Texas Instruments LM3631YFFR

Overview

LM3631YFFR from Texas Instruments is a highly integrated LCD backlight and bias power management IC for mobile displays. It integrates a 29-V backlight boost converter with two 25-mA constant-current LED drivers, programmable ±5.4-V LCD bias supplies (LDO_VPOS/CP_VNEG), and dual LDOs (LDO_OREF/LDO_CONT) - all in a 2.585 mm × 1.885 mm DSBGA-24 package. It supports up to 8 LEDs per string and delivers >88% backlight efficiency at 25 mA.

For engineers reviewing the LM3631YFFR datasheet, LM3631YFFR pinout, LM3631YFFR application, or LM3631YFFR equivalent, this device is selected for compact high-definition display power solutions requiring I²C-programmable sequencing, multi-rail voltage generation, and thermal-safe operation in space-constrained handheld devices.

Technical Context

The LM3631YFFR implements a synchronous boost topology for backlight driving (VOUT up to 29 V) and a separate high-frequency boost stage (2.5 MHz) for LCD bias (BST_OUT), followed by programmable LDOs and an inverting charge pump for negative bias generation. Its dual LED current sinks support 11-bit linear or 17-bit exponential dimming via I²C or external PWM input.

It features independent fault monitoring (OTP_SEL-configurable defaults), programmable power-good thresholds (90–95% of target), and thermal shutdown at 140°C with 20°C hysteresis. All outputs - including VPOS (4–6 V/100 mA), VNEG (–4 to –6 V/80 mA), OREF (4–6 V/50 mA), and CONT (1.8–3.3 V/80 mA) - are digitally adjustable and sequenced via register-controlled enable logic.

Key Specifications

Pinout & Package

LM3631YFFR uses a 24-bump DSBGA package (2.585 mm × 1.885 mm, 0.4-mm pitch) optimized for ultra-thin mobile PCBs. The package supports solder reflow per JEDEC J-STD-020 and includes exposed die attach for thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LCD backlight and bias power applications.

Compared with LM3632YFFR, LM3631YFFR offers lower system cost and smaller footprint for pure display power needs, while TPS65136RGTR provides greater flexibility in mixed-signal SoC designs where LED driving is handled externally.

Availability

LM3631YFFR is available at Aetrix Electronics and suitable for smartphone LCD power management, tablet display bias supply, portable medical monitor backlight, and automotive infotainment display requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LM3631YFFR 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in power management ICs for portable electronics.

The LM3631YFFR belongs to TI's display power management product line, designed specifically to consolidate backlight, positive/negative bias, and controller supply functions into one chip for high-resolution mobile LCDs.

FAQ

What is the maximum LED string voltage supported by the LM3631YFFR?

The LM3631YFFR backlight boost converter supports up to 29 V on the VOUT pin, enabling configurations such as 2 parallel strings of 6-series LEDs (2P6S) at typical forward voltages of ~3.5 V per LED. This allows full drive of 12 high-brightness white LEDs at 25 mA per string without external components. The LM3631YFFR datasheet specifies VOVP_BL = 28.8 V, confirming safe operation within this limit.

Does the LM3631YFFR support both I²C and PWM dimming simultaneously?

No - the LM3631YFFR supports either I²C-based digital dimming (11-bit linear or 17-bit exponential) or external PWM input on the PWM pin, but not both concurrently. When PWM is used, the I²C brightness registers are ignored. The LM3631YFFR must be configured at startup to select the dimming mode via register settings or hardware pin strapping (OTP_SEL).

How is the negative LCD bias voltage (VNEG) generated in the LM3631YFFR?

The LM3631YFFR generates VNEG using an internal inverting charge pump topology fed from BST_OUT. It does not use an external inductor or transformer. The CP_VNEG output is programmable from –4.0 V to –6.0 V in 50-mV steps, with built-in short-circuit and overvoltage protection. External flying capacitors C1 and C2 (connected to pins A4 and A2) are required for charge pump operation.

What are the thermal limitations of the LM3631YFFR in continuous operation?

The LM3631YFFR features thermal shutdown at TJ = 140°C with 20°C hysteresis. Its DSBGA-24 package has RθJA = 63.5°C/W. Under worst-case conditions (VIN = 2.7 V, full load on all rails), junction temperature rise must stay below 125°C for reliable operation. Layout with adequate copper pour on PGND and thermal vias under the die is essential - the LM3631YFFR datasheet recommends ≥4 thermal vias directly under the package center.

Can the LM3631YFFR power both the display controller and gamma reference simultaneously?

Yes - the LM3631YFFR integrates two independent LDOs for this purpose: LDO_CONT provides 1.8 V, 2.3 V, 2.8 V, or 3.3 V (selectable via I²C) to power the display timing controller, while LDO_OREF delivers a precision 4.0–6.0 V rail (also I²C-programmable) specifically for gamma DAC reference. Both outputs operate with <1.5% accuracy and include individual power-good flags for safe sequencing.