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onsemi NCP1521ASNT1G
- Part No.:
- NCP1521ASNT1G
- Manufacturer:
- onsemi
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
NCP1521ASNT1G.pdf
- Description:
- IC REG BUCK ADJ 600MA 5TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,980
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Product details
Overview
NCP1521ASNT1G from onsemi is a synchronous step-down DC-DC converter optimized for single-cell Li-ion or triple-cell alkaline/NiMH/NiCd battery-powered portable devices. It delivers up to 600 mA output current with adjustable voltage (0.9 V to 3.3 V), 1.5 MHz fixed-frequency PWM/PFM operation, 30 µA quiescent current in PFM mode, and integrated thermal shutdown and cycle-by-cycle current limiting - enabling compact, high-efficiency power management in smartphones and digital cameras.
For engineers reviewing the NCP1521ASNT1G datasheet, pinout, applications, or equivalent options, key selection criteria include its TSOP-5 package footprint, 2.7–5.5 V input range, 0.6 V internal feedback reference, synchronous MOSFET integration, and soft-start timing - all critical for low-noise, battery-life-optimized buck regulator design.
Technical Context
The NCP1521ASNT1G employs a constant-frequency, current-mode control architecture with internal P-channel and N-channel MOSFETs. Its 1.5 MHz oscillator enables use of small 2.2 µH inductors and 10 µF ceramic output capacitors, while the 0.6 V feedback reference supports precise output regulation via external resistor dividers.
It operates in automatic PWM/PFM mode switching: PWM above ~40 mA load (±3% output accuracy, >90% efficiency), PFM below that threshold (30 µA typical quiescent current). Protection features include 1200 mA cycle-by-cycle current limit, 160°C thermal shutdown with 25°C hysteresis, and undervoltage lockout at 2.5 V (typ).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 5.5 V - supports direct connection to single Li-ion (4.2 V max) or triple alkaline/NiMH (4.5 V fresh) batteries without pre-regulation. |
| Output Voltage Range | 0.9 V to 3.3 V - set externally via resistor divider; 0.6 V internal reference enables stable low-voltage core rail generation. |
| Switching Frequency | 1.5 MHz (typ) - allows miniaturized magnetics and capacitors; ±0.3 MHz variation over temperature and input voltage ensures predictable EMI profile. |
| Max Output Current | 600 mA - sustained delivery under thermal limits; peak inductor current limit fixed at 1200 mA (typ) prevents saturation during transients. |
| Quiescent Current | 30 µA (typ) in PFM mode - extends battery runtime in standby/sleep states without compromising wake-up response. |
| Feedback Reference | 0.6 V (typ) - tight ±3% tolerance over temperature enables accurate output setting with standard 1% resistors. |
| Shutdown Current | 0.3 µA (typ) - near-zero power draw when EN pin is pulled low, essential for system-level power gating. |
Pinout & Package
Package: TSOP-5 (Case 483-02), Pb-free, 3.0 mm × 1.5 mm × 1.0 mm profile - optimized for space-constrained portable PCB layouts with minimal thermal mass.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Analog Power Input | Primary supply input (2.7–5.5 V); requires local 4.7 µF ceramic bypass capacitor placed adjacent to minimize switching noise injection. |
| GND (Pin 2) | Analog/Power Ground | Common return for internal power stage and analog circuitry; must be connected to star ground point near input/output capacitors. |
| EN (Pin 3) | Digital Enable Input | Active-high logic control (1.2 V min high, 0.4 V max low); must not be left floating; ties to system PMIC or microcontroller GPIO. |
| FB (Pin 4) | Analog Feedback Input | Connects to resistor divider midpoint; senses output voltage against 0.6 V internal reference to regulate VOUT precisely. |
| LX (Pin 5) | Switch Node Output | Drives external inductor; carries high di/dt switching current; requires short, low-inductance trace to minimize EMI and voltage spikes. |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Rectification | Integrated P-ch and N-ch MOSFETs eliminate external Schottky diode, reducing conduction loss and improving full-load efficiency by ≥5% vs. asynchronous designs. |
