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Analog Devices Inc./Maxim Integrated MAX1821EUB+
- Part No.:
- MAX1821EUB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Special Purpose Regulators
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX1821EUB+.pdf
- Description:
- IC REG CONV WCDMA 1OUT 10UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:327
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Product details
Overview
MAX1821EUB+ from Maxim Integrated is a fixed-output, synchronous step-down DC-DC buck regulator optimized for microprocessor core supplies and portable RF power stages. It delivers 600mA guaranteed output current with 1MHz PWM switching, 150mV dropout at full load (including external inductor RDC), and operates from 2.6V to 5.5V input. Its programmable output voltage (1.25V–5.5V via external resistive divider) supports WCDMA PA biasing and low-voltage logic rails.
For engineers reviewing the MAX1821EUB+ datasheet, MAX1821EUB+ pinout, MAX1821EUB+ application, or MAX1821EUB+ equivalent, key selection criteria include its 1.25V feedback reference accuracy (±2%), 100% duty-cycle capability for ultra-low dropout, skip-mode quiescent current (180µA typ), and µMAX® 10-pin package compatibility with space-constrained handheld designs.
Technical Context
The MAX1821EUB+ implements a slope-compensated current-mode PWM controller with internal P-channel high-side and N-channel synchronous rectifier MOSFETs. It achieves <30µs transient response during full-scale output changes and supports forced PWM mode (via SKIP = BATT) to suppress switching harmonics in noise-sensitive RF sections.
Its error amplifier features 1.25V ±2% FB reference voltage, 30–85µS transconductance, and COMP pin clamping (0.2–2.28V) to optimize stability and load-step recovery. The device integrates undervoltage lockout (2.35V typ), 0.1µA shutdown current, and robust overcurrent protection with separate P-channel (0.75–1.55A) and N-channel (0.01–0.14A) current-limit thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 600mA guaranteed - supports sustained core supply loads without thermal derating in µMAX package. |
| Input Voltage Range | 2.6V to 5.5V - compatible with single Li+ battery (3.0–4.2V) and regulated 3.3V/5V system rails. |
| Feedback Reference | 1.25V ±2% - enables precise output setting (e.g., 1.5V, 1.8V, 3.3V) using standard 1% resistor dividers. |
| Dropout Voltage | 150mV at 600mA - includes internal MOSFET RDS(ON) and external inductor RDC, enabling operation near battery minimum. |
| Quiescent Current | 180µA typ in skip mode - extends battery life in standby states of portable instrumentation and PDAs. |
| Switching Frequency | 1MHz (internal oscillator) - allows use of compact 4.7µH inductors and ceramic output capacitors. |
| Shutdown Current | 0.1µA typ - ensures negligible drain during system sleep, critical for always-on sensor nodes. |
Pinout & Package
MAX1821EUB+ is housed in a 10-pin µMAX® package (3.0mm × 3.0mm × 0.8mm, exposed pad). Pin assignments are validated per Maxim's official datasheet Rev 3 (2005) and match the µMAX footprint across MAX1820/MAX1821 variants.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SKIP) | PWM/Skip-Mode Control Input | Logic-high (BATT) forces constant-frequency PWM; logic-low (GND) enables automatic pulse-skipping at light loads. |
| 2 (COMP) | Compensation Node | Connects to RC network (82kΩ + 330pF to GND) to stabilize loop response and ensure phase margin >45°. |
| 3 (FB) | Feedback Sense Input | Regulates to 1.25V; ties to center of external resistor divider to set output voltage (1.25V–5.5V range). |
| 4 (REF) | Internal Reference Bypass | Requires 0.047µF capacitor to GND to filter reference noise and prevent oscillation. |
| 5 (GND) | Analog Ground | Reference for error amplifier and control logic; must be star-connected to PGND near IC. |
| 6 (PGND) | Power Ground | High-current return path for LX switch node; isolated from analog GND to minimize noise coupling. |
