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Analog Devices Inc./Maxim Integrated MAX1837EUT33
- Part No.:
- MAX1837EUT33
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- SOT-23-6
- Datasheet:
-
MAX1837EUT33.pdf
- Description:
- IC REG BCK ADJ/1.25V 250MA SOT23
- Quantity:
- Payment:
- Shipping:
Inventory:6,148
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Product details
Overview
MAX1837EUT33 from Maxim Integrated is a high-efficiency, 6-pin SOT23 step-down DC-DC converter with preset 3.3V output, 4.5V–24V input range, 250mA load capability, 12µA quiescent current, and 100% duty-cycle operation enabling ultra-low dropout (120mV at 100mA). It integrates a 24V internal P-channel MOSFET and targets space-constrained battery-powered systems.
For engineers reviewing the MAX1837EUT33 datasheet, MAX1837EUT33 pinout, MAX1837EUT33 application, or MAX1837EUT33 equivalent, key selection criteria include its 3.3V fixed output accuracy (±3.6%), thermal shutdown at +160°C, dual-mode feedback (preset/adjustable), and compatibility with low-ESR ceramic or polymer output capacitors in compact portable designs.
Technical Context
The MAX1837EUT33 employs a proprietary current-limited control architecture that dynamically adjusts switching frequency based on load-eliminating unnecessary switching under light loads to maintain 12µA no-load supply current. Its 100% maximum duty cycle enables continuous conduction down to VIN − VOUT = 120mV, minimizing usable input voltage headroom.
This device operates in discontinuous conduction mode (DCM) across most loads, using internal current sensing and a 1.25V feedback reference to regulate output. The LX pin drives an external inductor (e.g., 22µH for MAX1837), while FB and OUT pins support both preset (FB = GND, OUT = VOUT) and adjustable (FB = divider tap, OUT = GND) configurations-with strict 5.5V upper limit on externally set outputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 24V - supports wide-input industrial and multi-cell battery systems without pre-regulation. |
| Output Voltage | 3.3V ±3.6% (3.168V–3.432V) - factory-trimmed precision for logic rail compliance. |
| Max Output Current | 250mA - sufficient for microcontrollers, sensors, and low-power peripherals in handheld devices. |
| Quiescent Current | 12µA - extends battery life in always-on monitoring applications with infrequent wake-ups. |
| Dropout Voltage | 120mV at 100mA - enables operation down to ~3.42V input when powering 3.3V loads from aging batteries. |
| Shutdown Current | 3µA - ensures minimal leakage during deep sleep modes in portable instrumentation. |
| Switching Frequency | Variable (≈1–2MHz typical) - scales with load to optimize efficiency; no external clock required. |
| Thermal Shutdown | +160°C with 10°C hysteresis - protects against sustained overload or poor PCB thermal design. |
Pinout & Package
MAX1837EUT33 is housed in a 6-pin SOT23 package (JEDEC MO-178AA) with exposed pad (EP) internally connected to GND for thermal and electrical integrity. Pin 1 is marked by a dot; EP must be soldered to a PCB ground plane for optimal thermal performance and EMI suppression.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FB | Dual-mode feedback input | Connect to GND for 3.3V preset mode; connect to resistive divider for adjustable output (1.25V–VIN); threshold is 1.25V ±4%. |
| 2 GND | Power and signal ground reference | Primary return path for internal circuitry, LX switch, and EP pad; star-ground connection critical for stability. |
| 3 IN | Main power input | Supplies internal bias and drives source of integrated 24V P-MOSFET; accepts 4.5V–24V with UVLO at 3.9V (typ). |
| 4 LX | Switch node | Drain of internal P-MOSFET; connects to inductor; switches between IN and GND; requires low-inductance layout. |
| 5 SHDN | Active-low enable/shutdown control | Pull low to reduce supply current to 3µA; must be tied to IN if output >5.5V; min slew rate 10V/ms. |
| 6 OUT | Output sense input | Internally connected to feedback divider; connect to VOUT in preset mode; tie to GND in adjustable mode. |
Key Features
| Feature | Design Value |
|---|---|
| 100% Duty Cycle Operation | Enables lowest possible dropout voltage (120mV @100mA), extending usable battery voltage range in 9V or Li-ion systems. |
