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Analog Devices Inc. LT1182CS
- Part No.:
- LT1182CS
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1182CS.pdf
- Description:
- IC REG CONV CCFL/LCD 1OUT 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:599
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Product details
Overview
LT1182CS from Analog Devices (formerly Linear Technology) is a dual current-mode switching regulator IC designed for Cold Cathode Fluorescent Lamp (CCFL) backlighting and dual-polarity LCD contrast control in portable displays. It integrates high-current CCFL (1.25A) and LCD (625mA) switches, 200kHz oscillator, reference, protection circuitry, and supports grounded/floating lamp configurations with open-lamp detection. Used in notebook computers and automotive displays requiring stable high-voltage AC lamp drive and variable contrast voltage.
For engineers reviewing the LT1182CS datasheet, LT1182CS pinout, LT1182CS application, or LT1182CS equivalent, key selection considerations include its dual-regulator architecture, ±10V to ±30V programmable LCD contrast range, 3V–30V input operation, shutdown quiescent current of 35µA, and SO-16 package thermal performance (θJA = 100°C/W).
Technical Context
The LT1182CS implements two independent current-mode PWM regulators: one for CCFL drive (CCFL VSW, ICCFL programming, DIO-based lamp current sensing) and one for LCD contrast (LCD VSW, FBP/FBN error amplifier, LCD VC loop compensation). Each uses cycle-by-cycle current limiting and internal slope compensation for stability at duty cycles >50%.
Its analog architecture includes separate AGND and PGND pins, high-side sense servo for CCFL current regulation (0.93–1.07A null current), and dual-input error amplifier for bipolar contrast control-enabling simultaneous positive and negative contrast generation without external polarity reversal circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 30V on VIN; 4.5V to 30V on BAT - supports wide battery and logic supply inputs without external regulators. |
| CCFL Switch Current Limit | 1.25A min at 50% duty cycle - sufficient to drive typical CCFLs up to 6mA lamp current with Royer transformer. |
| LCD Switch Current Limit | 625mA min at 50% duty cycle - enables direct drive of LCD segment bias networks requiring ±10V–±30V contrast voltage. |
| Switching Frequency | 200kHz typ - minimizes size of magnetic components (L1, L2, L3) while avoiding audible noise in display applications. |
| Quiescent Current | 9mA typ (no switching) - low power consumption critical for battery-powered palmtop and notebook systems. |
| Shutdown Current | 35µA typ - enables deep sleep mode during display off periods to extend system battery life. |
| Package Thermal Resistance | θJA = 100°C/W - defines junction temperature rise under load; TJ = TA + (PD × 100°C/W) per datasheet note. |
Pinout & Package
LT1182CS is housed in a 16-lead narrow SOIC (S package) with exposed pad not specified; thermal design must follow θJA = 100°C/W derating rule.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CCFL PGND (1) | CCFL switch emitter ground | High-current return path for CCFL switch; requires star-ground layout separation from AGND to avoid noise coupling. |
| ICCFL (2) | CCFL lamp current programming input | 0–100µA current sink sets lamp current; internally regulated to 0.45V summing node for precise current-to-voltage conversion. |
| DIO (3) | Grounded-lamp current sense interface | Connects to low side of lamp in grounded configuration; conducts bidirectional half-wave lamp current for sensing and servo nulling. |
| CCFL VC (4) | CCFL current comparator input & loop compensation node | Voltage between 0.95V–2.0V sets CCFL switch turn-off threshold; single capacitor provides stable single-pole compensation. |
| AGND (5) | Analog reference ground | Low-noise reference for 1.24V internal reference, ICCFL summing, and LCD error amplifier; must be isolated from power grounds. |
| SHUTDOWN (6) | Active-low enable control | Pull ≤0.6V to disable both regulators; reduces total supply current to 35µA - critical for system-level power management. |
| LCD VC (7) | LCD contrast current comparator input | Functions identically to CCFL VC but for LCD regulator; sets switch turn-off point for contrast voltage generation. |
| LCD PGND (8) | LCD switch emitter ground | Separate high-current ground for LCD switch; prevents LCD switching noise from corrupting CCFL or analog circuits. |
| LCD VSW (9) | LCD contrast switch collector | Drives LCD bias network with 625mA min current; supports unipolar contrast when FBN is disabled or grounded. |
| FBN (10) | Negative contrast error amplifier non-inverting input | Accepts resistor divider for negative contrast setting; offset by –12mV to define startup state; requires 0.01µF bypass to suppress switching noise. |
| FBP (11) | Positive contrast error amplifier inverting input | Summing node for positive contrast feedback; used with FBN to generate dual-polarity output without external op-amps. |
