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Texas Instruments LM2794TLX
- Part No.:
- LM2794TLX
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFBGA, DSBGA
- Datasheet:
-
LM2794TLX.pdf
- Description:
- IC LED DRV RGLTR PWM 14DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:4,989
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Product details
Overview
LM2794TLX from Texas Instruments is a current-regulated switched-capacitor white LED driver IC with four matched constant-current outputs, ±0.5% output current matching, 325–675 kHz switching frequency, and analog/PWM brightness control. It operates from 2.7V to 5.5V input and delivers up to 20 mA per channel for backlighting in single-cell Li-ion portable devices.
For engineers reviewing the LM2794TLX datasheet, LM2794TLX pinout, LM2794TLX application, or LM2794TLX equivalent, this page provides verified technical context, DSBGA-14 pin mapping, real-world current regulation behavior, thermal shutdown thresholds, and validated alternative options for LED backlight designs requiring high matching accuracy and inductorless operation.
Technical Context
The LM2794TLX implements a 1.5×/1× fractional CMOS charge pump with automatic mode transition at ~4.7 V input: it boosts to 1.5×VIN below that threshold and enters pass-through mode above it. Its four current sources are internally mirrored from ISET with 10:1 ratio and share a common POUT rail.
Brightness is controlled either by applying 0–3.0 V to BRGT (linear analog dimming) or by pulsing SD (PWM dimming), where LM2794TLX uses active-low shutdown logic. The device integrates soft-start, thermal shutdown at TJ = 150°C (typ.), and supports parallel output configurations without performance degradation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7 V to 5.5 V - supports full discharge curve of 1-cell Li-ion battery (3.0–4.2 V nominal, down to 2.7 V cutoff) |
| Output Current per Channel | Up to 20 mA - programmable via RSET; typical 15 mA at RSET = 124 Ω with BRGT = 0 V |
| Current Matching Accuracy | ±0.5% - ensures consistent brightness across four LEDs without external calibration |
| Switching Frequency | 325–675 kHz - fixed-frequency operation avoids audible noise and simplifies EMI filtering |
| Shutdown Current | 2.3 µA (typ.) - enables ultra-low-power standby in battery-critical applications |
| Charge Pump Output (POUT) | Unregulated 1.5×VIN - usable as auxiliary rail for keypad LEDs or low-precision loads |
| Operating Junction Temp | −30°C to +100°C - qualified for consumer handheld and industrial portable environments |
Pinout & Package
LM2794TLX is housed in a thin DSBGA package measuring 2.08 mm × 2.403 mm × 0.600 mm, optimized for space-constrained mobile PCBs. Pin numbering follows JEDEC-standard bottom-view layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A1 | C1+ | Positive terminal of flying capacitor C1 - connects to internal charge pump switch node |
| B2 | C1− | Negative terminal of flying capacitor C1 - forms first stage of 1.5× charge pump |
| C1 | VIN | Main power input - supplies both control circuitry and charge pump; accepts 2.7–5.5 V |
| D2 | GND | Power ground reference - must be low-impedance return path for all currents |
| E1 | C2− | Negative terminal of flying capacitor C2 - completes second-stage charge pump |
| E3, E5, E7, D6 | D1–D4 | Constant-current LED outputs - each sinks up to 20 mA; internally matched within ±0.5% |
| C7 | ISET | Current sense input - sets reference current via external resistor; mirrored 10:1 to D1–D4 |
| B6 | BRGT | Analog brightness control - 0–3.0 V input linearly scales LED current; 240 kΩ input resistance |
| A7 | SD | Active-low shutdown - pulls device into 2.3 µA sleep mode when logic low; no internal pull-up |
| A5 | C2+ | Positive terminal of flying capacitor C2 - ties to POUT rail during charge cycle |
| A3 | POUT | Charge pump output - unregulated 1.5×VIN rail; supports auxiliary loads up to ~80 mA total |
Key Features
| Feature | Design Value |
|---|---|
| No-inductor architecture | Eliminates magnetic components and associated EMI; reduces BOM count and board area by >30% vs. inductive boost drivers |
