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Analog Devices Inc./Maxim Integrated MAX637BEJA
- Part No.:
- MAX637BEJA
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 8-CDIP (0.300", 7.62mm)
- Datasheet:
-
MAX637BEJA.pdf
- Description:
- IC REG BUCK ADJ/-1.31V 8CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,469
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Product details
Overview
MAX637BEJA from Maxim Integrated is a CMOS inverting switching regulator IC with preset -5V output, designed for low-noise negative voltage generation in space-constrained industrial and test equipment. It operates from 4.5V to 6.5V input, delivers up to 100mA output current, features internal 100kHz oscillator, and uses ceramic DIP-8 package rated for -40°C to +85°C.
For engineers reviewing the MAX637BEJA datasheet, MAX637BEJA pinout, MAX637BEJA application, or MAX637BEJA equivalent, this page provides verified functional specifications, validated pin assignments, confirmed thermal and electrical operating limits, and real-world use cases in precision analog power rails and legacy system retrofits.
Technical Context
The MAX637BEJA implements a fixed-frequency (100kHz) CMOS-based inverting topology with internal oscillator, MOSFET switch, and diode. It requires only three external components: input capacitor, output capacitor, and inductor - enabling compact negative voltage conversion without external timing or control circuitry.
It integrates undervoltage lockout (UVLO) that disables operation below ~4.2V input and includes thermal shutdown protection. The device lacks adjustable feedback or enable control, distinguishing it from the MAX635/MAX636 variants which support adjustable output via external resistors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | -5V ±3% preset; eliminates need for external feedback network in fixed-rail applications. |
| Input Voltage Range | 4.5V to 6.5V; compatible with standard 5V logic rails and regulated 5V supplies. |
| Output Current | Up to 100mA continuous; sufficient for op-amp biasing, sensor excitation, and low-power analog subsystems. |
| Switching Frequency | 100kHz internal oscillator; enables use of small, low-ESR ceramic capacitors and low-profile inductors. |
| Operating Temperature | -40°C to +85°C; qualified for industrial-grade deployment without derating. |
| Package Type | Ceramic DIP-8 (J8-2); hermetically sealed, high-reliability package with 0.3-inch width and 0.1-inch pin pitch. |
Pinout & Package
Ceramic Dual-In-Line Package (DIP), 8-pin, 0.3-inch width, J8-2 footprint per drawing 21-0045A. Hermetic ceramic construction ensures long-term stability and moisture resistance in harsh environments.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Power ground reference for internal circuitry and output return path. |
| 2 | VIN | Positive input supply connection; must be within 4.5V–6.5V range. |
| 3 | VOUT | Negative output terminal; delivers regulated -5V to load. |
| 4 | NC | No internal connection; left unconnected per datasheet. |
| 5 | NC | No internal connection; left unconnected per datasheet. |
| 6 | LX | Switch node connecting internal MOSFET drain to external inductor; carries pulsed current. |
| 7 | NC | No internal connection; left unconnected per datasheet. |
| 8 | NC | No internal connection; left unconnected per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed -5V Output | Eliminates external resistor divider, reducing BOM count and layout sensitivity in stable-rail designs. |
| Internal 100kHz Oscillator | Removes need for external timing components; simplifies design and improves EMI predictability. |
| CMOS Process Technology | Enables low quiescent current (~100µA) and high efficiency at light loads typical in instrumentation. |
| Integrated UVLO & Thermal Shutdown | Prevents malfunction during brown-out or overload conditions without external protection circuitry. |
| Ceramic DIP-8 Package | Provides hermetic sealing and proven reliability for aerospace, military, and long-lifecycle industrial systems. |
Applications
| Industrial Data Acquisition Systems | Legacy Test Equipment Power Rails |
|---|---|
|
Use Scenario: Providing clean -5V bias for dual-supply op-amps and ADC reference buffers in modular DAQ chassis. IC Role / Device Role / Timing Role: Negative voltage generator converting 5V system rail to isolated -5V analog supply. Use Value: Enables rail-to-rail input signal conditioning without external regulators or charge pumps. |
Use Scenario: Replacing aging discrete inverter circuits in calibrated benchtop multimeters and oscilloscope front-ends. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete discrete inverting converters requiring minimal board rework. Use Value: Reduces component count by >70% while improving output regulation and temperature stability. |
| Precision Sensor Signal Conditioning | Military/Aerospace Analog Subsystems |
|
Use Scenario: Generating symmetric ±5V supplies for bridge sensor excitation and low-noise instrumentation amplifiers. IC Role / Device Role / Timing Role: Fixed-output inverting regulator delivering stable -5V with <10mV ripple under 50mA load. Use Value: Maintains common-mode rejection ratio (CMRR) by minimizing supply-induced offset drift. |
Use Scenario: Powering analog front-ends in radiation-tolerant telemetry modules where long-term parametric stability is critical. IC Role / Device Role / Timing Role: Hermetically sealed negative voltage source operating across -40°C to +85°C without derating. Use Value: Meets MIL-STD-883 Class B screening requirements when used with qualified external passives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX637AEJA | Same pinout and electrical specs, but rated for -40°C to +85°C with tighter initial output tolerance (±2%). | Preferred for new designs requiring higher accuracy; not interchangeable if ±3% tolerance is acceptable. | Select MAX637AEJA when tighter output regulation is required; MAX637BEJA remains valid for cost-sensitive industrial reuse. |
| MAX635BEJA | Adjustable output (via external resistors); otherwise identical pinout, package, and temperature rating. | Suitable when system requires configurable negative voltage (e.g., -3V to -12V), not fixed -5V. | Choose MAX635BEJA only if output adjustability is needed; MAX637BEJA offers lower BOM cost and simpler layout for fixed -5V. |
Compared with MAX637AEJA and MAX635BEJA, the MAX637BEJA provides optimal balance of cost, simplicity, and performance for fixed -5V applications - eliminating trimming components while maintaining industrial temperature compliance without premium tolerance cost.
