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Texas Instruments LM27966SQ
- Part No.:
- LM27966SQ
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LM27966SQ.pdf
- Description:
- IC LED DRV RGLTR I2C 30MA 24WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,173
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Product details
Overview
LM27966SQ from Texas Instruments is a highly integrated I²C-compatible white LED driver IC for mobile display backlighting, delivering up to 180mA total regulated output current across two independently controlled banks (5× main display + 1× auxiliary), with 0.3% typical current matching, adaptive 1×/1.5× charge-pump operation, and resistor-programmable full-scale current via RSET.
For engineers reviewing the LM27966SQ datasheet, LM27966SQ pinout, LM27966SQ application, or LM27966SQ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated package and pin functions, confirmed application use cases, and two rigorously cross-checked alternative parts - all grounded in TI's SNVS448B revision May 2013 datasheet and official WQFN-24 package documentation.
Technical Context
The LM27966SQ implements an adaptive CMOS charge pump that dynamically selects between 1× (pass-through) and 1.5× gain modes based on real-time forward voltage sensing at D1–D5 pins, ensuring optimal efficiency across 2.7V–5.5V input range. Its dual-bank architecture separates main display (D1–D5, 32-step PWM dimming) from auxiliary indicator (DAUX, 4-level analog dimming).
Current regulation relies on internal 1.25V reference applied to ISET, where external RSET sets full-scale current per sink as IDx = 200 × (1.25 V / RSET). The device uses dedicated hardware RESET (active-low) and supports I²C slave address 0x36 with SCL/SDIO/VIO level-shiftable interface operating up to 1.27 MHz switching frequency and 20 kHz PWM clock.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 5.5V - supports single-cell Li-ion battery operation without external LDO; enables direct connection to system rail. |
| Total Output Current | 180mA max - distributed across up to six LEDs (5 main + 1 auxiliary); requires thermal derating above 85°C ambient. |
| LED Current Matching | 0.3% typical - ensures uniform brightness across multi-LED displays; measured as worst-case deviation from average bank current. |
| Charge Pump Efficiency | 91% peak - achieved by minimizing switching losses and selecting optimal gain mode (1× or 1.5×) per load condition. |
| I²C Interface Address | 0x36 (7-bit) - fixed slave address; supports standard-mode I²C timing with t1 ≥ 2.5 µs clock period and VOL ≤ 400 mV at 3 mA. |
| Package Thermal Resistance | θJA = 41.3°C/W - measured on JEDEC-standard 2-layer board; requires exposed DAP soldering for effective heat dissipation. |
| Operating Junction Temp | –30°C to +100°C - defines safe silicon operation; thermal shutdown engages at TJ ≈ 170°C (typ.) and recovers at 165°C. |
Pinout & Package
LM27966SQ is housed in a 4 mm × 4 mm × 0.8 mm WQFN-24 package (TI package code RTW0024A) with wettable flank leads and thermally enhanced exposed DAP (Die Attach Pad) connected to GND internally. Pin 1 is marked by top-side dot; pins 9, 18, and DAP are all ground terminals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (24) | Main power input | Accepts 2.7–5.5V supply; powers charge pump and logic; must be decoupled with ≥1 µF ceramic capacitor near pin. |
| POUT (23) | Charge pump regulated output | Delivers boosted voltage to LED anodes; voltage tracks VIN in 1× mode or equals ~1.5×VIN in 1.5× mode; connects to COUT. |
| C1+, C1− (19,22), C2+, C2− (20,21) | Flying capacitor connections | Supports charge transfer in 1.5× mode; requires low-ESR 1 µF MLCCs (e.g., TDK C1608X5R1A105K) placed adjacent to pins. |
| D1–D5 (12–16), DAUX (3) | Constant-current LED sink outputs | Sink up to 30 mA each; D1–D5 include forward-voltage sensing for gain control; DAUX has no sensing and fixed 4-level dimming. |
| ISET (17) | Current set reference node | Internally biased to 1.25 V; external RSET to GND programs full-scale current per sink using IDx = 200 × (1.25 V / RSET). |
| SCL (1), SDIO (2), VIO (7) | I²C interface signals | VIO sets logic threshold for SCL/SDIO; supports level shifting; requires pull-up to VIO (not VIN); slave address 0x36. |
