My Inquiry
My Account
Texas Instruments LM27951SDX
- Part No.:
- LM27951SDX
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LM27951SDX.pdf
- Description:
- IC LED DRV RGLTR PWM 30MA 14WSON
- Quantity:
- Payment:
- Shipping:
Inventory:2,526
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM27951SDX from Texas Instruments is a switched-capacitor white LED current driver IC with adaptive 1.5×/1× gain selection, four tightly matched regulated current sources (up to 30 mA per channel), fixed 750 kHz switching frequency, and operation from 2.8 V to 5.5 V input. It drives display backlights requiring uniform brightness across multiple LEDs without inductors.
For engineers reviewing the LM27951SDX datasheet, LM27951SDX pinout, LM27951SDX application, or LM27951SDX equivalent, key selection criteria include LED current matching (0.2% typ.), charge pump output resistance (3.3 Ω), shutdown current (<1 µA), thermal protection (150°C junction limit), and WSON-14 package compatibility with high-density PCB layouts.
Technical Context
The LM27951SDX implements an adaptive CMOS charge pump that dynamically selects between 1.5× and 1× gain modes based on LED forward voltage and load conditions to maximize efficiency-achieving >85% peak efficiency while minimizing input ripple via constant-frequency pre-regulation. Its internal voltage reference and soft-start circuitry ensure controlled startup in ~330 µs.
Four independent current sources are biased from a common VOUT node and share a single ISET pin for global current programming via external RSET. The dedicated PWM pin enables brightness control without cycling the charge pump, preserving low-noise operation and avoiding input inrush transients associated with EN-based modulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Drive Current | Up to 30 mA per channel (programmable via RSET); supports 4-LED parallel configuration at full rated current. |
| Current Matching | 0.2% typical mismatch between D1–D4 outputs-ensures uniform luminance across multi-LED displays. |
| Input Voltage Range | 2.8 V to 5.5 V-compatible with single-cell Li-ion, Li-polymer, and 3.3 V/5 V system rails. |
| Switching Frequency | Fixed 750 kHz (±30%)-optimized for small ceramic capacitors and minimal conducted EMI in portable systems. |
| Shutdown Current | <1 µA at EN = 0 V-enables ultra-low-power standby in battery-critical applications. |
| Charge Pump Output Resistance | 3.3 Ω typical-determines VOUT droop under load; used to calculate maximum sustainable LED current per design equation. |
| Headroom Voltage | 360 mV at 30 mA-minimum VOUT–VDX differential required to maintain regulation; impacts minimum VIN vs. LED VF margin. |
Pinout & Package
LM27951SDX is housed in a 14-pin WSON package (4.0 mm × 3.0 mm × 0.8 mm, Package Code NHK0014A) with exposed die-attach pad (GND) for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| C2+ | Flying capacitor connection (C2) | High-side terminal of second flying capacitor; switches between VIN and VOUT during 1.5× mode. |
| VOUT | Pre-regulated charge pump output | Loosely regulated node supplying all four current sources; voltage depends on gain mode and load. |
| C1+ | Flying capacitor connection (C1) | High-side terminal of first flying capacitor; participates in both 1× and 1.5× charge transfer cycles. |
| D4–D1 | Regulated current source outputs | Four independent, matched sink outputs; each delivers programmed current to cathode of connected LED. |
| ISET | Global current set input | Accepts resistor to GND; sets all LED currents via 200× scaling of 1.25 V reference (IDx = 200 × 1.25 V / RSET). |
| EN | Enable logic input | Active-high enable with internal 150 kΩ pull-down; <0.4 V disables entire IC including charge pump and bias circuits. |
| PWM | Brightness control input | Active-high modulation pin; toggles current sources ON/OFF without disabling charge pump-reduces input noise. |
| VIN | Main power supply input | Supplies charge pump; must be ≥2.8 V and ≤5.5 V; decoupled with 3.3 µF ceramic capacitor. |
| C2− / C1− / GND | Capacitor return & ground | C2− and C1− connect flying capacitor low sides; GND is power and signal reference with exposed DAP for thermal conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Adaptive 1.5×/1× gain selection | Automatically transitions based on VDX headroom to sustain highest efficiency across input and LED VF variations. |
| No-inductor architecture | Relies solely on four low-ESR ceramic capacitors-eliminates magnetic components, reduces board area, and avoids EMI from inductor ringing. |
| Dedicated PWM brightness control | Enables flicker-free dimming (100 Hz–1 kHz) without disrupting charge pump operation-minimizes input current spikes and voltage dips. |
| Tight current matching (0.2% typ.) | Ensures consistent LED brightness across all four channels-critical for uniform backlighting in small-format LCDs and keypads. |
| Thermal shutdown protection | Disables output at 150°C junction temperature and recovers at 140°C-prevents permanent damage during sustained overload or poor heatsinking. |
Applications
| White LED Display Backlights | White LED Keypad Backlights |
|---|---|
|
Use Scenario: Driving 4-segment LCD display backlight in handheld medical device with 3.6 V Li-ion supply and space-constrained PCB. IC Role / Device Role / Timing Role: Adaptive charge pump current driver providing stable 20 mA per LED with automatic gain selection to maintain efficiency as battery discharges from 4.2 V to 3.0 V. Use Value: Eliminates inductor, reduces solution size by >40%, and ensures uniform brightness across segments despite LED VF variation (±0.1 V). |
Use Scenario: Illuminating membrane keypad in industrial HMI panel operating from 5 V rail with ambient temperature up to 85°C. IC Role / Device Role / Timing Role: Four-channel constant-current source delivering 15 mA per LED with thermal shutdown active above 115°C junction temperature. Use Value: Maintains consistent keypad visibility over full temperature range; <1 µA shutdown current extends battery life in sleep mode. |