| Matched current sources | ±0.5% matching between any two D1–D4 outputs ensures uniform backlight luminance without optical compensation |
| Hybrid brightness control | Simultaneous analog (BRGT) and PWM (SD) dimming enables flexible system-level brightness management |
| Thermal protection | Automatic shutdown at TJ = 150°C (typ.) and recovery at 140°C (typ.) prevents permanent damage under overload or poor heatsinking |
| Pass-mode efficiency | Direct VIN-to-POUT conduction above ~4.7 V improves efficiency by >15% vs. forced boost mode at high battery voltage |
Applications
| White LED Display Backlights | White LED Keypad Backlights |
|---|---|
Use Scenario: Driving four parallel white LEDs behind LCD display in handheld PC or PDA with 1-cell Li-ion supply. IC Role / Device Role / Timing Role: Constant-current source delivering 15 mA per LED with ±0.5% matching to eliminate visible brightness gradients. Use Value: Enables uniform, flicker-free illumination using only ceramic capacitors-no inductor required-reducing solution size by 40% vs. inductive alternatives. |
Use Scenario: Powering discrete white LEDs beneath rubber keypad in cellular phone with variable battery voltage (2.7–4.2 V). IC Role / Device Role / Timing Role: Regulated current sink driving 5–10 mA per LED via POUT rail with ballast resistors; leverages unregulated 1.5×VIN output. Use Value: Delivers adequate keypad illumination across full battery range while avoiding need for separate regulator-reduces component count and cost. |
| 1-Cell Li-Ion Portable Devices | Handheld Consumer Electronics |
Use Scenario: Backlighting small TFT displays in Bluetooth headsets or smartwatches powered by single Li-ion cell. IC Role / Device Role / Timing Role: Switched-capacitor LED driver operating down to 2.7 V input; maintains regulated current during battery discharge. Use Value: Extends usable runtime by 12–18 minutes compared to fixed-voltage drivers, due to efficient 1.5× boost and low quiescent current (5.5 mA active). |
Use Scenario: Controlling brightness of status indicator LEDs in portable medical monitors or barcode scanners. IC Role / Device Role / Timing Role: Dual-mode dimming interface: BRGT for smooth analog fade and SD for microcontroller-driven PWM with 100 µs turn-on time. Use Value: Supports both user-adjustable dimming (via potentiometer on BRGT) and firmware-controlled intensity (via GPIO on SD), increasing design flexibility. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2795TLX | Identical architecture and pinout, but features active-high SD pin with internal VIN pull-up; shutdown current identical (2.3 µA typ.) | Requires inverted logic control signal; compatible with open-drain microcontroller outputs without level-shifting | Select LM2795TLX when system GPIO drives SD high to disable, or when using open-drain logic; otherwise LM2794TLX is preferred for standard active-low control. |
| TPS61160DRVR | Inductor-based boost converter with integrated 30-V MOSFET; supports up to 30 mA per channel; no POUT rail; requires external inductor and diode | Better suited for higher forward-voltage LEDs (>4.0 V) or higher current (>20 mA/channel); less compact due to magnetics | Choose TPS61160DRVR only if driving >4.0 V LEDs or needing >20 mA per channel; LM2794TLX remains optimal for compact, low-noise, inductorless 3.0–3.8 V LED solutions. |
Compared with LM2795TLX, LM2794TLX offers simpler logic interface for active-low MCU control; compared with TPS61160DRVR, LM2794TLX eliminates EMI-sensitive inductors and reduces solution footprint by 65%, at the cost of lower maximum LED voltage support.
Availability
LM2794TLX is available at Aetrix Electronics and suitable for white LED backlighting, portable display power, and keypad illumination applications requiring stable component supply, long-term lifecycle support, and traceable sourcing for volume production.
Supply support for LM2794TLX 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 over 50 years of innovation in energy-efficient IC design.
The LM2794TLX belongs to TI's LED backlight driver product line, engineered specifically for space-constrained, battery-powered portable devices requiring precise current matching and inductorless operation.
FAQ
What is the function of the POUT pin on the LM2794TLX?
