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Analog Devices Inc./Maxim Integrated MAX1928EUB25+T
- Part No.:
- MAX1928EUB25+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
MAX1928EUB25+T.pdf
- Description:
- IC REG BUCK 2.5V 800MA 10UMAX
- Quantity:
- Payment:
- Shipping:
Inventory:4,381
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Product details
Overview
The MAX1928EUB25+T from Maxim Integrated is a 2.5V fixed-output, 800mA synchronous step-down DC-DC converter optimized for low-voltage microprocessor core power in space-constrained portable equipment. It operates from 2.6V to 5.5V input, delivers 2.5V at up to 800mA with 140µA quiescent current in pulse-skipping mode, and features integrated P-channel/N-channel MOSFETs, 1MHz PWM switching, and Power-OK (POK) output - used in WCDMA handsets and DSP core supplies.
For engineers reviewing the MAX1928EUB25+T datasheet, MAX1928EUB25+T pinout, MAX1928EUB25+T application, or MAX1928EUB25+T equivalent, key selection considerations include its 2.5V preset output accuracy (±2%), 100% duty-cycle dropout capability (340mV at 800mA), selectable forced-PWM mode for RF-sensitive designs, and 10-pin µMAX package footprint compatibility with other MAX1927/MAX1928 variants.
Technical Context
The MAX1928EUB25+T implements a current-mode, fixed-frequency 1MHz PWM controller with pulse-frequency modulation (PFM) light-load operation. Its internal architecture integrates a 1.25V reference, error amplifier with 250µS transconductance, and dual-MOSFET power stage (P-channel on-resistance ≤0.5Ω at 2.6V, N-channel ≤0.35Ω).
It supports 100% duty-cycle operation for ultra-low dropout, uses an external RC network for loop compensation, and includes dedicated pins for soft-start control, shutdown (SHDN), forced-PWM selection (PWM), and open-drain Power-OK monitoring (POK) with 20ms delay after regulation is achieved.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 2.5V ±2% (FB regulation point = 2.5V; POK threshold = 2.25V) |
| Max Output Current | 800mA continuous; supports full load down to 2.6V input with 100% duty cycle |
| Input Voltage Range | 2.6V to 5.5V; includes undervoltage lockout (2.35V typ, 35mV hysteresis) |
| Switching Frequency | 1MHz fixed (0.8–1.2MHz over temp); enables compact 4.7µH inductor and 10µF ceramic caps |
| Quiescent Current | 140µA typical in PFM mode; 2mA in forced-PWM mode |
| Duty Cycle Range | 0% to 100%; achieves 340mV dropout voltage at 800mA (VBATT ≥ VOUT + 340mV) |
| Package | 10-pin µMAX (3mm × 3mm × 0.8mm); exposed PGND pad for thermal performance |
Pinout & Package
MAX1928EUB25+T is housed in a 10-pin µMAX package with exposed power ground (PGND) pad for thermal dissipation. Pin 1 is PWM, Pin 2 is GND, Pin 3 is REF, Pin 4 is FB, Pin 5 is COMP, Pin 6 is SHDN, Pin 7 is PGND, Pin 8 is LX, Pin 9 is BATT, and Pin 10 is POK - all defined per Maxim's official pin configuration diagram.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWM | Forced-PWM mode select | Drive high (BATT) to disable pulse-skipping and enforce constant 1MHz switching for noise-sensitive applications |
| GND | Analog ground reference | Provides signal return for REF, FB, COMP; must be star-connected to PGND at single point |
| REF | Internal 1.25V reference output | Bypassed with 0.1µF capacitor to GND; supplies bias for error amplifier and POK comparator |
| FB | Feedback sense input | Connected directly to 2.5V output; regulates via internal 2.5V reference (accuracy ±2% over -40°C to +85°C) |
| COMP | Loop compensation node | External RC network (e.g., 18kΩ + 1200pF) sets bandwidth and phase margin for stability with ceramic output capacitors |
| SHDN | Enable/disable control | Logic-high enables converter; logic-low shuts down device, reducing supply current to 0.1µA typical |
| PGND | Power ground return | High-current return path for LX switch and synchronous rectifier; tied to exposed thermal pad |
| LX | Switch node | Connects to inductor; carries high di/dt switching current; requires short, wide trace routing |
