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Texas Instruments LM27964SQ-A
- Part No.:
- LM27964SQ-A
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LM27964SQ-A.pdf
- Description:
- IC LED DRV RGLTR I2C 24WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,520
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Product details
Overview
LM27964SQ-A from Texas Instruments is a charge-pump white LED driver IC designed for multi-display mobile lighting systems. It delivers up to 30mA per channel across four main-display (D1A–D4A), two sub-display (D1B–D2B), and one keypad (DKEY) current sinks, supports I²C-compatible 16-level PWM dimming for display banks and 4-level analog dimming for keypad, and operates from 2.7V to 5.5V input with adaptive 1×/3/2× gain switching - used in dual-LCD smartphones with independent brightness control.
For engineers reviewing the LM27964SQ-A datasheet, LM27964SQ-A pinout, LM27964SQ-A application, or LM27964SQ-A equivalent, key selection considerations include its WQFN-24 package footprint, resistor-programmable current scaling (ISETA/B/K), 0.2% inter-channel current matching, thermal headroom requirements (180mV typical), and variant-specific PWM frequency (10kHz or 23kHz).
Technical Context
The LM27964SQ-A implements an adaptive CMOS charge pump with automatic 1×/3/2× gain selection based on real-time forward voltage monitoring of active Dxx pins (excluding DKEY). Gain transitions occur at ~375mV headroom threshold to maintain regulation while maximizing efficiency across 2.7V–5.5V input range.
It integrates three independent current-sink banks: BankA (4×30mA max, 16-step PWM), BankB (2×30mA max, 16-step PWM), and DKEY (80mA max, 4-level analog scaling), all controlled via I²C interface (7-bit address 0x36) with dedicated brightness registers (A0h, B0h) and general-purpose enable register (10h).
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 LDO. |
| Max Total Output Current | 180mA - distributed as 120mA (BankA + BankB) + 60mA (DKEY), with per-pin limits enforced. |
| Current Matching Accuracy | 0.2% typical - ensures uniform luminance across multi-LED displays without binning compensation. |
| Charge Pump Efficiency | 87% peak - achieved via adaptive gain selection and low-loss MOSFET switching at 700kHz nominal fSW. |
| I²C Interface | Standard-mode compatible (400kHz), 7-bit address 0x36 - enables software-configurable per-bank enable/dimming without additional GPIOs. |
| Thermal Shutdown | Activates at TJ ≈ 170°C - protects against sustained overcurrent or poor PCB thermal design. |
| Headroom Requirement | 180mV typical at full-scale - defines minimum (VPOUT – VLED) margin needed for stable current regulation. |
Pinout & Package
LM27964SQ-A is housed in a 4mm × 4mm × 0.8mm WQFN-24 package (TI package code RTW0024A) with exposed thermal pad (DAP) for enhanced power dissipation. Pin numbering follows standard QFN top-view layout with pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (24) | Power Input | Main supply input; accepts 2.7V–5.5V; connects to input capacitor CIN. |
| POUT (23) | Charge Pump Output | Regulated output node driving all LED anodes; connects to flying caps C1/C2 and output cap COUT. |
| C1+, C1−, C2+, C2− (19,22,20,21) | Flying Capacitor Interface | Dual-capacitor charge-pump network enabling 1×/3/2× voltage gain without inductor. |
| D1A–D4A (13–16), D1B–D2B (4–5), DKEY (6) | LED Current Sink Outputs | Low-side constant-current drivers; each sinks programmed current to GND when enabled. |
| ISETA (17), ISETB (3), ISETK (12) | Current Reference Inputs | Resistor-to-GND sets full-scale current: IDxA/B = 200 × (1.25V/RSETA/B); IDKEY = 800 × (1.25V/RSETK). |
| SCL (1), SDIO (2), VIO (7) | I²C Bus Interface | Standard bidirectional I²C port; VIO sets logic level (1.8V to VIN); requires external pull-ups. |
| GND (9,10,18,DAP) | Ground Reference | Primary return path; DAP must be soldered to PCB ground plane for thermal and electrical integrity. |
| NC (8,11) | No Connect | Unbonded pins; must remain unconnected per TI design guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive 1×/3/2× Charge Pump | Automatically selects gain mode based on LED forward voltage to sustain regulation while minimizing power loss. |
