Analog Devices Inc. LT1947EMSE#PBF

Overview

LT1947EMSE#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, externally delayed), and VOFF (–8V/10mA) from a 2.7V–8V input. Designed for notebook and desktop LCD panels, it enables complete bias solutions under 1.2mm height using all-ceramic components.

For engineers reviewing the LT1947EMSE#PBF datasheet, LT1947EMSE#PBF pinout, LT1947EMSE#PBF application, or LT1947EMSE#PBF equivalent, key selection criteria include its 3MHz fixed-frequency operation, dual 1.26V feedback references, programmable VON delay via CT capacitor, thermally enhanced 10-lead MSOP package with exposed pad, and integrated high-side switch for VON timing control.

Technical Context

The LT1947EMSE#PBF implements two independent current-mode boost regulators sharing a 1.26V reference: SW1 (1.1A internal switch, up to 30V AVDD) and SW2 (350mA switch, up to 30V VO2). A level-shift charge pump off SW1 generates VOFF, while an external CT capacitor controls VON turn-on delay after AVDD stabilization.

Its 3MHz oscillator enables compact magnetics and low-profile ceramic capacitors. Undervoltage lockout disables operation below ~2.7V. The MSE package's exposed pad (Pin 11) must be soldered to PCB ground for thermal management (θJA = 40°C/W).

Key Specifications

Pinout & Package

LT1947EMSE#PBF uses a thermally enhanced 10-lead MSOP package (MSE) with exposed ground pad (Pin 11), requiring soldering to PCB for thermal performance (θJA = 40°C/W). Package dimensions: 3.0mm × 3.0mm × 1.1mm max height.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TFT-LCD bias generator applications.

Compared with LT1945EMS#PBF and LTC3589EUF#PBF, the LT1947EMSE#PBF uniquely integrates VON delay timing, dual-boost architecture, and charge-pump VOFF in a single 10-pin MSE package - delivering the most direct, layout-efficient solution for sequenced TFT-LCD bias without external timing components or configuration overhead.

Availability

LT1947EMSE#PBF is available at Aetrix Electronics and suitable for TFT-LCD notebook display panels, desktop monitor display panels, and handheld computer designs requiring stable component supply, industrial temperature support (–40°C to 85°C), and low-profile power solutions.

Supply support for LT1947EMSE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and consumer markets.

The LT1947EMSE#PBF belongs to Linear's TFT-LCD power management product line, engineered specifically to replace multi-component bias solutions with highly integrated, low-height, sequenced-output regulators for portable and space-constrained displays.

FAQ

What is the maximum output voltage capability of the LT1947EMSE#PBF for AVDD and VON rails?

The LT1947EMSE#PBF supports adjustable AVDD and VON outputs up to 30V each, as specified in the Absolute Maximum Ratings and confirmed in the Electrical Characteristics table (VON, VO2 Voltage = 30V). This is achieved using the internal 1.26V feedback reference and external resistor dividers on FB1 and FB2 pins. The device maintains regulation and stability within this range across its –40°C to 85°C operating temperature span.

How does the CT pin on the LT1947EMSE#PBF control VON timing, and what capacitor value yields a 2.3ms delay?

The CT pin on the LT1947EMSE#PBF connects to an external capacitor that charges from a 5.5µA internal current source. When the CT voltage reaches 1.28V, the internal Q3 switch turns on, connecting VO2 to VON. Using C = (5.5µA × t_DELAY) / 1.28V, a 10nF capacitor yields ~2.3ms delay. This precise, passive timing eliminates need for external controllers or RC networks in TFT-LCD power sequencing.

What is the thermal advantage of the MSE package used by the LT1947EMSE#PBF compared to the standard MSOP package?

The LT1947EMSE#PBF uses the thermally enhanced MSE package with an exposed ground pad (Pin 11), achieving θ_JA = 40°C/W - significantly lower than the standard MS package's θ_JA = 120°C/W. This 3× improvement in thermal resistance allows sustained 200mA AVDD output without derating in compact layouts, provided the exposed pad is soldered to a PCB ground plane with thermal vias.

Can the LT1947EMSE#PBF operate from a 2.7V input, and what happens below that threshold?

Yes, the LT1947EMSE#PBF operates down to 2.7V input, as stated in its Input Voltage Range specification. Below approximately 2.7V, the internal undervoltage lockout (UVLO) circuit disables switching to prevent erratic regulation and protect downstream circuitry. This ensures clean startup and shutdown behavior across the full specified input range, critical for battery-powered TFT-LCD applications experiencing voltage sag.

Does the LT1947EMSE#PBF require external diodes and inductors, and what are typical values used in reference designs?

Yes, the LT1947EMSE#PBF requires external components: two inductors (L1 = 3.3µH, L2 = 4.7µH), four diodes (D1 = MBRM120LT3, D2 = CMDSH-3, D3/D4 = BAT54S), and five ceramic capacitors (C1 = 2.2µF, C2 = 3.3µF ×2, C3 = 220nF, C4/C6 = 0.68µF). These values appear consistently across Figures 1, 3, and TA02–TA04 in the datasheet and enable full functionality including AVDD, VON, and VOFF generation.