MAX139CMH - 3.5-Digit ADC with LED Drivers | Maxim
料号： MAX139CMH ✓ 量产中MAX139CMH 概述
A panel-meter ADC is a specialized data-converter IC that measures an analog input voltage and produces a numeric representation suitable for LCD or LED indication. The MAX139CMH belongs to the dual-slope ADC family, integrating conversion timing, a voltage reference, a charge-pump circuit, and display-driver outputs. This integration allows a display instrument to combine analog front-end conditioning with direct digit and segment drive functions in one device.
Key characteristics include 3.5-digit resolution, dual-slope conversion, an internal bandgap reference, and direct LED drivers. The internal oscillator removes the need for an external timing crystal, while the charge-pump circuit supports negative input handling and auxiliary voltage generation. According to the manufacturer documentation, the operating circuits of the MAX138 and MAX139 are similar to those of the ICL7136 and ICL7137, except that the MAX138 and MAX139 use an internal oscillator and an external charge-pump capacitor connected to pins 38 and 40.
The MAX139CMH is suited to digital voltmeters, current-panel meters, laboratory instruments, process monitoring, and other systems that need stable decimal display output. Its direct LED-driver capability can reduce the number of separate display-driver ICs required in a meter design. The 44-MQFP package provides a defined gull-wing land pattern suitable for conventional surface-mount assembly and inspection.
The most important design consideration is that the external charge-pump capacitor must be connected to the specified pins, and the input, reference, digital-interface, and display connections must follow the manufacturer pin-description table. Because this converter integrates several analog and display functions, PCB layout should preserve a quiet analog input path while routing LED outputs and supply connections away from sensitive measurement nodes.
This product page organizes the manufacturer specifications, package information, pinout guidance, drop-in alternatives, and practical design notes into one engineering reference. It also identifies which parameters require confirmation from the current MAX139 datasheet before a new PCB or replacement decision is finalized.
直接替换替代料： MAX139CMH ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
该产品暂无直接替换替代料。
请求替代料MAX139CMH 最大额定值与电气特性
| ADC Resolution | 3.5 digits |
| Conversion Architecture | Dual-slope ADC |
| Integrated Reference | Internal bandgap reference |
| Oscillator | Internal oscillator |
| Charge-Pump Function | Integrated charge-pump voltage converter |
| Display Driver | Direct LED drivers |
| 封装 | 44-MQFP (10 mm x 10 mm) |
| Terminal Count | 44 terminals |
| Terminal Form | Gull wing |
| Package Shape | Square |
| Temperature Grade | Commercial |
| External Charge-Pump Capacitor Pin 38 | Required connection documented in datasheet |
| External Charge-Pump Capacitor Pin 40 | Required connection documented in datasheet |
MAX139CMH square 引脚配置指南
MAX139CMH（square 封装）的引脚配置。 该功率器件具有栅极、漏极和源极端子。对于无极性封装，请参阅制造商数据手册以了解确切的引脚 1 方向和封装尺寸细节。常见应用包括电源设计、电机驱动和负载开关。
暂无详细引脚数据： MAX139CMH.
请参阅 数据手册 以查看完整引脚配置。
典型应用
MAX139CMH 适用于 6 应用s: Digital Panel Voltmeters, Process-Monitoring Displays, Current-Panel Meters, Laboratory Digital Instruments, Temperature and Resistance Metering, Portable Measurement Instruments.
Digital Panel Voltmeters
The MAX139CMH fits digital panel voltmeters because it combines a 3.5-digit dual-slope converter, internal bandgap reference, internal oscillator, and direct LED display drivers in one 44-MQFP device. The meter can route a conditioned input into the conversion section and use the integrated digit and segment outputs to display the measurement without a separate driver IC. Before layout release, assign the input, reference, charge-pump capacitor, and display connections directly from the MAX139 pin-description table. Keep the analog input trace short, isolate it from LED return paths, and follow the capacitor connection between pins 38 and 40.
