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Analog Devices Inc./Maxim Integrated MAX1921EUT33+T
- Part No.:
- MAX1921EUT33+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- SOT-23-6
- Datasheet:
-
MAX1921EUT33+T.pdf
- Description:
- IC REG BUCK 3.3V 400MA SOT6
- Quantity:
- Payment:
- Shipping:
Inventory:2,470
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Product details
Overview
The MAX1921EUT33+T from Maxim Integrated is a fixed-output 3.3V, 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 accuracy, and internal soft-start - designed for space-constrained battery-powered equipment including CDMA power amplifier supplies and PDAs.
For engineers reviewing the MAX1921EUT33+T datasheet, MAX1921EUT33+T pinout, MAX1921EUT33+T application, or MAX1921EUT33+T equivalent, key selection criteria include guaranteed 400mA output at 3.3V with <50μA no-load supply current, shutdown current of 0.1μA, input range of 2V to 5.5V, and compatibility with ceramic output capacitors using voltage-positioning topology.
Technical Context
The MAX1921EUT33+T employs a proprietary current-limited control scheme with 400ns minimum on-time and off-time, enabling high efficiency across light-to-heavy loads while maintaining stable regulation without external compensation. Its internal synchronous rectifier eliminates the need for an external Schottky diode.
This device integrates factory-trimmed 3.3V feedback via the OUT pin (not FB), supports voltage positioning for improved transient response, and uses AGND/PGND separation to minimize noise coupling - all within a thermally optimized 6-pin SOT23 footprint rated for -40°C to +85°C operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% (initial), ±3% over full temperature/load range - enables direct replacement of LDOs in 3.3V rail applications. |
| Max Output Current | 400mA continuous - sufficient to power baseband processors or RF front-end ICs in handheld devices. |
| Input Voltage Range | 2V to 5.5V - supports single-cell Li+ (2.7–4.2V), alkaline (2–3.2V), and 3.3V/5V system rails. |
| Quiescent Current | 50μA typical - extends battery life in always-on or low-duty-cycle portable systems. |
| Shutdown Current | 0.1μA - reduces system standby power to negligible levels during deep sleep modes. |
| Switching Frequency | Up to 1.2MHz - allows use of compact 4.7μH–10μH inductors and 4.7μF–10μF ceramic output capacitors. |
| UVLO Threshold | 1.85V (rising), 1.50V (falling) with 200mV hysteresis - prevents erratic startup during brownout conditions. |
Pinout & Package
Package: 6-pin SOT23-6, lead-free (RoHS-compliant), thermal pad not present, footprint compatible with JEDEC MO-178AA.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - IN | Power input | Accepts 2V–5.5V; requires local 2.2μF ceramic bypass capacitor to PGND. |
| 2 - AGND | Analog ground reference | Must be connected to PGND at single-point star ground to avoid noise injection into feedback path. |
| 3 - SHDN | Active-low enable | Pull to GND for 0.1μA shutdown; tie to IN for normal operation; VIH ≥1.6V, VIL ≤0.4V. |
| 4 - LX | Switch node | Connects to inductor; high dv/dt node requiring short, wide trace routing away from sensitive analog paths. |
| 5 - PGND | Power ground return | Carries high-frequency switch current; must be low-inductance connection to CIN and COUT grounds. |
| 6 - OUT | Fixed-voltage sense | Internal resistor divider sets 3.3V output; no external feedback components required. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates external Schottky diode, improving efficiency >90% and reducing BOM count and board area. |
| Digital soft-start | Gradually ramps current limit in 25% steps to limit inrush current and reduce input capacitor stress. |
| Voltage positioning topology | Uses inductor DCR sensing to provide intentional load regulation, halving peak-to-peak output excursions during transients. |
| High-frequency operation | 1.2MHz max switching enables small magnetics and ceramics, cutting solution size vs. 500kHz alternatives by ~40%. |
| Low-noise design | AGND/PGND separation and dedicated OUT pin minimize coupling of switching noise into regulation loop. |
Applications
| CDMA Power Amplifier Supply | Handheld PDA Core Rail |
|---|---|
Use Scenario: Powers Class AB CDMA PA stages requiring stable 3.3V at up to 400mA with fast load transient response. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 3.3V from single-cell Li+ battery (2.7–4.2V). Use Value: Voltage positioning reduces output overshoot/undershoot by 50% during PA burst-mode transitions, eliminating need for oversized output capacitance. | Use Scenario: Supplies main processor core voltage in palm-sized PDAs with tight PCB area constraints. IC Role / Device Role / Timing Role: High-efficiency step-down converter replacing linear regulators to extend battery runtime. Use Value: 50μA quiescent current and 0.1μA shutdown current directly increase standby time by >3× versus comparable non-synchronous buck solutions. |
| Alkaline-Powered Wireless Terminal | Low-Power IoT Sensor Node |