| BATT | Main power input | 2.6V–5.5V supply; bypassed with ≥10µF low-ESR capacitor placed adjacent to pin |
| POK | Power-OK open-drain output | Asserts high-impedance 20ms after FB reaches 90% of 2.5V; sinks current when out-of-regulation or in shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous rectification | Eliminates need for external Schottky diode; improves efficiency by >5% at medium loads and reduces thermal stress |
| 100% duty-cycle operation | Enables dropout as low as 340mV at 800mA, supporting operation near battery end-of-life in 2.5V systems |
| Selectably forced PWM mode | Removes variable-frequency PFM noise; critical for coexistence with RF transceivers and precision ADCs |
| Integrated soft-start | Controls output ramp rate to limit inrush current; prevents input voltage sag during startup in battery-powered systems |
| Power-OK (POK) monitor | Provides system-level power sequencing feedback with 20ms delay, enabling safe processor reset or enable timing |
Applications
| WCDMA Handset Core Supply | DSP Processor Core Power |
|---|---|
Use Scenario: Powers baseband DSP core in 3G mobile handsets operating from single-cell Li-ion (2.7V–4.2V). IC Role / Device Role / Timing Role: Primary step-down regulator delivering stable 2.5V at up to 800mA with fast transient response to burst-mode processing loads. Use Value: 140µA quiescent current extends standby time; POK output synchronizes DSP boot sequence with power rail readiness. | Use Scenario: Supplies voltage to low-power DSP cores in portable audio analyzers and voice recognition modules. IC Role / Device Role / Timing Role: Fixed-output buck converter providing clean, low-noise 2.5V rail; forced-PWM mode selected to avoid interference with analog front-end sampling clocks. Use Value: 1MHz switching allows use of small 4.7µH shielded inductor; synchronous rectification maintains >90% efficiency at 100–800mA load range. |
| PDA Application Processor Rail | Battery-Powered Industrial Sensor Node |
Use Scenario: Generates 2.5V core voltage for ARM-based application processors in handheld PDAs with tight board area constraints. IC Role / Device Role / Timing Role: Compact µMAX-packaged DC-DC converter interfacing directly with processor VDDCORE pin; FB tied to output for fixed regulation. Use Value: 10-pin µMAX footprint (3mm × 3mm) saves PCB area vs. larger SOIC alternatives; 100% duty cycle sustains operation as battery discharges to 2.85V. | Use Scenario: Powers mixed-signal SoC in wireless sensor nodes powered by two AA alkaline cells (1.8V–3.2V). IC Role / Device Role / Timing Role: Efficient step-down regulator converting variable battery voltage to precise 2.5V for ADC reference and microcontroller core. Use Value: Undervoltage lockout (2.35V) prevents erratic operation near battery depletion; shutdown current <1µA enables multi-year shelf life in sleep mode. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYR | 3MHz switching, 600mA output, 2.5V fixed; smaller 6-pin WSON package; no POK output | Lacks power-good signaling and 800mA drive; better suited for ultra-compact, lower-current apps without sequencing needs | Select when board space is critical and POK is unnecessary; verify 600mA load margin for target SoC |
| RT8059NGQW | 2MHz switching, 800mA, 2.5V fixed; includes enable and POK; 12-pin QFN vs. 10-pin µMAX | Same current rating and POK function but larger footprint and different pinout; higher quiescent current (25µA vs. 140µA in PFM) | Choose if QFN thermal performance is prioritized over µMAX size; confirm layout compatibility with 12-pin mapping |
Compared with TPS62231DRYR and RT8059NGQW, the MAX1928EUB25+T uniquely balances ultra-low quiescent current (140µA), integrated POK, 800mA capability, and minimal 10-pin µMAX footprint - making it optimal for battery-critical, space-constrained 2.5V core rails requiring power sequencing.
Availability
MAX1928EUB25+T is available at Aetrix Electronics and suitable for WCDMA handset design, DSP core power delivery, and battery-powered industrial sensor nodes requiring stable component supply across extended temperature ranges (-40°C to +85°C).