| 7 (LX) | Switch Node | Connects to inductor; drives internal P-channel/N-channel MOSFET drains; high-impedance in shutdown. |
| 8 (BATT) | Input Supply | 2.6–5.5V input; requires 10µF low-ESR ceramic bypass capacitor to PGND for ripple suppression. |
| 9 (SHDN) | Active-Low Shutdown | Pulls to GND to disable regulator, reduce IQ to 0.1µA, and place VOUT in high-impedance state. |
| 10 (SYNC) | Sync Input (No Function) | Must be tied to GND - MAX1821EUB+ lacks synchronization capability; internal 1MHz oscillator only. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Eliminates need for external Schottky diode, improving efficiency by ≥5% at 300mA and reducing thermal stress. |
| 100% Duty-Cycle Operation | Enables dropout as low as 150mV at 600mA, supporting operation down to VIN = VOUT + 0.15V without regulation loss. |
| Fast Transient Response | <30µs settling time for full-scale output voltage steps - critical for dynamic PA biasing in WCDMA handsets. |
| Low Quiescent Current | 180µA typical in skip mode - extends battery runtime in handheld instruments with intermittent active periods. |
| Integrated Overcurrent Protection | Dual current limits (P-channel: 0.75–1.55A; N-channel: 0.01–0.14A) safeguard against short-circuit and reverse-inductor faults. |
Applications
| WCDMA Power Amplifier Bias | Microprocessor Core Supply |
|---|---|
|
Use Scenario: Supplies variable bias voltage to linear power amplifier in 3G cellular handsets during transmit power ramping. IC Role / Device Role / Timing Role: Adjustable buck regulator delivering 1.25–3.4V at up to 600mA with <30µs voltage settling for fast PA envelope tracking. Use Value: Enables efficient PA operation across full transmit power range while minimizing heat generation in compact handset PCBs. |
Use Scenario: Powers ARM9 or MIPS-based CPU cores in PDAs and embedded controllers requiring stable 1.5V/1.8V rails. IC Role / Device Role / Timing Role: Fixed-output synchronous buck converter with 1MHz switching and tight 1.25V reference for low-noise digital supply. Use Value: Delivers clean, regulated core voltage with minimal board area-no external diode or large inductors required. |
| Digital Camera Image Sensor | PCMCIA Card Power Management |
|
Use Scenario: Provides low-noise 2.8V supply to CMOS image sensors during high-speed capture sequences. IC Role / Device Role / Timing Role: Low-dropout buck regulator operating in forced PWM mode (SKIP = BATT) to suppress switching noise near analog pixel circuitry. Use Value: Reduces switching harmonics below 1MHz band, preventing interference with image signal integrity and ADC sampling. |
Use Scenario: Generates 3.3V or 5V auxiliary power for hot-pluggable PCMCIA cards in industrial laptops and data loggers. IC Role / Device Role / Timing Role: Compact µMAX-packaged buck regulator with UVLO (2.35V) and 0.1µA shutdown for safe card insertion/removal sequencing. Use Value: Ensures reliable power-up/down behavior and prevents bus contention during card hot-swap events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYT | 3MHz switching, 600mA, 1.8–6.5V input; 0.6V reference; smaller 6-pin WSON package. | Better suited for ultra-thin devices needing higher frequency and smaller inductors; lacks SYNC and REF pins. | Select when board space is critical and 1MHz EMI profile is not required. |
| RT8059NGSP | 2MHz switching, 600mA, 2.5–5.5V input; 0.6V reference; integrated soft-start; different pinout. | Offers faster transient response and built-in soft-start but no 100% duty-cycle mode - higher dropout at low VIN. | Prefer for applications requiring controlled startup sequencing and tighter output tolerance (±1%). |
Compared with TPS62231DRYT and RT8059NGSP, MAX1821EUB+ provides superior low-input dropout performance (150mV at 600mA) and proven RF-noise resilience in WCDMA PA biasing, making it optimal for legacy handheld designs where 1MHz fundamental switching and µMAX footprint compatibility are mandatory.
