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Analog Devices Inc. LTC3205EUF#PBF
- Part No.:
- LTC3205EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3205EUF#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 250MA 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,017
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Product details
Overview
LTC3205EUF#PBF from Analog Devices (formerly Linear Technology) is a highly integrated multidisplay LED controller IC featuring a fractional step-up/step-down charge pump, independent current control for main/sub white LEDs and RGB LEDs, 3-wire serial interface, 0.7% LED current matching, and up to 92% efficiency. It powers up to four main, two sub, and three RGB LEDs in handheld devices requiring precise dimming and color mixing.
For engineers reviewing the LTC3205EUF#PBF datasheet, LTC3205EUF#PBF pinout, LTC3205EUF#PBF application, or LTC3205EUF#PBF equivalent, key selection criteria include its dual-mode charge pump architecture (1:1 pass-through / 2:3 boost), programmable dimming states (4 for main/sub, 16 per RGB channel), 24-pin 4mm × 4mm QFN package, and compliance with ±0.3V absolute max ratings on digital pins referenced to DVCC.
Technical Context
The LTC3205EUF#PBF implements a patented constant-frequency 2:3 fractional charge pump with automatic mode switching: it starts in 1:1 direct-connect mode and transitions to 2:3 step-up mode upon detection of any MAIN or SUB LED current source dropout. Internal soft-start limits inrush current over 1.2ms during mode transitions.
LED current regulation uses servo-controlled reference pins (IMS and IRGB) that regulate to 1.223V; full-scale output currents scale linearly as 400× IMS (for MAIN/SUB) or 400× IRGB (for RGB), with programmable fractional settings (100%/50%/25%/0% for white LEDs; 0/15–15/15 duty cycle per RGB channel). RGB PWM operates at 3.5kHz, synchronized to 1/240 of the 800kHz oscillator.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 4.5V - supports single-cell Li-ion battery operation without external LDO. |
| Charge Pump Modes | 1:1 direct-connect (max efficiency when VIN ≥ VLED + 100mV) and 2:3 step-up (enables operation down to VIN = 3.0V for 3.8VF white LEDs). |
| Max Continuous LED Current | 250mA total - distributed across MAIN (4×50mA), SUB (2×50mA), and RGB (3×100mA) channels. |
| LED Current Matching | 0.7% - ensures uniform brightness across MAIN1–MAIN4 and SUB1–SUB2 outputs, critical for display homogeneity. |
| RGB Color Resolution | 4096 combinations - achieved via independent 4-bit PWM per R/G/B channel (16 levels × 16 × 16). |
| Shutdown Current | <1µA on VIN and DVCC - enables ultra-low-power standby in battery-critical applications. |
| Oscillator Frequency | 800kHz typical - sets charge pump switching frequency and defines RGB PWM base clock (3.5kHz = 800kHz/240). |
Pinout & Package
Package: 24-lead (4mm × 4mm × 0.8mm) plastic QFN with exposed PGND pad (Pin 25) requiring soldering to PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| MAIN1–MAIN4 (Pins 2,1,24,23) | Current source outputs | Drive white LEDs for main display; each sinks up to 50mA with 100%/50%/25%/0% software-selectable scaling. |
| SUB1–SUB2 (Pins 22,21) | Current source outputs | Drive white LEDs for sub-display; identical scaling and current capability as MAIN outputs. |
| RED/GREEN/BLUE (Pins 18,19,20) | Current source outputs | Drive RGB illuminator LEDs; each supports 16-step PWM dimming (0/15–15/15) for 4096-color mixing. |
| IMS (Pin 14) | Servo reference input | Resistor-to-ground sets 1.223V reference; determines full-scale current for MAIN/SUB outputs (IOUT = 400 × IIMS). |
| IRGB (Pin 13) | Servo reference input | Resistor-to-ground sets 1.223V reference; determines full-scale current for RGB outputs (IOUT = 400 × IIRGB). |
| CPO (Pin 15) | Charge pump output | Delivers regulated voltage (4.7V in 2:3 mode) to power white/blue/true-green LEDs; requires 1µF ceramic storage capacitor. |
| DIN/SCLK/LD (Pins 7,8,9) | 3-wire serial interface | Microcontroller-compatible command port: DIN shifts 16-bit data on SCLK rising edge; LD falling edge latches command register. |
| STEPUP (Pin 11) | Mode override | Logic-high forces permanent 2:3 boost mode - prevents dynamic switching during RF transmission or critical timing windows. |
| ENRGB (Pin 10) | RGB enable | High enables RGB current sources; low disables RGB and places device in shutdown if MAIN/SUB are also off. |
| VIN (Pin 16) | Input supply | Battery input (2.8–4.5V); powers charge pump; bypassed with 1µF ceramic capacitor. |
