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Analog Devices Inc. LTC1697EMS#PBF
- Part No.:
- LTC1697EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1697EMS#PBF.pdf
- Description:
- IC REG CCFL 1OUT 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,339
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Product details
Overview
LTC1697EMS#PBF from Analog Devices (formerly Linear Technology) is a synchronous current-mode PWM controller IC designed to drive a single 1W cold cathode fluorescent lamp (CCFL) in portable backlight systems. It integrates 1A internal MOSFET switches, operates from 2.8V–5.5V input, delivers fixed 300kHz switching frequency, achieves <2µA shutdown current, and supports both internal capacitor-programmed and external PWM dimming.
For engineers reviewing the LTC1697EMS#PBF datasheet, LTC1697EMS#PBF pinout, LTC1697EMS#PBF application, or LTC1697EMS#PBF equivalent, key selection criteria include lamp current accuracy (±2–6%), RPROG-based ILAMP programming (6.4kΩ–16kΩ), thermal shutdown at 125°C, MSOP-10 package compatibility, and CCFL-specific overvoltage protection via OVSEN.
Technical Context
The LTC1697EMS#PBF implements a fixed-frequency (240–370kHz), current-mode control architecture with lossless peak-current sensing and slope compensation. Its internal 1A NMOS/PMOS synchronous switch pair enables high-efficiency buck regulation into a Royer-class transformer driver stage.
Dimming is implemented via dual-path control: an on-chip 190–310Hz PWM oscillator (set by CDIM capacitor) modulates regulator enable/disable, while VDIM (1V–2V analog input) sets duty cycle from 0% to 100%. Lamp current feedback is derived from the LAMP pin's internal 50Ω resistor and scaled 1/40 current injection into VC for closed-loop regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 5.5V - supports direct operation from single Li-ion cell without pre-regulation |
| Switching Frequency | 300kHz (typ), 240–370kHz (min/max) - enables compact magnetics and low EMI in handheld layouts |
| Lamp Current Accuracy | ±2% to ±6% - ensures consistent brightness and maximizes CCFL lifetime across temperature |
| Shutdown Current | <2µA - preserves battery life during display-off states in portable instruments |
| Dimming Frequency Range | 190Hz–310Hz (CDIM = 0.022µF) - avoids audible noise while enabling smooth 0–100% intensity control |
| Thermal Limit | 125°C junction - provides self-protection during transient overloads without external circuitry |
| Overvoltage Sense Threshold | 0.95V–1.5V at OVSEN - disables SW output when open-lamp condition risks transformer overvoltage |
Pinout & Package
The LTC1697EMS#PBF is housed in a 10-lead MSOP package (3.0mm × 3.0mm × 1.1mm height) with exposed pad for thermal enhancement and standard 0.5mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CDIM (1) | Dimming Oscillator Capacitor Input | Connects to GND via 0.022µF capacitor to set internal PWM dimming frequency (5Hz/CDIM(µF)) |
| VDIM (2) | Analog Dimming Control | Accepts 1V–2V input to linearly scale dimming duty cycle; <0.4V triggers passive shutdown after ~50ms |
| 0VSEN (3) | Overvoltage Protection Sense | Monitors Royer transistor emitters; pulls SW duty cycle to 0% if sensed current exceeds 16.65–26.35µA |
| SW (4) | Power Switch Node | Drives external inductor; requires short trace routing to minimize EMI and ringing |
| GND (5) | Signal and Power Ground | Common reference for all analog and power circuits; must be low-impedance connection to PCB ground plane |
| LAMP (6) | Lamp Current Feedback | Internally tied to GND via 50Ω resistor; senses lamp RMS current magnitude for closed-loop regulation |
| VIN (7) | Main Supply Input | Accepts 2.8V–5.5V DC input; absolute max rating is 6V |
| VC (8) | Compensation Node | Summation point for lamp feedback, RPROG current, and control loop; requires 0.1µF capacitor to GND |