| General Purpose LED Lighting | Portable Consumer Electronics Lighting |
|
Use Scenario: Powering dual-white LED module (2× warm + 2× cool) in smart home sensor hub with PWM-dimming interface. IC Role / Device Role / Timing Role: Programmable current driver using single RSET to set 25 mA per LED and dedicated PWM pin for 500 Hz dimming without charge pump restart. Use Value: Enables smooth, silent dimming with no audible noise or input ripple-unlike EN-based PWM schemes. |
Use Scenario: Backlighting OLED status indicators in Bluetooth earbud charging case powered by 3.7 V battery. IC Role / Device Role / Timing Role: Ultra-low-quiescent current driver (1.9 mA IQ, <1 µA ISD) supporting rapid enable/disable cycles during intermittent UI feedback. Use Value: Extends standby battery life by minimizing leakage; WSON-14 footprint fits tight 8 mm × 8 mm PCB area budget. |
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 |
|---|---|---|---|
| LM3530SDX | 6-channel driver with I²C interface and dynamic headroom control; higher pin count (20-pin WQFN); requires firmware integration. | Supports programmable current per channel and ambient light compensation-suited for auto-brightness adaptive displays. | Select LM3530SDX when per-LED current tuning or closed-loop ambient light response is required; not drop-in compatible. |
| TPS61165DRVR | Inductor-based boost converter with analog/PWM dimming; higher efficiency at low VIN but larger solution size due to inductor. | Better suited for high-VF LEDs (>4.0 V) or single-LED strings where charge pump gain limitations apply. | Choose TPS61165DRVR when driving >4.0 V LEDs or when higher peak efficiency (>90%) justifies added board area and EMI filtering. |
Compared with LM27951SDX, LM3530SDX adds digital configurability at the cost of layout complexity and firmware dependency, while TPS61165DRVR trades capacitor-only simplicity for superior high-VF capability and efficiency-but introduces inductor-related design constraints.
Availability
LM27951SDX is available at Aetrix Electronics and suitable for white LED display backlights, keypad illumination, and portable consumer lighting applications requiring stable component supply, RoHS-compliant packaging, and long-term production continuity.
Supply support for LM27951SDX 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 expertise in precision power conversion and LED driver innovation.
The LM27951SDX belongs to TI's white LED backlight driver product line, engineered specifically for compact, inductor-free, high-efficiency illumination in space- and power-constrained portable electronics.
FAQ
What is the maximum LED forward voltage supported by the LM27951SDX?
The LM27951SDX supports LED forward voltages from 2.5 V to 3.9 V per diode. At minimum input voltage (2.8 V), it can drive LEDs up to ~3.6 V when configured for 30 mA per channel. Exceeding 3.9 V may cause regulation loss due to insufficient headroom-verified in Electrical Characteristics Table and Application Information section on maximum LED voltage.
How does the LM27951SDX select between 1.5× and 1× gain modes?
The LM27951SDX monitors the voltage difference between VOUT and VDX (LED cathode) and triggers transition at ~500 mV falling threshold. When headroom drops below this level, it switches to 1.5× mode to raise VOUT; when sufficient, it reverts to 1× for higher efficiency-detailed in Gain Select block diagram and VGDX specification.
Can multiple LM27951SDX outputs be paralleled for higher current per LED?
Yes-D1–D4 outputs can be wired in parallel to drive one or two LEDs at higher current. For a single 60 mA LED, configure each channel for 15 mA via RSET; for two LEDs, pair D1/D2 and D3/D4, setting each for 50% of target current. This is explicitly validated in the "Parallel DX Outputs" application note section.
What capacitor types are recommended for the LM27951SDX?
Only X7R or X5R multilayer ceramic capacitors (MLCCs) are recommended-specifically 1 µF for C1/C2 and 3.3 µF for CIN/COUT, all rated ≥10 V. Tantalum, aluminum electrolytic, Y5V, and Z5U ceramics are excluded due to high ESR or severe capacitance drift over temperature and bias-per Capacitor Selection guidelines.
Does the LM27951SDX require external compensation components?
No-the LM27951SDX uses internal compensation and requires no external RC networks. Its regulated current sources and charge pump loop are fully integrated and factory-trimmed; stability is guaranteed with the specified ceramic capacitor values and layout per the Typical Application Circuit and PCB Layout Considerations section.
LM27951SDX 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):
- 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)
LM27951SDX FAQ
1.How can I place an order for LM27951SDX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM27951SDX 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 LM27951SDX reliable?
The price and inventory of LM27951SDX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM27951SDX is usually 5 days.
3.What payment methods are accepted for LM27951SDX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM27951SDX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM27951SDX?
LM27951SDX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM27951SDX 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 LM27951SDX?
For technical support, including LM27951SDX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM27951SDX requirements.
6.How does Aetrix verify that LM27951SDX is sourced from the original manufacturer or authorized distributors?
All LM27951SDX 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 LM27951SDX meets industry standards.
7.What is the process for return or replacement of LM27951SDX?
All LM27951SDX units undergo pre-shipment inspection (PSI). If there is an issue with LM27951SDX, 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 LM27951SDX part is unused and in its original packaging.
Return procedure for LM27951SDX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM27951SDX Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
