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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 SOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:14,853
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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 such as 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 load capability at 3.3V output, shutdown current of 0.1μA, input voltage range of 2.0V to 5.5V (for 3.3V variant), SOT23-6 footprint compatibility, and synchronous rectification eliminating external Schottky diodes.
Technical Context
The MAX1921EUT33-T employs a proprietary current-limited control scheme with 400ns minimum on-time and off-time, enabling fast transient response and stable operation across 0–400mA loads. Its internal synchronous rectifier integrates both high-side and low-side MOSFETs, achieving >90% efficiency without external diodes.
This device operates in voltage-positioning mode when paired with ceramic output capacitors, using feed-forward compensation (CFF) and LX-node feedback to minimize load-transient undershoot/overshoot. Shutdown is logic-controlled via active-low SHDN pin, reducing supply current to 0.1μA while placing LX in high-impedance state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.5% initial accuracy; supports stable regulation under 400mA load at 2.0V–5.5V input. |
| Max Output Current | 400mA continuous; guaranteed delivery without thermal derating in SOT23-6 at TA ≤ +70°C. |
| Quiescent Current | 50μA typical at no load; enables ultra-low-power operation in always-on subsystems. |
| Shutdown Current | 0.1μA typical; reduces system standby power in portable devices with intermittent operation. |
| Switching Frequency | Up to 1.2MHz; permits use of small 4.7μH inductors and 4.7μF ceramic output capacitors. |
| Input Voltage Range | 2.0V to 5.5V for 3.3V output variant; supports single Li+ cell (2.7–4.2V) and dual AA/AAA (2.0–3.0V) sources. |
| UVLO Threshold | 1.85V (rising), 1.50V (falling); provides clean startup and brownout protection for battery-fed systems. |
Pinout & Package
Package: 6-pin SOT23-6 (JEDEC MO-178AA), RoHS-compliant, 2.9mm × 1.6mm footprint, 1.1mm height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - IN | Power input | Accepts 2.0V–5.5V; requires local 2.2μF ceramic bypass capacitor to PGND/AGND. |
| 2 - AGND | Analog ground reference | Must be connected to PGND at single-point star ground; references internal error amplifier and UVLO. |
| 3 - SHDN | Active-low enable control | Pull to GND for 0.1μA shutdown; tie to IN for normal operation; VIH ≥ 1.6V, VIL ≤ 0.4V. |
| 4 - OUT | Fixed-output voltage sense | Internally connected to factory-trimmed resistor divider for 3.3V regulation; not user-adjustable. |
| 5 - PGND | Power ground return | Carries high-frequency inductor current; connect directly to AGND near device to minimize noise coupling. |
| 6 - LX | Switch node | Drives external inductor; requires low-ESR ceramic output capacitor and careful PCB layout to suppress EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates external Schottky diode; improves efficiency >90% and reduces thermal stress in SOT23 package. |
| Internal digital soft-start | Limits inrush current during startup by ramping current limit in 25% steps; reduces input capacitor stress. |
| Voltage positioning architecture | Uses LX feedback + CFF feed-forward to halve peak-to-peak output excursions during 20mA→320mA transients. |
| Ultra-low shutdown current | 0.1μA shutdown supply current enables multi-week battery life in sleep-mode wireless handsets. |
| High-frequency operation | 1.2MHz max switching allows compact 4.7μH inductors and 4.7μF ceramic output caps - saving board area vs. 500kHz converters. |
Applications
| CDMA Power Amplifier Supply | Wireless Handset Core Logic |
|---|---|
Use Scenario: Powers RF power amplifier stages in CDMA cellular handsets requiring stable 3.3V at up to 400mA peak current. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 3.3V from single Li+ battery (2.7–4.2V). Use Value: Internal soft-start prevents input voltage sag during PA turn-on; synchronous rectification maintains >88% efficiency at 300mA load. |
Use Scenario: Supplies core logic voltage (3.3V) to baseband processors and memory in next-generation wireless handsets. IC Role / Device Role / Timing Role: High-efficiency point-of-load converter operating from shared battery rail with fast transient response. Use Value: Voltage positioning architecture reduces output voltage deviation to <±15mV during 100mA load steps, ensuring processor stability. |
| PDA/Palmtop Main System Rail | Battery-Powered Industrial Sensor Node |
