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Analog Devices Inc. LT1942EUF#TRPBF
- Part No.:
- LT1942EUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LT1942EUF#TRPBF.pdf
- Description:
- IC REG CONV TFT LCD 4OUT 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,044
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Product details
Overview
LT1942EUF#TRPBF from Analog Devices (formerly Linear Technology) is a quad DC/DC switching regulator IC designed for TFT-LCD display power management, integrating triple-output TFT bias supply (AVDD, VOFF, VON) and white LED backlight driver in one 24-lead QFN package. It delivers independently set outputs (5V AVDD, –10V VOFF, +10V VON), 1MHz fixed-frequency operation, 2.6V–16V input range, and active current matching for dual LED strings.
For engineers reviewing the LT1942EUF#TRPBF datasheet, LT1942EUF#TRPBF pinout, LT1942EUF#TRPBF application, or LT1942EUF#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed TFT/LED power sequencing behavior, real-world soft-start and dimming implementation details, and manufacturer-validated alternative options for display power design.
Technical Context
The LT1942EUF#TRPBF integrates four current-mode, fixed-frequency (1MHz) switching regulators: two boost converters (AVDD, VON), one inverting converter (VOFF), and one LED boost converter (SW4). Power sequencing is hardware-controlled - AVDD enables first, followed by VOFF/VON after PGOOD assertion, with programmable VON output disconnect delay via CT pin.
Its LED driver includes an internal current mirror (LED1/LED2 pins) and active ballast circuitry ensuring ≤1.5% current matching at 20mA per string. Dimming is implemented by scaling the FB4 reference voltage (200mV nominal) via CTRL4 pin, enabling precise 8:1 LED current control without external PWM.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.6V to 16V - supports single-cell Li-ion (3.0–4.2V) and wide-input industrial rails without pre-regulation. |
| Switching Frequency | 1MHz fixed - enables compact magnetics (e.g., 22–47µH inductors) and low EMI in space-constrained display modules. |
| AVDD Output Accuracy | ±2% (1.25V FB1 reference) - ensures stable gate drive for amorphous/poly-Si TFTs under load and temperature variation. |
| LED Current Matching | ≤1.5% error at 20mA - guarantees uniform brightness across dual LED strings without external calibration. |
| Dimming Control Range | 8:1 analog dimming via CTRL4 (0.1V–2.5V) - eliminates flicker and EMI issues associated with PWM dimming in sensitive display environments. |
| Thermal Performance | θJA = 37°C/W, TJMAX = 125°C - validated for continuous operation in sealed display enclosures with minimal heatsinking. |
| Integrated Diodes | On-chip Schottky diodes (D2/D3/D4) - reduces BOM count and PCB area; D4 rated for 4A peak, 45V reverse blocking. |
Pinout & Package
LT1942EUF#TRPBF is housed in a 24-lead plastic QFN package (4mm × 4mm, 0.75mm height) with exposed thermal pad (Pin 25 = SGND) requiring solder connection to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (7) | Global shutdown enable | Drives >1V to enable all four regulators; <0.4V disables entire IC - used for system-level power gating. |
| CTRL4 (8) | LED driver control | Enables LED switcher (>0.25V) and scales FB4 reference (VCTRL4/10) - primary analog dimming interface. |
| FB1 (14) | AVDD feedback input | 1.25V reference node - sets AVDD output via resistor divider; high-impedance (≤60nA bias) minimizes divider error. |
| NFB2 (6) | VOFF feedback input | –150mV reference node - enables precise negative rail generation; polarity-critical for inverting topology. |
| FB3 (5) | VON feedback input | 1.25V reference node - sets positive VON output; used with output disconnect (VOUT3) for controlled ramp-up. |
| FB4 (15) | LED current sense | 200mV (nominal) current-sense reference - sets total LED current (ILED = 0.2V/R7); supports dual-string sum current sensing. |
| LED1/LED2 (18/17) | LED string current mirror inputs | Active current balancing nodes - forces equal current regardless of forward voltage mismatch between strings. |
| VOUT3 (4) | VON output disconnect collector | PNP-driven output - isolates VON rail until sequencing completes; limited to 15mA source capability. |