| Three Independent LED Banks | Enables simultaneous control of main LCD (4 LEDs), sub LCD (2 LEDs), and keypad (up to 16 LEDs) with separate dimming schemes. |
| 0.2% Inter-Channel Current Matching | Ensures consistent brightness across all LEDs in a bank without external calibration or trimming. |
| I²C-Compatible Brightness Control | Supports 16-step PWM (BankA/B) and 4-level analog scaling (DKEY) via write-only registers A0h and B0h. |
| Resistor-Programmable Full-Scale Current | Allows precise current setting per bank using standard 1% resistors - no DAC or external reference required. |
Applications
| Mobile Phone Main Display Backlight | Mobile Phone Sub Display Backlight |
|---|---|
Use Scenario: Driving four parallel white LEDs behind a primary TFT-LCD panel in a dual-display smartphone. IC Role / Device Role / Timing Role: Constant-current sink controller with adaptive charge pump output and I²C-based 16-level PWM dimming. Use Value: Delivers uniform 30mA per LED with 0.2% matching, eliminating visible brightness gradients across the display area. |
Use Scenario: Powering two white LEDs for secondary monochrome or small-color LCD in clamshell or slider phones. IC Role / Device Role / Timing Role: Secondary LED driver bank with independent brightness register (A0h bits DxB3–DxB0) and shared POUT rail. Use Value: Enables distinct dimming profiles for main and sub displays without requiring separate driver ICs or routing overhead. |
| Mobile Phone Keypad Lighting | PDA Frontlight System |
Use Scenario: Supplying up to 80mA total to 8–16 discrete keypad LEDs with variable intensity levels. IC Role / Device Role / Timing Role: Dedicated analog-scaling current sink (DKEY) with 4 brightness steps (100%/70%/40%/20%) via B0h register. Use Value: Reduces bill-of-materials by integrating keypad drive into same IC as display backlight, avoiding extra current-setting resistors per LED. |
Use Scenario: Providing adjustable frontlight for reflective LCDs in handheld PDAs where battery life and compact form factor are critical. IC Role / Device Role / Timing Role: Single-chip solution delivering up to 180mA total output with programmable per-bank current and I²C host control. Use Value: Eliminates need for discrete boost converter + multiple current regulators, reducing PCB area by >40% versus discrete alternatives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3530UMX/NOPB | Single-bank 30mA driver with I²C interface; no sub-display or keypad banks; uses internal DAC instead of RSET scaling. | Limited to single-display systems; lacks independent keypad control and dual-bank architecture. | Select when only main-display backlight is required and board space permits simpler single-output topology. |
| TPS61165DRVR | Boost-based 40V white LED driver with 1.2MHz switching; supports up to 30mA per channel but no integrated keypad bank or I²C dimming registers. | Requires external PWM or analog dimming circuitry; not optimized for multi-bank mobile UI lighting. | Prefer for high-VF LED strings (>4V) or when higher output voltage headroom is needed beyond charge-pump limits. |
Compared with LM3530UMX/NOPB and TPS61165DRVR, the LM27964SQ-A uniquely integrates three functionally distinct LED banks with resistor-programmable current and embedded I²C brightness registers - enabling compact dual-display + keypad lighting in a single WQFN-24 package without external dimming components.
Availability
LM27964SQ-A is available at Aetrix Electronics and suitable for mobile phone backlighting, PDA frontlighting, and keypad illumination requiring stable component supply, long-lifecycle support, and qualified automotive-grade sourcing options.
Supply support for LM27964SQ-A 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 portable power and lighting solutions.
The LM27964SQ-A belongs to TI's white LED driver product line, engineered specifically for space-constrained, battery-powered mobile devices requiring independent multi-bank brightness control and high-efficiency charge-pump operation.
