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Texas Instruments LM27952SD
- Part No.:
- LM27952SD
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM27952SD.pdf
- Description:
- IC LED DRV RGLTR PWM 30MA 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,372
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Product details
Overview
LM27952SD from Texas Instruments is a white LED adaptive 1.5X/1X switched-capacitor current driver IC, delivering up to 30 mA per channel across four tightly regulated current sinks with 0.2% typical matching, operating from 3.0V–5.5V input, and achieving >85% peak efficiency in portable backlight applications.
For engineers reviewing the LM27952SD datasheet, LM27952SD pinout, LM27952SD application, or LM27952SD equivalent, key selection criteria include its fixed 750 kHz switching frequency, <1 µA shutdown current, WSON-14 (4.0 mm × 3.0 mm) package with exposed thermal pad, and PWM-controlled brightness without charge-pump cycling.
Technical Context
The LM27952SD implements an adaptive gain architecture that dynamically selects between 1.5× and 1× charge-pump operation based on LED forward voltage (2.5V–3.9V), maximizing efficiency across input voltage range. Its constant-frequency pre-regulation minimizes conducted EMI while maintaining tight current regulation.
It integrates four matched current sinks with headroom voltage as low as 240 mV at 21 mA, uses external RSET to program output current via ILED = 200 × (1.25 V / RSET), and features independent logic control: EN for global enable/shutdown and PWM for high-speed brightness modulation without disrupting VOUT stability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.0 V to 5.5 V - supports single-cell Li-ion and USB-powered systems without LDO pre-regulation. |
| Max Output Current per Channel | 30 mA - sufficient for driving four white LEDs at full brightness in small-display backlights. |
| Current Matching Accuracy | 0.2% (typ.) - ensures uniform luminance across multi-LED arrays without binning or calibration. |
| Switching Frequency | 750 kHz (±30%) - enables use of compact 1 µF flying capacitors and reduces EMI filtering burden. |
| Shutdown Current | <1 µA - preserves battery life during display-off states in portable devices. |
| Package | WSON-14 (4.0 mm × 3.0 mm × 0.8 mm) - thermally enhanced leadless package with exposed die-attach pad for PCB heat sinking. |
| Operating Junction Temp | −40°C to +115°C - qualified for industrial and extended-temperature consumer applications. |
Pinout & Package
The LM27952SD is housed in a 14-pin WSON package (Package Code: NHK0014A) measuring 4.0 mm × 3.0 mm × 0.8 mm, featuring an exposed die-attach pad (DAP) soldered to GND for thermal management. Pin numbering follows standard top-view orientation with Pin 1 at top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (C2+) | Flying capacitor C2 positive terminal | Connects to one plate of 1 µF ceramic flying capacitor used in 1.5× charge-pump stage. |
| 2 (VOUT) | Pre-regulated charge-pump output node | Supplies power to all four LED anodes; voltage adapts between ~3.0 V (1×) and ~4.5 V (1.5×) depending on load. |
| 3 (C1+) | Flying capacitor C1 positive terminal | Connects to one plate of second 1 µF flying capacitor; forms dual-capacitor charge-pump topology. |
| 4–7 (D4–D1) | Regulated current sink inputs | Each connects to cathode of one white LED; sinks programmed current with ≤360 mV headroom at full load. |
| 8 (ISET) | Current set reference node | Internal 1.25 V reference; RSET to GND sets all four LED currents via ILED = 200 × (1.25 V / RSET). |
| 9 (EN) | Enable logic input (active-high) | Logic high ≥1.0 V enables device; internal 150 kΩ pull-down ensures safe default shutdown state. |
| 10 (PWM) | Brightness control logic input (active-high) | Modulates current sinks ON/OFF at ≥100 Hz; keeps charge pump running to avoid input ripple and startup transients. |
| 11 (VIN) | Main power supply input | Accepts 3.0–5.5 V; powers internal circuitry and charge-pump stages; requires 3.3 µF input capacitor. |
| 12 (C2−) | Flying capacitor C2 negative terminal | Completes C2 connection; alternates polarity with C2+ during charge-pump switching cycles. |
