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onsemi FAN2502S285X
- Part No.:
- FAN2502S285X
- Manufacturer:
- onsemi
- Package:
- SC-74A, SOT-753
- Datasheet:
-
FAN2502S285X.pdf
- Description:
- IC REG LIN 2.85V 150MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,881
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Product details
Overview
FAN2502S285X from Fairchild Semiconductor is a 2.85 V fixed-output CMOS low-dropout (LDO) voltage regulator in SOT-23-5 package, delivering 150 mA output current with 150 mV dropout at full load, 25 µA ground current at 150 mA, and enable/shutdown control - designed for power management in portable battery-powered systems such as cellular handsets and notebook computers.
For engineers reviewing the FAN2502S285X datasheet, pinout, applications, or equivalent options, key selection criteria include ultra-low quiescent current, thermal protection, bypass-capacitor–enabled noise reduction, compatibility with ceramic/tantalum output capacitors (ESR 10 mΩ to 10 Ω), and operation across –40°C to +125°C junction temperature.
Technical Context
The FAN2502S285X uses a P-channel MOSFET series pass element with ~1 Ω on-resistance, enabling low dropout performance superior to bipolar LDOs. Its CMOS error amplifier features low input bias current and references a 1.32 V (typ) bandgap, ensuring stable regulation without external compensation.
Pin 4 functions as BYP - a passive node for connecting a 470 pF bypass capacitor to reduce output noise - distinguishing it from adjustable (ADJ) or error-flag (ERR) variants. Loop stability is maintained across wide ESR ranges due to internal compensation optimized for ceramic, tantalum, and aluminum electrolytic output capacitors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 2.85 V ±2% - ensures precise rail generation for 2.8 V–3.0 V logic and RF circuitry. |
| Dropout Voltage | 150 mV at 150 mA - enables regulation from 3.0 V input down to minimum 3.0 V supply, critical for single-cell Li-ion systems. |
| Ground Current | 25 µA at 150 mA - minimizes battery drain during active operation, extending runtime in always-on subsystems. |
| Shutdown Current | <1 µA when EN = 0 V - supports deep-sleep modes in portable devices without compromising wake-up latency. |
| Input Voltage Range | 2.7 V to 6.5 V - accommodates single-cell Li-ion (2.7–4.2 V), Li-polymer, and regulated 5 V supplies. |
| Thermal Shutdown | 150°C junction limit - protects against sustained overload or poor PCB heatsinking without external circuitry. |
| PSRR | 43 dB at 120 Hz - suppresses ripple from switching converters feeding the LDO input. |
| Output Noise | <7 µV/√Hz (10 Hz–1 kHz) with 10 µF COUT and 0.01 µF CBYP - meets low-noise requirements for RF front-ends and ADC reference rails. |
Pinout & Package
SOT-23-5 surface-mount package (EIAJ SC-74A), 2.9 mm × 1.6 mm footprint, 1.1 mm height, with exposed pad not electrically connected - requires standard reflow profile and no thermal pad soldering.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Power Input | Accepts 2.7–6.5 V unregulated input; requires ≥2.2 µF local ceramic decoupling for transient response. |
| 2 - GND | Power Ground | Reference return for regulator core and error amplifier; must connect to low-impedance local ground plane. |
| 3 - EN | Digital Enable | Active-high logic input (VIH ≥ 2.0 V); floating causes erratic operation; tie to VIN if always-on use. |
| 4 - BYP | Bypass Node | Passive terminal for 470 pF–10 nF capacitor to ground - reduces high-frequency output noise without affecting regulation. |
| 5 - VOUT | Regulated Output | Delivers stable 2.85 V ±2%; requires ≥1 µF output capacitor (ceramic/tantalum) for loop stability. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low ground current | 25 µA at 150 mA load - extends battery life in portable applications where load current varies widely. |
| Low-noise bypass architecture | 470 pF capacitor on BYP pin reduces output noise by >10× in 10 Hz–1 kHz band - critical for analog sensor and RF IC power rails. |
