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Analog Devices Inc. LTC3524EUF#PBF
- Part No.:
- LTC3524EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Management - Specialized
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3524EUF#PBF.pdf
- Description:
- IC TFT BIAS SUPPLY ADJ 24-QFN
- Quantity:
- Payment:
- Shipping:
Inventory:266
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Product details
Overview
LTC3524EUF#PBF from Analog Devices (formerly Linear Technology) is a highly integrated dual-boost power converter with integrated charge pumps for TFT LCD bias and white LED backlighting. It delivers up to 25mA at 3–6V (VOUT), ±20V at 2mA (VN/VH), and drives up to ten LEDs (2×5-series) with 20mA per string, operating from a single 2.5–6V Li-ion supply in portable displays.
For engineers reviewing the LTC3524EUF#PBF datasheet, LTC3524EUF#PBF pinout, LTC3524EUF#PBF application, or LTC3524EUF#PBF equivalent, key selection criteria include independent enable control of LCD/LED sections, internal sequencing for safe panel initialization, True Color PWM dimming support, and QFN-24 package compatibility with space-constrained handheld designs.
Technical Context
The LTC3524EUF#PBF integrates two independent 1.5MHz current-mode boost converters: one synchronous (LCD bias, up to 90% efficiency) and one nonsynchronous NPN-based (LED driver, up to 78% efficiency). Both share a common VIN input but operate with separate feedback loops, soft-start, and shutdown controls.
Three regulated charge pump stages - doubler (V2x), inverter (VN), and quadrupler (VH) - derive from VOUT and operate at 94kHz with internal sequencing: V2x activates first (~90% VOUT), followed by VN after 2ms, then VH after another 2ms. Each pump uses dedicated flying and filter capacitors and features programmable regulation via FBH (1.225V), FBN (1.0V), and FBVO (1.225V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.5V to 6.0V - supports direct connection to single-cell Li-ion/polymer batteries without pre-regulation. |
| VOUT Boost Output | 3.0V to 6.0V, 25mA max - adjustable main TFT analog supply with 1.225V FBVO reference and >90% efficiency at 3.6V input. |
| VN / VH Outputs | VN: up to –20V at 2mA; VH: up to +20V at 2mA - regulated negative and quadrupled positive rails for gate drivers, sequenced internally. |
| LED Drive Capability | Two independently enabled strings, up to 5 LEDs each, 20mA per string (RPROG = 100kΩ), with open-circuit OVP at 24V. |
| Switching Frequency | 1.5MHz (boost converters), 94kHz (charge pumps) - enables use of sub-10μH inductors and 0.1μF ceramic flying capacitors. |
| Shutdown Current | <2μA - achieved when ELCD, ELED1, and ELED2 are all low; ensures battery longevity in standby. |
| Package | 24-pin QFN (4mm × 4mm × 0.75mm) with exposed pad - thermally enhanced, footprint-optimized for portable display modules. |
Pinout & Package
The LTC3524EUF#PBF is housed in a 24-lead plastic QFN package (4mm × 4mm × 0.75mm) with an exposed thermal pad (Pin 25) that must be soldered to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ELCD (1) | Enable for LCD bias section | Active-high control; initiates soft-start and internal sequencing; pulls outputs to GND during shutdown. |
| VIN (2) | Main power input | Common 2.5–6V supply for both boost converters; requires ≥2.2μF X5R bypass capacitor. |
| FBVO (3) | VOUT feedback input | 1.225V reference node; sets VOUT via resistive divider (e.g., 324kΩ/220kΩ for 5V). |
| VOUT (4) | Main LCD bias output | Programmable 3–6V rail; feeds V2x doubler and serves as input to charge pump chain. |
| SW1 (5) | LCD boost switch node | Connects to 4.7–15μH inductor; synchronous PMOS rectifier reduces conduction loss. |
| C2– (6), C2+ (7) | Doubler flying capacitor terminals | Form 2×VOUT charge pump stage; require 0.1μF X5R ceramic capacitors. |
| V2x (8) | Doubler output | Supplies ~2×VOUT to VH quadrupler and/or VN inverter; bypassed with 0.47μF X5R cap. |
| VNIN (9) | VN inverter input voltage | Connected to VOUT, V2x, or VH to set negative rail magnitude; determines |VN| capability. |
| CN+ (10) | VN flying capacitor positive node | Alternates between GND and VNIN; requires 0.1μF X5R capacitor and external Schottky diodes. |
| NC (11) | No connect | Must be tied to GND per datasheet; no internal connection. |
| VN (12) | Negative charge pump output | Regulated negative rail (e.g., –7.5V); feedback via FBN (1.0V reference); bypassed with ≥0.47μF X5R. |
| FBN (13) | VN feedback input | 1.0V reference; sets VN via resistor divider from VOUT to VN (e.g., 470kΩ/1MΩ for –7.5V). |
| FBH (14) | VH feedback input | 1.225V reference; programs VH (e.g., 220kΩ/1MΩ for +12.5V); connects to CH+/CH– quadrupler. |
| VH (15) | Quadrupler output | Up to +20V at 2mA; used for high-side gate drive; bypassed with 0.47μF X5R capacitor. |
