Texas Instruments LM3633YFQR

Overview

LM3633YFQR from Texas Instruments is a highly integrated LED power management IC for smartphone illumination systems, combining a 40-V boost converter with integrated 1-A/40-V MOSFET and a 2X charge pump to drive three parallel high-voltage LED strings (up to 40 V, 30 mA each) and six low-voltage indicator LEDs (20.2 mA max per sink). It delivers up to 90% efficiency at 1 MHz switching and supports I²C-programmable 11-bit dimming, PWM-based CABC, and independent pattern generation for RGB indicators.

For engineers reviewing the LM3633YFQR datasheet, LM3633YFQR pinout, LM3633YFQR application, or LM3633YFQR equivalent, this page provides verified technical context on adaptive headroom control, HV/LV current sink matching (±2.0% HV, ±3.1% LV), programmable OVP thresholds (16/24/32/40 V), thermal shutdown (140°C), and DSBGA-20 package constraints critical for compact handset PCB layout.

Technical Context

The LM3633YFQR implements dual-regulation architecture: its boost converter dynamically adjusts output voltage to maintain minimal headroom (VHR_HV = 190–400 mV) across HVLED1–HVLED3, while the charge pump delivers regulated 2X gain (VCPOUT = 4.42 V typ) for LVLED1–LVLED6. Feedback is per-string-regulating the highest forward-voltage string sets VHR, dropping excess voltage across lower-Vf strings' current sinks.

Control is fully banked: HVLEDs assign to Control Banks A/B (5-bit full-scale current + 11-bit brightness); LVLEDs map to Banks C–H with independent pattern generators (on/off delay, ramp timing, duty cycle). Switching frequency is selectable (500 kHz or 1 MHz) or auto-shifted based on brightness code threshold to optimize conduction vs. switching losses.

Key Specifications

Pinout & Package

LM3633YFQR uses a 2.04 mm × 1.78 mm, 20-pin DSBGA (YFQ) package with 0.4-mm pitch and bottom-side solder balls. Thermal resistance R_θJA = 55.3°C/W enables operation up to 125°C junction temperature in space-constrained smartphone modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED driver applications.

Compared with LM3632YFQR and TPS61165RTVR, the LM3633YFQR uniquely integrates 3 HVLED sinks, 6 LVLED sinks, charge pump, and pattern engines in one 27-mm² solution - eliminating 3–5 discrete components and enabling true single-chip smartphone illumination.

Availability

LM3633YFQR is available at Aetrix Electronics and suitable for smartphone backlighting, RGB indicator systems, keypad illumination, and content-adaptive display control requiring stable component supply across high-volume production cycles.

Supply support for LM3633YFQR 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 and lighting IC design.

The LM3633YFQR belongs to TI's mobile lighting power management product line, engineered specifically for space-constrained, battery-operated smartphones requiring integrated high-voltage backlight and low-voltage indicator control in a single chip.

FAQ

What is the maximum LED string voltage supported by the LM3633YFQR?

The LM3633YFQR supports up to 40 V on its HVLED1–HVLED3 pins, verified by absolute maximum rating (45 V) and recommended operating condition (40 V). This enables driving configurations such as 3p5s (3 parallel strings of 5 series LEDs) with typical white LED Vf ≈ 3.2 V, providing 1.8 V headroom margin at end-of-life. The device regulates boost output to maintain minimal headroom voltage (VHR_HV = 190–400 mV), ensuring efficiency across voltage variations.

How does the LM3633YFQR handle mismatched LED forward voltages across HVLED strings?

The LM3633YFQR uses adaptive feedback: it monitors HVLED1, HVLED2, and HVLED3 simultaneously and regulates the boost output to the minimum voltage required by the highest-Vf string. Excess voltage for lower-Vf strings is dropped across their respective current sinks, maintaining precise current regulation (±2.0% matching) without external compensation. This eliminates need for string balancing resistors and preserves efficiency in real-world assemblies with Vf binning variation.

Can the LM3633YFQR drive LVLEDs without using the integrated charge pump?

No - the LVLED1–LVLED6 current sinks are internally powered exclusively by the CPOUT rail generated by the integrated 2X charge pump. There is no alternate power path or external bias option for LVLEDs. The charge pump requires external 1-µF ceramic capacitors between C+ and C−, and CPOUT must be bypassed to GND with another 1-µF ceramic capacitor. Attempting to supply LVLEDs from an external rail will result in undefined behavior or failure to regulate current.

What is the purpose of the HWEN pin on the LM3633YFQR, and what happens when it is left floating?

The HWEN pin is a high-impedance hardware enable input that must be actively driven high (≥1.2 V) to power up the LM3633YFQR or low (≤0.4 V) to force shutdown (IQ < 5.5 µA). If left floating, the pin's undefined state may cause erratic startup, intermittent operation, or failure to enter shutdown - violating the absolute maximum rating for input voltage. A 100-kΩ pull-up to VIN is recommended for reliable default-enable behavior in smartphone power sequencing.

Does the LM3633YFQR support simultaneous independent dimming of HVLED and LVLED groups?

Yes - the LM3633YFQR supports fully independent control: HVLED1–HVLED3 are assigned to Control Banks A/B with 11-bit brightness and 5-bit full-scale current; LVLED1–LVLED6 map to Banks C–H with separate 8-bit brightness, ramp timing, and pattern parameters. I²C writes to distinct register banks allow concurrent updates - e.g., fading HVLEDs while pulsing LVLED4–LVLED6 - with no cross-interference or shared timing constraints.