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Texas Instruments LM27951SD/NOPB
- Part No.:
- LM27951SD/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM27951SD/NOPB.pdf
- Description:
- IC LED DRV RGLTR PWM 30MA 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,473
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Product details
Overview
LM27951SD/NOPB from Texas Instruments is a switched-capacitor white LED current driver IC with adaptive 1.5×/1× charge pump architecture, four matched regulated current sources (up to 30 mA each), fixed 750-kHz switching frequency, <1 µA shutdown current, and operation from 2.8 V to 5.5 V input - used in compact display backlighting where inductor-free power conversion is required.
For engineers reviewing the LM27951SD/NOPB datasheet, LM27951SD/NOPB pinout, LM27951SD/NOPB application, or LM27951SD/NOPB equivalent, key selection criteria include LED current matching (0.2% typical), gain-mode transition threshold (500 mV headroom), ISET-based current programming (200× scaling), thermal protection (150°C trip), and WSON-14 package compatibility with high-density portable PCB layouts.
Technical Context
The LM27951SD/NOPB implements an adaptive gain-switching charge pump that dynamically selects between 1× and 1.5× modes based on real-time headroom voltage (VOUT − VDX), ensuring optimal efficiency across varying LED forward voltages (2.5 V–3.9 V) and input supply (2.8 V–5.5 V). Its constant-frequency pre-regulation minimizes conducted EMI without requiring external filtering.
Four independent, tightly matched current sources (D1–D4) are internally referenced to a stable 1.25 V at ISET, enabling precise LED current control via external RSET (e.g., 12.5 kΩ sets 20 mA per LED). The dedicated PWM pin allows brightness modulation without cycling the charge pump, preserving output stability and reducing input ripple versus EN-controlled dimming.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8 V to 5.5 V - supports single-cell Li-ion (3.0–4.2 V) and USB-powered systems without LDO pre-regulation. |
| Max Output Current per Channel | 30 mA - enables driving four standard white LEDs (e.g., 3.2 V @ 20 mA) simultaneously with uniform brightness. |
| Current Matching Accuracy | 0.2% typical - ensures <±0.06 mA variation between D1–D4 outputs at 30 mA, critical for display grayscale fidelity. |
| Switching Frequency | 750 kHz (±30%) - fixed-frequency operation simplifies EMI filtering and avoids audible noise in handheld devices. |
| Shutdown Current | <1 µA - extends battery life in always-on portable displays during sleep mode. |
| Charge Pump Output Resistance | 3.3 Ω - determines VOUT droop under load; used to calculate maximum sustainable LED current at low VIN. |
| Headroom Voltage Requirement | 360 mV @ 30 mA - minimum (VOUT − VDX) needed to maintain regulation; drops to 240 mV at 20 mA. |
Pinout & Package
LM27951SD/NOPB is housed in a 4.00 mm × 3.00 mm, 14-pin no-pullback WSON package with exposed thermal pad (Die-Attach Pad = GND) for enhanced power dissipation in space-constrained applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| C2+, C2−, C1+, C1− | Flying capacitor terminals | Connect external 1 µF ceramic capacitors to implement 1.5×/1× charge pump stages; polarity-sensitive layout required. |
| VIN | Main power input | Accepts 2.8–5.5 V supply; requires ≥3.3 µF low-ESR ceramic input capacitor (CIN) near pin for stability. |
| VOUT | Pre-regulated charge-pump output | Loosely regulated node (≈4.5 V typical); supplies all four current sources; requires ≥3.3 µF output capacitor (COUT). |
| D1–D4 | Regulated current source outputs | Four independent, matched sinks for white LEDs; each delivers up to 30 mA with 0.2% matching. |
| ISET | Current set reference input | Internal 1.25 V reference; RSET to GND programs LED current as IDx = 200 × (1.25 V / RSET). |
| EN | Enable logic input | Active-high (VIH ≥1 V); internal 150 kΩ pulldown ensures default shutdown; controls full system power state. |
| PWM | Brightness control input | Active-high logic input (VIH ≥1 V); modulates D1–D4 without disabling charge pump - reduces input ripple vs EN dimming. |