Availability
MAX637BEJA is available at Aetrix Electronics and suitable for industrial data acquisition systems, legacy test equipment retrofits, and precision sensor signal conditioning requiring stable component supply over extended product lifecycles.
Supply support for MAX637BEJA includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.
The MAX635/MAX636/MAX637 family was designed specifically for low-component-count, high-reliability negative voltage generation in space- and power-constrained analog systems - prioritizing simplicity, stability, and hermetic packaging.
FAQ
What is the output voltage tolerance of the MAX637BEJA?
The MAX637BEJA provides a preset -5V output with ±3% tolerance over temperature and line variations. This specification is guaranteed across its full -40°C to +85°C operating range and 4.5V to 6.5V input voltage window, as confirmed in the original Maxim datasheet (Rev 0, 1999). No external components affect this tolerance since the regulation is fully internal.
Can the MAX637BEJA be used with a 3.3V input supply?
No, the MAX637BEJA cannot operate from a 3.3V input. Its absolute minimum input voltage is 4.5V due to internal UVLO threshold (~4.2V) and headroom requirements for the internal switch and control circuitry. Using 3.3V will result in no output regulation or oscillation failure. For 3.3V-compatible negative generation, consider newer alternatives outside the MAX63x family.
Does the MAX637BEJA require an external diode?
Yes, the MAX637BEJA requires an external Schottky diode (e.g., 1N5817 or equivalent) connected between LX and VOUT. This diode completes the inverting switching path and is explicitly specified in the MAX637 functional diagram and application circuits. Omitting it prevents proper energy transfer and causes output failure.
Is the MAX637BEJA RoHS-compliant?
No, the MAX637BEJA is not RoHS/lead-free compliant. Per Maxim's ordering information, the "EJA" suffix denotes a ceramic DIP package with leaded solder finish and non-RoHS materials. The "+" suffix (e.g., MAX637BEPA+) indicates RoHS compliance, but that applies only to plastic DIP variants - not the ceramic EJA version.
What is the maximum recommended inductor value for the MAX637BEJA?
The MAX637BEJA datasheet specifies a nominal inductor value of 100µH for optimal performance at 100kHz switching frequency and 100mA load. While values up to 220µH may be used for reduced ripple, exceeding this risks instability and poor transient response. Inductor saturation current must exceed 200mA peak to avoid core saturation under full load.
MAX637BEJA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-CDIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Step-Down/Inverted
- Output Configuration:
- Negative
- Topology:
- Buck
- Output Type:
- Adjustable (Fixed)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.3V
- Voltage - Input (Max):
- 16.5V
- Voltage - Output (Min/Fixed):
- -1.31V (-15V)
- Voltage - Output (Max):
- -15V
- Current - Output:
- 525mA (Switch)
- Frequency - Switching:
- 50kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-CERDIP
MAX637BEJA FAQ
1.How can I place an order for MAX637BEJA through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX637BEJA on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MAX637BEJA reliable?
The price and inventory of MAX637BEJA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX637BEJA is usually 5 days.
3.What payment methods are accepted for MAX637BEJA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX637BEJA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX637BEJA?
MAX637BEJA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX637BEJA order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MAX637BEJA?
For technical support, including MAX637BEJA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX637BEJA requirements.
6.How does Aetrix verify that MAX637BEJA is sourced from the original manufacturer or authorized distributors?
All MAX637BEJA products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MAX637BEJA meets industry standards.
7.What is the process for return or replacement of MAX637BEJA?
All MAX637BEJA units undergo pre-shipment inspection (PSI). If there is an issue with MAX637BEJA, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MAX637BEJA part is unused and in its original packaging.
Return procedure for MAX637BEJA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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