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Analog Devices Inc. LT1186FCS#PBF
- Part No.:
- LT1186FCS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Lighting, Ballast Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1186FCS#PBF.pdf
- Description:
- IC CCFL CNTRL 225KHZ 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,767
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Product details
Overview
LT1186FCS#PBF from Analog Devices (formerly Linear Technology) is a DAC-programmable, fixed-frequency current-mode CCFL switching regulator with integrated 8-bit 50µA full-scale current-output DAC, 200kHz oscillator, and high-side NPN power switch. It delivers precise lamp-current control (0–6mA typical) for cold cathode fluorescent backlighting in battery-powered displays, supports grounded/floating lamp configurations, and features open-lamp protection and shutdown retention of DAC setting.
For engineers reviewing the LT1186FCS#PBF datasheet, LT1186FCS#PBF pinout, LT1186FCS#PBF application, or LT1186FCS#PBF equivalent, key selection criteria include its 4.5V–30V wide battery input range, SPI/pulse-mode digital interface, 50µA DAC full-scale accuracy, 1.25A minimum switch current capability, and SO-16 narrow package compatibility with space-constrained portable display power designs.
Technical Context
The LT1186FCS#PBF implements a fixed 200kHz current-mode control architecture where the internal NPN switch turns off when sensed current reaches a DAC-programmed threshold at the CCFL VC pin. Its lamp-current programming block converts 0–50µA DAC output into a proportional 0–250µA source current at CCFL VC, enabling direct "bits-to-nits" intensity control.
It supports two mutually exclusive digital interfaces: standard 3-wire SPI (CLK/CS/DIN/DOUT) for bidirectional 8-bit register access, or 1-/2-wire pulse mode (DIN/CLK only) for increment-only or increment/decrement counter control. On power-up, CS pin level determines default interface mode, and DAC retains last setting during active-low SHDN.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 200 kHz typical; minimizes magnetic component size and enables compact Royer transformer design. |
| DAC Resolution | 8-bit; provides 256 discrete lamp current steps for smooth brightness control without hysteresis. |
| DAC Full-Scale Current | 50 µA ±3 µA; directly programs lamp current from 0 to 6 mA in typical display applications. |
| Input Voltage Range (BAT) | 4.5 V to 30 V; supports wide battery chemistries (Li-ion, Li-Poly, multi-cell alkaline) without external regulation. |
| Quiescent Supply Current | 6 mA typical at half-scale DAC output; enables low-power operation in active display modes. |
| Shutdown Supply Current | 35 µA typical; reduces system standby power while preserving DAC setting across sleep/wake cycles. |
| CCFL Switch Current Limit | 1.25 A minimum at 50% duty cycle; ensures robust drive for high-brightness CCFLs up to ~15-inch panels. |
| Package | 16-pin narrow SOIC; surface-mount compatible with automated PCB assembly and thermal management via PGND pad. |
Pinout & Package
The LT1186FCS#PBF is housed in a 16-pin narrow SOIC (SO-16N) package with exposed thermal pad (not electrically connected). Pin 1 is CCFL PGND; pins are arranged in dual rows with standard 0.050" pitch. Thermal resistance θJA = 100°C/W enables operation up to +100°C ambient in properly laid-out designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - CCFL PGND | Emiter of internal NPN power switch | Carries full switch current; must connect to dedicated power ground plane to minimize noise coupling into analog circuitry. |
| 2 - ICCFL | DAC programming current input | Regulated to 465 mV internally; accepts 0–50 µA DC current to set lamp current; ties directly to IOUT pin. |
| 3 - DIO | Lamp current return path | Provides bidirectional conduction path for grounded-lamp configurations; must be grounded in floating-lamp setups. |
| 4 - CCFL VC | Lamp current servo node | Output of DAC programming block and input to current comparator; voltage (0.95–2.0 V) sets switch-off threshold. |
| 5 - AGND | Analog reference ground | Low-current return for internal reference and ICCFL summing node; requires star-ground connection to avoid regulation error. |
| 6 - SHDN | Active-low shutdown control | Pulling low disables oscillator and power switch, reducing supply current to 35 µA while retaining DAC state. |
| 7 - CLK | Digital interface clock input | Schmitt-triggered; synchronizes data transfer in SPI mode or increments/decrements counter in pulse mode. |
| 8 - CS | Chip select / mode select | Logic low enables SPI data transfer; power-up level selects default interface (high = pulse mode, low = SPI). |
| 9 - DIN / UP/DN | Digital data input or control direction | In SPI mode: serial data input; in pulse mode: logic level selects increment-only (high) or increment/decrement (low). |
| 10 - DOUT | Digital data output | Three-state output; returns previous 8-bit DAC value in SPI mode; high-impedance in pulse mode. |