| Auto PWM/PFM Mode Switching | Seamless transition at ~40 mA load; maintains >90% efficiency at medium loads while dropping to 30 µA IQ in light-load PFM for extended battery life. |
| Integrated Soft-Start | 350 µs (typ) controlled ramp-up prevents inrush current surge into output capacitor, eliminating need for external soft-start circuitry. |
| Thermal Shutdown Protection | 160°C trip threshold with 25°C hysteresis ensures safe recovery after overload; disables both MOSFETs and control circuitry until junction cools to 135°C. |
| Current Limit & Short-Circuit Protection | 1200 mA (typ) cycle-by-cycle limit prevents inductor saturation; under short-circuit, input current clamps to 300 mA (typ), enabling safe fault containment. |
Applications
| Smartphone Core Power | Digital Camera Sensor Rail |
|---|---|
|
Use Scenario: Supplying 1.2 V or 1.8 V core voltage to application processors or baseband ICs in battery-operated smartphones. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering regulated core power with fast transient response to CPU DVFS demands. Use Value: 95.3% peak efficiency at 3.3 V out/4.2 V in enables minimal thermal dissipation in sealed enclosures; 1.5 MHz switching avoids AM radio band interference. |
Use Scenario: Generating clean, low-noise 2.8 V or 3.3 V bias for CMOS image sensors in compact digital still/video cameras. IC Role / Device Role / Timing Role: Low-ripple, high-PSRR step-down converter powering noise-sensitive analog sensor front-ends. Use Value: 30 µA quiescent current preserves battery during viewfinder standby; feed-forward capacitor (18 pF) ensures stable loop response across temperature. |
| USB-Powered Audio DAC | Wireless Modem RF Subsystem |
|
Use Scenario: Providing 1.1 V or 1.5 V supply to portable USB audio DACs drawing ≤500 mA from 5 V USB bus. IC Role / Device Role / Timing Role: Efficient intermediate voltage regulator stepping down USB 5 V to low-voltage digital/analog rails. Use Value: 2.7–5.5 V input range accepts unregulated USB sources; shutdown current <1 µA enables full-system power-off without leakage paths. |
Use Scenario: Powering 3.3 V I/O and 1.8 V logic rails in LTE/Wi-Fi modems requiring burst-mode efficiency and low EMI. IC Role / Device Role / Timing Role: High-frequency buck converter synchronized to modem sleep/wake cycles for dynamic power scaling. Use Value: Automatic PWM/PFM mode adapts to data transmission bursts (PWM) and idle listening (PFM), extending operational time per charge. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS62231DRYT | 2.25 MHz switching frequency; 0.6 V reference; 600 mA rating; 17 µA IQ in PFM; requires external soft-start capacitor. | Better light-load efficiency but narrower 2.05–6.5 V input range; less tolerant of low-input battery sag. | Preferred for ultra-low-IQ systems where 2.25 MHz EMI filtering is feasible; verify EN logic compatibility (active-high same, but threshold differs). |
| AP3418W6-7 | 1.5 MHz frequency; 0.6 V reference; 600 mA rating; 45 µA IQ; no integrated thermal shutdown; smaller SOT-23-6 package. | Lacks thermal protection and has higher quiescent current; requires external current limit sensing for robustness. | Selected when board space is more constrained than thermal safety margin; only suitable for well-ventilated, low-ambient-temperature environments. |
Compared with TPS62231DRYT and AP3418W6-7, the NCP1521ASNT1G provides superior thermal robustness (integrated 160°C shutdown), lower quiescent current (30 µA vs. 45 µA), and guaranteed 2.7 V UVLO - making it the preferred choice for unregulated battery inputs where reliability under voltage sag and temperature stress is critical.
Availability
NCP1521ASNT1G is available at Aetrix Electronics and suitable for smartphone power management, digital camera sensor biasing, USB-powered audio systems, wireless modem subsystems, and portable medical monitors requiring stable component supply across production lifecycles.
Supply support for NCP1521ASNT1G 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The NCP1521ASNT1G belongs to onsemi's NCP15xx family of high-frequency synchronous buck converters, designed specifically for space- and battery-life-constrained portable electronics requiring minimal external components and robust protection.
