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Analog Devices Inc. LT1947EMS#PBF
- Part No.:
- LT1947EMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT1947EMS#PBF.pdf
- Description:
- IC REG CONV TFT LCD 3OUT 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:202
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Product details
Overview
LT1947EMS#PBF from Analog Devices (formerly Linear Technology) is a triple-output TFT-LCD bias generator IC integrating two adjustable switching regulators and a charge-pump negative rail generator. It delivers AVDD up to 30V/200mA, VON up to 30V/10mA with programmable delay, and VOFF down to –10V/10mA from a 2.7V–8V input. Used in notebook and desktop LCD panels for high-voltage bias supply.
For engineers reviewing the LT1947EMS#PBF datasheet, LT1947EMS#PBF pinout, LT1947EMS#PBF application, or LT1947EMS#PBF equivalent, key selection criteria include its 3MHz fixed-frequency operation, dual current-mode switchers (1.1A SW1 / 350mA SW2), externally programmable VON delay via CT capacitor, all-ceramic component support, and thermally enhanced 10-lead MSOP package with exposed ground pad.
Technical Context
The LT1947EMS#PBF implements two independent current-mode DC/DC converters sharing a 1.26V internal reference: SW1 generates AVDD (adjustable up to 30V) with 1.1A switch; SW2 generates VO2 (also adjustable up to 30V), which feeds a high-side NPN switch (Q3) to produce the delayed VON output. A charge pump off SW1 generates VOFF.
Timing control uses a 5.5µA CT current source charging an external capacitor; when CT voltage reaches 1.28V, Q3 turns on, enabling VON. The 3MHz oscillator enables compact magnetics (e.g., 3.3µH/4.7µH chip inductors) and fast transient response, while undervoltage lockout disables operation below ~2.7V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 8V - supports single-cell Li-ion, 3.3V, or 5V system rails without pre-regulation. |
| AVDD Output Capability | Up to 30V at 200mA - sufficient for modern TFT-LCD gate drivers and source drivers requiring high positive bias. |
| VON Output Capability | Up to 30V at 10mA with programmable delay - enables sequenced power-up of panel logic and analog sections. |
| VOFF Output Capability | Up to –10V at 10mA - generated via charge pump from SW1 node, eliminating need for separate inverting converter. |
| Switching Frequency | 3MHz (typical) - allows use of sub-1mm-height ceramic capacitors and low-profile chip inductors for ultra-thin display designs. |
| SW1 Current Limit | 1.1A (min) - ensures robust AVDD generation under load transients and short-circuit conditions. |
| SW2 Current Limit | 350mA (min) - provides adequate headroom for VO2/VON path including Q3 saturation drop (~200mV). |
Pinout & Package
LT1947EMS#PBF is housed in a thermally enhanced 10-lead MSOP package (MSE) with exposed ground pad (Pin 11), requiring soldering to PCB for thermal and electrical performance. Package dimensions: 3.00mm × 3.00mm × 1.10mm max height.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 (Pin 1) | AVDD feedback input | Connects to resistor divider; sets AVDD = 1.26V × (1 + R1/R2); precision 1.26V reference enables ±1% output regulation. |
| FB2 (Pin 2) | VON/VO2 feedback input | Connects to second resistor divider; sets VON = 1.26V × (1 + R3/R4) – 160mV; accounts for Q3 emitter-base drop. |
| CT (Pin 3) | Delay timing capacitor node | 5.5µA current source charges external capacitor; 10nF yields ~2.3ms delay from AVDD regulation to VON enable. |
| SW1 (Pin 4) | Main switch node | Drives external inductor L1 and diode D1; high dv/dt node requiring minimized trace area to reduce EMI. |
| GND (Pin 5) | Power and signal ground | Primary ground return; must connect directly to local ground plane; exposed pad (Pin 11) is also GND and must be soldered. |
| VIN (Pin 6) | Input supply | Accepts 2.7V–8V; requires local 2.2µF ceramic bypass capacitor placed adjacent to pin. |
| SW2 (Pin 7) | Secondary switch node | Drives L2 and D2; same EMI-sensitive layout rules apply as SW1. |
| SHDN (Pin 8) | Shutdown control | Logic-high (>2.4V) enables operation; logic-low (<0.4V) reduces quiescent current to 1µA. |