| Wide ESR tolerance | Stable with output capacitors having ESR from 10 mΩ to 10 Ω - eliminates need for low-ESR tantalum; enables cost-effective ceramic solutions. |
| Thermal limiting | Automatic shutdown at 150°C junction temperature - prevents damage during short-circuit or high ambient conditions without external sensors. |
| Enable-controlled shutdown | Reduces total supply current to <1 µA - supports system-level power sequencing and low-power sleep states. |
| CMOS process technology | Enables low dropout and low quiescent current simultaneously - unlike older BiCMOS designs that trade one for the other. |
Applications
| Cellular Handset RF Power Amplifier Bias | Laptop USB Peripheral Rail |
|---|---|
Use Scenario: Providing clean, stable 2.85 V bias to GaAs power amplifier stages in GSM/TDMA handsets operating from single-cell Li-ion batteries. IC Role / Device Role / Timing Role: Primary LDO regulator supplying PA collector voltage; BYP pin used with 470 pF capacitor to suppress switching noise coupling into RF path. Use Value: 150 mV dropout allows operation down to 3.0 V input, maximizing usable battery capacity; 43 dB PSRR rejects noise from baseband processor switching supplies. |
Use Scenario: Powering USB 2.0 transceivers and hub controllers in ultraportable notebooks where space and thermal budget are constrained. IC Role / Device Role / Timing Role: Local point-of-load regulator converting 5 V system rail to 2.85 V logic interface voltage; EN pin synchronized with USB suspend/resume signaling. Use Value: 25 µA ground current minimizes standby drain; SOT-23-5 footprint saves board area versus larger packages; thermal shutdown prevents overheating during hot-plug events. |
| Digital Camera Image Sensor Core Supply | Portable Medical Pulse Oximeter Analog Front-End |
Use Scenario: Delivering low-noise 2.85 V to CMOS image sensor analog core and column ADC drivers in compact digital cameras. IC Role / Device Role / Timing Role: Low-noise LDO with BYP capacitor filtering; output capacitor selected for minimal ESR drift over temperature to maintain ADC reference stability. Use Value: <7 µV/√Hz noise floor preserves SNR in 12-bit+ image capture; wide capacitor ESR tolerance simplifies BOM by allowing X7R ceramics instead of costly tantalums. |
Use Scenario: Supplying precision analog circuitry (LED drivers, photodiode amplifiers, sigma-delta ADC reference) in battery-powered pulse oximeters requiring long clinical runtime. IC Role / Device Role / Timing Role: Primary analog rail regulator; EN pin controlled by microcontroller to disable sensor chain during idle periods. Use Value: <1 µA shutdown current extends battery life between measurements; ±2% output accuracy ensures consistent LED drive and signal gain calibration across temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MCP1700T-285I/TT | 250 mA rated output, 1.6 µA quiescent current, but higher 250 mV dropout at 250 mA; no BYP pin - uses different noise-reduction method. | Lacks dedicated bypass node; requires external RC filter for comparable noise performance - increases component count and layout complexity. | Prefer when higher output current headroom is needed and noise sensitivity is moderate; verify thermal margin at 150 mA in same PCB layout. |
| TCS2102-2.85V | 150 mA output, 20 µA ground current, 180 mV dropout at 150 mA, SOT-23-5, but no enable pin - always-on operation only. | No EN control eliminates power sequencing capability; unsuitable for systems requiring dynamic rail enable/disable. | Select only for simple always-on applications where shutdown functionality is unnecessary and lowest possible quiescent current is prioritized. |
Compared with MCP1700T-285I/TT and TCS2102-2.85V, the FAN2502S285X uniquely combines 150 mV dropout, 25 µA ground current, EN control, and a dedicated BYP pin - making it optimal for noise-sensitive, battery-constrained portable systems requiring both efficiency and signal integrity.