| VIN (12) | Main IC supply input | 3V–30V tolerant; powers internal LDO (2.4V); supplies logic, oscillator, and control blocks - independent of BAT/Royer rails. |
| Royer (13) | Royer converter center-tap sense | In floating-lamp mode, works with BAT pin to sense primary-side Royer current; not present on LT1184 variants. |
| BAT (14) | Battery/charger supply for Royer & LCD converters | 4.5V–30V input; biases lamp current programming block and open-lamp protection; connects to internal 0.1Ω high-side sense resistor. |
| Bulb (15) | Open-lamp protection comparator input | Monitors voltage across Royer primary via external divider; triggers clamp action on CCFL VC if lamp opens or fails to strike. |
| CCFL VSW (16) | CCFL switch collector | Drives Royer transformer primary; rated for 60V breakdown; delivers up to 1.25A with <1Ω on-resistance for high efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent regulators | Simultaneous CCFL backlight and LCD contrast control in one IC - eliminates need for two separate controllers and reduces BOM count. |
| Programmable dual-polarity contrast | Grounding POSCON or NEGCON selects +10V–+30V or –10V––30V output - enables flexible LCD biasing without external H-bridge or polarity-reversal ICs. |
| Floating or grounded lamp support | Configurable via DIO and Royer/BAT connections - accommodates diverse CCFL transformer topologies including center-tapped and push-pull Royer designs. |
| Open-lamp protection | Integrated Bulb pin comparator clamps CCFL VC to prevent overvoltage during lamp failure - protects transformer and downstream circuitry without external components. |
| Current-mode control with slope compensation | Stable operation up to 85% duty cycle - avoids subharmonic oscillation in CCFL/LCD regulators driving highly reactive loads. |
Applications
| CCFL Backlight Control | LCD Contrast Generation |
|---|---|
Use Scenario: Driving cold cathode fluorescent lamps in notebook computer displays using a Royer transformer topology with grounded or floating lamp configuration. IC Role / Device Role / Timing Role: LT1182CS acts as the primary CCFL controller, generating 200kHz PWM to drive the CCFL VSW switch, regulating lamp current via ICCFL programming and DIO-based current sensing. Use Value: Enables 90% efficient floating CCFL configuration with fast transient response due to simplified single-pole loop compensation on CCFL VC pin. | Use Scenario: Generating adjustable positive or negative contrast voltage for STN or TN LCD panels in portable instrumentation with battery-constrained power budgets. IC Role / Device Role / Timing Role: LT1182CS functions as a dual-input error amplifier (FBP/FBN) controlling LCD VSW to produce variable DC contrast bias from 3V–30V input. Use Value: Delivers ±10V to ±30V contrast range with 625mA peak current - sufficient to drive large-area LCDs without external boost stages or polarity inverters. |
| Automotive Display Power | Retail Terminal Display Management |
Use Scenario: Providing robust CCFL backlighting and contrast control in vehicle infotainment displays subject to wide ambient temperature (–40°C to +105°C) and supply voltage variation. IC Role / Device Role / Timing Role: LT1182CS operates across 0°C–100°C ambient range with built-in open-lamp protection and thermal shutdown margin (TJMAX = 100°C). Use Value: Maintains stable lamp current regulation over temperature via low-drift ICCFL summing voltage (0.45V ±40mV) and compensated CCFL VSW current limit. | Use Scenario: Managing display power in kiosk and point-of-sale terminals where reliability, long-term availability, and EMI-controlled switching frequency are critical. IC Role / Device Role / Timing Role: LT1182CS serves as the integrated display power controller, coordinating CCFL dimming (via PWM on ICCFL) and LCD contrast adjustment (via analog voltage on FBP/FBN). Use Value: Reduces component count by integrating dual regulators, reference, protection, and shutdown - simplifying compliance testing and field service. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar CCFL/LCD contrast regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1183CS | Unipolar LCD contrast only; REF pin exposed for simplified lamp current programming; no FBN pin. | Cannot generate negative contrast; suited for simpler LCDs requiring only positive bias. | Select LT1183CS when dual-polarity contrast is unnecessary and REF access simplifies system calibration. |
| LT1184CS | CCFL-only function; no LCD regulator section; grounded-lamp configuration only; no Royer pin. | Cannot drive LCD contrast; lacks floating-lamp support and dual-regulator flexibility. | Choose LT1184CS for cost-sensitive CCFL-only applications where LCD control is handled externally. |
Compared with LT1183CS and LT1184CS, the LT1182CS uniquely supports both CCFL backlighting and dual-polarity LCD contrast in a single device - offering the highest integration level for full-display power management in space-constrained portable systems.
