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onsemi CS5231-3GDFR8
- Part No.:
- CS5231-3GDFR8
- Manufacturer:
- onsemi
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CS5231-3GDFR8.pdf
- Description:
- IC REG LINEAR 3.3V 500MA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,681
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Product details
Overview
CS5231-3GDFR8 from onsemi is a fixed-output 3.3 V, 500 mA linear regulator with integrated auxiliary supply control logic for seamless dual-input power management. It delivers ±2.0% output accuracy, supports glitch-free transition between 5.0 V main and 3.3 V auxiliary supplies, and includes current limit protection and thermal shutdown with 25°C hysteresis. It is used in PCI Network Interface Cards to maintain uninterrupted ASIC power during ACPI Sleep State transitions.
For engineers reviewing the CS5231-3GDFR8 datasheet, pinout, applications, or equivalent options, this page provides verified technical context, SOIC-8 package details, real-world load regulation (≤15 mV), reverse current limit (≤1.0 mA), and validated alternatives for dual-rail power management designs.
Technical Context
The CS5231-3GDFR8 integrates a composite NPN-PNP pass transistor for low-dropout operation and low quiescent current (3.0 mA at 500 mA load). Its auxiliary drive (AuxDrv) output features internal 10 kΩ pull-up and NPN sink, enabling precise 4.4 V turn-off / 4.5 V turn-on thresholds with 100 mV hysteresis to prevent oscillation during supply transitions.
It implements reverse current protection by disabling the pass transistor before VIN falls below VOUT, limiting reverse flow to ≤1.0 mA when VIN = 0 V. The IC requires ≥10 µF output capacitance with ESR < 1.0 Ω for stability and uses no external feedback-output voltage is internally fixed at 3.3 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 3.3 V ±2.0% - guarantees stable ASIC bias under full 10–500 mA load range without external trimming. |
| Max Output Current | 500 mA - continuous regulated delivery; current limit trips at 0.55–1.2 A to protect against shorts. |
| Dropout Voltage | Not specified as standalone parameter; enabled by composite pass transistor architecture - supports regulation down to VIN ≈ 4.4 V. |
| AuxDrv Thresholds | Turn-on: 4.35–4.65 V; Turn-off: 4.25–4.55 V - ensures reliable switchover with 75–125 mV hysteresis to avoid chatter. |
| Quiescent Current | 3.0 mA at 500 mA load - enables efficient operation in always-on subsystems without excessive idle loss. |
| Reverse Output Current | ≤1.0 mA at VIN = 0 V - prevents backfeed into main rail or ground during auxiliary-only operation. |
| Thermal Shutdown | 150–210°C activation with 25°C hysteresis - self-recovering protection without external reset required. |
Pinout & Package
CS5231-3GDFR8 is housed in an SOIC-8 package (Case 751-07), with internally fused leads and GND-connected tab-equivalent pins (pins 2, 3, 6, 7). Pin 1 is NC; pin 5 is AuxDrv - actively driven low when VIN < ~4.5 V to enable external PFET.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 | No Connect (NC) | Unbonded; must remain floating - no electrical function or thermal path. |
| Pin 2, Pin 3, Pin 6, Pin 7 | GND | Common ground reference and substrate connection; all four pins tied internally - critical for thermal dissipation and noise immunity. |
| Pin 4 | VIN | Main input supply (4.75–6.0 V nominal); absolute max 14 V - powers regulator core and internal bias. |
| Pin 5 | VOUT | Regulated 3.3 V output; supplies load directly and feeds external PFET source - not remotely senseable. |
| Pin 8 | AuxDrv | Open-drain auxiliary drive output; sinks up to 50 mA to ground when VIN < threshold - controls gate of external PFET. |
Key Features
| Feature | Design Value |
|---|---|
| Glitch-free dual-supply transition | Enables zero-interruption 3.3 V output during 5.0 V brownout via controlled PFET switching - meets Intel "Instantly Available" requirement. |