| DVCC (Pin 12) | Logic reference | Sets logic threshold (1.5–5.5V range) for DIN/SCLK/LD/STEPUP/ENRGB; must be stable for reliable serial communication. |
| PGND (Pin 25) | Power ground | Exposed pad; connects to low-impedance PCB ground plane to handle high-frequency charge pump return current. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic mode-switching charge pump | Eliminates manual mode selection; maintains >90% efficiency across battery discharge curve (2.8–4.5V) by dynamically selecting 1:1 or 2:3 topology. |
| Independent current programming | Separate IMS and IRGB pins allow optimized current setting for white (main/sub) vs. RGB LEDs - avoids overdesign and thermal imbalance. |
| Low-noise constant-frequency operation | 800kHz fixed oscillator minimizes EMI susceptibility and simplifies input filtering versus variable-frequency alternatives. |
| Four programmable dimming states | Hardware-supported 100%/50%/25%/0% scaling for main/sub displays reduces MCU firmware overhead and ensures glitch-free brightness transitions. |
| Minimal external components | Requires only four 1µF ceramic flying/output capacitors and two resistors (IMS, IRGB) - eliminates inductors and reduces BOM cost/footprint. |
Applications
| Cellular Phone Main/Sub Display | Wireless PDA RGB Status Indicator |
|---|---|
|
Use Scenario: Dual-panel LCD backlighting in compact cellular handsets with independent brightness control for primary screen and secondary status panel. IC Role / Device Role / Timing Role: Multidisplay LED controller managing six white LEDs (4 main + 2 sub) and three RGB indicator LEDs from a single Li-ion cell. Use Value: Enables simultaneous high-efficiency backlighting and status illumination with <0.7% current mismatch - ensuring consistent color temperature and eliminating visible panel seams. |
Use Scenario: Dynamic color-coded system status feedback in enterprise-grade wireless PDAs (e.g., network connectivity, battery level, alert priority). IC Role / Device Role / Timing Role: RGB illuminator driver generating 4096 colors via independent 4-bit PWM per channel, synchronized to internal 3.5kHz clock. Use Value: Delivers precise, flicker-free color rendering without MCU PWM timer resource consumption - freeing CPU for application processing. |
| Multidisplay Handheld Gaming Device | Portable Medical Diagnostic Display |
|
Use Scenario: High-brightness main LCD and low-power sub-display for game HUD overlays and battery/runtime indicators in handheld gaming consoles. IC Role / Device Role / Timing Role: Fractional charge pump LED driver supporting 100mA main panel current and 25mA sub-panel current with automatic 1:1→2:3 transition during battery sag. Use Value: Maintains full display brightness down to 3.0V battery voltage - extending usable gameplay time by 12–15% versus fixed-ratio solutions. |
Use Scenario: Clinical-grade diagnostic tablet with calibrated white backlight (main) and non-distracting RGB alert indicators (sub) for ECG waveform anomalies or vital sign thresholds. IC Role / Device Role / Timing Role: Precision LED current controller delivering 0.7% matching across four main LEDs and independent RGB dimming for ISO 13485-compliant visual alerts. Use Value: Meets medical display luminance uniformity standards (IEC 62304 Annex C) while enabling fail-safe RGB alert activation with <1µA shutdown current. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multidisplay LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX1571ETL+T | Single 2.7–5.5V input; supports only main display (4 white LEDs) and RGB - no sub-display channel; uses I²C interface instead of 3-wire serial. | Lacks dedicated SUB1/SUB2 outputs and independent IMS/IRGB scaling - unsuitable for dual-panel architectures requiring separate brightness control. | Select when RGB-only or main-display-only functionality suffices and I²C bus availability simplifies system integration. |
| TPS65136RGTR | Fixed 2.7–5.5V input; integrates boost converter + linear regulators (no fractional charge pump); supports 4 white + 3 RGB but no sub-display outputs. | Higher quiescent current (25µA vs. 1µA shutdown) and lower peak efficiency (85% vs. 92%) - compromises battery life in always-on portable diagnostics. | Prefer for cost-sensitive consumer devices where sub-display functionality is omitted and thermal constraints permit linear regulation. |
Compared with MAX1571ETL+T and TPS65136RGTR, the LTC3205EUF#PBF uniquely delivers integrated sub-display support, fractional charge pump efficiency above 90%, and hardware-programmable dimming states - making it the only solution meeting dual-panel handheld requirements with <1µA shutdown and 0.7% current matching.
