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onsemi FAN7311N
- Part No.:
- FAN7311N
- Manufacturer:
- onsemi
- Category:
- Power Management - Specialized
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
FAN7311N.pdf
- Description:
- IC INVERTER DRIVE LCD BKLT 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,683
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Product details
Overview
FAN7311N from Fairchild Semiconductor is a dedicated LCD backlight inverter drive IC implementing ZVS full-bridge topology for cold cathode fluorescent lamp (CCFL) control. It supports 5V–25.5V input, programmable striking frequency, analog/burst dimming, and open-lamp protection - enabling stable high-voltage AC generation for multi-lamp LCD monitor backlight systems.
For engineers reviewing the FAN7311N datasheet, pinout, applications, or equivalent options, this device is selected for CCFL backlight power conversion where precision voltage reference (±2%), soft-start, and lamp regulation under open-circuit conditions are required in space-constrained 20-pin DIP designs.
Technical Context
The FAN7311N integrates phase-shift PWM control with dedicated circuitry for series-parallel resonant converter operation, supporting typical switching frequencies from 30 kHz to 250 kHz depending on transformer and lamp characteristics. It implements patented phase-shift control to achieve zero-voltage switching across the full-bridge output stage.
It provides four gate-drive outputs (OUTA/OUTB/OUTC/OUTD) with complementary pairs, internal 2% precision reference, and dual dimming interfaces (BDIM for burst, ADIM for analog). Open-lamp regulation (OLR) and open-lamp protection (OLP) are implemented via dedicated pins with external resistor networks for lamp status sensing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | ZVS full-bridge - enables efficient high-frequency AC generation with reduced switching loss for CCFL transformers |
| Input Voltage Range | 5 V to 25.5 V - supports wide-range DC input from 12 V or 19 V LCD monitor supplies |
| Operating Frequency | 30 kHz to 250 kHz - adjustable via RT/CT pins to match lamp impedance and transformer resonance |
| Voltage Reference Accuracy | ±2% - ensures stable feedback loop performance for EA_IN/E A_OUT regulation without external trimming |
| Dimming Interface | Analog (ADIM) and burst (BDIM) - allows flexible brightness control compatible with MCU or PWM controller signals |
| Lamp Protection | Open-lamp detection & regulation (OLP/OLR) - prevents overvoltage during lamp failure using external resistor dividers |
| Package Type | 20-pin DIP - through-hole mounting suitable for cost-sensitive LCD monitor PCBs with manual or wave soldering |
Pinout & Package
Package: 20-pin Dual In-line Package (DIP), lead-free per JEDEC J-STD-020B, operating temperature range –25°C to +85°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OUTA) | High-side gate driver output A | Drives upper MOSFET in full-bridge leg A; complements OUTB |
| 2 (PGND) | Power ground | Return path for high-current gate drivers and output stage |
| 3 (OUTB) | Low-side gate driver output B | Drives lower MOSFET in full-bridge leg A; complements OUTA |
| 4 (RT1) | Resonant timing resistor input | Sets striking frequency via external resistor to ground |
| 5 (CT) | Timing capacitor connection | Works with RT1 to define oscillator frequency and soft-start ramp |
| 6 (OUTC) | High-side gate driver output C | Drives upper MOSFET in full-bridge leg B; complements OUTD |
| 7 (ADIM) | Analog dimming input | 0–3.3 V analog signal adjusts lamp current linearly |
| 8 (EA_IN) | Error amplifier inverting input | Connects to feedback network for closed-loop lamp current regulation |
| 9 (EA_OUT) | Error amplifier output | Internal transconductance amplifier output for loop compensation |
| 10 (OUTD) | Low-side gate driver output D | Drives lower MOSFET in full-bridge leg B; complements OUTC |
| 11 (RT) | Main timing resistor input | Sets operating frequency (30–250 kHz) with CT capacitor |
| 12 (BCT) | Burst dimming timing capacitor | Defines burst frequency and duty cycle when BDIM is active |
| 13 (BDIM) | Burst dimming enable input | Logic-level input (0/3.3 V) toggles burst-mode dimming |
| 14 (OLP) | Open-lamp protection input | Monitors lamp status via external resistor divider; triggers shutdown on open circuit |