| CH+ (16), CH– (17) | Quadrupler flying capacitor nodes | Alternate between V2x and VH; require 0.1μF X5R ceramics; CH– referenced to GND. |
| LED2 (18), LED1 (19) | LED string outputs | Anode connections for two independent LED strings; each supports up to 5 series white LEDs. |
| VLED (20) | LED boost output | Up to 21V; powers both LED strings; requires ≥1μF (analog) or ≥4.7μF (PWM) X5R output cap. |
| SW2 (21) | LED boost switch node | Collector of internal NPN switch; connects to 3.3–15μH inductor and external Schottky diode. |
| ELED2 (22), ELED1 (24) | LED string enable/PWM inputs | Active-high digital dimming control; threshold 0.4–1.2V; low = disable; simultaneous low = shutdown. |
| PROG (23) | LED current programming | Single resistor (e.g., 100kΩ) sets 20mA/string; analog dimming possible via summed voltage. |
| GND / Exposed Pad (25) | Signal and power ground | Mandatory solder connection to PCB ground plane; critical for thermal performance and noise control. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated LCD bias + LED driver | Eliminates need for separate ICs and discrete charge pumps, reducing BOM count and board area by >40% in PDA/camera displays. |
| Internal power-up/down sequencing | Guarantees safe LCD panel initialization (V2x → VN → VH) and rapid discharge (VN → VH → VOUT) to prevent image retention or latch-up. |
| True Color PWM dimming | Enables flicker-free brightness control from 0.5% to 100% duty cycle using ELED1/ELED2 pins at 100–500Hz, preserving color fidelity. |
| Independent enable control | Allows dynamic power management: LCD bias active while LED strings disabled (or vice versa), extending battery life in UI navigation modes. |
| Open-LED protection | Clamps VLED at 24V if either string opens, maintaining regulated current in the remaining string and preventing overvoltage damage. |
Applications
| PDA Display Power | Digital Camera Backlight |
|---|---|
|
Use Scenario: Powering 3.5-inch QVGA TFT panel with dual-gate driver and dual-string WLED backlight in ultra-thin PDA. IC Role / Device Role / Timing Role: Single-chip solution generating +5V (VOUT), –7.5V (VN), +12.5V (VH), and driving 8 LEDs at 20mA total. Use Value: Reduces component count by 7 discrete regulators/capacitors; sequencing prevents ghosting during wake-from-sleep transitions. |
Use Scenario: Backlighting 2.7-inch VGA LCD in compact digital still camera with variable scene brightness detection. IC Role / Device Role / Timing Role: LED driver with analog dimming (via PROG voltage summing) and PWM burst mode for low-light video capture. Use Value: Achieves 10,000:1 effective dimming range using combined analog + PWM control, eliminating visible banding in video playback. |
| Handheld GPS Display | Portable Media Player UI |
|
Use Scenario: Driving sunlight-readable transflective TFT with high-voltage gate bias and minimal LED current in outdoor GPS units. IC Role / Device Role / Timing Role: Delivers +6V (VOUT), –9.7V (VN), +18V (VH) at 1.5mA each and powers 4 LEDs at 15mA for optimal contrast under direct sun. Use Value: High-efficiency 90% LCD boost extends battery runtime to >12 hours; low-noise 1.5MHz operation avoids RF interference with GPS receiver. |
Use Scenario: Supporting OLED-compatible TFT interface in 4.3-inch media player with touch-responsive UI requiring fast on/off transitions. IC Role / Device Role / Timing Role: Rapid shutdown (<5ms full discharge) via ELCD control enables instant screen blanking during menu navigation or sleep mode. Use Value: Sub-2μA shutdown current preserves battery during 72-hour standby; sequenced discharge prevents display artifacts during resume. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TFT LCD bias and LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS65131RGTR | Single 1.2MHz boost + dual charge pumps; no integrated LED driver; supports only one LED string (max 30mA). | Requires external LED driver IC for dual-string operation; lacks True Color PWM and open-LED protection. | Choose when only LCD bias is needed and board space allows separate LED IC; not suitable for integrated backlight solutions. |
| MAX8649ETE+ | 2.25MHz dual boost (LCD + LED); no charge pumps; generates only positive rails (VPOS, VLED); no negative bias capability. | Cannot replace VN/VH functions; requires external inverter for negative gate drive; limited to smaller panels needing only +5V/+15V. | Use where negative bias is unnecessary and higher switching frequency justifies reduced inductor size; incompatible with standard TFT gate driver requirements. |
Compared with TPS65131RGTR and MAX8649ETE+, the LTC3524EUF#PBF uniquely integrates full three-rail LCD bias (±V, +2V) with dual-string LED driving and sequencing in one QFN-24 package - enabling complete display power solutions without supplemental ICs or layout compromises.