| 11 - IOUT | DAC current output | Delivers 50 µA full-scale current; tied internally to ICCFL to form closed-loop lamp current programming path. |
| 12 - VCC | Logic supply input | Accepts 3.3 V or 5 V; powers internal logic and 2.4 V LDO; quiescent current stable across this range. |
| 13 - ROYER | Floating-lamp current sense input | Inverting input of high-side current amplifier; used with BAT pin to monitor Royer primary current in floating configurations. |
| 14 - BAT | Battery input / high-side sense reference | 4.5–30 V input; supplies Royer converter and bias for programming block; connects to open-lamp protection clamp. |
| 15 - BULB | Open-lamp protection comparator input | Monitors voltage across Royer primary; triggers clamp action if exceeds programmed threshold (e.g., 7 V). |
| 16 - CCFL VSW | Collector of internal NPN switch | Drives Royer transformer primary; rated for 60 V breakdown and ≥1.25 A continuous current at 50% duty cycle. |
Key Features
| Feature | Design Value |
|---|---|
| Bits-to-Nits™ DAC programming | Direct 0–50 µA DAC output maps linearly to 0–6 mA lamp current, enabling precise, hysteresis-free brightness control. |
| Grounded or floating lamp support | Single IC supports both topologies: DIO pin used for grounded lamps; ROYER/BAT pins enable floating-lamp differential drive. |
| Open-lamp protection | Integrated BULB-BAT comparator clamps CCFL VC on overvoltage, forcing voltage-mode operation to prevent transformer saturation. |
| Retained DAC setting in shutdown | Active-low SHDN reduces supply current to 35 µA while preserving 8-bit DAC counter state for instant brightness restoration. |
| Current-mode stability | Cycle-by-cycle current limiting and inherent input-voltage rejection simplify loop compensation and improve transient response. |
| Wide input voltage tolerance | 4.5–30 V BAT range accommodates 1–6 cell Li-ion packs and legacy AC adapters without external pre-regulation. |
Applications
| Notebook Computers | Palmtop Computers |
|---|---|
Use Scenario: Backlighting 10–15 inch LCD panels in clamshell notebooks with battery life optimization. IC Role / Device Role / Timing Role: CCFL switching regulator with DAC-based lamp current control and open-lamp fault detection. Use Value: Enables >90% efficient Royer drive with zero DC lamp bias, extending battery runtime by minimizing CCFL-related drain (~50% of total). |
Use Scenario: Driving compact CCFLs in handheld PDAs and early smartphones with height-constrained enclosures (<10 mm). IC Role / Device Role / Timing Role: Integrated current-mode controller and 8-bit DAC for space-efficient, low-component-count backlight solution. Use Value: Eliminates need for external DAC and op-amps; SO-16N footprint fits tight board real estate while supporting 1-wire pulse mode for minimal GPIO usage. |
| Portable Instruments | Retail Terminals |
Use Scenario: Illuminating high-contrast LCDs in battery-operated test equipment (multimeters, oscilloscopes) requiring stable brightness over temperature. IC Role / Device Role / Timing Role: Precision lamp current regulator with 50 µA DAC full-scale accuracy and <±2 LSB DNL for repeatable intensity calibration. Use Value: Maintains consistent display luminance across –40°C to +100°C operating range, critical for field-deployed instrumentation. |
Use Scenario: Powering CCFL backlights in point-of-sale terminals and kiosks with intermittent use and long standby periods. IC Role / Device Role / Timing Role: Low-quiescent-current CCFL controller with 35 µA shutdown mode and retained DAC state for instant-on functionality. Use Value: Reduces standby power consumption by >99% vs active mode, lowering energy cost and thermal load in always-on retail environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar CCFL regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1185FCS#PBF | Same pinout and DAC architecture but lacks pulse-mode interface; SPI-only with identical 8-bit/50µA DAC and 200kHz frequency. | Requires microcontroller with dedicated SPI peripheral; not suitable for GPIO-constrained systems needing 1-wire control. | Select when SPI interface is preferred and DAC retention in shutdown is required; otherwise, LT1186FCS#PBF offers greater interface flexibility. |
| MAX8722AETI+ | Higher integration: includes boost controller, gate drivers, and fault protection; no integrated DAC; uses external PWM or analog dimming. | Targets larger displays with higher lamp voltages; requires external dimming signal generation and more external components. | Choose for complex multi-lamp systems or where programmable overvoltage/overcurrent thresholds are needed beyond LT1186FCS#PBF's fixed protection. |
Compared with LT1185FCS#PBF and MAX8722AETI+, the LT1186FCS#PBF uniquely combines DAC-based analog dimming, dual-interface flexibility (SPI/pulse), and open-lamp protection in a single SO-16N package-making it optimal for cost-sensitive, space-constrained portable displays requiring simple, reliable brightness control.