| RPROG (9) | Lamp Current Programming | Connects to GND via precision resistor (6.4kΩ–16kΩ) to set ILAMP = 32V/RPROG (2mA–5mA range) |
| SHDN (10) | Active-Low Shutdown | Pull below 0.4V to disable regulator; draws <1µA when asserted; pull above 1.2V to enable |
Key Features
| Feature | Design Value |
|---|---|
| Synchronous Buck Architecture | Integrated 1A NMOS/PMOS switches eliminate external rectifier losses, achieving >90% efficiency in CCFL drive stage |
| Accurate Lamp Current Regulation | ±2% typical accuracy over temperature ensures stable brightness and extends CCFL lifetime beyond 20,000 hours |
| Two-Mode Dimming Control | Supports both internal capacitor-programmed PWM (190–310Hz) and external 150–500Hz PWM override via VDIM pin |
| Open-Lamp Protection | OVSEN pin interface prevents transformer overvoltage failure during lamp removal or open-circuit fault conditions |
| Thermal Shutdown + UVLO | Combines 125°C junction limit with 2.77V undervoltage lockout to ensure safe startup and fault recovery |
Applications
| Handheld GPS with Map Display | Portable Instrument Backlight |
|---|---|
Use Scenario: High-resolution color map rendering under variable ambient light requiring adjustable, flicker-free backlight intensity. IC Role / Device Role / Timing Role: CCFL controller providing constant-current AC drive to LCD backlight with analog-dimming interface for real-time brightness adaptation. Use Value: Enables 0–100% dimming without hysteresis or pop-on, preserving battery life while maintaining display readability across lighting conditions. | Use Scenario: Battery-powered multimeter or oscilloscope with monochrome LCD needing reliable, long-life illumination during field use. IC Role / Device Role / Timing Role: Synchronous buck regulator delivering precise 3–5mA lamp current to maximize CCFL lifetime and minimize thermal drift. Use Value: Achieves ±2% lamp current accuracy and <2µA shutdown current, extending operational time between charges and reducing recalibration frequency. |
| Handheld TV/Video Monitor | PDA Display Backlight |
Use Scenario: Compact video playback device requiring silent, EMI-clean backlight drive compatible with sensitive RF front-end circuits. IC Role / Device Role / Timing Role: Fixed-frequency (300kHz) current-mode controller generating sinusoidal-equivalent lamp drive via Royer transformer interface. Use Value: Minimizes conducted and radiated emissions through synchronous rectification and slope-compensated PWM, avoiding interference with tuner or Wi-Fi modules. | Use Scenario: Legacy PDA with grayscale LCD where space constraints demand minimal BOM count and ultra-low quiescent power. IC Role / Device Role / Timing Role: Integrated CCFL driver with internal MOSFETs, single-resistor lamp current setting, and MSOP-10 footprint. Use Value: Reduces component count by eliminating external switches and sense resistors while delivering 2.8V–5.5V operation directly from Li-ion cell. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar CCFL controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1184F | SO-16 package; 200kHz switching; no integrated synchronous rectifier; requires external MOSFETs | Higher board area; lower efficiency due to external diode losses; wider input range (3V–30V) | Choose LT1184F only when higher input voltage (>5.5V) or SOIC layout compatibility is required |
| LT1786 | SSOP-16; 8V–24V input; SMBus-compatible; supports wide dimming range up to 1000:1 | Not suitable for single-cell Li-ion systems; targets industrial/automotive CCFL arrays, not handheld 1W lamps | Select LT1786 only for multi-lamp, high-voltage, or digitally controlled backlight systems |
Compared with LT1184F and LT1786, the LTC1697EMS#PBF offers optimal integration for single-cell portable devices-combining MSOP-10 size, synchronous switching, sub-2µA shutdown, and RPROG-based lamp current tuning-making it uniquely suited for space- and battery-constrained CCFL backlight designs.