| GND | Power ground | Primary return path; Die-Attach Pad must be soldered to PCB ground plane for thermal and electrical integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive 1.5×/1× gain selection | Automatically switches between gain modes based on real-time headroom (VOUT − VDX), maximizing efficiency across input and LED voltage variations. |
| Four matched current sources | 0.2% typical matching ensures consistent LED brightness without software calibration - essential for uniform display backlighting. |
| No-inductor architecture | Uses only four low-cost, small-footprint ceramic capacitors (CIN, COUT, C1, C2); eliminates EMI-prone magnetics and saves board area. |
| Dedicated PWM dimming pin | Enables flicker-free brightness control (100 Hz–1 kHz) while keeping charge pump active - avoids input current spikes seen with EN-based dimming. |
| Thermal shutdown protection | Disables output at TJ ≥150°C (typical) and recovers at TJ ≤140°C (typical), preventing damage during sustained high-current or poor-thermal-layout conditions. |
Applications
| Smartphone Display Backlight | Tablet Keypad Illumination |
|---|---|
|
Use Scenario: Driving four parallel white LEDs behind a 4.3-inch TFT LCD panel in a battery-powered smartphone. IC Role / Device Role / Timing Role: Adaptive switched-capacitor current driver providing matched 20 mA per LED with dynamic gain selection to sustain regulation as battery discharges from 4.2 V to 3.0 V. Use Value: Eliminates inductor, reduces solution size by >40%, and maintains ±0.5% brightness uniformity across display corners over temperature and lifetime. |
Use Scenario: Illuminating alphanumeric keys on a ruggedized industrial tablet with ambient light sensing and variable brightness control. IC Role / Device Role / Timing Role: Four-channel current sink delivering 15 mA per LED, modulated via MCU-generated 500 Hz PWM signal applied to PWM pin. Use Value: Enables smooth 100:1 dimming range without visible flicker or input rail disturbance, supporting IP65-rated sealed front-panel design. |
| Portable Medical Device Indicator | Wearable Fitness Tracker Display |
|
Use Scenario: Powering status LEDs (green/red/blue) on a handheld pulse oximeter with strict EMC and battery-life requirements. IC Role / Device Role / Timing Role: Single-chip solution sourcing 10 mA per LED from 3.3 V rail, using EN pin for system-level power gating during standby. Use Value: Achieves <1 µA shutdown current and passes CISPR-22 Class B radiated emissions with minimal filtering - critical for FDA-cleared designs. |
Use Scenario: Backlighting a 0.96-inch OLED segment in a wrist-worn fitness tracker operating from a 3.7 V Li-po cell. IC Role / Device Role / Timing Role: Regulated current driver delivering 25 mA per LED with 750 kHz switching - avoids audible noise and supports rapid brightness transitions. Use Value: Enables <200 ms wake-from-sleep response and extends battery runtime by 18% versus inductive boost alternatives at 20 mA load. |
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 |
|---|---|---|---|
| TPS61160DRVR | Inductor-based boost converter; higher peak efficiency (>90%) but requires external inductor and generates more EMI. | Preferred for >5 LED strings or higher Vf (>4.0 V); unsuitable where board space or EMI sensitivity prohibits inductors. | Select TPS61160DRVR when LED forward voltage exceeds 3.9 V or when >30 mA per channel is required. |
| MAX16832ATA+ | Linear LED driver; no switching noise, but dissipates excess power as heat - limited to low-Vf, low-current use cases. | Suitable only for 1–2 LEDs at ≤15 mA with VIN − Vf < 0.5 V; inefficient above 20 mA due to thermal constraints. | Choose MAX16832ATA+ only for ultra-low-noise analog instrumentation indicators with tight thermal budgets. |
Compared with TPS61160DRVR and MAX16832ATA+, the LM27951SD/NOPB uniquely balances inductor-free compactness, adaptive efficiency across battery discharge, and four-channel matching - making it optimal for space-constrained, multi-LED portable displays where EMI and uniformity are prioritized over absolute peak efficiency.
Availability
LM27951SD/NOPB is available at Aetrix Electronics and suitable for smartphone display backlights, tablet keypad illumination, portable medical device indicators, wearable fitness tracker displays, and other compact LED lighting applications requiring stable component supply and long-term manufacturability.
