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Texas Instruments LM27952SDX
- Part No.:
- LM27952SDX
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM27952SDX.pdf
- Description:
- IC LED DRV RGLTR PWM 30MA 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,501
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Product details
Overview
LM27952SDX from Texas Instruments is a white LED adaptive 1.5X/1X switched capacitor current driver in a 14-pin WSON package (4.0 mm × 3.0 mm × 0.8 mm), delivering up to 30 mA per channel across four tightly matched current sinks with 0.2% typical current matching, operating from 3.0 V to 5.5 V input, and achieving >85% peak efficiency in display backlight applications.
For engineers reviewing the LM27952SDX datasheet, LM27952SDX pinout, LM27952SDX application, or LM27952SDX equivalent, key selection considerations include regulated current sink headroom (240–360 mV), fixed 750 kHz switching frequency, PWM brightness control without charge-pump cycling, and 14-pin WSON thermal performance (θJA = 45°C/W).
Technical Context
The LM27952SDX implements an adaptive gain-switching charge pump architecture that dynamically selects between 1.5× and 1× modes based on LED forward voltage (2.5 V–3.9 V) to maximize efficiency across its 3.0 V–5.5 V input range. It uses constant-frequency pre-regulation to minimize conducted EMI.
Its four independent current sinks are controlled via a single external RSET resistor connected to the ISET pin (1.25 V reference), enabling precise LED current programming (e.g., 21 mA ±8% with 12.5 kΩ). Shutdown current is <1 µA, and startup time is 330 µs typical.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.0 V to 5.5 V - supports single-cell Li-ion, Li-polymer, and 3.3 V/5 V rail systems without level-shifting. |
| Max Output Current per Sink | 30 mA - enables driving four standard white LEDs at full brightness in parallel configurations. |
| Current Matching Accuracy | 0.2% (typ.) - ensures uniform luminance across multi-LED displays without manual calibration. |
| Switching Frequency | 750 kHz (±30%) - balances EMI suppression and capacitor size; avoids audible noise and simplifies filtering. |
| Voltage Headroom (VHR) | 240–360 mV - defines minimum voltage drop across each current sink to maintain regulation at full load. |
| Shutdown Current | <1 µA - preserves battery life in portable devices during standby or sleep modes. |
| Thermal Resistance θJA | 45°C/W - requires minimal PCB copper area for thermal relief; DAP (Die-Attach Pad) must be soldered to GND plane. |
Pinout & Package
LM27952SDX is housed in a 14-pin WSON package (Package Code: NHK0014A; dimensions: 4.0 mm × 3.0 mm × 0.8 mm) with an exposed die-attach pad (DAP) thermally connected to GND. The DAP must be soldered to a dedicated GND thermal land on the PCB for optimal thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 C2+ | Flying capacitor C2 positive terminal | Connects to one plate of flying capacitor C2 used in 1.5× charge pump stage. |
| 2 VOUT | Pre-regulated charge pump output | Loosely regulated node supplying power to all four current sinks; voltage depends on gain mode and load. |
| 3 C1+ | Flying capacitor C1 positive terminal | Connects to one plate of flying capacitor C1 used in 1× or 1.5× charge pump operation. |
| 4–7 D4–D1 | Regulated current sink inputs | Four independent LED cathode connections; each sinks programmed current with matched accuracy. |
| 8 ISET | Current set reference input | Internal 1.25 V reference; RSET to GND sets LED current as 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 default shutdown. |
| 10 PWM | Brightness control logic input (active-high) | Modulates current sinks ON/OFF without disabling charge pump - reduces input ripple vs. EN-based PWM. |
| 11 VIN | Main input supply | Accepts 3.0–5.5 V; powers internal circuitry and charge pump; requires local 3.3 µF ceramic decoupling. |
| 12 C2− | Flying capacitor C2 negative terminal | Completes C2 connection for charge transfer in 1.5× gain mode. |
| 13 GND | Power and signal ground | Reference for all voltages; connects to DAP for thermal conduction and low-impedance return path. |
| 14 C1− | Flying capacitor C1 negative terminal | Completes C1 connection; shared with C2− in some topologies but electrically distinct per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive 1.5X/1X Gain Switching | Automatically transitions between charge pump gains to sustain >85% efficiency across varying LED VF and input voltage. |
| Four Matched Current Sinks | 0.2% typical matching ensures consistent brightness across 4-LED arrays without binning or trimming. |
| PWM-Controlled Brightness | Dedicated PWM pin allows duty-cycle-based dimming while keeping charge pump active - eliminates input current spikes. |
| No Inductor Required | Uses only four low-ESR ceramic capacitors (CIN, COUT, C1, C2); reduces BOM cost, board area, and EMI risk. |
| Low-Noise Fixed-Frequency Operation | 750 kHz switching minimizes conducted noise on VIN and avoids audio-band interference in sensitive portable designs. |
Applications
| White LED Display Backlights | White LED Keypad Backlights |
|---|---|
Use Scenario: Driving 4 parallel white LEDs behind a small-format LCD panel (e.g., 3.5″–5″ smartphone or PDA display). IC Role / Device Role / Timing Role: Adaptive switched-capacitor current driver providing regulated, matched current to each LED cathode via D1–D4 pins. Use Value: Eliminates need for inductors and delivers uniform brightness across display area with <0.2% current mismatch. | Use Scenario: Illuminating alphanumeric keypad buttons in handheld medical or industrial devices requiring low-power, long-battery-life operation. IC Role / Device Role / Timing Role: Four-channel current sink managing discrete LED anodes tied to VOUT and cathodes routed to D1–D4 under microcontroller PWM control. Use Value: Enables smooth 100–1000 Hz PWM dimming without input voltage droop, extending battery runtime by >30% vs. EN-based dimming. |