| 13 (GND) | Power and signal ground reference | Primary return path; must be connected to exposed DAP for optimal thermal performance. |
| 14 (C1−) | Flying capacitor C1 negative terminal | Completes C1 connection; works with C1+ to implement bidirectional charge transfer. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive 1.5X/1X Gain Selection | Automatically switches between gain modes based on LED VF to sustain >85% efficiency across VIN and load variations. |
| No Inductor Required | Uses only four low-ESR ceramic capacitors (two 1 µF flying, one 3.3 µF input, one 3.3 µF output), reducing BOM cost and board area. |
| Four Matched Current Sinks | 0.2% typical current matching ensures consistent LED brightness without per-channel trimming or feedback loops. |
| Dedicated PWM Control Pin | Enables flicker-free brightness adjustment (100 Hz–1 kHz) while keeping charge pump active-eliminating input current spikes seen with EN-based dimming. |
| Thermal Shutdown Protection | Disables output at TJ ≥150°C (typ.), re-enables at TJ ≤140°C (typ.), preventing permanent damage under sustained overload or poor heatsinking. |
Applications
| White LED Display Backlights | White LED Keypad Backlights |
|---|---|
Use Scenario: Driving 4 parallel white LEDs behind a 3.5-inch TFT LCD panel in a handheld medical monitor. IC Role / Device Role / Timing Role: Adaptive switched-capacitor current driver providing stable 25 mA per LED with automatic gain selection to maintain efficiency as battery voltage drops from 4.2 V to 3.3 V. Use Value: Eliminates need for inductor-based boost converter, reducing solution height to <1 mm and enabling ultra-thin bezel design. | Use Scenario: Illuminating membrane keypad LEDs in an industrial HMI panel requiring uniform brightness across 12 keys (3 × LM27952SD). IC Role / Device Role / Timing Role: Four-channel constant-current sink regulating 15 mA per LED with 0.2% matching to prevent visible intensity variation across keys. Use Value: Enables single-resistor programming (RSET = 16.7 kΩ) for precise, production-ready current setting without calibration. |
| General Purpose LED Lighting | Portable Consumer Electronics |
Use Scenario: Powering dual-LED indicator strings in a rechargeable power tool battery pack status display. IC Role / Device Role / Timing Role: Parallel-connected D1–D2 and D3–D4 outputs deliver 60 mA total to two high-brightness LEDs using shared RSET. Use Value: Doubles per-channel current capability without redesign-supports higher-lumen LEDs while retaining same footprint and control logic. | Use Scenario: Backlighting OLED status icons in Bluetooth earbuds with strict size and quiescent current constraints. IC Role / Device Role / Timing Role: Low-noise current driver operating at 750 kHz with <1 µA shutdown current and PWM dimming at 500 Hz. Use Value: Extends battery runtime by minimizing idle power loss and avoids audible noise from lower-frequency PWM or inductor whine. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED current driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3409QMY/NOPB | Inductor-based buck-boost LED driver; supports higher output voltage (up to 42 V) and wider input (4.5–36 V); no integrated current matching. | Suitable for automotive LED lighting where VIN exceeds 5.5 V or string voltage >5 V; requires external sense resistors per channel. | Select when driving longer LED strings or operating from 12 V/24 V supplies; not drop-in compatible due to topology and pinout differences. |
| TPS61165DRVR | Inductorless 1.5×/1× charge-pump LED driver; 5-channel (not 4), 30 mA/channel, 2.7–5.5 V input; includes I²C interface for programmable current and fault reporting. | Preferred for designs requiring digital control, channel disable, or overvoltage protection; larger WSON-16 package (4.0 × 4.0 mm). | Choose when system-level configurability (e.g., dynamic current scaling via I²C) outweighs minimal footprint advantage of LM27952SD. |
Compared with LM3409QMY/NOPB and TPS61165DRVR, the LM27952SD offers the smallest solution size and lowest component count for 4-LED, single-cell Li-ion backlighting, but lacks programmability and high-voltage capability-making it optimal for cost-sensitive, space-constrained portable displays.