Availability
LT1182CS is available at Aetrix Electronics and suitable for notebook computers, automotive displays, portable instruments, and retail terminals requiring stable component supply with industrial temperature range support (0°C to 100°C).
Supply support for LT1182CS 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 product support, documentation, and manufacturing continuity for the LT1182CS and related display power ICs.
The LT1182CS belongs to Linear's CCFL/LCD display power controller family, engineered specifically for portable and automotive display systems requiring high-efficiency, dual-output, and fault-protected lamp and contrast regulation.
FAQ
What is the maximum lamp current the LT1182CS can regulate in a CCFL application?
The LT1182CS regulates CCFL lamp current up to 6mA typical in standard Royer-based applications. This is achieved by programming the ICCFL pin with 0–100µA, which scales the internal CCFL high-side sense servo current (0.93–1.07A) to set the CCFL VSW switch current limit. The LT1182CS datasheet confirms this capability in the Typical Application schematic (TA01) and ICCFL Summing Voltage specifications.
How does the LT1182CS support both positive and negative LCD contrast voltage generation?
The LT1182CS supports dual-polarity LCD contrast through dedicated FBP (inverting) and FBN (non-inverting) error amplifier inputs. Grounding POSCON enables positive contrast (10V–30V), while grounding NEGCON enables negative contrast (–10V––30V). The internal offset on FBN (–12mV) ensures defined startup behavior, and the transconductance (650–1150 µmhos) allows precise feedback control of LCD VSW to generate either polarity without external polarity-reversal circuitry.
Can the LT1182CS operate in a floating-lamp CCFL configuration?
Yes, the LT1182CS supports floating-lamp CCFL configurations using the Royer and BAT pins as high-side current sense inputs. In this mode, the IC senses primary-side Royer converter current to regulate lamp current without requiring the lamp to be referenced to ground. The datasheet explicitly states that LT1182CS supports both grounded and floating lamp configurations - unlike LT1184CS, which supports grounded-lamp only.
What is the purpose of the DIO pin on the LT1182CS, and how should it be connected?
The DIO pin on the LT1182CS serves as the bidirectional current sense interface for grounded-lamp CCFL configurations. It connects to the low-voltage side of the lamp and conducts alternating half-cycles of lamp current. One diode conducts during negative half-cycles, diverting 10% of its current to the CCFL VC pin for servo nulling. For floating-lamp operation, the DIO pin must be grounded. The LT1182CS datasheet specifies this behavior in the PIN FUNCTIONS section and Typical Application diagram.
Does the LT1182CS include open-lamp protection, and how does it function?
Yes, the LT1182CS includes integrated open-lamp protection via the Bulb pin. A 7V threshold comparator monitors voltage between BAT and Bulb pins. When lamp start-up fails or the lamp opens, the comparator activates and sinks current into the CCFL VC pin, forcing the regulator into voltage-mode operation to clamp output voltage. This prevents transformer overvoltage and secondary-side damage. The protection is confirmed in the ABSOLUTE MAXIMUM RATINGS and PIN FUNCTIONS sections of the LT1182CS datasheet.
LT1182CS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Converter, CCFL, LCD
- Voltage - Input:
- 3V ~ 30V
- Number of Outputs:
- 1
- Voltage - Output:
- -
- Operating Temperature:
- 0°C ~ 100°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LT1182CS FAQ
1.How can I place an order for LT1182CS through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1182CS 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 LT1182CS reliable?
The price and inventory of LT1182CS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1182CS is usually 5 days.
3.What payment methods are accepted for LT1182CS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1182CS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1182CS?
LT1182CS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1182CS 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 LT1182CS?
For technical support, including LT1182CS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1182CS requirements.
6.How does Aetrix verify that LT1182CS is sourced from the original manufacturer or authorized distributors?
All LT1182CS 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 LT1182CS meets industry standards.
7.What is the process for return or replacement of LT1182CS?
All LT1182CS units undergo pre-shipment inspection (PSI). If there is an issue with LT1182CS, 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 LT1182CS part is unused and in its original packaging.
Return procedure for LT1182CS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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