The POUT pin on the LM2794TLX is the unregulated output of the 1.5× switched-capacitor charge pump, delivering approximately 1.5×VIN. It serves as an auxiliary power rail capable of supplying additional current-up to ~80 mA total-to secondary loads such as keypad LEDs or low-precision peripherals. Because POUT is unregulated, its voltage droops under load per VPOUT = 1.5×VIN − ITOTAL × ROUT (ROUT ≈ 3.0 Ω), so it is best used with fixed-input systems or paired with a linear regulator like the LP3985-4.5V for stable output. LM2794TLX does not regulate POUT; regulation applies only to the four D1–D4 current-sink outputs.
How does brightness control work on the LM2794TLX?
The LM2794TLX supports two independent brightness control methods: analog dimming via the BRGT pin (0–3.0 V input linearly scales LED current) and digital dimming via PWM applied to the SD pin (active-low shutdown). When BRGT = 0 V and SD is held high, full current flows; pulsing SD at ≥100 Hz modulates average LED current proportionally to duty cycle. For example, with RSET set for 15 mA, a 50% SD duty cycle yields ~7.5 mA average current. LM2794TLX allows simultaneous use-e.g., BRGT sets max current, SD fine-tunes perception-enabling flexible system-level lighting control without firmware changes.
What is the recommended capacitor type and value for LM2794TLX operation?
The LM2794TLX requires four external 1.0 µF ceramic capacitors: CIN (input), C1 and C2 (flying), and CHOLD (hold). X7R or X5R dielectrics are strongly recommended due to tight tolerance (±10%), stable capacitance over temperature (X7R: ±15% from −55°C to 125°C), and low ESR (<15 mΩ). Y5V/Z5U types are discouraged-their capacitance can drop to 10% of nominal under bias or temperature, risking startup failure or regulation loss. All capacitors must be surface-mount multilayer ceramics; tantalum, aluminum electrolytic, and OS-CON types are incompatible due to high ESR. LM2794TLX performance-including efficiency, noise, and current matching-is validated only with proper ceramic selection per TI SNVS168L.
Can multiple Dx outputs be paralleled on the LM2794TLX?
Yes, D1–D4 outputs on the LM2794TLX may be freely paralleled-for example, D1+D2 to drive one LED at 30 mA while D3+D4 drive another at 30 mA. Each output retains its programmed current (e.g., 15 mA per channel), so total current sums linearly. Current matching remains ±0.5% between paralleled channels because internal mirroring is preserved. No derating or layout modification is needed; electrical specifications-including max voltage (VDX ≤ 3.8 V), line/load regulation, and thermal limits-apply identically to paralleled configurations. LM2794TLX datasheet Figure 25 and Section "Parallel Dx Outputs" confirm this capability is fully characterized and production-qualified.
What is the shutdown behavior of the LM2794TLX?
The LM2794TLX features an active-low shutdown pin (SD): pulling SD low disables the charge pump and current sources, reducing supply current to 2.3 µA (typ.). During shutdown, POUT collapses, D1–D4 sink no current, and BRGT/ ISET inputs are inactive. There is no internal pull-up or pull-down on SD-external logic must drive it definitively. Recovery time from shutdown is ~100 µs (typ.), defined as time for LED current to reach 90% of target after SD goes high. This fast wake-up supports burst-mode backlighting in UIs requiring rapid on/off transitions. LM2794TLX shutdown state is electrically isolated from VIN/GND paths, ensuring zero current leakage into disabled outputs.
LM2794TLX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-WFBGA, DSBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Switched Capacitor (Charge Pump)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 4
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 3.8V
- Current - Output / Channel:
- 20mA
- Frequency:
- 515kHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DSBGA
LM2794TLX FAQ
1.How can I place an order for LM2794TLX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2794TLX 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 LM2794TLX reliable?
The price and inventory of LM2794TLX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2794TLX is usually 5 days.
3.What payment methods are accepted for LM2794TLX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2794TLX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2794TLX?
LM2794TLX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2794TLX 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 LM2794TLX?
For technical support, including LM2794TLX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2794TLX requirements.
6.How does Aetrix verify that LM2794TLX is sourced from the original manufacturer or authorized distributors?
All LM2794TLX 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 LM2794TLX meets industry standards.
7.What is the process for return or replacement of LM2794TLX?
All LM2794TLX units undergo pre-shipment inspection (PSI). If there is an issue with LM2794TLX, 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 LM2794TLX part is unused and in its original packaging.
Return procedure for LM2794TLX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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