Availability
MAX1821EUB+ is available at Aetrix Electronics and suitable for WCDMA cellular phone power amplifiers, microprocessor core supplies, and digital camera image sensor rails requiring stable component supply across extended production lifecycles.
Supply support for MAX1821EUB+ 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 MAX1820/MAX1821 product line was engineered specifically for battery-powered RF systems-emphasizing ultra-low quiescent current, fast transient response, and synchronous efficiency in space-constrained WCDMA handset designs.
FAQ
What is the maximum output voltage supported by MAX1821EUB+?
MAX1821EUB+ supports a programmable output voltage range of 1.25V to 5.5V, set by an external resistive divider connected to the FB pin. The upper limit is constrained by the input voltage (VIN ≤ 5.5V) and internal 1.25V reference accuracy (±2%), ensuring stable regulation up to VBATT − dropout. For example, with VIN = 5.0V, MAX1821EUB+ can reliably deliver 4.85V output under 600mA load.
Does MAX1821EUB+ support external clock synchronization?
No, MAX1821EUB+ does not support external clock synchronization. Its SYNC pin is nonfunctional and must be tied to GND per the datasheet. The device uses an internal free-running 1MHz oscillator (0.8–1.2MHz over temperature). Synchronization capability is exclusive to MAX1820X/Y variants and MAX1821X, which require specific AC-coupled 13MHz or 19.8MHz inputs.
What is the recommended compensation network for MAX1821EUB+?
The recommended compensation network for MAX1821EUB+ is an 82kΩ resistor in series with a 330pF capacitor connected from the COMP pin to GND. This configuration stabilizes the control loop across the full 1.25–5.5V output range and 0–600mA load, ensuring ≥45° phase margin and minimal output overshoot during load transients.
How does MAX1821EUB+ behave during input undervoltage conditions?
MAX1821EUB+ incorporates undervoltage lockout (UVLO) with a 2.35V typical threshold and 1% hysteresis. When BATT falls below ~2.2V during discharge, the device disables switching, pulls SHDN inactive, and places VOUT in high-impedance state. This prevents erratic regulation and protects downstream circuitry until VIN rises above ~2.55V, ensuring clean power-up sequencing.
Can MAX1821EUB+ operate with ceramic output capacitors only?
Yes, MAX1821EUB+ is fully compatible with ceramic output capacitors. Its current-mode control architecture and internal compensation are designed for low-ESR ceramics (e.g., 4.7µF X5R). The datasheet explicitly states that the optional 1pF capacitor (C2 in Figure 3) "can be omitted if ceramic output capacitor is used," confirming stable operation without tantalum or electrolytic types.
MAX1821EUB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Converter, WCDMA Power Amplifier Applications
- Voltage - Input:
- 2.6V ~ 5.5V
- Number of Outputs:
- 1
- Voltage - Output:
- 1.25V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-uMAX/uSOP
MAX1821EUB+ FAQ
1.How can I place an order for MAX1821EUB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1821EUB+ 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 MAX1821EUB+ reliable?
The price and inventory of MAX1821EUB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1821EUB+ is usually 5 days.
3.What payment methods are accepted for MAX1821EUB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1821EUB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1821EUB+?
MAX1821EUB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1821EUB+ 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 MAX1821EUB+?
For technical support, including MAX1821EUB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1821EUB+ requirements.
6.How does Aetrix verify that MAX1821EUB+ is sourced from the original manufacturer or authorized distributors?
All MAX1821EUB+ 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 MAX1821EUB+ meets industry standards.
7.What is the process for return or replacement of MAX1821EUB+?
All MAX1821EUB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX1821EUB+, 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 MAX1821EUB+ part is unused and in its original packaging.
Return procedure for MAX1821EUB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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