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Analog Devices Inc./Maxim Integrated MAX1921EUT15+T
- Part No.:
- MAX1921EUT15+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- SOT-23-6
- Datasheet:
-
MAX1921EUT15+T.pdf
- Description:
- IC REG BUCK 1.5V 400MA SOT6
- Quantity:
- Payment:
- Shipping:
Inventory:90,000
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Product details
Overview
The MAX1921EUT15+T from Maxim Integrated is a fixed-output 1.5V, 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 accuracy, and internal soft-start-designed for battery-powered wireless handsets and CDMA power amplifier supplies.
For engineers reviewing the MAX1921EUT15+T datasheet, MAX1921EUT15+T pinout, MAX1921EUT15+T application, or MAX1921EUT15+T equivalent, key selection criteria include guaranteed 400mA output at 1.5V, shutdown current of 0.1μA, input voltage range of 2.0V to 5.5V, and compatibility with ceramic output capacitors in space-constrained portable designs.
Technical Context
The MAX1921EUT15+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 load range. Its internal synchronous rectifier eliminates external Schottky diodes while maintaining >90% efficiency at medium loads.
This device integrates factory-trimmed 1.5V feedback, UVLO with 1.95V rising threshold and 200mV hysteresis, and logic-controlled active-low shutdown. It operates over –40°C to +85°C and supports voltage positioning via LX-node feed-forward for reduced load-transient overshoot/undershoot.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 1.5V ±1.5% (initial), ±3% over full temperature/load range-enables direct replacement of LDOs in low-voltage core rails. |
| Max Output Current | 400mA continuous-supports RF power amplifiers and baseband processors in handheld devices. |
| Input Voltage Range | 2.0V to 5.5V-compatible with single Li+ cells (2.7–4.2V), alkaline stacks, and 3.3V/5V system rails. |
| Quiescent Current | 50μA (no load)-extends battery life in always-on subsystems like standby radios or sensor interfaces. |
| Shutdown Current | 0.1μA-minimizes leakage during deep sleep modes in portable electronics. |
| Switching Frequency | Up to 1.2MHz-permits use of small 4.7µH inductors and 4.7µF ceramic output capacitors, reducing board area. |
| UVLO Threshold | 1.95V (rising), 1.65V (falling) with 200mV hysteresis-prevents erratic startup/shutdown near battery depletion. |
Pinout & Package
Package: 6-pin SOT23-6, lead-free, RoHS-compliant, 2.9mm × 1.6mm footprint with 0.95mm height-optimized for high-density portable PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - IN | Power Input | 2.0V–5.5V supply input; requires local 2.2µF ceramic bypass capacitor to PGND. |
| 2 - AGND | Analog Ground | Reference ground for internal error amplifier and UVLO; must be connected to PGND at single point. |
| 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 - OUT | Fixed-Voltage Sense | Internal resistor divider taps 1.5V output; no external feedback components required. |
| 5 - PGND | Power Ground | High-current return path for LX switch and synchronous rectifier; connect to AGND star point. |
| 6 - LX | Switch Node | Connects to inductor; drives internal high-side MOSFET and synchronous rectifier; requires low-ESR ceramic output cap. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Eliminates external Schottky diode, improving efficiency by ~10% and reducing thermal stress in 6-pin SOT23. |
| Digital Soft-Start | Gradually ramps current limit in 25% steps to limit inrush and reduce input capacitor sizing requirements. |
| Voltage Positioning Architecture | Leverages inductor DCR for feed-forward load transient compensation-halves peak-to-peak output excursions vs. conventional buck. |
| High-Frequency Operation | 1.2MHz max switching enables compact 4.7µH/4.7µF ceramic LC filter-reducing solution size by >40% vs. 500kHz alternatives. |
| Low-IQ Shutdown | 0.1μA shutdown current ensures negligible battery drain during extended idle periods in handheld devices. |
Applications
| CDMA Power Amplifier Supply | Wireless Handset Core Rail |
|---|---|
Use Scenario: Powers Class AB/Class E CDMA PA stages requiring stable 1.5V at up to 400mA during transmission bursts. IC Role / Device Role / Timing Role: Primary step-down regulator delivering regulated 1.5V from single-cell Li+ input (2.7–4.2V). Use Value: Synchronous rectification and 1.2MHz operation minimize output ripple (<15mVpp) and enable fast load transient recovery (<5µs), preserving PA linearity. | Use Scenario: Supplies low-voltage logic cores (e.g., baseband DSP, audio codec) in next-gen smartphones and feature phones. IC Role / Device Role / Timing Role: High-efficiency buck converter replacing linear regulators to extend battery runtime under dynamic load profiles. Use Value: 50μA quiescent current and 0.1μA shutdown mode directly improve standby time by >30% versus legacy solutions. |
| PDA/Palmtop Memory Interface | Handheld Terminal I/O Rail |
Use Scenario: Provides clean 1.5V supply to low-power SRAM or NOR flash memory in battery-operated PDAs. IC Role / Device Role / Timing Role: Fixed-output DC-DC regulator with tight initial accuracy (±1.5%) ensuring reliable memory read/write margins. Use Value: Internal voltage positioning reduces undershoot during memory access bursts, preventing data corruption at 1.5V VDD. | Use Scenario: Powers RS-232 transceivers, LED backlights, or keypad controllers in rugged handheld terminals. IC Role / Device Role / Timing Role: Compact, robust buck converter supporting wide input (2.0–5.5V) to accommodate varying battery chemistries. Use Value: UVLO hysteresis (200mV) prevents oscillation during brown-out conditions common in alkaline or NiMH battery packs. |
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 | 1.5V fixed, 400mA, 2.05–6.5V input, 3.6MHz switching, 22μA IQ-smaller package (2mm × 2mm WSON), higher frequency. | Requires smaller inductor (1.0µH) but demands tighter layout due to 3.6MHz noise; less tolerant of high-ESR input caps. | Select when board space is critical and input voltage exceeds 5.5V; verify EMI filtering for RF-sensitive zones. |
| RT8059GJ6 | 1.5V fixed, 500mA, 2.5–5.5V input, 1.5MHz switching, 30μA IQ-integrated soft-start, lower RDS(on) high-side FET (0.35Ω typ). | Better light-load efficiency below 10mA; slightly wider input range limitation excludes 2.0V Li+ start-up capability. | Prefer for applications needing >400mA headroom or operating exclusively above 2.5V input; not suitable for 2.0V cold-start scenarios. |
Compared with TPS62231DRYR and RT8059GJ6, the MAX1921EUT15+T offers unique 2.0V startup capability, proven voltage positioning for minimal load transients, and industry-standard SOT23-6 footprint-making it optimal for cost-sensitive, battery-depletion-resilient portable designs where layout simplicity and reliability outweigh ultra-high-frequency miniaturization.