Supply support for LM27951SD/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 and embedded processing technologies, with leadership in power management, signal chain, and high-reliability ICs for industrial, automotive, and consumer markets.
The LM27951SD/NOPB belongs to TI's white LED driver product line, engineered specifically for inductor-free, high-matching backlight solutions in portable displays - emphasizing minimal footprint, adaptive efficiency, and robust thermal behavior in thermally constrained enclosures.
FAQ
What is the recommended capacitor type and value for LM27951SD/NOPB flying capacitors C1 and C2?
The LM27951SD/NOPB requires two 1 µF X7R or X5R multilayer ceramic capacitors (MLCCs) for C1 and C2, rated ≥6.3 V. These must be placed as close as possible to their respective pins (C1+/C1−, C2+/C2−) with short, wide traces. Y5V or Z5U dielectrics are explicitly discouraged due to severe capacitance loss over temperature and voltage - a nominal 1 µF Y5V part may drop to 0.1 µF, causing regulation failure.
How does the LM27951SD/NOPB determine when to switch between 1× and 1.5× charge pump gain modes?
The LM27951SD/NOPB monitors headroom voltage (VOUT − VDX) in real time. When this voltage falls below 500 mV (typical), the device automatically transitions from 1× to 1.5× gain to maintain LED current regulation. This transition is seamless and occurs without interrupting output - ensuring stable brightness as input voltage declines or LED forward voltage increases with temperature.
Can multiple output channels (D1–D4) of the LM27951SD/NOPB be paralleled to drive a single high-current LED?
Yes - D1–D4 can be wired in parallel to drive one or two LEDs at higher currents. For a single 60 mA LED, configure RSET so each channel delivers 15 mA (e.g., RSET = 16.7 kΩ). All electrical specifications - including current matching, headroom, and thermal limits - remain valid. No internal changes or configuration bits are needed; the IC operates identically in parallel or independent mode.
What is the function of the ISET pin on the LM27951SD/NOPB, and how is LED current calculated?
The ISET pin on the LM27951SD/NOPB provides a 1.25 V (typical) internal reference. Connecting an external resistor RSET between ISET and GND sets the LED current per channel as IDx = 200 × (1.25 V / RSET). For example, RSET = 12.5 kΩ yields 20 mA per LED. This scaling factor (200×) is laser-trimmed at wafer test and contributes to the 0.2% typical current matching across D1–D4.
Does the LM27951SD/NOPB support analog dimming, or is PWM the only brightness control method?
The LM27951SD/NOPB supports only digital PWM dimming via its dedicated PWM pin - it does not support analog (DC voltage) dimming. The PWM input accepts logic-level signals (0 V = off, ≥1 V = on) at frequencies from 100 Hz to 1 kHz. Minimum ON time must be ≥30 µs to ensure regulation loop stability. Analog dimming would require external current-sense feedback and is not implemented in this device.
LM27951SD/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Switched Capacitor (Charge Pump)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 4
- Voltage - Supply (Min):
- 2.8V
- 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)
LM27951SD/NOPB FAQ
1.How can I place an order for LM27951SD/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM27951SD/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 LM27951SD/NOPB reliable?
The price and inventory of LM27951SD/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM27951SD/NOPB is usually 5 days.
3.What payment methods are accepted for LM27951SD/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM27951SD/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM27951SD/NOPB?
LM27951SD/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM27951SD/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 LM27951SD/NOPB?
For technical support, including LM27951SD/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM27951SD/NOPB requirements.
6.How does Aetrix verify that LM27951SD/NOPB is sourced from the original manufacturer or authorized distributors?
All LM27951SD/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 LM27951SD/NOPB meets industry standards.
7.What is the process for return or replacement of LM27951SD/NOPB?
All LM27951SD/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM27951SD/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 LM27951SD/NOPB part is unused and in its original packaging.
Return procedure for LM27951SD/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM27951SD/NOPB Tags
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BCR402RE6327HTSA1
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
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BCR421UE6327HTSA1
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LYT1604D-TL
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HV9910CLG-G
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CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
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BCR420UFD-7
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BCR421UFD-7
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