| General Purpose LED Lighting | Portable Consumer Electronics Lighting |
Use Scenario: Powering dual-LED indicator strings in USB peripherals or IoT edge nodes where space and EMI are constrained. IC Role / Device Role / Timing Role: Parallel-connected D1/D2 and D3/D4 outputs drive two 60 mA LEDs using single RSET configuration. Use Value: Doubles per-sink current capability (to 60 mA) while retaining tight matching and eliminating external current-setting components. | Use Scenario: Backlighting status LEDs in Bluetooth earbuds or wearables powered by 3.7 V Li-ion cells with strict thermal limits. IC Role / Device Role / Timing Role: Efficient 1.5×/1× charge pump delivering stable current despite battery voltage decay from 4.2 V to 3.0 V. Use Value: Maintains >82% efficiency across full discharge curve, reducing thermal load on compact PCBs with no heatsink required. |
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 |
|---|---|---|---|
| LM3530TMX/NOPB | 16-pin WQFN; I²C programmable current (1–30 mA/channel); supports dynamic brightness scaling via register writes. | Requires MCU firmware integration and I²C bus; not suitable for simple GPIO/PWM-only systems. | Select when digital control, channel-by-channel adjustment, or ambient light compensation is needed. |
| TPS61165DRVR | Inductor-based boost converter; higher peak efficiency (>90%) at low ILED; wider VIN (2.7–5.5 V); no adaptive gain switching. | Generates higher EMI; requires inductor and more board area; less suited for ultra-thin or EMI-sensitive layouts. | Select when driving >4 LEDs or needing >30 mA per channel with higher VF LEDs (up to 4.5 V). |
Compared with LM3530TMX/NOPB, LM27952SDX offers simpler GPIO/PWM control and smaller footprint but lacks digital configurability; compared with TPS61165DRVR, it eliminates inductor-related design complexity and EMI filtering but trades off peak efficiency and maximum LED voltage support.
Availability
LM27952SDX is available at Aetrix Electronics and suitable for white LED display backlights, keypad illumination, and portable consumer electronics lighting requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.
Supply support for LM27952SDX 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 ICs, with decades of expertise in precision analog design and high-volume manufacturing.
The LM27952SDX belongs to TI's white LED driver product line, engineered specifically for space-constrained, battery-powered portable displays and indicators requiring high current matching, low EMI, and inductor-free operation.
FAQ
What is the recommended capacitor type and value for LM27952SDX?
The LM27952SDX requires four low-ESR ceramic capacitors: CIN and COUT = 3.3 µF (e.g., TDK C2012X7R1A335K), and C1 and C2 = 1 µF (e.g., TDK C1608X7R1A105K). X7R or X5R dielectrics are mandatory; Y5V/Z5U types are prohibited due to excessive capacitance drift over temperature and bias.
How does LM27952SDX achieve adaptive gain switching between 1.5X and 1X modes?
The LM27952SDX monitors the voltage at the VDX node (internal to the current sinks) and transitions between 1.5× and 1× charge pump gain when VDX crosses 450 mV. This ensures optimal efficiency by selecting the lowest possible gain that maintains regulation across varying LED forward voltage and input conditions.
Can LM27952SDX drive more than four LEDs?
Yes - the D1–D4 outputs of LM27952SDX can be paralleled to drive fewer LEDs at higher current. For example, connecting D1–D4 together drives one LED at up to 120 mA (4 × 30 mA), provided RSET is adjusted so each sink delivers 25% of total target current; all electrical specifications remain valid in this configuration.
What is the function of the Die-Attach Pad (DAP) on the LM27952SDX WSON package?
The exposed DAP on the LM27952SDX is electrically and thermally connected to GND. It must be soldered to a dedicated GND thermal land (ideally 3.0 mm × 1.6 mm) on the PCB, optionally with thermal vias to inner ground planes, to achieve the specified θJA = 45°C/W and prevent thermal shutdown during sustained 30 mA/channel operation.
Does LM27952SDX support analog dimming in addition to PWM control?
No - LM27952SDX only supports digital brightness control via the PWM pin (active-high logic) or global enable/disable via the EN pin. Analog dimming is not supported; LED current is strictly set by RSET, and modulation is achieved exclusively through PWM duty cycle variation applied to the PWM pin.
LM27952SDX 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)
LM27952SDX FAQ
1.How can I place an order for LM27952SDX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM27952SDX 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 LM27952SDX reliable?
The price and inventory of LM27952SDX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM27952SDX is usually 5 days.
3.What payment methods are accepted for LM27952SDX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM27952SDX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM27952SDX?
LM27952SDX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM27952SDX 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 LM27952SDX?
For technical support, including LM27952SDX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM27952SDX requirements.
6.How does Aetrix verify that LM27952SDX is sourced from the original manufacturer or authorized distributors?
All LM27952SDX 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 LM27952SDX meets industry standards.
7.What is the process for return or replacement of LM27952SDX?
All LM27952SDX units undergo pre-shipment inspection (PSI). If there is an issue with LM27952SDX, 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 LM27952SDX part is unused and in its original packaging.
Return procedure for LM27952SDX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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