| RESET (10) | Hardware reset input | Active-low; drives all registers to default state when pulled low; normal operation requires high (≥1.2 V) or floating (internal pull-up). |
| GND (9,18,DAP) | Ground reference | Three dedicated GND pins plus exposed DAP - all must be connected to solid ground plane for thermal and noise performance. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive 1×/1.5× charge pump | Switches gain automatically based on D1–D5 forward voltage sensing to maximize efficiency across input voltage range. |
| Two independent LED banks | Main display (D1–D5) supports 32-step PWM dimming; auxiliary (DAUX) offers 4-level analog dimming - enabling separate brightness control. |
| 0.3% LED current matching | Guarantees consistent luminance across multi-LED arrays without software calibration; critical for uniform smartphone display backlighting. |
| No-inductor architecture | Eliminates magnetic components and EMI concerns; reduces BOM cost and PCB area versus inductive boost solutions. |
| Hardware RESET with register retention | External active-low reset forces default register states while preserving I²C address and configuration integrity during power sequencing. |
Applications
| Smartphone Main Display Backlight | PDA Front Panel Indicator Lighting |
|---|---|
|
Use Scenario: Driving five parallel white LEDs behind a 3.5-inch TFT LCD in a battery-powered smartphone. IC Role / Device Role / Timing Role: Constant-current sink controller with adaptive charge-pump voltage regulation and I²C brightness control. Use Value: Delivers 20–30 mA per LED with 0.3% matching, enabling uniform brightness and eliminating visible banding under varying battery voltage (3.0–4.2 V). |
Use Scenario: Powering a single status LED on a handheld PDA front bezel, requiring independent dimming from main display. IC Role / Device Role / Timing Role: Auxiliary current sink with 4-level analog dimming, isolated from main display control path. Use Value: Enables discrete UI feedback (e.g., charging, Bluetooth, notification) without modifying main display brightness settings or firmware logic. |
| Portable Media Player UI Lighting | Industrial Handheld Device Status Indication |
|
Use Scenario: Illuminating soft-touch buttons and scroll wheel on a music player with limited PCB space and strict EMI limits. IC Role / Device Role / Timing Role: Compact, inductorless LED driver with low-noise 20 kHz PWM dimming and minimal external components. Use Value: Achieves flicker-free illumination using charge-pump topology - avoids inductor-induced radiated emissions that would fail FCC Class B certification. |
Use Scenario: Providing ruggedized status indication in a factory-floor handheld scanner operating at –30°C to +85°C ambient. IC Role / Device Role / Timing Role: Thermally robust LED driver with extended junction temperature rating (–30°C to +100°C) and hardware RESET for cold-start reliability. Use Value: Maintains stable LED current over wide temperature range and survives repeated cold/warm cycling without calibration drift or latch-up. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3530SQ | Same WQFN-24 package; adds ambient light sensor input and 8-bit I²C dimming resolution; higher quiescent current (4.5 mA vs 3.32 mA). | Requires ALS integration for auto-brightness; not drop-in - needs modified firmware and additional sensor circuitry. | Select LM3530SQ only if ambient light adaptation is required; otherwise LM27966SQ offers simpler implementation and lower IQ. |
| TPS61165DRVR | Inductor-based boost converter; 1.2 A switch current; supports up to 38 V LED string voltage; no integrated current matching. | Designed for high-Vf LED strings (e.g., RGB, automotive); lacks multi-bank independent control and current matching. | Choose TPS61165DRVR for >4.0 V LED forward voltage or >30 mA per channel; LM27966SQ remains optimal for compact, matched, low-Vf mobile displays. |
Compared with LM3530SQ and TPS61165DRVR, the LM27966SQ uniquely balances inductorless simplicity, precise multi-LED current matching, and dual-bank independent control - making it the preferred choice for space-constrained, battery-operated displays demanding uniform luminance and minimal EMI.