Availability
FAN2502S285X is available at Aetrix Electronics and suitable for cellular handset RF bias, laptop USB peripheral rails, digital camera image sensor supplies, portable medical device analog front-ends, and other portable electronics requiring stable component supply with tight voltage tolerance and low-noise performance.
Supply support for FAN2502S285X 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016; its legacy LDO portfolio remains widely deployed in portable electronics.
The FAN2502/FAN2503 family was engineered specifically for GSM/TDMA cellular handsets and portable computing - emphasizing micropower operation, low dropout, thermal robustness, and compact packaging to meet stringent size and battery-life requirements.
FAQ
What is the maximum input voltage rating for the FAN2502S285X?
The FAN2502S285X has an absolute maximum input voltage of 7 V, but its recommended operating range is 2.7 V to 6.5 V. Exceeding 6.5 V may degrade long-term reliability or trigger internal protection circuits. For typical use with single-cell Li-ion batteries (2.7–4.2 V) or regulated 5 V supplies, operation within this range ensures full specification compliance and thermal safety.
Does the FAN2502S285X require an external bypass capacitor on the BYP pin?
The FAN2502S285X does not require an external bypass capacitor on the BYP pin to function, but adding a 470 pF capacitor significantly reduces output noise - especially in the 10 Hz–1 kHz band - improving performance for analog and RF loads. In cost-sensitive or noise-tolerant applications, the BYP capacitor may be omitted without affecting regulation stability or basic functionality.
Can the FAN2502S285X be used with ceramic output capacitors?
Yes, the FAN2502S285X is explicitly designed to operate stably with ceramic output capacitors ranging from 1 µF upward, including X7R and Y5V dielectrics. Its internal compensation makes it insensitive to ESR variations - unlike many older LDOs - so standard 0603 or 0805 ceramic capacitors provide reliable loop stability without requiring low-ESR tantalum alternatives.
What happens to the output of the FAN2502S285X during thermal shutdown?
During thermal shutdown, the FAN2502S285X disables its output transistor, causing VOUT to drop to near 0 V until the junction temperature falls below the hysteresis threshold (~140°C). The device then automatically resumes regulation. This behavior protects against permanent damage during sustained overload or inadequate PCB heatsinking, and occurs independently of the EN pin state.
Is the FAN2502S285X pin-compatible with other devices in the FAN2502/FAN2503 family?
Yes, all FAN2502/FAN2503 variants share identical SOT-23-5 pinouts and mechanical footprints. The FAN2502S285X (BYP pin) is pin-compatible with FAN2502S25X through FAN2502S33X and FAN2503S285X, enabling design reuse across voltage options and functional variants - though pin 4's electrical behavior (BYP vs. ERR) must be verified in schematic and layout.
FAN2502S285X Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 6.5V
- Voltage - Output (Min/Fixed):
- 2.85V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.18V @ 150mA
- Current - Output:
- 150mA
- Current - Quiescent (Iq):
- 50 µA
- Current - Supply (Max):
- -
- PSRR:
- 43dB (120Hz)
- Control Features:
- Enable
- Protection Features:
- Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
FAN2502S285X FAQ
1.How can I place an order for FAN2502S285X through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN2502S285X 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 FAN2502S285X reliable?
The price and inventory of FAN2502S285X are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN2502S285X is usually 5 days.
3.What payment methods are accepted for FAN2502S285X?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN2502S285X transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN2502S285X?
FAN2502S285X orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN2502S285X 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 FAN2502S285X?
For technical support, including FAN2502S285X datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN2502S285X requirements.
6.How does Aetrix verify that FAN2502S285X is sourced from the original manufacturer or authorized distributors?
All FAN2502S285X 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 FAN2502S285X meets industry standards.
7.What is the process for return or replacement of FAN2502S285X?
All FAN2502S285X units undergo pre-shipment inspection (PSI). If there is an issue with FAN2502S285X, 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 FAN2502S285X part is unused and in its original packaging.
Return procedure for FAN2502S285X:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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