analog excitation.
推薦
Resistance and Bridge Measurement
The ICL7135CQI+ can support resistance, strain, and bridge-based measurement products when the analog signal is conditioned to fit the 2.0000 V full-scale capability. Differential inputs are useful for rejecting shared excitation-related disturbance, and the multiplexed BCD outputs simplify direct display integration. The converter's high-impedance input reduces loading of the transducer network, allowing more conservative source resistance in many designs. Practical implementation still requires low-noise reference design, protection from sensor wiring transients, calibration storage, and PCB layouts that keep sensitive analog paths away from switching and display-driver return currents.
推薦
推薦產品摘要
工程參考資料，適用於 ICL7135CQI+ — 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 | ICL7135CQI+T | ICL7135CQI |
|---|---|---|---|
| Package | PLCC-28 | PLCC-28 - same | PLCC-28 - same |
| Brand | Analog Devices | Analog Devices | Analog Devices |
| ADC Resolution | 4.5 digits | 4.5 digits | 4.5 digits |
| Architecture | Dual-slope ADC | Dual-slope ADC | Dual-slope ADC |
| Input Configuration | Differential | Differential | Differential |
| Output Interface | Multiplexed parallel BCD | Multiplexed parallel BCD | Multiplexed parallel BCD |
| Full-Scale Capability | 2.0000 V | 2.0000 V | 2.0000 V |
| Accuracy | ±1 count in 20,000 | ±1 count in 20,000 | ±1 count in 20,000 |
| Operating Temperature | 0 °C to 70 °C | 0 °C to 70 °C | 0 °C to 70 °C |
| Screening Level | Commercial | Commercial | Commercial |
主要差異化特點
- Direct multiplexed BCD display interface (對比TLC7135CDWR)
- Differential 4.5-digit conversion (對比ICL7116CPL+)
- Same-package order-code reuse (對比ICL7135CQI)
設計說明
Route the differential input and reference connections as compact, matched paths and place associated filtering and bypass components close to the device. Keep display-driver outputs and their return currents away from the analog input and reference nodes because multiplexed BCD outputs can introduce switching activity into the board. Use the manufacturer pin-description and layout guidance when assigning the 28 PLCC lands, and confirm all connections in the schematic before releasing the PCB.
Do not treat the 2.0000 V full-scale capability as permission to apply an arbitrary voltage to the converter input. The documented input range is -2 V to 2 V, while absolute-maximum ratings, reference limits, and supply requirements must be checked separately in the manufacturer datasheet. Add appropriate input protection where sensor wiring is exposed to transients, and avoid allowing unused inputs to float.
A dual-slope converter can provide useful rejection of periodic interference when its integration period, analog filtering, and reference arrangement are designed coherently. However, display multiplexing, digital ground returns, and power-supply ripple can still affect the measurement. Star-route analog returns where appropriate, isolate display current paths, and verify the final noise performance with the intended display and power-supply configuration installed.
合規資訊
RoHS compliance is stated in the component information. No vehicle-grade qualification is indicated for this commercial-grade converter; REACH, lead-free, halogen-free, and conflict-minerals status are not stated.