Availability
LM27952SD is available at Aetrix Electronics and suitable for white LED display backlights, keypad illumination, and portable consumer electronics requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.
Supply support for LM27952SD 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 connectivity technologies, with decades of leadership in power management and LED driver innovation.
The LM27952SD belongs to TI's white LED backlight driver product line, engineered specifically for ultra-compact, high-efficiency, inductorless solutions in space-constrained portable displays and human-interface lighting.
FAQ
What is the recommended capacitor type and value for LM27952SD flying capacitors?
The LM27952SD requires two 1 µF low-ESR X7R or X5R ceramic capacitors (e.g., TDK C1608X7R1A105K) for C1 and C2. These must be surface-mount MLCCs with ESR <20 mΩ; tantalum, aluminum electrolytic, and Y5V/Z5U dielectrics are explicitly not recommended due to high ESR and capacitance drift. The LM27952SD datasheet specifies these values for stable 750 kHz charge-pump operation and optimal efficiency.
How does the LM27952SD achieve adaptive gain switching between 1.5X and 1X modes?
The LM27952SD monitors the voltage at its VDX node (internal to the current sinks) and transitions between 1.5× and 1× gain when VDX crosses 450 mV (typ.). This threshold corresponds to the headroom required for proper current regulation. When LED forward voltage rises (e.g., due to temperature or aging), the device automatically selects 1.5× mode to maintain regulation-ensuring consistent LM27952SD performance without external intervention.
Can multiple LM27952SD outputs be paralleled to drive a single high-current LED?
Yes-D1 through D4 outputs of the LM27952SD can be connected in parallel to drive one or two LEDs at higher current. For a 60 mA target, configure RSET so each sink delivers 15 mA (i.e., RSET = 16.7 kΩ). All electrical specifications-including headroom, matching, and thermal limits-remain valid. This configuration retains the LM27952SD's efficiency and PWM dimming capability while doubling per-LED drive strength.
What is the minimum PWM frequency supported by the LM27952SD for flicker-free dimming?
The LM27952SD supports PWM dimming from 100 Hz to 1 kHz. Frequencies below 100 Hz may cause visible flicker; above 1 kHz, interference with internal regulation or audible noise may occur. The LM27952SD also requires a minimum ON time of 30 µs per cycle-so at 1 kHz, duty cycle must exceed 3%. This ensures stable current regulation and avoids perceptible artifacts in backlight applications using the LM27952SD.
Does the LM27952SD require an external voltage reference or feedback network for current regulation?
No-the LM27952SD integrates a precision 1.25 V reference at the ISET pin and closed-loop current regulation circuitry. LED current is set solely by RSET connected between ISET and GND, per ILED = 200 × (1.25 V / RSET). No external op-amps, references, or compensation components are needed. This self-contained architecture simplifies layout and ensures consistent LM27952SD performance across temperature and process variation.
LM27952SD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-WFDFN 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:
- 4
- Voltage - Supply (Min):
- 3V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 2.5V ~ 3.9V
- Current - Output / Channel:
- 30mA
- Frequency:
- 750kHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-WSON (4x3)
LM27952SD FAQ
1.How can I place an order for LM27952SD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM27952SD 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 LM27952SD reliable?
The price and inventory of LM27952SD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM27952SD is usually 5 days.
3.What payment methods are accepted for LM27952SD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM27952SD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM27952SD?
LM27952SD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM27952SD 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 LM27952SD?
For technical support, including LM27952SD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM27952SD requirements.
6.How does Aetrix verify that LM27952SD is sourced from the original manufacturer or authorized distributors?
All LM27952SD 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 LM27952SD meets industry standards.
7.What is the process for return or replacement of LM27952SD?
All LM27952SD units undergo pre-shipment inspection (PSI). If there is an issue with LM27952SD, 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 LM27952SD part is unused and in its original packaging.
Return procedure for LM27952SD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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