MAX138EPL+ - 3.5-Digit ADC with LED Drivers | Analog Devices
MPN： MAX138EPL+ ✓ 啟用中MAX138EPL+ 概覽
A dual-slope ADC is a type of integrating analog-to-digital converter that measures an unknown input by comparing it against a reference over fixed integration periods. Its architecture is well suited to panel meters, laboratory instruments, and industrial displays because it converts slow or quasi-static input voltages into stable digital counts. Within the broader hierarchy of ADC to data-converter IC to signal-chain IC, the MAX138 combines conversion, voltage-reference, charge-pump, and display-interface functions.
The MAX138EPL+ includes several integrated features that simplify a three-and-a-half-digit display design. Its internal bandgap reference supports repeatable measurements without an external precision reference. The charge pump permits bipolar input measurement from a single positive supply, while the direct LED drivers reduce the external circuitry required for common-anode multiplexed displays. The manufacturer lists the MAX138 as a production device in a 3.5-digit ADC family designed for single +2.5V to +7V operation.
The MAX138 is a dual-slope converter rather than a high-speed SAR ADC. This makes it appropriate for continuously changing panel-meter readings rather than waveform sampling or high-rate data acquisition. Its integrated display circuitry places it in the LCD and LED driver category at distributors, while its core function remains analog-to-digital conversion. The industrial-temperature option is identified for MAX138EPL+ in distributor technical data.
Typical uses include digital panel meters, process-monitoring instruments, laboratory test equipment, temperature-controller displays, weighing-system indicators, and portable measurement products. In these systems, the converter can accept bipolar sensor signals, generate a negative input reference through its charge pump, and update a local LED display without requiring a separate seven-segment driver IC.
Designers should verify the exact LCD or LED polarity, digit-drive topology, input ranges, reference accuracy, and timing requirements against the manufacturer datasheet before layout. A 40-pin through-hole DIP package is straightforward to prototype and automate but occupies considerably more board area than a surface-mount alternative. Decoupling, analog-ground routing, and protection of the analog input remain important for stable panel-meter readings.
This page consolidates the verified manufacturer specifications, distributor availability, package details, and carefully qualified drop-in comparison options. It also distinguishes verified MAX138-family substitutes from broader functional equivalents so engineers can assess PCB reuse, supply compatibility, display-drive requirements, and production availability without relying on unsupported cross-reference claims.
直接替換替代品，適用於 MAX138EPL+ — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
MAX138CPL+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX131CPL+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX131AEPL+
✅ 直接替換📋 參考替代品（不在目錄中）
MAX138EPL+ 最大額定值與電氣特性
| ADC Resolution | 3.5 digits |
| ADC Architecture | Dual-slope |
| Supply Voltage Range | +2.5 V to +7 V |
| Input Capability | Bipolar inputs |
| Integrated Reference | Bandgap reference |
| Charge Pump | Integrated charge-pump voltage converter |
| Display Driver | Direct LED drivers |
| 封裝 | DIP-40 |
| Terminal Count | 40 terminals |
| 安裝類型 | Through-hole |
| Temperature Grade | Industrial |
| Manufacturer Document Revision | Data Sheet Rev. 2 |
MAX138EPL+ dip-40 腳位配置指南
MAX138EPL+（dip-40 封裝）的腳位配置。 此功率元件具有閘極、汲極與源極端子。對於非極性封裝，請參閱製造商資料表以取得確切的第 1 腳方向與佈局詳細資訊。常見應用包括電源設計、馬達驅動與負載切換。
無詳細腳位定義資料： MAX138EPL+.
請參閱 資料表 以查看完整腳位配置。
典型應用
MAX138EPL+ 適用於 6 應用s: Digital Panel Meters, Process Monitoring Instruments, Temperature Controller Displays, Laboratory Measurement Instruments, Weighing-System Indicators, Portable Measurement Products.
Digital Panel Meters
The MAX138EPL+ fits digital panel meters because it combines a 3.5-digit dual-slope ADC with a bandgap reference, charge pump, and direct LED drivers in one DIP-40 package. Its single +2.5V to +7V supply simplifies instrumentation powered from a regulated laboratory or industrial rail. The converter and display functions share the device, reducing the component count compared with separate ADC and LED-driver circuits. Designers should confirm whether the meter uses common-anode or common-cathode seven-segment displays and verify the exact digit-drive timing in the manufacturer datasheet.
推薦
Process Monitoring Instruments
The MAX138EPL+ is appropriate for process-monitoring equipment that displays a slowly changing pressure, flow, level, or position measurement. Its dual-slope architecture is suited to quasi-static panel readings, and the bipolar-input capability permits a single positive supply to be used with sensors whose signals extend below ground. The integrated bandgap reference supports a compact instrument, while the +2.5V to +7V operating range covers common low-voltage industrial rails. Input protection, scaling, and grounding still require careful design.
