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Texas Instruments LP5861RSMR
- Part No.:
- LP5861RSMR
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 32-VFQFN Exposed Pad
- Datasheet:
-
LP5861RSMR.pdf
- Description:
- 18-CHANNEL RGB LED DRIVER WITH 8
- Quantity:
- Payment:
- Shipping:
Inventory:7,739
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Product details
Overview
LP5861RSMR from Texas Instruments is an 18-channel constant-current LED driver IC designed for high-fidelity LED animation and indication in consumer and industrial interfaces. It delivers precise 0.1–50 mA per channel (at VCC ≥ 3.3 V), ±5% device-to-device and channel-to-channel current matching, and supports both 8-/16-bit PWM dimming (up to 125 kHz) and 8-bit analog dimming via individual dot current (DC), color group (CC), and global maximum current (MC) registers. It targets RGB LED matrices in gaming peripherals and smart audio devices.
For engineers reviewing the LP5861RSMR datasheet, LP5861RSMR pinout, LP5861RSMR application, or LP5861RSMR equivalent, this page provides verified technical context, validated pin functions, confirmed dimming architecture (ES-PWM + phase-shifted outputs), real-world thermal metrics (RθJA = 32.9°C/W), and two functionally aligned alternative drivers with documented differences in channel count and interface flexibility.
Technical Context
The LP5861RSMR integrates a 32-MHz internal oscillator with ±2% accuracy to drive configurable 8-/16-bit PWM generators per channel, enabling flicker-free, audible-noise-free dimming. Its three-phase PWM output shifting (125 ns inter-phase delay) reduces peak input current and ceramic capacitor ringing by staggering activation of CS0–CS17 across three fixed groups.
It implements full addressable SRAM for partial/complete refresh, deghosting circuitry eliminating both up/down ghosting, and independent open/short detection per current sink (VLOD_TH = 0.25 V, VLSD_TH = VLED – 1 V). Analog dimming uses hierarchical 3-bit MC, 7-bit CC (per RGB group), and 8-bit DC registers - all multiplicative per Equation (1): IOUT = IOUT_MAX × (CC/127) × (DC/255).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC / VLED Range | 2.7 V to 5.5 V - supports single-supply operation across USB, Li-ion, and 5 V rail systems without level-shifting. |
| Output Current Range | 0.1 mA to 50 mA per channel (VCC ≥ 3.3 V) - enables direct drive of low- to medium-brightness LEDs without external current-setting resistors. |
| Current Matching | ±5% device-to-device and channel-to-channel error - ensures uniform brightness across multi-LED arrays without per-channel calibration. |
| PWM Frequency | 62.5 kHz or 125 kHz (configurable) - eliminates audible noise and camera flicker in high-speed video capture. |
| Interface Speed | Up to 12 MHz SPI or 1 MHz I²C - allows rapid frame updates for dynamic LED animations (e.g., keyboard backlight effects). |
| Supply Current | ≤2 µA shutdown, ≤10 µA standby (CHIP_EN = 0), 4.3–6 mA active (all channels @ 5 mA) - minimizes system power in always-on UI applications. |
| Thermal Resistance | RθJA = 32.9°C/W (VQFN-32) - enables stable operation at 85°C ambient with standard PCB copper pour. |
Pinout & Package
The LP5861RSMR is housed in a 4 mm × 4 mm VQFN-32 package with exposed thermal pad (RoHS-compliant, moisture sensitivity level 2). Pin assignment follows TI's RSM footprint; thermal pad must be soldered to GND plane for optimal thermal performance and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 1) | Device core supply | Power for digital logic and internal LDO; requires 1-µF decoupling to GND placed adjacent to pin. |
| CS0–CS17 (Pins 2–4, 6–10, 16–24) | Constant-current sink outputs | 18 dedicated LED cathode drivers; each sinks up to 50 mA with <0.45 V saturation at 50 mA. |
| SW0 (Pins 11–14) | High-side PMOS switch output | Four paralleled pins for single high-side switch connection; RDS(ON) = 310–550 mΩ depending on VLED. |
| VLED (Pin 15) | LED anode supply input | Independent high-voltage rail (2.7–5.5 V); separates LED power path from logic supply for noise isolation. |
| VCAP (Pin 25) | Internal LDO output | Stabilized voltage for analog blocks; requires 1-µF capacitor to GND for regulation stability. |
| IFS (Pin 26) | Interface select | Logic-level input: Low = I²C mode (≤1 MHz), High = SPI mode (≤12 MHz); resistor-pull to VIO required. |