| Integrated auxiliary drive logic | Dedicated AuxDrv pin with built-in hysteresis and 10 kΩ pull-up eliminates need for external comparators or timing components. |
| Fused SOIC-8 leads | Internal fusing on pins 2–3–6–7 enhances reliability under overcurrent or thermal stress - reduces field failure risk in high-volume PC cards. |
| Low reverse current design | Prevents >1 mA backflow from VOUT to VIN or GND when main supply collapses - preserves auxiliary rail integrity and system efficiency. |
| Thermal shutdown with hysteresis | Self-recovering protection at 150–210°C with 25°C recovery margin - avoids latch-up and enables autonomous restart after cooling. |
Applications
| PCI Network Interface Card (NIC) | Desktop Computer Power Management |
|---|---|
Use Scenario: System enters ACPI S3 Sleep State; 5.0 V rail drops below 4.4 V while 3.3 V auxiliary remains active. IC Role / Device Role / Timing Role: CS5231-3GDFR8 detects VIN collapse and asserts AuxDrv to turn on external PFET, switching ASIC power source from 5.0 V to 3.3 V auxiliary within 1.0–10 µs. Use Value: Maintains uninterrupted 3.3 V supply to NIC ASIC with no voltage glitch - satisfies Intel "Instantly Available" specification for instant resume. |
Use Scenario: Motherboard VRM supplies 5.0 V to chipset; auxiliary 3.3 V rail available from standby power domain. IC Role / Device Role / Timing Role: CS5231-3GDFR8 acts as failover regulator for low-power chipset peripherals requiring continuous 3.3 V during main rail shutdown. Use Value: Eliminates need for separate LDO + discrete supervisor circuit - reduces BOM count and PCB area by >40% vs. discrete solution. |
| PCMCIA/PCI Hot-Swap Interface | Multi-Source Industrial Power Supply |
Use Scenario: Card insertion triggers inrush; main 5.0 V may sag transiently before stabilizing. IC Role / Device Role / Timing Role: CS5231-3GDFR8 sustains VOUT from auxiliary 3.3 V until VIN recovers above 4.5 V, then seamlessly transfers back. Use Value: Prevents peripheral lockup or data corruption during hot-plug events - enables robust field-replaceable module operation. |
Use Scenario: Industrial controller accepts either 5.0 V DC or 3.3 V backup battery; must guarantee uninterrupted MCU core voltage. IC Role / Device Role / Timing Role: CS5231-3GDFR8 monitors primary input and activates auxiliary path within microseconds upon undervoltage detection. Use Value: Provides deterministic, sub-10 µs switchover - exceeds IEC 61000-4-29 immunity requirements for critical control systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-input linear regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS7A6033QDGQRQ1 | Automotive-grade 3.3 V LDO (500 mA); no auxiliary drive - requires external supervisor + MOSFET for switchover. | Lacks integrated AuxDrv logic; needs ≥4 extra components to replicate CS5231-3GDFR8's glitch-free transition. | Select only if AEC-Q100 qualification is mandatory and dual-supply handoff can be implemented externally. |
| NCP1117ST33T3G | Fixed 3.3 V, 1 A LDO; no auxiliary control, no VIN threshold detection, no reverse current blocking. | Provides basic regulation only - cannot manage two input sources or prevent backfeed from VOUT. | Use only for single-rail applications where auxiliary switchover and reverse protection are unnecessary. |
Compared with TPS7A6033QDGQRQ1 and NCP1117ST33T3G, the CS5231-3GDFR8 uniquely integrates auxiliary drive logic, hysteresis-controlled switchover, and reverse current blocking in a single SOIC-8 package - reducing component count, layout complexity, and validation effort for ACPI-compliant power management.
Availability
CS5231-3GDFR8 is available at Aetrix Electronics and suitable for PCI Network Interface Cards, desktop computer power domains, and PCMCIA/PCI hot-swap interfaces requiring stable component supply with guaranteed long-term continuity.