FAQ
What is the recommended inductor value for NCP1521ASNT1G in standard applications?
The NCP1521ASNT1G is internally compensated for optimal stability with a 2.2 µH inductor and 10 µF output capacitor. The datasheet specifies inductance range of 1.0 µH to 4.7 µH; using 2.2 µH ensures ≥45° phase margin and fast transient response. Inductor saturation current must exceed 600 mA + half the ripple current, and DCR should be <0.3 Ω for best efficiency. Coilcraft DO1605-T and TDK VLF3010AT series are validated choices.
Does NCP1521ASNT1G support 100% duty cycle operation for low-dropout conditions?
Yes, the NCP1521ASNT1G supports 100% duty cycle operation, enabling low-dropout regulation when input voltage approaches output voltage. In this mode, the internal P-channel MOSFET fully turns on, minimizing voltage drop. The minimum input voltage to sustain regulation is calculated as VOUT + IOUT × (RDS(on)_Pch + RINDUCTOR); typical RDS(on) is 300 mΩ, so at 600 mA load, dropout is ~180 mV plus inductor IR drop.
How does the NCP1521ASNT1G handle short-circuit faults on the output?
Under output short-circuit, the NCP1521ASNT1G limits inductor current to 1200 mA (typ) via cycle-by-cycle sensing and clamps input current to ~300 mA (typ). The device remains in hiccup-like current-limited mode without thermal shutdown, dissipating minimal power. Once the short is removed, it automatically resumes normal soft-start operation - no external reset required. This behavior is confirmed in Figure 22 of the datasheet.
What is the purpose of the feed-forward capacitor (Cff) in NCP1521ASNT1G circuits?
The feed-forward capacitor (Cff), typically 18 pF ceramic (X7R/X5R/COG), is connected between FB and LX pins to improve loop stability and transient response. It introduces a zero in the feedback path that compensates for the LC filter pole, ensuring phase margin >45° across operating conditions. Omitting Cff or using incorrect value risks oscillation or excessive output voltage overshoot during load steps - as verified in application note NCP1521/D Section 11.
Can NCP1521ASNT1G be used with input voltages below 2.7 V?
No - the NCP1521ASNT1G has a 2.7 V minimum input voltage specification and 2.5 V typical undervoltage lockout (UVLO) threshold. Operation below 2.7 V is outside recommended conditions and may cause erratic regulation, failure to start, or undefined protection behavior. For sub-2.7 V battery systems (e.g., deeply discharged NiMH), a different regulator such as the NCP1529 (1.8–5.5 V input) is required.
NCP1521ASNT1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- SOT-23-5 Thin, TSOT-23-5
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.5V
- Voltage - Output (Min/Fixed):
- 0.9V
- Voltage - Output (Max):
- 3.3V
- Current - Output:
- 600mA
- Frequency - Switching:
- 1.5MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 5-TSOP
NCP1521ASNT1G FAQ
1.How can I place an order for NCP1521ASNT1G through Aetrix?
Please submit a Request for Quotation (RFQ) for NCP1521ASNT1G 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 NCP1521ASNT1G reliable?
The price and inventory of NCP1521ASNT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for NCP1521ASNT1G is usually 5 days.
3.What payment methods are accepted for NCP1521ASNT1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for NCP1521ASNT1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for NCP1521ASNT1G?
NCP1521ASNT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your NCP1521ASNT1G 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 NCP1521ASNT1G?
For technical support, including NCP1521ASNT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your NCP1521ASNT1G requirements.
6.How does Aetrix verify that NCP1521ASNT1G is sourced from the original manufacturer or authorized distributors?
All NCP1521ASNT1G 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 NCP1521ASNT1G meets industry standards.
7.What is the process for return or replacement of NCP1521ASNT1G?
All NCP1521ASNT1G units undergo pre-shipment inspection (PSI). If there is an issue with NCP1521ASNT1G, 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 NCP1521ASNT1G part is unused and in its original packaging.
Return procedure for NCP1521ASNT1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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