| Current-Limited Control Scheme | Eliminates fixed-frequency PWM losses; reduces no-load current to 12µA and enables variable-frequency DCM for peak efficiency across load range. |
| Integrated 24V P-Channel MOSFET | Removes need for external high-voltage switch; simplifies BOM and layout while supporting up to 24V input without external components. |
| Dual-Mode Feedback (Preset/Adjustable) | Factory-set 3.3V output (FB=GND, OUT=VOUT) or user-adjustable 1.25V–VIN (FB=divider, OUT=GND); avoids redesign for multiple voltage rails. |
| Thermal Overload Protection | Auto-recovering shutdown at +160°C junction temperature with 10°C hysteresis prevents permanent damage during sustained overloads. |
| Low-Noise Layout Support | Dedicated EP pad and defined high-current paths (IN→LX→L1→COUT→GND) minimize EMI and improve stability in noise-sensitive analog subsystems. |
Applications
| Handheld Medical Sensors | Industrial 4–20mA Loop Supplies |
|---|---|
Use Scenario: Powering low-noise analog front-ends and BLE transceivers in portable pulse oximeters and glucose meters operating from single 9V or dual AA cells. IC Role / Device Role / Timing Role: Primary 3.3V step-down regulator delivering stable rail to ADC, op-amps, and RF ICs; operates in DCM to minimize conducted EMI near sensitive analog signals. Use Value: 12µA quiescent current extends battery life beyond 12 months in intermittent-use devices; 100% duty cycle maintains regulation until battery drops to 3.42V. | Use Scenario: Providing isolated 3.3V bias for loop-powered field transmitters in hazardous-area process control systems with 24V DC supply. IC Role / Device Role / Timing Role: Local point-of-load regulator converting 24V loop supply to clean 3.3V for sensor excitation, signal conditioning, and HART modem ICs. Use Value: 24V input rating eliminates need for external pre-regulator; thermal shutdown protects against fault conditions in sealed enclosures with limited airflow. |
| Notebook Subsystem Rails | Backup Power Management |
Use Scenario: Generating auxiliary 3.3V rail for embedded controller, keyboard backlight, or smart battery interface in legacy notebook platforms with 12V or 19V main adapters. IC Role / Device Role / Timing Role: Secondary buck converter supplying non-critical subsystems; enabled via system-level SHDN signal during suspend-to-RAM states. Use Value: 3µA shutdown current minimizes standby drain; SOT23 footprint allows placement near load, reducing IR drop and improving transient response. | Use Scenario: Maintaining real-time clock (RTC) and SRAM retention during AC power loss in industrial HMIs and programmable logic controllers using supercapacitor backup. IC Role / Device Role / Timing Role: Low-quiescent buck regulator charging and regulating backup capacitor to 3.3V; operates from main 12V/24V rail during normal operation. Use Value: 12µA no-load draw maximizes hold-up time; 100% duty cycle ensures full capacitor utilization even as main supply decays below 4V. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYR | 3.3V fixed, 300mA, 2.05–6.0V input, 17µA IQ, 2.25MHz fixed frequency | Requires lower input voltage; better suited for single-cell Li-ion or 3.3V systems with tight ripple specs | Select when higher switching frequency and tighter output tolerance (±1%) are prioritized over wide-input flexibility. |
| LT1930ES5#TRMPBF | 3.3V fixed, 250mA, 3.6–25V input, 100µA IQ, 1.2MHz fixed frequency | Higher quiescent current; lacks 100% duty cycle, resulting in higher dropout (~300mV) | Choose when board-level EMI filtering is preferred over ultra-low IQ, and thermal margin exceeds 20°C. |
Compared with TPS62231DRYR and LT1930ES5#TRMPBF, MAX1837EUT33 uniquely combines 24V input capability, 100% duty cycle, and 12µA quiescent current-making it optimal for long-life, wide-input battery systems where dropout and standby power dominate design constraints.
Availability
MAX1837EUT33 is available at Aetrix Electronics and suitable for handheld medical sensors, industrial 4–20mA loop supplies, notebook subsystem rails, and backup power management requiring stable component supply and long-term manufacturability.
Supply support for MAX1837EUT33 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.
