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Texas Instruments LM2796TL/NOPB
- Part No.:
- LM2796TL/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 18-WFBGA
- Datasheet:
-
LM2796TL/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 18DSBGA
- Quantity:
- Payment:
- Shipping:
Inventory:500
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Product details
Overview
LM2796TL/NOPB from Texas Instruments is a dual-group white LED driver IC with integrated 3/2× switched-capacitor boost converter, delivering up to 20mA per LED across seven regulated current outputs (4+3), operating from 2.7V–5.5V input, and supporting independent PWM dimming for main and sub-LCD backlighting in mobile phones.
For engineers reviewing the LM2796TL/NOPB datasheet, LM2796TL/NOPB pinout, LM2796TL/NOPB application, or LM2796TL/NOPB equivalent, key selection considerations include its 18-bump DSBGA package, 1.5×/1× charge pump gain switching at ~4.7V, ±1% current matching between outputs in each group, 100Hz–1kHz PWM control range, and ISET-based LED current programming via external resistor.
Technical Context
The LM2796TL/NOPB implements a dual-mode charge pump that automatically switches between 1.5× gain (VIN ≤4.75V) and 1× pass-through (VIN ≥4.55V), minimizing power loss while maintaining sufficient headroom for white LEDs with VF ≈3.3–4.0V. Its internal current mirror architecture uses tightly matched devices and mismatch cancellation to achieve ≤1% current matching within Group A (D1A–D4A) and Group B (D1B–D3B).
LED current is set by an external RSET resistor connected between ISET and GND, where IDxx = 100 × (1.25V / RSET); typical values yield 10mA (RSET = 12.5kΩ), 15mA (8.35kΩ), or 20mA (6.25kΩ). Soft-start limits inrush current with ~100µs turn-on time, and thermal shutdown engages at TJ ≈160°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.7V to 5.5V - supports full Li-ion battery discharge curve without external regulation. |
| LED Output Current | Up to 20mA per channel - programmable via RSET; enables uniform brightness across 7 LEDs. |
| Current Matching | ≤1% between outputs in same group - ensures consistent backlight luminance on segmented displays. |
| Charge Pump Gain | 3/2× (≤4.75V) or 1× (>4.55V) - auto-selects optimal efficiency mode based on VIN. |
| PWM Dimming Frequency | 100Hz to 1kHz - avoids visible flicker while preventing interference with internal drivers. |
| Quiescent Current | 3.5–6mA (active), 3–4.5µA (shutdown) - minimizes standby power in portable devices. |
| Package | 18-bump Thin DSBGA (2.1mm × 2.4mm × 0.6mm) - ultra-compact footprint for space-constrained handsets. |
Pinout & Package
LM2796TL/NOPB is housed in an 18-bump thin DSBGA package (YZR0018), with 0.4mm pitch and bottom-side solder bumps. The package supports fine-pitch PCB assembly and requires controlled reflow per MSL Level-1 (260°C peak).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power input | Accepts 2.7V–5.5V Li-ion supply; feeds charge pump and internal bias circuitry. |
| GND | Ground reference | Common return for all current sources, charge pump, and logic inputs. |
| POUT | Charge pump output | Unregulated boosted voltage (~1.5×VIN or VIN); supplies current sources and flying capacitors. |
| C1+, C1−, C2+, C2− | Flying capacitor terminals | Interface with external 1µF ceramic capacitors to implement 3/2× charge pump topology. |
| EN | Master enable | Active-high logic input; disables entire IC (charge pump + all current sources) when low. |
| EN-A, EN-B | Group enable inputs | Independent active-high controls for Group A (4 LEDs) and Group B (3 LEDs); accept PWM for dimming. |
| D1A–D4A, D1B–D3B | Constant-current LED outputs | Seven top-side current sinks; drive LEDs cathode-to-GND, simplifying layout and reducing trace inductance. |
| ISET | Current set reference | Internal 1.25V reference node; RSET value determines all LED currents via IDxx = 100 × (1.25V / RSET). |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent LED groups | Enables simultaneous backlighting of main LCD (4 LEDs) and sub-LCD/keypad (3 LEDs) with separate brightness control. |
| Auto-switching 3/2× charge pump | Optimizes efficiency across full battery range: boosts at low VIN, bypasses at high VIN to reduce losses. |
| Top-side current sink architecture | Allows direct cathode connection to GND - eliminates need for high-side routing or external FETs. |
| Integrated soft-start | Controls reference ramp to limit input inrush current during enable, ensuring stable startup without voltage droop. |
| Thermal shutdown protection | Disables operation at TJ ≈160°C and recovers at ≈120°C - prevents permanent damage under sustained overload. |
Applications
| Mobile Phone Main LCD Backlight | Mobile Phone Sub-LCD or Keypad Lighting |
|---|---|
Use Scenario: Driving four white LEDs behind a primary TFT display in a GSM/UMTS handset powered by a single-cell Li-ion battery. IC Role / Device Role / Timing Role: Constant-current LED driver with 3/2× charge pump providing regulated 15mA per LED at VIN = 3.0V–3.6V. Use Value: Maintains uniform brightness across display area despite battery voltage sag, with <1% current mismatch between channels. | Use Scenario: Illuminating three white LEDs for secondary display or keypad in dual-screen feature phones. IC Role / Device Role / Timing Role: Independent current source group enabling separate PWM dimming from main display without shared control logic. Use Value: Enables context-aware lighting (e.g., dimmed keypad during calls, bright sub-display during media playback) using same IC. |
| PDA Display Backlight | Compact Portable Device LED Lighting |
Use Scenario: Powering 7-segment or dot-matrix backlight in legacy PDA with limited board area and no dedicated boost converter. IC Role / Device Role / Timing Role: Integrated switched-capacitor LED driver eliminating need for inductor-based DC/DC, reducing BOM count and EMI. Use Value: Achieves >85% efficiency at 15mA per LED while fitting into 2.1mm × 2.4mm footprint - critical for handheld form factors. | Use Scenario: General-purpose white LED illumination in compact consumer electronics such as Bluetooth headsets or smartwatches. IC Role / Device Role / Timing Role: Low-voltage LED driver supporting wide input range (2.7V–5.5V) and flexible current programming for diverse LED forward voltages. Use Value: Eliminates need for multiple discrete drivers; one LM2796TL/NOPB replaces up to seven individual current sources plus boost circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM27952SDX/NOPB | Single-output 20mA white LED driver with 1.5× charge pump; no multi-group capability or PWM enable pins. | Suitable only for monochrome or single-zone lighting; lacks independent group control for dual-display systems. | Select when driving ≤1 LED or requiring minimal pin count and simpler control interface. |
| TPS61160DRVR | Single-inductor boost converter with 30mA max output; supports analog + PWM dimming but no built-in current matching. | Requires external current-setting resistors per LED; higher EMI due to inductive switching; larger solution size. | Select when higher per-LED current (>20mA) or wider input range (up to 6.5V) is required, and layout space permits inductor use. |
Compared with LM27952SDX/NOPB, the LM2796TL/NOPB provides true dual-group control and superior current matching for segmented displays; compared with TPS61160DRVR, it eliminates inductor-related EMI and reduces component count, though at lower per-channel current ceiling and fixed 7-output topology.