Use Scenario: Powers microcontroller and 2.4GHz transceiver in battery-operated field terminal using two AA cells (2.0–3.2V). IC Role / Device Role / Timing Role: Input-range-optimized buck converter maintaining 3.3V output down to 2.0V input. Use Value: UVLO hysteresis (200mV) prevents oscillation during gradual battery depletion, ensuring clean power-down sequencing. | Use Scenario: Supplies 3.3V to ultra-low-power MCU and BLE radio in energy-harvesting sensor nodes. IC Role / Device Role / Timing Role: Efficient DC-DC stage enabling operation from weak or intermittent sources (e.g., solar cell + capacitor). Use Value: 1.2MHz operation allows use of miniature 0603-size inductors and 0402 MLCCs, reducing total solution volume to <12mm². |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Texas Instruments TPS62231DRVR | 3.3V fixed, 400mA, 2.05–6.5V input, 1.8MHz switching, 17μA IQ | Higher switching frequency enables smaller passives; lower IQ improves ultra-light-load efficiency | Preferred when minimizing solution size or optimizing for sub-1mA load conditions is critical |
| Analog Devices ADP2303ARMZ-3.3-R7 | 3.3V fixed, 600mA, 3–20V input, 600kHz switching, 2.5mA IQ | Wider input range and higher current rating; higher IQ and lower frequency increase passive size | Preferred for industrial applications with unregulated 5V/12V inputs where robustness outweighs size constraints |
Compared with TPS62231DRVR and ADP2303ARMZ-3.3-R7, the MAX1921EUT33+T offers best-in-class 50μA quiescent current for mid-load battery systems and proven voltage positioning for RF load transients - making it optimal for handheld wireless designs where efficiency, size, and transient performance are jointly constrained.
Availability
MAX1921EUT33+T is available at Aetrix Electronics and suitable for CDMA power amplifier supplies, handheld PDA core rails, and alkaline-powered wireless terminals requiring stable component supply with full RoHS compliance and extended temperature support.
Supply support for MAX1921EUT33+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) is a U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, communications, and consumer applications.
The MAX1920/MAX1921 product line was engineered specifically for space-constrained, battery-powered portable electronics - delivering high efficiency at ultralow quiescent current without sacrificing transient response or solution size.
FAQ
What is the input voltage range supported by the MAX1921EUT33+T?
The MAX1921EUT33+T supports an input voltage range of 2.0V to 5.5V. For the 3.3V output variant, operation is guaranteed down to 2.0V input, enabling reliable use with single-cell alkaline (2.0–3.2V) and Li+ (2.7–4.2V) batteries. The UVLO threshold is 1.85V (rising) with 200mV hysteresis, preventing unstable startup during battery discharge.
Does the MAX1921EUT33+T require external feedback resistors?
No, the MAX1921EUT33+T does not require external feedback resistors. It uses an internal resistor divider connected to the OUT pin to set the fixed 3.3V output. This eliminates external components and layout sensitivity associated with feedback networks - unlike the adjustable MAX1920, which requires an external FB resistor divider.
How does the MAX1921EUT33+T achieve high efficiency at light loads?
The MAX1921EUT33+T achieves high efficiency at light loads through its proprietary current-limited control scheme, which reduces peak inductor current after the 400ns minimum on-time. Combined with 50μA quiescent current and synchronous rectification, this enables >85% efficiency even at 1mA load - critical for extending battery life in always-on portable systems.
What is the purpose of the separate AGND and PGND pins on the MAX1921EUT33+T?
The separate AGND and PGND pins on the MAX1921EUT33+T isolate analog reference circuitry from high-current switching paths. AGND serves as the quiet ground reference for the internal voltage divider and error amplifier, while PGND carries pulsed inductor return current. Connecting them at a single star point minimizes noise coupling and ensures ±1.5% output accuracy under dynamic load conditions.
Can the MAX1921EUT33+T be used with ceramic output capacitors?
Yes, the MAX1921EUT33+T is fully compatible with ceramic output capacitors when used in the voltage-positioning configuration shown in Figure 1 of the datasheet. This topology leverages inductor DCR sensing and feed-forward compensation (CFF) to ensure stability and superior transient response - eliminating the ESR dependency required by traditional buck controllers.
MAX1921EUT33+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):
- 3.3V
- 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
MAX1921EUT33+T FAQ
1.How can I place an order for MAX1921EUT33+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1921EUT33+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 MAX1921EUT33+T reliable?
The price and inventory of MAX1921EUT33+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1921EUT33+T is usually 5 days.
3.What payment methods are accepted for MAX1921EUT33+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1921EUT33+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1921EUT33+T?
MAX1921EUT33+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1921EUT33+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 MAX1921EUT33+T?
For technical support, including MAX1921EUT33+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1921EUT33+T requirements.
6.How does Aetrix verify that MAX1921EUT33+T is sourced from the original manufacturer or authorized distributors?
All MAX1921EUT33+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 MAX1921EUT33+T meets industry standards.
7.What is the process for return or replacement of MAX1921EUT33+T?
All MAX1921EUT33+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1921EUT33+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 MAX1921EUT33+T part is unused and in its original packaging.
Return procedure for MAX1921EUT33+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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