Availability
LTC3205EUF#PBF is available at Aetrix Electronics and suitable for cellular phones, wireless PDAs, multidisplay handheld devices, portable medical diagnostics, and gaming consoles requiring stable component supply across extended product lifecycles.
Supply support for LTC3205EUF#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains its legacy of high-performance analog/power management ICs with rigorous automotive and industrial qualification.
The LTC3205EUF#PBF belongs to Linear's multidisplay LED controller product line, designed specifically for battery-powered handhelds requiring simultaneous white backlighting and RGB status indication with minimal external components and ultra-low shutdown current.
FAQ
What is the maximum total LED current supported by the LTC3205EUF#PBF?
The LTC3205EUF#PBF supports up to 250mA total continuous LED current: 200mA across MAIN1–MAIN4 (50mA each), 100mA across SUB1–SUB2 (50mA each), and 300mA across RED/GREEN/BLUE (100mA each). However, the absolute maximum specified for ICPO is 250mA, and combined MAIN/SUB/RGB loading must stay within thermal limits defined by θJA = 37°C/W. Derating is required above 85°C ambient.
How does the LTC3205EUF#PBF achieve 0.7% LED current matching?
The LTC3205EUF#PBF achieves 0.7% matching through laser-trimmed current mirror circuitry and matched layout of MAIN1–MAIN4 and SUB1–SUB2 output transistors on the same die. This matching is measured under identical thermal conditions and applies only between outputs sharing the same reference (IMS for MAIN/SUB, IRGB for RGB), not across different output groups.
Can unused MAIN or SUB LED pins be left floating on the LTC3205EUF#PBF?
No - unused MAIN1–MAIN4 or SUB1–SUB2 pins must be connected to CPO. If left floating or grounded, they will enter dropout and force the LTC3205EUF#PBF into 2:3 boost mode unnecessarily, reducing efficiency. Connecting to CPO disables the current source while maintaining ~1V headroom, drawing only 10µA test current.
What is the purpose of the STEPUP pin on the LTC3205EUF#PBF?
The STEPUP pin on the LTC3205EUF#PBF forces permanent 2:3 charge pump operation regardless of LED dropout conditions. This prevents dynamic mode switching during sensitive operations like GSM transmission bursts or Bluetooth packet transfers, eliminating potential noise coupling into RF sections caused by charge pump transients.
Does the LTC3205EUF#PBF require external compensation components?
No - the LTC3205EUF#PBF uses an internally compensated linear control loop. Stability relies solely on proper selection of the CPO output capacitor (≥0.6µF ceramic with low ESR) and flying capacitors (≥0.7µF each). Adding external compensation components will destabilize the regulator and is strictly prohibited per the datasheet.
LTC3205EUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Switched Capacitor (Charge Pump)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 9
- Voltage - Supply (Min):
- 2.8V
- Voltage - Supply (Max):
- 4.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 250mA
- Frequency:
- 800kHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LTC3205EUF#PBF FAQ
1.How can I place an order for LTC3205EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3205EUF#PBF 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 LTC3205EUF#PBF reliable?
The price and inventory of LTC3205EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3205EUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3205EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3205EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3205EUF#PBF?
LTC3205EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3205EUF#PBF 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 LTC3205EUF#PBF?
For technical support, including LTC3205EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3205EUF#PBF requirements.
6.How does Aetrix verify that LTC3205EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3205EUF#PBF 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 LTC3205EUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3205EUF#PBF?
All LTC3205EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3205EUF#PBF, 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 LTC3205EUF#PBF part is unused and in its original packaging.
Return procedure for LTC3205EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC3205EUF#PBF Tags
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BCR402RE6327HTSA1
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BCR430UXTSA2
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BCR420UE6433HTMA1
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BCR420UE6327HTSA1
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BCR421UE6327HTSA1
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HV9910CLG-G
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BCR420UFD-7
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BCR421UFD-7
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