Availability
LTC3524EUF#PBF is available at Aetrix Electronics and suitable for portable media players, handheld GPS units, and digital camera displays requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC3524EUF#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 precision analog and power management product lines with full datasheet, simulation model, and application note support.
The LTC3524EUF#PBF belongs to Linear's legacy display power management IC family, designed specifically for space-constrained, battery-powered TFT LCD modules requiring tightly coordinated bias and backlight power with minimal external components.
FAQ
What is the maximum LED string voltage supported by the LTC3524EUF#PBF?
The LTC3524EUF#PBF supports up to 21V on the VLED output, sufficient for two strings of five 3.6V white LEDs (18V total) plus overhead for internal sensing and current sharing. An open-LED fault condition clamps VLED at 24V to protect the IC and remaining string.
How does the LTC3524EUF#PBF achieve power sequencing between VOUT, VN, and VH?
The LTC3524EUF#PBF implements internal sequencing: V2x begins charging once VOUT reaches ~90% of target; VN starts after a 2ms delay; VH activates after another 2ms delay. During shutdown, discharge follows reverse order - VN first, then VH, then VOUT - ensuring safe LCD panel reset without voltage inversion.
Can the LTC3524EUF#PBF drive only one LED string while keeping the LCD bias active?
Yes. The LTC3524EUF#PBF allows independent control: set ELED1 = high and ELED2 = low to enable only LED1, or vice versa. The LCD bias remains fully operational with ELCD = high, enabling flexible power management for UI-only or video playback modes.
What external components are mandatory for basic LTC3524EUF#PBF operation?
Mandatory components include: 2.2μF X5R VIN capacitor; 4.7–15μH inductor on SW1; 3.3–15μH inductor on SW2; 0.1μF X5R flying capacitors (C2+, C2–, CN+, CH+, CH–); 0.47μF X5R filter caps on V2x, VN, VH; 1–10μF X5R on VOUT; and RPROG (e.g., 100kΩ) from PROG to GND.
Is the LTC3524EUF#PBF pin-compatible with other members of the LTC3524 family?
Yes. The LTC3524EUF#PBF shares identical pinout and functionality with LTC3524EUF, LTC3524EUF#TRPBF, and LTC3524EUF#TR across the –40°C to 85°C temperature range. Only packaging (lead-free vs leaded) and reel format differ; no design changes are required when substituting.
LTC3524EUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- LCD Display
- Current - Supply:
- -
- Voltage - Supply:
- 2.5V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LTC3524EUF#PBF FAQ
1.How can I place an order for LTC3524EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3524EUF#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 LTC3524EUF#PBF reliable?
The price and inventory of LTC3524EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3524EUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3524EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3524EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3524EUF#PBF?
LTC3524EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3524EUF#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 LTC3524EUF#PBF?
For technical support, including LTC3524EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3524EUF#PBF requirements.
6.How does Aetrix verify that LTC3524EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3524EUF#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 LTC3524EUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3524EUF#PBF?
All LTC3524EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3524EUF#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 LTC3524EUF#PBF part is unused and in its original packaging.
Return procedure for LTC3524EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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