The MAX1836/MAX1837 product line was designed specifically for low-power, wide-input DC-DC conversion in space-constrained portable and industrial equipment-emphasizing ultra-low IQ, 100% duty cycle, and integrated high-voltage switching.
FAQ
What is the guaranteed output voltage tolerance for MAX1837EUT33 under full load?
The MAX1837EUT33 guarantees a 3.3V output within ±3.6% (3.168V to 3.432V) across 0–250mA load, -40°C to +85°C, and 4.5V–24V input. This specification is verified per the Electrical Characteristics table in the official Maxim datasheet (Rev 3, 7/06), with typical variation tighter at ±1.5% under nominal conditions. The MAX1837EUT33 uses factory-trimmed internal feedback to achieve this accuracy without external components.
Can MAX1837EUT33 operate with input voltage below 4.5V?
No-MAX1837EUT33 has a hard input undervoltage lockout (UVLO) threshold of 3.9V (typical), with guaranteed turn-on only above 4.4V and turn-off below 3.45V. Operation below 4.5V violates Absolute Maximum Ratings and will cause unregulated output or shutdown. For sub-4.5V applications, consider the MAX17503 or similar low-input buck regulators. The MAX1837EUT33 is strictly specified for 4.5V–24V operation.
How does the 100% duty cycle feature of MAX1837EUT33 improve system performance?
The 100% duty cycle allows the internal P-MOSFET to remain continuously on when input voltage approaches output voltage-reducing dropout to just 120mV at 100mA. This extends usable battery life in 9V or multi-cell systems by enabling regulation down to VIN = 3.42V for a 3.3V rail. Unlike conventional buck converters requiring minimum VIN–VOUT headroom, MAX1837EUT33 maintains regulation until the MOSFET's RDS(ON) and inductor resistance dominate losses.
What is the recommended inductor value for MAX1837EUT33 in a 3.3V/250mA application?
For MAX1837EUT33 delivering 3.3V at 250mA from 12V input, Maxim recommends a 22µH shielded inductor (e.g., Sumida CDRH5D28-220) with ≥625mA saturation current and low DC resistance (<100mΩ). This value balances peak current ripple, efficiency, and physical size. Lower values (e.g., 10µH) increase ripple and stress the internal switch; higher values (e.g., 47µH) reduce ripple but extend transient response time. The MAX1837EUT33 datasheet Figure 2 confirms 22µH as optimal for this configuration.
Does MAX1837EUT33 support adjustable output voltages, and what are the limitations?
Yes-MAX1837EUT33 supports adjustable output from 1.25V to VIN using external resistors on FB, with OUT tied to GND. However, when setting VOUT >5.5V, the SHDN pin must be permanently connected to IN (disabling shutdown), as the internal circuitry cannot safely regulate higher voltages with active shutdown. The feedback reference is precisely 1.25V ±4%, and resistor values should be selected from 10kΩ–100kΩ for optimal noise immunity. This functionality is fully documented for MAX1837EUT33 in the "Design Information" section of the datasheet.
MAX1837EUT33 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-6
- Packaging:
- Bulk
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable (Fixed)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 24V
- Voltage - Output (Min/Fixed):
- 1.25V (3.3V)
- Voltage - Output (Max):
- 24V
- Current - Output:
- 250mA
- Frequency - Switching:
- -
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-6
MAX1837EUT33 FAQ
1.How can I place an order for MAX1837EUT33 through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1837EUT33 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 MAX1837EUT33 reliable?
The price and inventory of MAX1837EUT33 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1837EUT33 is usually 5 days.
3.What payment methods are accepted for MAX1837EUT33?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1837EUT33 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1837EUT33?
MAX1837EUT33 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1837EUT33 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 MAX1837EUT33?
For technical support, including MAX1837EUT33 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1837EUT33 requirements.
6.How does Aetrix verify that MAX1837EUT33 is sourced from the original manufacturer or authorized distributors?
All MAX1837EUT33 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 MAX1837EUT33 meets industry standards.
7.What is the process for return or replacement of MAX1837EUT33?
All MAX1837EUT33 units undergo pre-shipment inspection (PSI). If there is an issue with MAX1837EUT33, 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 MAX1837EUT33 part is unused and in its original packaging.
Return procedure for MAX1837EUT33:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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