| 15 (VIN) | Power supply input | 5–25.5 V DC input powering internal bias and gate drivers |
| 16 (ENA) | Enable input | Active-high logic input enabling full-bridge operation and soft-start |
| 17 (REF) | 2% precision voltage reference output | 2.5 V reference for external feedback or sensor biasing |
| 18 (OLR) | Open-lamp regulation input | Feedback node for closed-loop lamp current control during normal operation |
| 19 (GN) | Ground (signal) | Analog ground reference for error amplifier and reference circuitry |
| 20 (SP) | Soft-start pin | Connects to external capacitor to control startup ramp time and inrush current |
Key Features
| Feature | Design Value |
|---|---|
| ZVS full-bridge topology | Reduces switching losses and EMI in high-frequency CCFL inverters by ensuring zero-voltage turn-on of all four MOSFETs |
| Programmable striking frequency | Enables reliable lamp ignition at low temperatures via RT1 pin, independent of main operating frequency set by RT/CT |
| Dual dimming interface (ADIM + BDIM) | Supports both smooth analog brightness control and high-efficiency burst-mode dimming without external logic |
| Integrated 2% precision reference | Eliminates need for external reference IC or trimming resistors in lamp current feedback paths |
| Open-lamp regulation & protection | Provides continuous current regulation during lamp aging and automatic shutdown on lamp removal or breakage |
| Soft-start capability | Prevents inrush current and transformer saturation during power-up via SP pin capacitor timing |
Applications
| 19-inch LCD Monitor | LCD TV Backlight System |
|---|---|
|
Use Scenario: Driving four CCFLs in parallel for uniform backlighting in desktop LCD monitors. IC Role / Device Role / Timing Role: Primary inverter controller managing full-bridge gate timing, lamp ignition, and analog dimming via ADIM pin. Use Value: Enables compact, low-component-count design with built-in OLP/OLR - reducing BOM count and improving field reliability against lamp failure. |
Use Scenario: Powering multiple CCFL strings in mid-size LCD TVs with variable brightness control. IC Role / Device Role / Timing Role: Central PWM and phase-shift controller coordinating ZVS operation across two full-bridge legs (OUTA/OUTB and OUTC/OUTD). Use Value: Delivers stable 30–250 kHz operation matched to transformer resonance, minimizing audible noise and EMI in consumer audio-visual environments. |
| Industrial Panel Display | Medical Imaging Monitor |
|
Use Scenario: Backlight control in ruggedized industrial displays requiring extended temperature operation (–25°C to +85°C). IC Role / Device Role / Timing Role: High-efficiency inverter driver with programmable striking frequency (RT1) for reliable cold-start ignition. Use Value: Maintains consistent lamp brightness across wide ambient temperatures using integrated 2% reference and open-lamp regulation. |
Use Scenario: Precision backlight management in diagnostic-grade medical monitors demanding stable luminance and fail-safe behavior. IC Role / Device Role / Timing Role: Safety-critical lamp controller providing dual protection (OLP + OLR) and soft-start to prevent transformer stress during power cycling. Use Value: Ensures immediate shutdown on lamp fault while sustaining regulated output during gradual lamp degradation - critical for clinical image fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LCD backlight inverter drive applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC3895N | Fixed-frequency PWM controller without integrated CCFL-specific features (no ADIM/BDIM, no OLP/OLR pins) | Requires external circuitry for lamp regulation and dimming; used in custom resonant converters, not direct CCFL solutions | Select only when designing non-standard topologies requiring full control flexibility over gate timing and feedback |
| IRS2153D | Half-bridge driver with bootstrap supply; lacks full-bridge outputs, OLP/OLR, and dimming interfaces | Targeted at low-cost single-lamp inverters; cannot support multi-lamp or regulated CCFL systems without added ICs | Choose for cost-driven single-lamp applications where lamp protection and analog dimming are not required |
Compared with UCC3895N and IRS2153D, the FAN7311N delivers purpose-built CCFL functionality - including dual dimming modes, open-lamp regulation, and full-bridge ZVS control - reducing system-level component count and validation effort in certified LCD monitor designs.