| VO2 (Pin 9) | SW2 output / Q3 emitter | Provides regulated positive voltage to Q3 emitter; internal connection enables VON generation with minimal external components. |
| VON (Pin 10) | Delayed positive output | Final output enabled after CT timeout; used for sequenced panel power-up to prevent latch-up or inrush issues. |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output TFT-LCD bias solution | Integrates AVDD, VON (delayed), and VOFF in one IC - eliminates need for three discrete converters and reduces BOM count by >40%. |
| 3MHz fixed-frequency operation | Enables use of 0603/0805-size inductors and <1.2mm total height - critical for slim notebook and handheld display modules. |
| All-ceramic capacitor support | Eliminates electrolytics and tantalums - improves reliability, lifetime, and temperature stability across –40°C to 85°C operating range. |
| Externally programmable VON delay | CT pin allows precise sequencing (e.g., AVDD → VOFF → VON) using a single capacitor - prevents panel damage during power-up. |
| Thermally enhanced MSE package | Exposed pad lowers θJA to 40°C/W - sustains full 200mA AVDD load at 85°C ambient without derating. |
Applications
| Notebook Display Panels | Desktop Monitor Panels |
|---|---|
Use Scenario: Powering 13.3"–15.6" active-matrix TFT-LCD panels in ultrabooks with strict height constraints (<1.2mm stack height). IC Role / Device Role / Timing Role: Generates AVDD (8V/200mA), VON (24V/10mA), and VOFF (–8V/10mA) with 2.3ms VON delay to match panel driver IC startup sequence. Use Value: Enables complete bias solution using only ceramic caps and chip inductors - meets mechanical thickness targets while maintaining ±1% output regulation. | Use Scenario: Biasing 21.5"–27" high-resolution IPS panels in commercial monitors requiring stable multi-rail sequencing. IC Role / Device Role / Timing Role: Delivers AVDD (12V/120mA), VON (20V/10mA), and VOFF (–6V/20mA); CT capacitor adjusted for 3ms delay to coordinate with backlight controller enable. Use Value: Reduces component footprint by 65% vs. discrete solutions; 3MHz switching minimizes conducted EMI in EMC-sensitive office environments. |
| Digital Cameras | Handheld Computers |
Use Scenario: Supplying bias rails for 3.5"–5" OLED-compatible TFT backplanes in DSLR electronic viewfinders and mirrorless camera displays. IC Role / Device Role / Timing Role: Provides AVDD (7.5V/200mA), VON (15V/10mA), and VOFF (–10V/20mA); soft-start via SHDN RC network prevents camera processor reset during power-up. Use Value: 2.7V minimum input supports single-cell Li-ion battery operation down to end-of-discharge; shutdown current <1µA extends standby time. | Use Scenario: Powering display subsystems in ruggedized industrial PDAs and medical handhelds with wide temperature requirements. IC Role / Device Role / Timing Role: Generates AVDD (10V/150mA), VON (24V/10mA), and VOFF (–6V/10mA); operates over full –40°C to 85°C range with guaranteed specs. Use Value: Exposed-pad MSE package ensures thermal stability in sealed enclosures; all-ceramic design avoids capacitance drift at low temperatures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TFT-LCD bias generator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3425 | Single-output 3MHz boost converter (up to 34V/500mA); no integrated VON delay or VOFF generation. | Requires external charge pump and timing circuit for full triple-rail functionality - increases BOM and layout complexity. | Choose LTC3425 only if AVDD is sole requirement and space permits discrete VON/VOFF implementation. |
| LT3467 | Dual-output (positive/negative) 1.2MHz converter; VOUT+ up to 34V/350mA, VOUT– down to –34V/100mA; no programmable delay. | Generates AVDD and VOFF natively but lacks VON delay function - unsuitable for panels requiring strict power sequencing. | Choose LT3467 when VON delay is unnecessary and higher VOFF current (>10mA) is required. |
Compared with LTC3425 and LT3467, the LT1947EMS#PBF uniquely integrates all three rails-including programmable VON delay-within a single 3MHz, all-ceramic, thermally optimized package, making it the only direct solution for space-constrained, sequenced TFT-LCD biasing.