Availability
LTC1697EMS#PBF is available at Aetrix Electronics and suitable for handheld GPS units, portable instrumentation, and PDA display backlighting requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for LTC1697EMS#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 its legacy precision analog and power management portfolio with full technical documentation and long-term product support.
The LTC1697EMS#PBF belongs to Linear's CCFL backlight controller family, engineered specifically for high-efficiency, low-noise, single-lamp drive in battery-powered portable electronics with stringent size and power constraints.
FAQ
What is the recommended capacitor value for CDIM on the LTC1697EMS#PBF to achieve standard dimming frequency?
The LTC1697EMS#PBF datasheet specifies a nominal 0.022µF capacitor on the CDIM pin to set the internal dimming PWM frequency to approximately 250Hz (5Hz ÷ 0.022µF). This value avoids audible noise while ensuring smooth lamp intensity transitions. Deviations outside ±10% may shift frequency into perceptible ranges or reduce dimming linearity. Always verify with actual scope measurement of VDIM waveform in final layout.
Can the LTC1697EMS#PBF drive lamps requiring more than 5mA current?
No-the LTC1697EMS#PBF is specified for lamp currents between 2mA and 5mA, as confirmed by the RP(RANGE) parameter (6.4kΩ–16kΩ) and ILAMP = 32V/RPROG equation. Attempting to program beyond 5mA violates the electrical characteristics table and risks exceeding internal current limit (0.9–1.6A switch rating) and thermal limits. For higher-current lamps, consider LT1786 or discrete controller solutions.
How does the LTC1697EMS#PBF handle open-lamp fault conditions?
The LTC1697EMS#PBF uses the 0VSEN pin to detect open-lamp faults: when the lamp disconnects, Royer transistor emitter voltage rises, causing current to flow out of OVSEN. Once this current reaches 16.65–26.35µA, the LTC1697EMS#PBF forces SW duty cycle to 0%, halting energy transfer and protecting the transformer. No latch-up occurs-operation resumes automatically when fault clears and VDIM/SHDN remain valid.
Is the LTC1697EMS#PBF pin-compatible with other Linear CCFL controllers like LT1184F?
No-the LTC1697EMS#PBF uses a 10-pin MSOP package with unique pin assignments (e.g., CDIM, 0VSEN, LAMP), while LT1184F uses a 16-pin SOIC package with different signal mapping (e.g., DIM, FB, OSC). There is no pin-to-pin or functional drop-in replacement. Layout redesign and schematic revision are required when substituting between these families.
What is the role of the RPROG resistor in LTC1697EMS#PBF operation?
The RPROG resistor on the LTC1697EMS#PBF sets lamp current using ILAMP = 32V/RPROG. A 6.4kΩ resistor yields 5mA; 16kΩ yields 2mA. It connects between RPROG (Pin 9) and GND. This 1% tolerance resistor directly determines CCFL brightness and lifetime-tight tolerance ensures repeatable current accuracy across production units and temperature.
LTC1697EMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Controller, Cold Cathode Fluorescent Lamp (CCFL)
- Voltage - Input:
- 2.8V ~ 5.5V
- Number of Outputs:
- 1
- Voltage - Output:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LTC1697EMS#PBF FAQ
1.How can I place an order for LTC1697EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1697EMS#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 LTC1697EMS#PBF reliable?
The price and inventory of LTC1697EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1697EMS#PBF is usually 5 days.
3.What payment methods are accepted for LTC1697EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1697EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1697EMS#PBF?
LTC1697EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1697EMS#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 LTC1697EMS#PBF?
For technical support, including LTC1697EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1697EMS#PBF requirements.
6.How does Aetrix verify that LTC1697EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1697EMS#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 LTC1697EMS#PBF meets industry standards.
7.What is the process for return or replacement of LTC1697EMS#PBF?
All LTC1697EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1697EMS#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 LTC1697EMS#PBF part is unused and in its original packaging.
Return procedure for LTC1697EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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