Availability
FAN7311N is available at Aetrix Electronics and suitable for LCD monitor backlight systems, industrial panel displays, and medical imaging equipment requiring stable component supply, long-term manufacturability, and through-hole assembly compatibility.
Supply support for FAN7311N 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 fabless semiconductor company specializing in power management, analog, and interface ICs before its acquisition by ON Semiconductor in 2016.
The FAN7311N belongs to Fairchild's LCD backlight inverter controller product line, designed specifically for cost-effective, high-reliability CCFL power conversion in consumer and industrial displays.
FAQ
What is the primary function of the FAN7311N in an LCD backlight system?
The FAN7311N serves as a dedicated full-bridge inverter controller for cold cathode fluorescent lamps (CCFLs), generating high-frequency AC voltage to drive multiple lamps. It manages ZVS switching, lamp ignition, analog/burst dimming, and open-lamp protection - all within a single 20-pin DIP package. The FAN7311N replaces discrete timing and protection circuits, simplifying design for 19-inch LCD monitors and similar displays.
Does the FAN7311N support both analog and burst dimming simultaneously?
No, the FAN7311N supports either analog dimming (via ADIM pin) or burst dimming (via BDIM pin), but not both concurrently. ADIM accepts a 0–3.3 V analog signal for linear brightness control, while BDIM is a digital enable that activates burst-mode operation defined by BCT capacitor timing. The FAN7311N does not include internal logic to mix or switch between these modes dynamically.
How is open-lamp protection implemented in the FAN7311N?
The FAN7311N uses two dedicated pins - OLP (open-lamp protection) and OLR (open-lamp regulation) - each connected to external resistor dividers across the CCFL string. OLP triggers immediate shutdown upon detecting open-circuit conditions, while OLR maintains regulated lamp current during normal operation. This dual-path approach ensures safety compliance and sustained performance as lamps age. The FAN7311N requires no additional comparators or microcontrollers to implement this protection.
What is the role of the RT1 pin on the FAN7311N?
The RT1 pin sets the lamp striking frequency independently from the main operating frequency controlled by the RT pin. During startup, the FAN7311N uses RT1 to generate a higher initial frequency (typically >100 kHz) that ensures reliable CCFL ignition, especially at low temperatures. Once the lamp ignites, the controller transitions to the lower, more efficient operating frequency set by RT/CT. This staged timing is intrinsic to the FAN7311N's architecture.
Can the FAN7311N be used with LED backlights instead of CCFLs?
No, the FAN7311N is not suitable for LED backlighting. Its gate drive outputs, feedback architecture, and protection features are optimized for high-impedance, high-voltage AC operation of CCFLs - not constant-current DC driving of LEDs. LED backlight systems require different topologies (e.g., boost + current sink), dimming protocols (PWM or I²C), and protection schemes. The FAN7311N lacks LED-specific functions such as current-sense amplification or digital interface support.
FAN7311N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Applications:
- LCD TV/Monitor
- Current - Supply:
- -
- Voltage - Supply:
- 5V ~ 25.5V
- Operating Temperature:
- -25°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
FAN7311N FAQ
1.How can I place an order for FAN7311N through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN7311N 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 FAN7311N reliable?
The price and inventory of FAN7311N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN7311N is usually 5 days.
3.What payment methods are accepted for FAN7311N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN7311N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN7311N?
FAN7311N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN7311N 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 FAN7311N?
For technical support, including FAN7311N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN7311N requirements.
6.How does Aetrix verify that FAN7311N is sourced from the original manufacturer or authorized distributors?
All FAN7311N 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 FAN7311N meets industry standards.
7.What is the process for return or replacement of FAN7311N?
All FAN7311N units undergo pre-shipment inspection (PSI). If there is an issue with FAN7311N, 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 FAN7311N part is unused and in its original packaging.
Return procedure for FAN7311N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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