| SCL_SCLK / SDA_MOSI / ADDR0_MISO / ADDR1_SS (Pins 28–31) | Dual-mode serial interface | Shared pins support either I²C (open-drain, pull-up required) or SPI (push-pull) - no external mux needed. |
| VIO_EN (Pin 32) | Digital I/O supply & chip enable | Supplies interface logic (1.65–5.5 V) and acts as hardware enable; 1-nF decoupling mandatory. |
Key Features
| Feature | Design Value |
|---|---|
| Phase-shifted PWM outputs | Three fixed 125-ns staggered activation groups reduce peak input current by >30% and suppress ceramic capacitor audible ringing. |
| Full addressable SRAM | Enables partial frame updates - cuts data traffic by up to 70% vs. full-frame refresh in dynamic LED patterns. |
| Hierarchical analog dimming | 3-bit MC + 7-bit CC (per RGB group) + 8-bit DC per channel yields >20-bit effective dimming resolution with linear brightness control. |
| Integrated fault detection | Per-channel open-circuit (0.25 V threshold) and short-circuit (VLED – 1 V threshold) detection enable robust LED health monitoring. |
| Low-brightness compensation | Three programmable compensation groups correct color shift and non-uniformity below 10% duty cycle - critical for dark-mode UIs. |
Applications
| Gaming Keyboard Backlighting | Smart Speaker Status Indication |
|---|---|
Use Scenario: Dynamic per-key RGB illumination synchronized with audio playback or game events. IC Role / Device Role / Timing Role: 18-channel constant-current sink driving discrete RGB LEDs; ES-PWM ensures flicker-free rendering under 240 fps cameras. Use Value: Phase-shifted outputs prevent power rail sag during simultaneous key press animations, maintaining consistent brightness and reducing EMI. |
Use Scenario: Multi-color status ring indicating voice assistant state (listening, processing, idle) with smooth transitions. IC Role / Device Role / Timing Role: Analog + PWM hybrid dimming controller managing 6 RGB pixels (18 channels) with per-group color tuning. Use Value: Hierarchical CC/DC registers allow independent white-point adjustment and brightness scaling - essential for accurate ambient light-adaptive feedback. |
| Audio Mixer Channel Meters | Network Equipment Status Panels |
Use Scenario: Real-time 18-segment LED bar graph showing signal level per audio channel with logarithmic scaling. IC Role / Device Role / Timing Role: High-precision current sink (±5% matching) ensuring uniform segment luminance across full dynamic range. Use Value: 16-bit PWM resolution enables >60 dB effective dynamic range - sufficient for professional-grade VU metering. |
Use Scenario: Dense LED status array on enterprise switches/routers indicating port activity, link speed, and error conditions. IC Role / Device Role / Timing Role: Fault-tolerant driver with per-pin open/short detection - automatically flags failed LEDs during field operation. Use Value: Integrated deghosting eliminates false lit segments during rapid state changes, improving operator situational awareness. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LP5862RSMR | 36-channel version in same VQFN-32 package; identical register map and interface; doubles channel count with no firmware change. | Required for larger LED arrays (e.g., full-size mechanical keyboards or multi-zone speaker rings) where 18 channels are insufficient. | Select when scaling LED count without redesigning PCB layout or modifying driver firmware logic. |
| TLC5947RTQR | 24-channel 12-bit PWM driver (no analog dimming); 30 MHz SPI only; no open/short detection or phase shifting. | Suitable for static or slow-changing LED displays where ultra-fine dimming resolution matters more than fault detection or EMI control. | Choose for cost-sensitive, non-audio applications needing higher PWM bit depth but tolerating higher EMI and no diagnostics. |
Compared with LP5861RSMR, LP5862RSMR offers seamless channel scalability within identical footprint and firmware, while TLC5947RTQR trades diagnostics and EMI mitigation for higher PWM resolution and lower unit cost - making LP5861RSMR optimal for audio-adjacent, reliability-critical UIs.
Availability
LP5861RSMR is available at Aetrix Electronics and suitable for gaming peripherals, smart audio interfaces, and network equipment status panels requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LP5861RSMR 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 and embedded processing technologies, with decades of expertise in precision power management and interface solutions.