Availability
LM2796TL/NOPB is available at Aetrix Electronics and suitable for mobile phone display lighting, PDA backlighting, and compact portable device LED illumination requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2796TL/NOPB 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 company specializing in analog, embedded processing, and digital signal processing technologies, with leadership in power management and precision analog solutions.
The LM2796TL/NOPB belongs to TI's white LED driver product line, designed specifically for energy-efficient, space-constrained backlighting in battery-powered handheld devices with dual-display architectures.
FAQ
What is the maximum total LED current supported by the LM2796TL/NOPB?
The LM2796TL/NOPB supports up to 20mA per LED across all seven outputs, with a typical maximum combined current of 105mA (7 × 15mA) when using recommended 2.2µF input/output capacitors. At VIN = 3.0V and VLED = 3.6V, the device sustains 15mA per LED across all channels. Exceeding this requires verifying headroom voltage (VPOUT – VLED > 22mV/mA × ILED) and thermal limits.
How does the LM2796TL/NOPB handle input voltage transitions between 3/2× and 1× charge pump modes?
The LM2796TL/NOPB uses internal hysteresis to switch between 3/2× and 1× gain modes: gain drops to 1× at VIN ≥4.55V (typ.) and restores to 1.5× at VIN ≤4.75V (typ.). This prevents oscillation near the threshold and ensures stable POUT voltage during battery voltage drift. No external control or configuration is needed - the transition is fully autonomous.
Can the LM2796TL/NOPB drive LEDs with forward voltages above 4.0V?
Yes, the LM2796TL/NOPB can drive LEDs with VF up to ~4.2V when VIN ≥3.0V and RSET is selected for lower current (e.g., 10mA), provided headroom voltage remains sufficient: (1.5 × VIN) – VF > 22mV/mA × ILED. For example, at VIN = 3.3V and ILED = 10mA, minimum headroom is 220mV, allowing VF up to ~4.1V. Higher VF requires higher VIN or reduced current.
What is the purpose of the ISET pin on the LM2796TL/NOPB, and how is LED current calculated?
The ISET pin on the LM2796TL/NOPB provides a 1.25V internal reference used to set LED current via external resistor RSET. Current per output is calculated as IDxx = 100 × (1.25V / RSET). For 15mA output, RSET = 8.35kΩ; for 20mA, RSET = 6.25kΩ. The ISET pin must be connected directly to GND through RSET - no series capacitance or filtering is permitted.
Does the LM2796TL/NOPB require special PCB layout considerations for the DSBGA package?
Yes, the LM2796TL/NOPB's 18-bump DSBGA (YZR0018) requires adherence to TI Application Note SNVA009: use microvia-in-pad or solder-mask-defined pads, 0.4mm pitch alignment, and thermal relief on GND connections. Flying capacitor traces (C1±, C2±) must be short and symmetric; POUT and VIN traces need low-inductance routing with local 2.2µF ceramic decoupling. Avoid thermal vias under the die area unless explicitly validated.
LM2796TL/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 18-WFBGA
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Switched Capacitor (Charge Pump)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 7
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 20mA
- Frequency:
- 500kHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 18-DSBGA
LM2796TL/NOPB FAQ
1.How can I place an order for LM2796TL/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2796TL/NOPB 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 LM2796TL/NOPB reliable?
The price and inventory of LM2796TL/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2796TL/NOPB is usually 5 days.
3.What payment methods are accepted for LM2796TL/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2796TL/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2796TL/NOPB?
LM2796TL/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2796TL/NOPB 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 LM2796TL/NOPB?
For technical support, including LM2796TL/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2796TL/NOPB requirements.
6.How does Aetrix verify that LM2796TL/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2796TL/NOPB 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 LM2796TL/NOPB meets industry standards.
7.What is the process for return or replacement of LM2796TL/NOPB?
All LM2796TL/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2796TL/NOPB, 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 LM2796TL/NOPB part is unused and in its original packaging.
Return procedure for LM2796TL/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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