Use Scenario: Provides main 3.3V system rail for PDAs, palmtops, and handy-terminals powered by dual alkaline cells (2.0–3.0V). IC Role / Device Role / Timing Role: Step-down regulator supporting wide-input operation down to 2.0V while maintaining regulation. Use Value: UVLO threshold of 1.85V ensures reliable startup from fresh alkaline cells; 50μA quiescent current extends runtime between charges. |
Use Scenario: Powers microcontroller, radio transceiver, and analog sensors in long-life industrial sensor nodes with coin-cell or Li-SOCl₂ backup. IC Role / Device Role / Timing Role: Low-quiescent, shutdown-capable DC-DC converter enabling periodic wake-up and measurement cycles. Use Value: 0.1μA shutdown current allows >10-year battery life in duty-cycled deployments; SOT23-6 footprint fits compact sensor modules. |
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 TPS62231DRYR | 3.3V fixed, 400mA, 2.05–6.5V input, 17μA IQ, 2.25MHz switching, 5-pin WSON. | Higher switching frequency enables smaller passives but requires tighter layout control; lacks internal soft-start. | Select for higher efficiency at light loads and space-constrained layouts where 2.25MHz operation is acceptable. |
| Analog Devices ADP2303AUJZ-3.3-R7 | 3.3V fixed, 600mA, 3.0–20V input, 2.2MHz, 6-pin TSOT-23, includes power-good flag. | Wider input range and higher current rating; larger package and higher minimum input voltage (3.0V). | Select when input exceeds 3.0V or when power-good signaling is required; not suitable for sub-3.0V battery sources. |
Compared with the MAX1921EUT33-T, the TPS62231DRYR offers lower quiescent current and higher frequency but requires external soft-start circuitry, while the ADP2303AUJZ-3.3-R7 supports higher input voltages and load currents but cannot operate below 3.0V - making the MAX1921EUT33-T uniquely suited for 2.0V–3.0V alkaline/Li+ battery systems demanding integrated soft-start and minimal BOM count.
Availability
The MAX1921EUT33-T is available at Aetrix Electronics and suitable for CDMA power amplifier supplies, wireless handset core logic rails, and PDA/palmtop main system rails requiring stable component supply, consistent parametric performance, and long-term production continuity.
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) designs precision analog, mixed-signal, and power-management ICs for industrial, automotive, communications, and consumer applications.
The MAX1920/MAX1921 product line delivers high-efficiency, ultra-small-footprint step-down converters targeting battery-powered portable electronics where size, efficiency, and low IQ are critical design constraints.
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 its 3.3V output variant, enabling direct operation from single Li+ cells (2.7–4.2V), dual alkaline/AAA batteries (2.0–3.0V), or regulated 3.3V/5V system rails. This range is confirmed in the Electrical Characteristics table under "Startup Voltage" and "Input Voltage Range" for MAX1921EUT33.
Does the MAX1921EUT33-T require an external feedback resistor network?
No, the MAX1921EUT33-T does not require an external feedback resistor network. It features a factory-preset 3.3V output achieved via internal trimming of the voltage-divider connected to the OUT pin - unlike the adjustable MAX1920 which uses the FB pin and external resistors. The OUT pin is dedicated solely to internal sensing.
What is the maximum guaranteed output current for the MAX1921EUT33-T?
The MAX1921EUT33-T guarantees 400mA continuous output current across the full operating temperature range (–40°C to +85°C) when used with appropriate external components (e.g., 4.7μH inductor, 4.7μF ceramic output capacitor) and within thermal limits of the SOT23-6 package. This is specified in the General Description and confirmed in the Absolute Maximum Ratings.
How does the MAX1921EUT33-T achieve high efficiency without an external Schottky diode?
The MAX1921EUT33-T achieves >90% efficiency through integrated synchronous rectification - it contains both high-side and low-side MOSFETs on-die. During the off-phase of the high-side switch, the low-side MOSFET conducts instead of a lossy external diode, eliminating forward-voltage drop and associated conduction losses.
Can the MAX1921EUT33-T be used with ceramic output capacitors?
Yes, the MAX1921EUT33-T is explicitly optimized for ceramic output capacitors. Its voltage-positioning architecture - using LX node feedback and a feed-forward capacitor (CFF) - ensures stability and minimizes transient overshoot/undershoot with low-ESR ceramics, as demonstrated in Figures 1 and 15 of the datasheet.
MAX1921EUT33-T 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:
- 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-23-6
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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