MAX133CMH+ - 3.75-Digit 20 CPS ADC | Maxim | Multimeter
MPN： MAX133CMH+ ✗ 停產MAX133CMH+ 概覽
An integrating analog-to-digital converter is a voltage-to-digital conversion IC that integrates an input voltage over a fixed measurement interval. This measurement category belongs to the broader ADC hierarchy, which supports instrumentation, data logging, weighing, process monitoring, and panel-meter designs. Unlike successive-approximation ADCs, integrating converters are commonly selected when low-frequency measurements and specific front-end characteristics are important.
The MAX133 provides a nominal 3.75-digit indication with internal resolution of ±40,000 counts. Its extra guard digit supports autozero or tare operations that reduce the effect of offset when displaying a 4,000-count measurement, providing resolution equivalent to one tenth of a displayed count. Its 50 ms conversion time corresponds to the verified sampling rate of 20 conversions per second. The one-channel integrating architecture is tailored for direct measurement and front-panel instrument use.
The MAX133 and MAX134 form closely related integrating ADC families for digital multimeters, data loggers, and weigh scales. Their functional emphasis is measurement resolution rather than high-speed signal acquisition. Because the MAX133 is designed around the behavior of a 3.75-digit meter, its input network, reference arrangement, integration period, and display-processing strategy must be evaluated together when designing a new analog measurement board.
Typical uses include handheld and bench digital multimeters, panel meters, weighing instruments, laboratory data loggers, and low-frequency industrial monitoring systems. The MAX133 can support the central measurement path where a regulated reference, input conditioning, and the meter’s display and controls are coordinated. The 44-pin MQFP package provides the pins required for analog inputs, reference connections, digital interface signals, supply rails, and associated control functions.
Designers should preserve the recommended analog and reference layout because integrating converters remain sensitive to reference noise, grounding, leakage, and unwanted input signals during the 50 ms conversion interval. Input filtering should be selected for the intended source impedance rather than for the highest possible bandwidth. Power sequencing, bypass placement, and separation between the measurement input and digital interface also deserve attention.
This page consolidates verified manufacturer and distributor information with practical application guidance, package-aware alternatives, comparison parameters, and design notes. It also identifies where source data does not establish a complete pinout, electrical limit, or verified drop-in cross-reference rather than filling those gaps with assumptions.
直接替換替代品，適用於 MAX133CMH+ — 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。
MAX134CMH+
✅ 直接替換聯絡詢價
查看資料表 →MAX133CMH+D
✅ 直接替換📋 參考替代品（不在目錄中）
MAX133CMH+ 最大額定值與電氣特性
| ADC Type | Integrating analog-to-digital converter |
| Displayed Resolution | 3.75 digits |
| Internal Resolution | ±40,000 counts |
| Guard-Digit Resolution | 1/10 of a displayed count |
| Conversion Time | 50 ms |
| 取樣率 | 20 samples/s |
| Channel Count | 1 channel |
| Conversion Method | Proprietary integrating method |
| 封裝 | 44-pin MQFP (10 mm × 10 mm) |
| Package Family | MQFP |
| Terminal Count | 44 terminals |
| Terminal Form | Gull wing |
| Package Shape | Square |
| Temperature Grade | Commercial |
| RoHS 狀態 | Compliant |
MAX133CMH+ square 腳位配置指南
MAX133CMH+（square 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。
無詳細腳位定義資料： MAX133CMH+.
請參閱 資料表 以查看完整腳位配置。
典型應用
MAX133CMH+ 適用於 6 應用s: Handheld Digital Multimeter, Bench-Top Measurement Instrument, Weigh-Scale Front End, Industrial Data Logger, Digital Panel Meter, Low-Frequency Process Monitoring.
Handheld Digital Multimeter
The MAX133CMH+ is suited to the central measurement channel of a 3.75-digit handheld multimeter because the manufacturer positions the MAX133 specifically for integrating ADCs used in these instruments. Its 50 ms conversion time supports a 20-conversion-per-second operating rate, while the ±40,000-count internal resolution provides a guard-digit range beyond the nominal 3.75-digit display. The meter frontend can use this extra resolution for autozero, tare, reference correction, or display scaling. Designers must still implement the input protection, range switching, reference source, and calibration sequence required by the complete measurement path.
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Bench-Top Measurement Instrument
MAX133CMH+ can form the measurement core of a bench-top instrument requiring a stable numeric reading rather than a high-speed waveform. Its 3.75-digit format, 50 ms conversion interval, and ±40,000-count internal range align with panel instruments, laboratory meters, and service equipment that update at a human-readable rate. The extra guard digit supports autozero or tare to one tenth of a displayed count, which can improve offset behavior without changing the displayed digit count. For laboratory use, reference stability and input leakage are as important as the ADC itself because they directly determine the accuracy of the displayed measurement.