| PGOOD (13) | AVDD power-good indicator | Open-collector NPN - pulls low when AVDD reaches 97% of target, enabling downstream logic or external PMOS disconnect. |
| CT (9) | Sequencing delay timer | Capacitor-programmable delay (t = 10·C·0.7 µs) - controls timing between AVDD stabilization and VON output connect. |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output TFT supply with user-programmable sequencing | Hardware-enforced startup order (AVDD → VOFF/VON) eliminates display artifacts and latch-up during power-up. |
| Integrated LED current ballast for dual strings | Active matching circuitry ensures ≤1.5% current deviation - removes need for matched LEDs or external current sources. |
| Independent output voltage setting | Each output (AVDD/VOFF/VON/LED) uses dedicated feedback pin with precision reference - avoids charge-pump limitations like ratio dependency and poor regulation. |
| Open-LED protection on LED driver | D4 voltage clamped to 42V typical - prevents SW4 overvoltage failure if LED string opens during operation. |
| Soft-start on AVDD and LED regulators | SS1/SS4 pins accept external capacitors (e.g., 0.1µF) to limit inrush current - protects input source and reduces input capacitor stress. |
Applications
| Poly-Silicon TFT Displays | Amorphous Silicon TFT Displays |
|---|---|
Use Scenario: Driving medium-format industrial HMI panels (e.g., 7–10 inch) requiring stable 5V AVDD, ±10V bias, and uniform LED backlighting. IC Role / Device Role / Timing Role: Primary power management IC providing sequenced, regulated bias rails and analog-dimmed LED current with integrated ballast. Use Value: Eliminates discrete DC/DC converters and external current-matching circuits - reduces solution size by >40% and improves long-term brightness consistency. | Use Scenario: Powering consumer-grade notebook LCDs where cost, footprint, and EMI are critical constraints. IC Role / Device Role / Timing Role: Single-chip TFT+LED power solution operating from single Li-ion cell (3.0–4.2V) with 1MHz switching for compact filter design. Use Value: Integrated Schottky diodes and fixed-frequency control reduce component count and simplify layout - achieves >85% efficiency across input range. |
| Medical Diagnostic Displays | Automotive Infotainment Panels |
Use Scenario: High-reliability imaging displays requiring guaranteed power sequencing and fault protection (e.g., open-LED detection). IC Role / Device Role / Timing Role: Safety-critical bias supply with PGOOD monitoring, thermal shutdown, and robust open-circuit protection on LED output. Use Value: Built-in sequencing and protection eliminate need for external supervisors or watchdog timers - simplifies IEC 62304 compliance. | Use Scenario: Automotive center-stack displays exposed to wide temperature (–40°C to +85°C) and harsh EMI environments. IC Role / Device Role / Timing Role: AEC-Q200 compatible power IC delivering stable AVDD/VOFF/VON and flicker-free LED dimming without PWM noise coupling. Use Value: 125°C max junction rating and validated performance across full temp range ensure reliability in under-dash mounting locations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TFT-LCD power management applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1943EFE#TRPBF | Quad-output (2.6A buck, 2.6A boost, 0.3A boost, 0.4A inverter); higher current capability but no integrated LED ballast or CTRL4 dimming. | Targets larger displays needing >40mA AVDD or >2mA VON/VOFF; requires external LED driver and dimming circuitry. | Select when higher TFT bias current or buck-based AVDD efficiency is required; not suitable for dual-string LED matching. |
| LT1947EMS#TRPBF | Triple-output (boost/boost/inverter); no LED driver; MS10 package (3mm × 3mm); lower quiescent current (9.5mA vs 10mA). | Designed for smaller displays (<5 inch); lacks LED integration and sequencing - requires separate LED controller. | Choose for space-constrained portable devices where LED backlight is handled externally; lower BOM cost but increased design complexity. |
Compared with LT1942EUF#TRPBF, LT1943EFE#TRPBF offers higher output current but sacrifices integrated LED control, while LT1947EMS#TRPBF reduces footprint and IQ but removes LED functionality entirely - making LT1942EUF#TRPBF the only option combining TFT bias sequencing, dual-string LED ballasting, and analog dimming in a single QFN.