FAQ
What is the PWM frequency of the LM27964SQ-A for display LED dimming?
The LM27964SQ-A uses a fixed internal PWM frequency of 10kHz for BankA and BankB LED dimming. This value is factory-set and cannot be adjusted via I²C register writes. The 10kHz frequency avoids audible noise while maintaining efficient switching losses and is distinct from the LM27964SQ-C variant, which operates at 23kHz. All LM27964SQ-A units deliver this exact PWM timing regardless of external configuration.
How do I set the full-scale current for the keypad LED bank on the LM27964SQ-A?
To set the full-scale current for the keypad LED bank (DKEY), connect a resistor RSETK between the ISETK pin (pin 12) and GND. The resulting current is calculated as IDKEY = 800 × (1.25V ÷ RSETK). For example, a 16.9kΩ resistor yields ~60mA full-scale. The LM27964SQ-A does not use PWM for keypad dimming - instead, it supports four analog brightness levels (100%, 70%, 40%, 20%) selected via bits DKEY1–DKEY0 in register B0h.
Does the LM27964SQ-A support connecting multiple LEDs in parallel to a single Dxx output?
Yes, the LM27964SQ-A allows parallel connection of D1A–D4A or D1B–D2B outputs to drive higher-current single LEDs. When doing so, program RSETA or RSETB such that each individual sink contributes 25% (for 4-way) or 50% (for 2-way) of the target total current. For instance, to drive one 60mA LED using all four BankA outputs, configure RSETA for 15mA per sink. The LM27964SQ-A maintains regulation and matching integrity in this configuration.
What is the purpose of the VIO pin on the LM27964SQ-A?
The VIO pin on the LM27964SQ-A sets the logic voltage level for the I²C interface (SCL and SDIO), decoupling bus signaling from the main VIN supply. It accepts 1.8V to VIN and determines VIH/VIL thresholds - for example, with VIO = 1.8V, VIH ≥ 1.31V and VIL ≤ 0.49V. An external pull-up resistor from SDIO to VIO is mandatory to meet VOL specification (≤400mV at 2mA). This feature enables direct interfacing with 1.8V microcontrollers without level-shifting circuitry.
Can the LM27964SQ-A operate with only the keypad bank enabled and both display banks disabled?
Yes, the LM27964SQ-A can operate with only the keypad bank (DKEY) enabled while BankA and BankB are disabled (ENA = ENB = 0 in register 10h). In this mode, the charge pump defaults to 3/2× gain to ensure sufficient headroom for the keypad current sink, since forward voltage monitoring is inactive on DKEY. The device draws only ~5µA in shutdown (ISD) when all banks are disabled, making it suitable for low-power keypad illumination duty cycles.
LM27964SQ-A 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:
- 7
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 2V ~ 4V
- Current - Output / Channel:
- 30mA, 80mA
- Frequency:
- 700kHz
- Dimming:
- I2C
- Applications:
- Backlight
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-WQFN (4x4)
LM27964SQ-A FAQ
1.How can I place an order for LM27964SQ-A through Aetrix?
Please submit a Request for Quotation (RFQ) for LM27964SQ-A 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 LM27964SQ-A reliable?
The price and inventory of LM27964SQ-A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM27964SQ-A is usually 5 days.
3.What payment methods are accepted for LM27964SQ-A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM27964SQ-A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM27964SQ-A?
LM27964SQ-A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM27964SQ-A 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 LM27964SQ-A?
For technical support, including LM27964SQ-A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM27964SQ-A requirements.
6.How does Aetrix verify that LM27964SQ-A is sourced from the original manufacturer or authorized distributors?
All LM27964SQ-A 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 LM27964SQ-A meets industry standards.
7.What is the process for return or replacement of LM27964SQ-A?
All LM27964SQ-A units undergo pre-shipment inspection (PSI). If there is an issue with LM27964SQ-A, 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 LM27964SQ-A part is unused and in its original packaging.
Return procedure for LM27964SQ-A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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