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Process-Monitoring Displays
The MAX139CMH is useful in process-monitoring instruments that present a measured value locally rather than sending it to a remote controller. Its 3.5-digit resolution supports compact decimal panel indication, while the integrated bandgap reference reduces the number of discrete reference functions required near the measurement front end. The direct LED drivers allow the same device to handle display excitation alongside conversion. Preserve measurement accuracy by separating the analog input and reference routing from display outputs, using a stable ground strategy, and checking the complete electrical limits against the production input range and ambient conditions.
推荐
Current-Panel Meters
The MAX139CMH can serve as the conversion and display core of a current-panel meter when the sensor signal is first converted into a suitable voltage. The dual-slope conversion architecture suits stable, continuously monitored readings, and the integrated reference supports a self-contained meter design. Its direct LED drivers are particularly useful for four-digit instrument displays. The design must verify the permitted differential input range, common-mode limits, and reference accuracy in the manufacturer datasheet. Shunt Kelvin routing and careful separation between the measurement node and LED-driver return current are important for avoiding display-dependent errors.
推荐
Laboratory Digital Instruments
The MAX139CMH suits laboratory instruments that need a stable, human-readable measurement rather than a high-rate data stream. A 3.5-digit dual-slope converter with an integrated bandgap reference and direct LED outputs can simplify front-panel digital meters for bench power supplies, resistance measurements, and general-purpose instrumentation. Its internal oscillator eliminates a separate timing crystal, while the charge-pump section still requires careful capacitor selection and placement. Validate accuracy, input settling behavior, conversion timing, and supply limits in the MAX139 datasheet before assigning an instrument-grade accuracy specification.
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Temperature and Resistance Metering
The MAX139CMH can form the display core of a temperature or resistance meter when a bridge, thermistor, or resistive sensor is conditioned into the converter's supported input range. The integrated reference and direct LED drivers allow a compact instrument architecture, and the dual-slope converter is appropriate for slowly changing measurements rather than waveform capture. Engineers should calculate the sensor excitation and scaling network, confirm the maximum and minimum input voltages, and verify that the chosen charge-pump capacitor meets the manufacturer's guidance. Guard against leakage and ground gradients when working with high-impedance sensor networks.
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Portable Measurement Instruments
The MAX139CMH is suitable for portable instruments where a compact front panel must display a measured value while consuming fewer discrete components. Its internal bandgap reference and internal oscillator reduce external support requirements, and the direct LED drivers can simplify a battery-operated panel meter. The charge-pump capacitor and analog input network still require careful layout to prevent display activity from perturbing the measurement. Review the supply-voltage limits and operating-temperature range in the manufacturer datasheet, and test the instrument across the intended battery range before production release.
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推荐产品汇总
工程参考数据： MAX139CMH ——对比、设计指导和合规信息。
选型指南
关键差异点
- Integration of measurement conversion and LED excitation （对比 MAX138EPL+)
- No external timing crystal required （对比 ICL7135CPI+)
- Direct LED display output in the meter converter （对比 ICL7106CPL+)
设计说明
Assign every connection from the MAX139 datasheet pin-description table and follow the manufacturer charge-pump layout. Pins 38 and 40 require the external charge-pump capacitor, so place that component close to the IC and minimize the loop area around the associated pins. Keep the analog input and reference routing on the quiet side of the board and route display outputs away from sensitive measurement nodes.
Treat the reference, analog input, and display-driver circuits as separate layout domains even though they share one IC. Provide a direct ground return for the converter and place input filtering close to the associated pins. LED segment and digit outputs can carry changing current, so routing them across or beneath sensitive analog traces can create coupling. Verify the final ground and return-current arrangement against the recommended application circuit in the MAX139 datasheet.
Do not substitute the MAX138, ICL7135, or ICL7106 solely because they also perform dual-slope conversion. The MAX139 combines a 3.5-digit converter, bandgap reference, charge-pump circuit, internal oscillator, and direct LED drivers, and those functions must be matched to the PCB pins and electrical requirements. Confirm supply limits, input range, display-drive capability, external capacitor value, and temperature grade before approving a replacement.
合规信息
The current product information does not state RoHS, REACH, lead-free, halogen-free, or conflict-minerals status. AEC-Q100 is not applicable to this commercial-grade panel-meter ADC.