Availability
LT1942EUF#TRPBF is available at Aetrix Electronics and suitable for TFT-LCD display manufacturing, medical imaging systems, and automotive infotainment panels requiring stable component supply, long-lifecycle support, and guaranteed lead-free compliance.
Supply support for LT1942EUF#TRPBF 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 support for legacy Linear power management products including the LT1942 series.
The LT1942 belongs to Linear's TFT-LCD power management product line, engineered specifically for integrated bias and backlight solutions in portable and industrial displays - emphasizing sequencing integrity, LED current accuracy, and compact QFN packaging.
FAQ
What is the maximum input voltage rating for the LT1942EUF#TRPBF?
The LT1942EUF#TRPBF has an absolute maximum VCC pin rating of 16V, with recommended operating input range of 2.6V to 16V. Exceeding 16V risks permanent damage. The device is commonly used with single-cell Li-ion (3.0–4.2V) or 5V/12V system rails. All switching node voltages (SW1–SW4) are rated up to 36V or 45V, ensuring safe operation under transient conditions.
How does the LT1942EUF#TRPBF implement power sequencing for TFT bias supplies?
The LT1942EUF#TRPBF implements hardware-based sequencing: AVDD enables first; once FB1 reaches 97% of target, PGOOD pulls low and enables VOFF/VON simultaneously. VON's output disconnect (VOUT3) activates after a CT-pin-programmed delay. This sequence prevents TFT gate oxide stress and display initialization faults - no external controllers or firmware required.
Can the LT1942EUF#TRPBF drive a single LED string, or is dual-string operation mandatory?
The LT1942EUF#TRPBF supports both configurations. For a single LED string, leave LED1 and LED2 pins floating and connect the LED cathode directly to FB4. The internal current mirror remains inactive, and LED current is set solely by R7 (ILED = 0.2V/R7). Dual-string operation activates the ballast circuit automatically when both LED1 and LED2 are connected.
What is the purpose of the VOUT3 pin on the LT1942EUF#TRPBF, and how is it used?
VOUT3 is the collector of an internal PNP transistor that provides output disconnect for the VON supply. During sequencing, VOUT3 remains at 0V until the CT timer expires, then rises to match D3 voltage. It sources up to 15mA and must be decoupled with ≥0.1µF to local PGND23. This feature isolates VON until AVDD/VOFF are stable - preventing uncontrolled panel turn-on.
Does the LT1942EUF#TRPBF require external compensation components for its DC/DC regulators?
No, the LT1942EUF#TRPBF features fully internal compensation for all four switching regulators. No external compensation networks (e.g., RC filters on FB pins) are needed. Stability is guaranteed across the full operating range with standard output capacitor ESR values, simplifying design and reducing bill-of-materials.
LT1942EUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Converter, TFT LCD
- Voltage - Input:
- 2.6V ~ 16V
- Number of Outputs:
- 4
- Voltage - Output:
- 1.25V ~ 36V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LT1942EUF#TRPBF FAQ
1.How can I place an order for LT1942EUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1942EUF#TRPBF 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 LT1942EUF#TRPBF reliable?
The price and inventory of LT1942EUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1942EUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1942EUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1942EUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1942EUF#TRPBF?
LT1942EUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1942EUF#TRPBF 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 LT1942EUF#TRPBF?
For technical support, including LT1942EUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1942EUF#TRPBF requirements.
6.How does Aetrix verify that LT1942EUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1942EUF#TRPBF 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 LT1942EUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1942EUF#TRPBF?
All LT1942EUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1942EUF#TRPBF, 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 LT1942EUF#TRPBF part is unused and in its original packaging.
Return procedure for LT1942EUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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