Availability
LT1186FCS#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instruments, and retail terminals requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for LT1186FCS#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains full technical and supply chain support for legacy Linear products including the LT1186F series.
The LT1186F product line was designed specifically for energy-efficient, digitally controllable CCFL backlighting in portable LCD devices, emphasizing low quiescent current, wide input voltage range, and robust lamp protection.
FAQ
What is the function of the DIO pin on the LT1186FCS#PBF?
The DIO pin on the LT1186FCS#PBF serves as the common connection between two internal diodes and functions as the lamp current return path in grounded-lamp configurations. In such setups, bidirectional lamp current flows through DIO, allowing half-wave rectification and averaging for stable current control. When using a floating-lamp topology, the DIO pin must be grounded to disable this path and route sensing through the ROYER and BAT pins instead. This dual-mode capability is integral to the LT1186FCS#PBF's flexible CCFL drive architecture.
Does the LT1186FCS#PBF retain its DAC setting during shutdown?
Yes, the LT1186FCS#PBF retains its 8-bit DAC counter value during active-low shutdown. When the SHDN pin is pulled low, the IC reduces total supply current to 35 µA typical while maintaining the DAC output current setting. Upon removal of the shutdown signal, the LT1186FCS#PBF resumes operation immediately at the previously programmed lamp current level-enabling instant-on brightness control without reinitialization delay or microcontroller intervention.
What is the maximum lamp current achievable with the LT1186FCS#PBF?
The LT1186FCS#PBF supports up to 6 mA typical lamp current in standard display applications, corresponding to its 0–50 µA DAC full-scale programming range. This is achieved by scaling the DAC output current (via the CCFL VC servo) to regulate average lamp current. The actual maximum depends on external components-including Royer transformer turns ratio, lamp impedance, and input voltage-but the LT1186FCS#PBF's 1.25 A minimum switch current rating and 60 V VSW breakdown ensure headroom for driving lamps up to ~15 inches in diagonal size under nominal conditions.
Can the LT1186FCS#PBF operate with a 3.3 V logic supply?
Yes, the LT1186FCS#PBF is fully specified to operate with a 3.3 V VCC supply. Its digital inputs (CLK, CS, DIN) have VIH thresholds of 1.9 V (min) and VIL thresholds of 0.45 V (max) at VCC = 3.3 V, ensuring reliable interfacing with 3.3 V microcontrollers. The internal 2.4 V LDO remains functional across the 3 V to 6.5 V VCC range, and quiescent current variation is minimal-making the LT1186FCS#PBF suitable for modern low-voltage portable systems without level-shifting circuitry.
How does open-lamp protection work in the LT1186FCS#PBF?
Open-lamp protection in the LT1186FCS#PBF is implemented via the BULB pin, which monitors voltage across the Royer transformer primary. When this voltage exceeds a threshold (e.g., 7 V), an internal comparator sinks current into the CCFL VC pin, pulling it down and forcing the regulator into voltage-mode operation. This prevents uncontrolled switch duty cycle growth and transformer saturation during lamp removal or failure. The BULB-BAT clamp voltage is externally adjustable via a resistor divider, allowing customization for different lamp start voltages and operating conditions-ensuring robust fault handling without external components.
LT1186FCS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Bits-to-Nits™
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- CCFL Controller
- Frequency:
- 175kHz ~ 225kHz
- Voltage - Supply:
- 4.5V ~ 30V
- Current - Supply:
- 6 mA
- Current - Output Source/Sink:
- -
- Dimming:
- No
- Operating Temperature:
- 0°C ~ 100°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LT1186FCS#PBF FAQ
1.How can I place an order for LT1186FCS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1186FCS#PBF 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 LT1186FCS#PBF reliable?
The price and inventory of LT1186FCS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1186FCS#PBF is usually 5 days.
3.What payment methods are accepted for LT1186FCS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1186FCS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1186FCS#PBF?
LT1186FCS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1186FCS#PBF 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 LT1186FCS#PBF?
For technical support, including LT1186FCS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1186FCS#PBF requirements.
6.How does Aetrix verify that LT1186FCS#PBF is sourced from the original manufacturer or authorized distributors?
All LT1186FCS#PBF 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 LT1186FCS#PBF meets industry standards.
7.What is the process for return or replacement of LT1186FCS#PBF?
All LT1186FCS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1186FCS#PBF, 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 LT1186FCS#PBF part is unused and in its original packaging.
Return procedure for LT1186FCS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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