Supply support for CS5231-3GDFR8 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 silicon solutions for automotive, industrial, cloud, medical, and IoT applications.
The CS5231-3GDFR8 belongs to onsemi's legacy power management portfolio designed specifically for ACPI-compliant PC architectures - prioritizing seamless dual-rail switchover, low quiescent current, and robust thermal protection in space-constrained SOIC packages.
FAQ
What is the maximum input voltage rating for CS5231-3GDFR8?
The absolute maximum VIN rating for CS5231-3GDFR8 is 14 V, but its specified operating range is strictly 4.75 V to 6.0 V. Exceeding 6.0 V risks violating line regulation specs and increasing thermal stress; sustained operation above 7.0 V requires derating per Figure 21 in the datasheet. The CS5231-3GDFR8 must not be operated outside its 4.75–6.0 V functional window without verifying thermal margin and output stability.
Does CS5231-3GDFR8 support remote output voltage sensing?
No, CS5231-3GDFR8 does not support remote sensing - its feedback network is fully internal and fixed at 3.3 V. Output voltage accuracy depends entirely on PCB trace resistance between the IC's VOUT pin and the load. To minimize error, place the CS5231-3GDFR8 as close as possible to both the load and output capacitor, and use wide copper traces for VOUT and GND connections.
What is the purpose of the NC pin (Pin 1) on CS5231-3GDFR8?
Pin 1 of the CS5231-3GDFR8 is a true No Connect - it is unbonded and electrically isolated from all internal circuitry. It must remain unconnected on the PCB; routing a trace to it or using it as a mechanical anchor may compromise SOIC-8 package integrity or cause latent assembly defects. The CS5231-3GDFR8 functions identically whether Pin 1 is left floating or omitted from footprint design.
How does CS5231-3GDFR8 prevent reverse current flow when VIN is absent?
The CS5231-3GDFR8 prevents reverse current by turning off its internal composite pass transistor before VIN drops below VOUT, limiting reverse conduction to ≤1.0 mA. This behavior is inherent to its architecture - no external diode or MOSFET is needed. When VIN = 0 V, the CS5231-3GDFR8 draws only leakage current from VOUT, preserving auxiliary rail stability and minimizing power loss.
Can CS5231-3GDFR8 be used with input voltages below 4.75 V?
No - CS5231-3GDFR8 is not characterized or guaranteed to operate below 4.75 V. Its VIN undervoltage lockout activates near 4.4 V, and regulation is only specified across 4.75–6.0 V. Attempting to operate the CS5231-3GDFR8 at 4.5 V may result in unregulated output, delayed AuxDrv response, or thermal instability due to insufficient headroom for the composite pass device.
CS5231-3GDFR8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 14V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- -
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 3 mA
- Current - Supply (Max):
- 6 mA
- PSRR:
- -
- Control Features:
- -
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
CS5231-3GDFR8 FAQ
1.How can I place an order for CS5231-3GDFR8 through Aetrix?
Please submit a Request for Quotation (RFQ) for CS5231-3GDFR8 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 CS5231-3GDFR8 reliable?
The price and inventory of CS5231-3GDFR8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CS5231-3GDFR8 is usually 5 days.
3.What payment methods are accepted for CS5231-3GDFR8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CS5231-3GDFR8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CS5231-3GDFR8?
CS5231-3GDFR8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CS5231-3GDFR8 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 CS5231-3GDFR8?
For technical support, including CS5231-3GDFR8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CS5231-3GDFR8 requirements.
6.How does Aetrix verify that CS5231-3GDFR8 is sourced from the original manufacturer or authorized distributors?
All CS5231-3GDFR8 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 CS5231-3GDFR8 meets industry standards.
7.What is the process for return or replacement of CS5231-3GDFR8?
All CS5231-3GDFR8 units undergo pre-shipment inspection (PSI). If there is an issue with CS5231-3GDFR8, 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 CS5231-3GDFR8 part is unused and in its original packaging.
Return procedure for CS5231-3GDFR8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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