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Weigh-Scale Front End
The MAX133CMH+ is appropriate for a low-speed weigh-scale front end where load-cell voltage changes are converted into stable displayed counts. Analog Devices explicitly identifies weigh scales among the data-acquisition applications for the MAX133 family. A 50 ms conversion time provides 20 readings per second, a useful rate for a stationary platform or slowly changing load, while the ±40,000-count internal range offers resolution beyond the 3.75-digit user-facing display. The instrumentation amplifier, excitation source, bridge wiring, shielding, and system calibration must be designed around the converter’s specified input and reference requirements.
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Industrial Data Logger
MAX133CMH+ fits an industrial data logger that records slowly changing process variables such as temperature, pressure, or tank level. The converter’s 20-samples/s rate is sufficient for supervisory measurements without the timing demands of a high-speed acquisition system. Its integrating architecture, 3.75-digit format, and extra guard digit support repeatable panel readings and front-end offset correction. In a field logger, however, long cable runs and noisy transducers require careful isolation, filtering, grounding, and reference design; otherwise, environmental interference can dominate the ADC measurement even when the displayed conversion count is adequate.
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Digital Panel Meter
MAX133CMH+ provides the measurement function for a digital panel meter that presents a stable 3.75-digit value of a conditioned analog signal. The 50 ms conversion period is appropriate for panel updates, and the ±40,000-count internal resolution can support calibration or autozero operations beyond the visible display resolution. A practical implementation can use the converter output with a display controller and input-conditioning network to monitor supply, temperature, pressure, or position. The analog input should be bandwidth-limited to the slow signal being measured, while the reference and power layout should minimize noise that could create flickering or inconsistent panel readings.
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Low-Frequency Process Monitoring
MAX133CMH+ can be used in a low-frequency process-monitoring subsystem where the controller needs repeated numeric measurements rather than continuous high-rate sampling. Its 20-conversions-per-second capability gives a defined update cadence, and the integrating conversion method is consistent with the slow response of many temperature, level, and pressure sensors. The extra internal count range offers flexibility for offset compensation and calibration. System designers must verify that the complete MAX133 electrical specification supports the selected sensor excitation, signal range, reference arrangement, and environmental isolation, because those conditions are not established by the supplied excerpts.
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推薦產品摘要
工程參考資料，適用於 MAX133CMH+ — 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 | MAX134CMH+ | MAX133CMH+D |
|---|---|---|---|
| Package | 44-pin MQFP (10 mm × 10 mm) | 44-pin MQFP | 44-pin MQFP (10 mm × 10 mm) |
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| ADC Type | Integrating ADC | Integrating ADC | Integrating ADC |
| Displayed Resolution | 3.75 digits | 3.75 digits | 3.75 digits |
主要差異化特點
- Purpose-built 3.75-digit instrument resolution (對比MAX134CMH+)
- Defined 50 ms conversion timing (對比MAX134CMH+)
- Same 44-MQFP format as the listed ordering option (對比MAX133CMH+D)
設計說明
Keep the measurement input, reference network, converter ground, and supply bypass in a compact analog region. The integrating conversion process depends on accurate reference and input behavior throughout each 50 ms measurement interval, so long traces and high-impedance nodes can increase error. Route digital interface signals away from sensitive analog pins, use a continuous ground reference where appropriate, and verify the final layout against the manufacturer’s recommended PCB example.
Do not assume that the 3.75-digit display rating specifies the complete input or reference range. The supplied excerpts establish ±40,000-count internal resolution but do not provide the supply voltage, differential or single-ended input configuration, or reference voltage. Obtain the complete MAX133 electrical characteristics before selecting divider values, protection components, or reference circuitry. Likewise, the MAX134CMH+ alternative should not be approved solely from its family relationship because its differentiating operating parameter is not quantified in the verified excerpt.
Band-limit the analog input according to the slowest signal of interest rather than exposing the measurement node to unnecessary high-frequency noise. Excess bandwidth can disturb an integrating conversion and increase variability in the displayed result. Place input filtering close to the converter or the measurement front end, use components with suitable temperature coefficients and leakage behavior, and evaluate the complete source impedance and settling sequence. The guard-digit resolution should be used for calibration or autozero only after those system-level errors are controlled.
合規資訊
RoHS-compliant status is stated in the verified MAX133CMH+D family result. The supplied excerpts do not establish exact-suffix REACH, lead-free, halogen-free, conflict-minerals, or automotive qualification status. AEC-Q100 is treated as not applicable because the verified temperature grade is commercial.