Availability
LT1947EMS#PBF is available at Aetrix Electronics and suitable for notebook display panels, desktop monitor panels, digital cameras, and handheld computers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LT1947EMS#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and consumer markets.
The LT1947EMS#PBF belongs to Linear's legacy TFT-LCD power management product line, engineered specifically for ultra-thin, low-noise, multi-rail display biasing in portable and commercial visual systems.
FAQ
What is the maximum achievable AVDD output voltage from the LT1947EMS#PBF?
The LT1947EMS#PBF supports an AVDD output voltage up to 30V, set by the external resistor divider on FB1 (AVDD = 1.26V × (1 + R1/R2)). This is confirmed in the Absolute Maximum Ratings table (VON, VO2 voltage = 30V) and Electrical Characteristics (FB1 voltage = 1.26V typ). Operation at 30V requires appropriate external components rated for ≥36V (e.g., SW1 voltage rating = 36V).
How is the VON delay time calculated for the LT1947EMS#PBF?
The VON delay time for the LT1947EMS#PBF is determined by the CT capacitor value and the internal 5.5µA current source: tDELAY = (CT × 1.28V) / 5.5µA. A 10nF capacitor yields ~2.3ms delay, as verified in the Typical Performance Characteristics (Figure 1947 G03) and Applications section. The CT pin voltage threshold is 1.28V (typ), and the current source is specified as 4–6.5µA.
Does the LT1947EMS#PBF require external diodes and inductors?
Yes, the LT1947EMS#PBF requires external components: two chip inductors (L1 for AVDD, L2 for VO2/VON), four diodes (D1–D4 for rectification and charge pump), and multiple ceramic capacitors (C1–C6). These are explicitly shown in Figure 1 and the Bill of Materials on pages 1–2 of the datasheet. No internal power switches or passive components are integrated beyond the controllers and references.
What is the thermal performance difference between the MS and MSE packages of the LT1947EMS#PBF?
The MSE package (used in LT1947EMS#PBF) features an exposed ground pad that reduces thermal resistance to θJA = 40°C/W, versus θJA = 120°C/W for the standard MS package (LT1947EMS). This 3× improvement allows the LT1947EMS#PBF to sustain full 200mA AVDD load at 85°C ambient without derating, whereas the MS version would require significant output current reduction above 60°C.
Can the LT1947EMS#PBF operate from a 2.7V input supply?
Yes, the LT1947EMS#PBF is fully specified to operate from 2.7V to 8V input, with guaranteed performance over the full –40°C to 85°C temperature range. The Absolute Maximum Ratings confirm VIN voltage = 8V, and the Electrical Characteristics table lists "Input Voltage Range" as 2.7V (min) to 8V (max). Undervoltage lockout disables switching below ~2.7V, protecting the device during brownout conditions.
LT1947EMS#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:
- Converter, TFT LCD
- Voltage - Input:
- 2.7V ~ 8V
- Number of Outputs:
- 3
- Voltage - Output:
- Adj up to 30V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-MSOP
LT1947EMS#PBF FAQ
1.How can I place an order for LT1947EMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1947EMS#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 LT1947EMS#PBF reliable?
The price and inventory of LT1947EMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1947EMS#PBF is usually 5 days.
3.What payment methods are accepted for LT1947EMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1947EMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1947EMS#PBF?
LT1947EMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1947EMS#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 LT1947EMS#PBF?
For technical support, including LT1947EMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1947EMS#PBF requirements.
6.How does Aetrix verify that LT1947EMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT1947EMS#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 LT1947EMS#PBF meets industry standards.
7.What is the process for return or replacement of LT1947EMS#PBF?
All LT1947EMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1947EMS#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 LT1947EMS#PBF part is unused and in its original packaging.
Return procedure for LT1947EMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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