Availability
LM27966SQ is available at Aetrix Electronics and suitable for smartphone display lighting, PDA backlighting, and portable media player UI illumination requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM27966SQ 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, embedded processing, and power management technologies, with decades of experience in precision power and signal chain ICs.
The LM27966SQ belongs to TI's white LED driver product line, engineered specifically for energy-efficient, compact, and thermally constrained mobile display applications where uniform brightness and battery longevity are critical.
FAQ
What is the maximum number of LEDs the LM27966SQ can drive simultaneously?
The LM27966SQ can drive up to six LEDs simultaneously: five in the main display bank (D1–D5) and one in the auxiliary bank (DAUX). Each sink supports up to 30 mA, with total output current capped at 180 mA. Driving more than six LEDs requires external current-sharing circuitry or a different driver IC.
How does the LM27966SQ achieve 0.3% LED current matching?
The LM27966SQ achieves 0.3% typical current matching through laser-trimmed, matched current-sink transistors within each bank and tightly controlled internal reference voltage (1.25 V ±1%). Matching is measured as the worst-case deviation from the average current across all active sinks in a bank - verified over temperature and process variation in TI's production test flow.
Can the LM27966SQ operate without connecting the D5 pin?
Yes, but only if EN-D5 bit in the General Purpose Register (0x10) is set to '0' and D5 is grounded. Leaving D5 unconnected disables forward-voltage sensing for the main bank, forcing the charge pump into 1.5× mode across the entire input range - reducing efficiency and increasing power dissipation. TI explicitly recommends grounding unused D5.
What is the role of the RSET resistor in the LM27966SQ circuit?
The RSET resistor connected between ISET (Pin 17) and GND sets the full-scale current for all LED sinks via the equation IDx = 200 × (1.25 V / RSET). For example, a 16.9 kΩ RSET yields ~15 mA per sink. RSET value directly determines brightness headroom, thermal load, and minimum input voltage requirements - making it a critical design parameter for the LM27966SQ.
Does the LM27966SQ support automatic gain selection based on LED forward voltage?
Yes - the LM27966SQ continuously monitors forward voltage at D1–D5 pins. When any active Dx pin voltage drops to ~175 mV (VDxTH), the charge pump transitions from 1× to 1.5× mode to maintain current regulation. This adaptive gain selection maximizes efficiency by using pass-through mode whenever possible - a core feature confirmed in the SNVS448B datasheet section "LED Forward Voltage Monitoring".
LM27966SQ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Switched Capacitor (Charge Pump)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 6
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 2V ~ 4V
- Current - Output / Channel:
- 30mA
- Frequency:
- 1.27MHz
- Dimming:
- I2C
- Applications:
- Backlight
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-WQFN (4x4)
LM27966SQ FAQ
1.How can I place an order for LM27966SQ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM27966SQ 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 LM27966SQ reliable?
The price and inventory of LM27966SQ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM27966SQ is usually 5 days.
3.What payment methods are accepted for LM27966SQ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM27966SQ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM27966SQ?
LM27966SQ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM27966SQ 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 LM27966SQ?
For technical support, including LM27966SQ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM27966SQ requirements.
6.How does Aetrix verify that LM27966SQ is sourced from the original manufacturer or authorized distributors?
All LM27966SQ 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 LM27966SQ meets industry standards.
7.What is the process for return or replacement of LM27966SQ?
All LM27966SQ units undergo pre-shipment inspection (PSI). If there is an issue with LM27966SQ, 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 LM27966SQ part is unused and in its original packaging.
Return procedure for LM27966SQ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM27966SQ Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
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BCR421UE6327HTSA1
Infineon Technologies
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LYT1604D-TL
Power Integrations
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HV9910CLG-G
Microchip Technology
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CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
Diodes Incorporated
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