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Analog Devices Inc./Maxim Integrated MAX1921EUT25+T
- Part No.:
- MAX1921EUT25+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- SOT-23-6
- Datasheet:
-
MAX1921EUT25+T.pdf
- Description:
- IC REG BUCK 2.5V 400MA SOT6
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
The MAX1921EUT25+T from Maxim Integrated is a fixed-output 2.5V, 400mA synchronous step-down DC-DC converter in a 6-pin SOT23 package, featuring 50μA quiescent current, 1.2MHz max switching frequency, ±1.5% initial output voltage accuracy, and internal soft-start - designed for battery-powered portable electronics requiring compact, high-efficiency power conversion.
For engineers reviewing the MAX1921EUT25+T datasheet, MAX1921EUT25+T pinout, MAX1921EUT25+T application, or MAX1921EUT25+T equivalent, key selection criteria include guaranteed 400mA load capability at 2.5V, factory-preset output (no external feedback resistors), shutdown current of 0.1μA, input range of 2.0V–5.5V, and compatibility with ceramic output capacitors in space-constrained layouts.
Technical Context
The MAX1921EUT25+T employs a proprietary current-limited control scheme with 400ns minimum on-time and off-time, enabling stable operation across light-to-heavy loads while maintaining high efficiency (>90%) via integrated synchronous rectification. It operates without external compensation when used with ceramic output capacitors and implements voltage positioning to minimize load-transient overshoot/undershoot.
This device integrates a fixed 2.5V feedback reference (via internal resistor divider connected to OUT pin), supports logic-controlled shutdown (SHDN active-low), and features UVLO with 1.9V rising threshold and 200mV hysteresis - ensuring reliable startup and brownout protection in Li+-cell and multi-alkaline powered systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 2.5V ±1.5% (initial), ±3% over -40°C to +85°C - eliminates need for external feedback network. |
| Max Output Current | 400mA continuous - supports core logic rails and RF power amplifier bias in handheld devices. |
| Input Voltage Range | 2.0V to 5.5V - compatible with single Li+ (2.7–4.2V), dual AA (2.0–3.2V), and 3.3V/5V system rails. |
| Quiescent Supply Current | 50μA (no load, no switching) - extends battery life in always-on or low-duty-cycle applications. |
| Shutdown Current | 0.1μA - enables ultra-low-power sleep modes in portable instrumentation and wearables. |
| Switching Frequency | Up to 1.2MHz - allows use of small 4.7μH inductors and 4.7μF ceramic output capacitors. |
| UVLO Threshold | 1.95V (rising), 1.65V (falling) with 200mV hysteresis - prevents erratic operation during battery discharge. |
Pinout & Package
MAX1921EUT25+T is housed in a RoHS-compliant, lead-free 6-pin SOT23 package (JEDEC MO-178AA), footprint-compatible with standard SOT23-6 land patterns and suitable for reflow assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - IN | Power input supply | Accepts 2.0V–5.5V; requires local 2.2μF ceramic bypass capacitor to PGND. |
| 2 - AGND | Analog ground reference | Must be connected to PGND at a single-point star ground to minimize noise coupling into feedback path. |
| 3 - SHDN | Active-low enable/shutdown control | Pull to GND for 0.1μA shutdown; connect to IN for normal operation; VIH ≥ 1.6V, VIL ≤ 0.4V. |
| 4 - OUT | Fixed-output voltage sense node | Internally connected to 2.5V divider; no external components required - defines regulated output. |
| 5 - PGND | Power ground return | Carries high-frequency inductor current; must be tied to AGND near device to reduce ground bounce. |
| 6 - LX | Switch node connection | Drives external inductor; requires low-inductance layout to minimize EMI and switching losses. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates external Schottky diode, improves efficiency >90%, reduces thermal stress in SOT23 package. |
| Internal digital soft-start | Limits inrush current by ramping current limit from 25% to 100% in steps - reduces input capacitor stress. |
| Voltage positioning architecture | Uses LX feed-forward (R1/CFF) with ceramic COUT to halve peak-to-peak output excursions during load transients. |
| Factory-preset 2.5V output | Guaranteed ±1.5% initial accuracy at +25°C - removes design uncertainty and BOM count vs. adjustable variants. |
| Ultra-low shutdown current | 0.1μA shutdown supply current - enables multi-year shelf life in battery-backed IoT sensors and medical patches. |
Applications
| CDMA Power Amplifier Supply | Wireless Handset Core Logic Rail |
|---|---|
Use Scenario: Provides stable 2.5V bias to CDMA PA stages in dual-mode handsets operating from single Li+ cell. IC Role / Device Role / Timing Role: Primary step-down regulator delivering 400mA with fast transient response to handle PA burst current demands. Use Value: Internal soft-start prevents input droop during PA turn-on; 1.2MHz switching enables compact 4.7μH/4.7μF filter. |
Use Scenario: Powers baseband processor I/O or memory interface in next-generation smartphones with tight PCB area constraints. IC Role / Device Role / Timing Role: Fixed-output buck converter supplying clean, regulated 2.5V rail with <50μA quiescent draw in standby. Use Value: 0.1μA shutdown current extends battery runtime during deep-sleep cycles; SOT23-6 footprint saves >30% board area vs. QFN alternatives. |
| PDA/Palmtop Application Processor Core | Battery-Powered Industrial Sensor Node |
Use Scenario: Supplies 2.5V core voltage to ARM9-class application processors in handheld terminals running real-time OS. IC Role / Device Role / Timing Role: High-efficiency DC-DC converter maintaining regulation across 20mA–400mA dynamic load profile. Use Value: Voltage positioning minimizes undershoot during CPU wake-up bursts; ±3% accuracy over temperature ensures timing margin compliance. |