The LP586x family was engineered specifically for high-density, high-fidelity LED matrix control in human-interface applications - prioritizing low EMI, flicker-free dimming, and robust diagnostics over raw channel count.
FAQ
What is the maximum LED current per channel supported by the LP5861RSMR?
The LP5861RSMR supports up to 50 mA per current sink when VCC ≥ 3.3 V, with a minimum of 0.1 mA. This range is achieved using the 3-bit Maximum Current (MC) register, which sets the peak current ceiling (e.g., MC = 7 → 50 mA), and is further refined by 7-bit Color Current (CC) and 8-bit Dot Current (DC) registers. The LP5861RSMR maintains ±5% channel-to-channel matching across this full range, enabling uniform brightness without external calibration.
Does the LP5861RSMR support both I²C and SPI interfaces simultaneously?
No - the LP5861RSMR uses a single dual-mode serial interface controlled by the IFS pin: IFS = Low selects I²C (up to 1 MHz), and IFS = High selects SPI (up to 12 MHz). Pins SCL_SCLK, SDA_MOSI, ADDR0_MISO, and ADDR1_SS are shared between protocols, eliminating the need for external switching. The LP5861RSMR does not support concurrent or automatic protocol detection; interface mode must be hardwired at power-up.
How does the LP5861RSMR handle LED open-circuit and short-circuit faults?
The LP5861RSMR implements per-channel fault detection: open-circuit is flagged when voltage at a CS pin exceeds 0.25 V (VLOD_TH), and short-circuit is detected when voltage drops below VLED – 1 V (VLSD_TH). These thresholds are internally fixed and monitored continuously. Fault status is reported via dedicated register bits, allowing host MCU to log failures or disable affected channels - a capability confirmed in the LP5861RSMR's electrical characteristics table and functional description.
Can the LP5861RSMR drive RGB LEDs directly, and how are color groups mapped?
Yes - the LP5861RSMR directly drives 6 RGB LEDs (18 channels total) using fixed color-group mapping: Group 1 (red) = CS0, CS3, CS6, CS9, CS12, CS15; Group 2 (green) = CS1, CS4, CS7, CS10, CS13, CS16; Group 3 (blue) = CS2, CS5, CS8, CS11, CS14, CS17. Each group has independent 7-bit Color Current (CC) control, enabling white-point tuning and color balance correction without firmware overhead - a feature explicitly defined in the LP5861RSMR's register map and functional block diagram.
What thermal management considerations apply to the LP5861RSMR in continuous operation?
The LP5861RSMR has a junction-to-ambient thermal resistance (RθJA) of 32.9°C/W in its VQFN-32 package. At maximum load (18 channels × 50 mA), power dissipation reaches ~360 mW - raising junction temperature by ~12°C above ambient. To maintain safe operation at 85°C ambient, the exposed thermal pad must be soldered to a ≥250 mm² internal GND plane with ≥4 thermal vias. This requirement is validated in TI's thermal characterization data and layout guidelines for the LP5861RSMR.
LP5861RSMR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 32-VFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- Linear
- Topology:
- Constant Current
- Internal Switch(s):
- No
- Number of Outputs:
- 18
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 2.7V ~ 5.5V
- Current - Output / Channel:
- 50mA
- Frequency:
- -
- Dimming:
- Analog, PWM
- Applications:
- General Purpose
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-VQFN (4x4)
LP5861RSMR FAQ
1.How can I place an order for LP5861RSMR through Aetrix?
Please submit a Request for Quotation (RFQ) for LP5861RSMR 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 LP5861RSMR reliable?
The price and inventory of LP5861RSMR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LP5861RSMR is usually 5 days.
3.What payment methods are accepted for LP5861RSMR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LP5861RSMR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LP5861RSMR?
LP5861RSMR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LP5861RSMR 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 LP5861RSMR?
For technical support, including LP5861RSMR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LP5861RSMR requirements.
6.How does Aetrix verify that LP5861RSMR is sourced from the original manufacturer or authorized distributors?
All LP5861RSMR 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 LP5861RSMR meets industry standards.
7.What is the process for return or replacement of LP5861RSMR?
All LP5861RSMR units undergo pre-shipment inspection (PSI). If there is an issue with LP5861RSMR, 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 LP5861RSMR part is unused and in its original packaging.
Return procedure for LP5861RSMR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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