Availability
MAX1921EUT15+T is available at Aetrix Electronics and suitable for CDMA power amplifier supplies, wireless handset core rails, PDA memory interfaces, handheld terminal I/O rails, and battery-powered industrial sensors requiring stable component supply and long-term manufacturability.
Supply support for MAX1921EUT15+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 markets.
The MAX1920/MAX1921 product line was designed specifically for ultra-compact, high-efficiency DC-DC conversion in battery-powered portable electronics-emphasizing low quiescent current, small external components, and robust transient performance.
FAQ
What is the guaranteed output current capability of the MAX1921EUT15+T?
The MAX1921EUT15+T guarantees 400mA continuous output current at 1.5V across the full operating temperature range (–40°C to +85°C) and input voltage range (2.0V to 5.5V). This rating is validated per the Electrical Characteristics table and Typical Operating Characteristics curves, including Efficiency vs. Load Current plots for VOUT = 1.5V. The device maintains regulation without thermal shutdown under these conditions when used with recommended external components.
Does the MAX1921EUT15+T require external feedback resistors?
No, the MAX1921EUT15+T does not require external feedback resistors. It features a factory-preset 1.5V output implemented via an internal resistor divider connected to the OUT pin. Unlike the adjustable MAX1920, this device uses a dedicated OUT pin (Pin 4) instead of FB, eliminating the need for external resistor networks and simplifying layout for fixed-voltage applications.
What is the minimum input voltage required for the MAX1921EUT15+T to start up and regulate?
The MAX1921EUT15+T has a guaranteed startup voltage of 2.0V, as specified in the Electrical Characteristics table under "Startup Voltage" for the MAX1921EUT15 variant. Its UVLO rising threshold is 1.95V (typical), allowing reliable operation down to fully depleted single Li+ cells or two alkaline cells, making it suitable for deep-discharge battery applications.
How does the MAX1921EUT15+T achieve high efficiency without an external Schottky diode?
The MAX1921EUT15+T achieves >90% efficiency through integrated synchronous rectification: it uses an internal low-RDS(on) NMOS transistor as the low-side switch instead of a discrete Schottky diode. This eliminates forward voltage drop losses (typically 0.3–0.4V), reduces conduction loss, and improves thermal performance-all within the same 6-pin SOT23 package as non-synchronous alternatives.
Can the MAX1921EUT15+T be used with ceramic output capacitors?
Yes, the MAX1921EUT15+T is explicitly optimized for ceramic output capacitors, as confirmed in the General Description and Design Procedure sections. The typical application circuit (Figure 1) specifies 4.7µF X5R/X7R ceramic COUT with feed-forward capacitor CFF, and the voltage positioning architecture leverages inductor DCR for stability-eliminating ESR dependency and enabling smaller, more reliable ceramic solutions.
MAX1921EUT15+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- SOT-23-6
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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):
- 1.5V
- Voltage - Output (Max):
- -
- Current - Output:
- 400mA
- Frequency - Switching:
- Up to 1.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-6
MAX1921EUT15+T FAQ
1.How can I place an order for MAX1921EUT15+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1921EUT15+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 MAX1921EUT15+T reliable?
The price and inventory of MAX1921EUT15+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1921EUT15+T is usually 5 days.
3.What payment methods are accepted for MAX1921EUT15+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1921EUT15+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1921EUT15+T?
MAX1921EUT15+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1921EUT15+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 MAX1921EUT15+T?
For technical support, including MAX1921EUT15+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1921EUT15+T requirements.
6.How does Aetrix verify that MAX1921EUT15+T is sourced from the original manufacturer or authorized distributors?
All MAX1921EUT15+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 MAX1921EUT15+T meets industry standards.
7.What is the process for return or replacement of MAX1921EUT15+T?
All MAX1921EUT15+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1921EUT15+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 MAX1921EUT15+T part is unused and in its original packaging.
Return procedure for MAX1921EUT15+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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