Use Scenario: Powers ultra-low-power microcontroller, ADC, and wireless transceiver in remote environmental monitoring nodes. IC Role / Device Role / Timing Role: Primary power stage converting 3.0V alkaline stack to precise 2.5V sensor/reference rail. Use Value: 50μA quiescent current enables >5-year battery life; UVLO hysteresis prevents oscillation near end-of-life cell voltage. |
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 | 2.5V fixed, 400mA, 2.05–6.5V input, 1.8MHz switching, 22μA IQ - higher frequency, lower IQ, but requires external compensation with ceramic COUT. | Supports wider input range and faster transient response; lacks integrated voltage positioning architecture. | Preferred where minimal IQ dominates design priority and layout allows tighter loop control. |
| RT8059GJ6 | 2.5V fixed, 500mA, 2.5–5.5V input, 1.5MHz switching, 30μA IQ - higher current rating and slightly lower IQ, but no soft-start or UVLO hysteresis spec. | Offers headroom for future load growth; lacks guaranteed startup below 2.5V - unsuitable for 2xAA or depleted Li+ cells. | Best suited for 3.3V-input systems with margin for peak current and less stringent low-voltage startup requirements. |
Compared with TPS62231DRYR and RT8059GJ6, the MAX1921EUT25+T delivers superior load-transient suppression via voltage positioning, guaranteed 2.0V startup, and integrated soft-start - making it uniquely suited for battery-fed portable equipment where input voltage sag and burst loading are critical.
Availability
MAX1921EUT25+T is available at Aetrix Electronics and suitable for wireless handset power management, PDA core logic supplies, and battery-powered industrial sensor nodes requiring stable component supply, full traceability, and long-term lifecycle support.
Supply support for MAX1921EUT25+T 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) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and portable applications.
The MAX1920/MAX1921 product line was engineered specifically for space-constrained, battery-operated devices needing high-efficiency, low-quiescent-current DC-DC conversion with factory-preset outputs and minimal external components.
FAQ
What is the guaranteed output current capability of the MAX1921EUT25+T?
The MAX1921EUT25+T guarantees 400mA continuous output current at 2.5V across the full operating temperature range (-40°C to +85°C). This rating is validated under worst-case conditions including maximum ambient temperature, minimum input voltage (2.0V), and specified PCB copper area per the datasheet thermal derating curve for the SOT23-6 package.
Does the MAX1921EUT25+T require external feedback resistors to set the output voltage?
No. The MAX1921EUT25+T uses an internal resistor divider connected to the OUT pin to fix the output at 2.5V - no external feedback resistors are needed. This simplifies layout, reduces BOM count, and eliminates resistor tolerance errors that affect output accuracy in adjustable buck converters like the MAX1920.
What is the minimum input voltage required for the MAX1921EUT25+T to start up and regulate?
The MAX1921EUT25+T starts up and begins regulation when the input voltage rises above 1.95V (typical), as defined by its UVLO rising threshold. Startup is guaranteed down to 2.0V input for the MAX1921EUT25+T variant, enabling reliable operation from partially discharged alkaline or Li+ cells.
How does the MAX1921EUT25+T achieve low output voltage ripple during load transients?
The MAX1921EUT25+T achieves low output voltage ripple during load transients through its voltage positioning architecture: it feeds forward the LX node via R1/CFF to anticipate load changes, reducing peak-to-peak excursions by approximately 50% compared to conventional buck regulators - a key advantage confirmed in the Typical Operating Characteristics plots for 1.5V and 2.5V outputs.
Can the MAX1921EUT25+T be used with a tantalum output capacitor instead of ceramic?
Yes - the MAX1921EUT25+T supports both ceramic and tantalum output capacitors. When using tantalum, the application circuit omits R1 and CFF and relies on the capacitor's ESR for stability. Recommended ESR is ~25mV ripple at the feedback node, and minimum capacitance is calculated based on inductor current and ESR per the datasheet's Design Procedure section.
MAX1921EUT25+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-6
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- -
- Current - Output:
- 400mA
- Frequency - Switching:
- Up to 1.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-6
MAX1921EUT25+T FAQ
1.How can I place an order for MAX1921EUT25+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1921EUT25+T 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 MAX1921EUT25+T reliable?
The price and inventory of MAX1921EUT25+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1921EUT25+T is usually 5 days.
3.What payment methods are accepted for MAX1921EUT25+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1921EUT25+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1921EUT25+T?
MAX1921EUT25+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1921EUT25+T 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 MAX1921EUT25+T?
For technical support, including MAX1921EUT25+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1921EUT25+T requirements.
6.How does Aetrix verify that MAX1921EUT25+T is sourced from the original manufacturer or authorized distributors?
All MAX1921EUT25+T 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 MAX1921EUT25+T meets industry standards.
7.What is the process for return or replacement of MAX1921EUT25+T?
All MAX1921EUT25+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1921EUT25+T, 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 MAX1921EUT25+T part is unused and in its original packaging.
Return procedure for MAX1921EUT25+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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