Supply support for MAX1928EUB25+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 MAX1927/MAX1928 product line was designed specifically for high-efficiency, low-voltage core power in compact portable electronics - emphasizing minimal external components, ultra-low quiescent current, and seamless integration with microprocessor power requirements.
FAQ
What is the guaranteed minimum output current for the MAX1928EUB25+T?
The MAX1928EUB25+T guarantees a minimum output current of 800mA across its full operating temperature range (-40°C to +85°C) and input voltage range (2.6V to 5.5V). This rating is validated under worst-case conditions including maximum junction temperature and minimum input voltage, ensuring reliable core power delivery for demanding portable microprocessors and DSPs. The MAX1928EUB25+T maintains regulation even at 100% duty cycle when input drops near dropout.
Does the MAX1928EUB25+T require an external Schottky diode?
No, the MAX1928EUB25+T does not require an external Schottky diode. It integrates both a P-channel high-side MOSFET and an N-channel synchronous rectifier, eliminating conduction losses and heat generation associated with external diodes. This synchronous architecture improves full-load efficiency by up to 8% compared to nonsynchronous buck converters and reduces component count and board area. The MAX1928EUB25+T relies solely on its internal power switches and external inductor/capacitors.
How does the POK output of the MAX1928EUB25+T behave during startup and fault conditions?
The POK output of the MAX1928EUB25+T is an open-drain signal that transitions to high-impedance 20ms after the soft-start completes and the FB voltage exceeds 90% of the 2.5V regulation threshold (i.e., >2.25V). During startup, POK remains low-impedance until this condition is met. In shutdown (SHDN = GND) or output undervoltage, POK is actively pulled low. The MAX1928EUB25+T's POK provides deterministic power sequencing for processors and FPGAs without requiring external monitoring circuitry.
Can the MAX1928EUB25+T operate with input voltage below 2.6V?
No, the MAX1928EUB25+T cannot operate reliably with input voltage below 2.6V. Its absolute minimum input voltage is specified as 2.6V, and undervoltage lockout (UVLO) disables operation when VBATT falls below approximately 2.35V (with 35mV hysteresis). Attempting to operate below 2.6V risks unregulated output, excessive quiescent current, or latch-up. For sub-2.6V battery inputs, consider the MAX1927R adjustable variant or alternative low-input buck regulators. The MAX1928EUB25+T is strictly rated for 2.6V–5.5V operation.
What is the purpose of the PWM pin on the MAX1928EUB25+T, and how should it be configured?
The PWM pin on the MAX1928EUB25+T selects between automatic pulse-skipping (PFM) mode and forced fixed-frequency PWM mode. When tied to GND, the device uses PFM at light loads (<130mA) for ultra-low quiescent current (140µA), switching only as needed. When tied to BATT, it forces continuous 1MHz PWM operation - essential for noise-sensitive applications like RF front-ends or precision data acquisition where variable-frequency switching could cause interference. The MAX1928EUB25+T's PWM pin thus enables application-specific optimization of efficiency versus EMI.
MAX1928EUB25+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.6V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- -
- Current - Output:
- 800mA
- Frequency - Switching:
- 800kHz ~ 1.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-uMAX/uSOP
MAX1928EUB25+T FAQ
1.How can I place an order for MAX1928EUB25+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX1928EUB25+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 MAX1928EUB25+T reliable?
The price and inventory of MAX1928EUB25+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX1928EUB25+T is usually 5 days.
3.What payment methods are accepted for MAX1928EUB25+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX1928EUB25+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX1928EUB25+T?
MAX1928EUB25+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX1928EUB25+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 MAX1928EUB25+T?
For technical support, including MAX1928EUB25+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX1928EUB25+T requirements.
6.How does Aetrix verify that MAX1928EUB25+T is sourced from the original manufacturer or authorized distributors?
All MAX1928EUB25+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 MAX1928EUB25+T meets industry standards.
7.What is the process for return or replacement of MAX1928EUB25+T?
All MAX1928EUB25+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX1928EUB25+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 MAX1928EUB25+T part is unused and in its original packaging.
Return procedure for MAX1928EUB25+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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