推薦
Temperature Controller Displays
A temperature-control panel can use the MAX138EPL+ to convert a conditioned sensor voltage into a three-and-a-half-digit local reading. The MAX138EPL+ accepts bipolar inputs and includes a charge pump, which is useful when the thermocouple or sensor-conditioning stage produces a signal around ground. Its direct LED drivers allow the controller to present the value locally without a separate display-driver IC. Because temperature accuracy depends on the sensor, reference accuracy, and input path, designers should budget separately for probe and analog-conditioning error.
推薦
Laboratory Measurement Instruments
The MAX138EPL+ supports laboratory instruments requiring a readable measurement rather than a high-speed digital waveform. Its 3.5-digit dual-slope conversion architecture is suitable for slowly varying voltages, and the integrated reference reduces the number of precision components in a meter design. Operation from a single +2.5V to +7V supply also simplifies portable bench instruments. The DIP-40 footprint favors prototypes and through-hole assembly, while the complete pinout, input thresholds, and conversion timing must be taken directly from the manufacturer datasheet.
推薦
Weighing-System Indicators
The MAX138EPL+ can serve as the measurement front end in a compact weighing indicator because load-cell signals are slow bipolar voltages that are well matched to a dual-slope ADC. The internal charge pump supports bipolar sensing from a single positive supply, while the integrated reference and LED drivers support a self-contained display design. The MAX138EPL+ operates from +2.5V to +7V, which is compatible with common regulated supply rails. For commercial weighing equipment, verify excitation requirements, input bandwidth, calibration resolution, and regulatory requirements separately from the ADC itself.
推薦
Portable Measurement Products
The MAX138EPL+ is suitable for portable meters because its measurement and display functions are integrated while its supply range begins at +2.5V. A single positive rail reduces the number of required power sources, and the dual-slope conversion method supports stable readings from slowly changing sensor outputs. The DIP-40 package is easy to prototype and hand solder but is larger than a surface-mount option, which is an important constraint for compact handheld products. Battery life and display loading should be evaluated with the complete system power budget.
推薦
推薦產品摘要
工程參考資料，適用於 MAX138EPL+ — 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 | MAX138CPL+ | MAX131CPL+ | MAX131AEPL+ |
|---|---|---|---|---|
| Package | DIP-40 | DIP-40 - same package | DIP-40 - same package | DIP-40 - same package |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| ADC Resolution | 3.5 digits | 3.5 digits | 3.5 digits | 3.5 digits |
| ADC Architecture | Dual-slope | Dual-slope | Dual-slope | Dual-slope |
| Integrated Reference | Bandgap reference | Reference | Bandgap reference | Bandgap reference |
| Charge Pump | Integrated | Integrated | Integrated | Integrated |
| Display Driver | Direct LED drivers | Onboard LCD display drivers | Onboard 3.5-digit display drivers | Onboard 3.5-digit display drivers |
主要差異化特點
- Lower upper supply voltage than the MAX131 alternatives (對比MAX131CPL+)
- Verified industrial-temperature ordering configuration (對比MAX138CPL+)
- Direct LED-driver integration for panel instruments (對比TC7136CPL)
設計說明
Route the analog input, reference, and charge-pump-related connections away from digital display-drive and switching nodes. Place the device's required bypass capacitors directly at the supply pins and keep the analog-input trace short to minimize pickup. Although the supplied data does not specify the required capacitor values, the manufacturer datasheet should determine capacitance, voltage rating, tolerance, and placement.
Do not substitute a 40-pin ADC solely because the package and digit count match. MAX131CPL+ and MAX131AEPL+ are documented with a +4.5V to +14V supply range, whereas MAX138EPL+ operates from +2.5V to +7V. Confirm supply limits, input thresholds, display polarity, conversion timing, temperature grade, and every unused pin before treating a candidate as a production drop-in replacement.
Budget the digital display-driver current separately from the ADC and reference current when sizing the supply. The verified data establishes the +2.5V to +7V operating range but does not provide the complete current-consumption specification. Use the manufacturer datasheet for quiescent current, digit-drive current, charge-pump load, and supply decoupling, especially when several LED digits are active simultaneously.
The DIP-40 footprint is convenient for prototyping and automated through-hole assembly but occupies substantial board area. Provide adequate spacing around the socket or package, observe the manufacturer's row spacing, and avoid placing tall heat-generating parts against the IC. If production volume or board area later becomes critical, redesign around a verified surface-mount equivalent rather than assuming that every 40-pin DIP alternative is mechanically interchangeable.
合規資訊
The supplied manufacturer and distributor search results do not explicitly state RoHS, REACH, AEC-Q100, lead-free, halogen-free, or conflict-minerals status. Compliance values are therefore recorded as unknown rather than inferred from the part number or package.
