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Microchip Technology MIC3291-18YML-TR
- Part No.:
- MIC3291-18YML-TR
- Manufacturer:
- Microchip Technology
- Category:
- LED Drivers
- Package:
- 8-VFDFN Exposed Pad, 8-MLF®
- Datasheet:
-
MIC3291-18YML-TR.pdf
- Description:
- IC LED DRIVER RGLTR 1.2A 8MLF
- Quantity:
- Payment:
- Shipping:
Inventory:1,016
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Product details
Overview
MIC3291-18YML-TR from Micrel is a 1.2MHz PWM boost LED driver IC optimized for constant-current white LED backlighting in portable devices. It integrates an internal Schottky diode, supports up to four WLEDs via 18V over-voltage protection, delivers >500mA switch current, maintains ±5% LED current accuracy with a 250mV feedback reference, and operates from 2.5V–6.5V input-enabling direct use with single-cell Li-Ion batteries.
For engineers reviewing the MIC3291-18YML-TR datasheet, MIC3291-18YML-TR pinout, MIC3291-18YML-TR application, or MIC3291-18YML-TR equivalent, this page provides verified technical context, package-specific pin functions, linear 16-step single-wire brightness control timing, OVP-limited output voltage range, and real-world efficiency vs. LED current data per load configuration.
Technical Context
The MIC3291-18YML-TR implements constant-frequency current-mode PWM control at 1.2MHz using an internal bipolar switch and slope-compensated current loop. Its gm error amplifier compares the voltage across an external sense resistor to a digitally selectable 237–263mV feedback reference, enabling precise LED current regulation independent of input voltage variation.
Digital brightness control uses a true single-wire interface: logic-level pulses on the DC pin configure 16 linear steps (FB = 25mV–250mV), preset startup level, toggle count-up/count-down mode (tMODE_UP = 100–160µs; tMODE_DOWN = 420–500µs), or trigger shutdown (tSHUTDOWN ≥ 1260µs). The device includes UVLO (2.1V typ), thermal shutdown (150°C), and 18V OVP clamping.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.2MHz fixed-reduces size of external inductor (e.g., 10µH) and output capacitor (e.g., 0.47µF). |
| Feedback Reference Voltage | 250mV ±5%-sets LED current as ILED = 250mV / RSENSE, enabling high accuracy with low-power sense resistors. |
| OVP Threshold | 18V nominal (16.5–18V)-limits output to safely drive up to four series white LEDs (~4.5V each). |
| Input Voltage Range | 2.5V to 6.5V-supports single-cell Li-Ion (fully charged to 4.2V) and 3–4 cell alkaline/NiMH without pre-regulation. |
| Shutdown Current | <1µA-preserves battery life during display-off states in handheld devices. |
| Switch Current Limit | 500–1200mA-handles peak inductor current for multi-LED strings while maintaining stability. |
| Operating Junction Temp | −40°C to +125°C-validated for automotive-adjacent portable electronics and extended-temperature industrial displays. |
Pinout & Package
The MIC3291-18YML-TR is housed in a 2mm × 2mm, 8-pin leadless MLF® package (JEDEC MO-220 variant) with exposed thermal pad. Pin 1 is marked by a dot; the backside GND pad must be soldered for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OUT) | Output & OVP node | Connects to anode of LED string; clamps at 18V during overvoltage events to protect LEDs. |
| 2 (VIN) | Power input | Supplies internal circuitry and switch; accepts 2.5V–6.5V-no external regulator needed for Li-Ion sources. |
| 3 (DC) | Digital control input | Single-wire interface for brightness programming, mode change, and shutdown-requires no MCU GPIO per LED channel. |
| 4 (GND) | Ground return | Primary ground reference for analog and digital blocks; connects to PCB ground plane under exposed pad. |
| 5 (NC) | No connect | Internally unconnected-must remain floating; no routing or stitching required. |
| 6 (FB) | Current sense input | Connects to LED cathode via external sense resistor; regulates LED current by holding FB at 250mV. |
| 7 (SW) | Switch node | Drives external inductor; carries high di/dt switching current-requires short, low-inductance layout to SW and VIN. |
| 8 (GND) | Ground return | Second ground terminal-must be tied to same ground net as Pin 4 and thermal pad for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Single-wire 16-step linear brightness control | Eliminates dedicated PWM generator or I²C interface-reduces MCU resource usage and BOM count in space-constrained handsets. |
| Integrated Schottky diode | Removes need for external 20V/500mA diode-saves 1.5mm² board area and reduces forward drop losses in boost path. |
| Presettable startup brightness | Allows OEMs to define default backlight level (e.g., Level 6) at power-on without firmware initialization delay. |
| 18V over-voltage protection | Hardware-enforced clamp prevents LED overvoltage failure when string impedance changes or open-circuit occurs. |
| 250mV precision feedback reference | Enables use of 1% tolerance, low-value sense resistors (e.g., 12.4Ω for 20mA) without calibration overhead. |
Applications
| Mobile Handsets | LCD Handset Backlighting |
|---|---|
Use Scenario: Powering 4-series white LED backlight in QVGA–WVGA smartphone displays with dynamic brightness scaling. IC Role / Device Role / Timing Role: Constant-current boost controller with single-wire dimming interface and 18V OVP for LED string protection. Use Value: Enables <1µA shutdown current and 1.2MHz operation to minimize passive component size-critical for thin handset form factors. | Use Scenario: Driving 3–4 white LEDs in clamshell phone main/sub displays with ambient light adaptive dimming. IC Role / Device Role / Timing Role: PWM current-mode LED driver with programmable startup level and thermal shutdown for reliability. Use Value: Delivers ±5% LED current accuracy across −40°C to +85°C operating range-ensures consistent display luminance in varying environments. |
| Digital Cameras | Portable Media Players |
Use Scenario: Illuminating LCD viewfinder and rear panel in compact digital still/video cameras powered by dual AA cells. IC Role / Device Role / Timing Role: High-efficiency boost converter with UVLO (2.1V) and 2.5V–6.5V input range for alkaline battery compatibility. Use Value: Maintains >85% efficiency at 15mA output across 2.8V–4.2V input-maximizes battery runtime between charges. | Use Scenario: Controlling white LED backlight in 2.4"–3.5" TFT screens of MP3/MP4 players using single Li-Ion cell. IC Role / Device Role / Timing Role: Single-wire digital LED driver supporting 16-step linear dimming without external clock or data lines. Use Value: Reduces system-level GPIO count and firmware complexity-allows use of low-cost 8-bit MCUs with limited peripherals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX16832ATA+T | Higher 2MHz switching frequency; requires external Schottky diode; 20V OVP; no single-wire interface-uses analog dimming or PWM input. | Targets higher-density LED arrays (e.g., 6–8 LEDs); less suitable for ultra-low-pin-count portable designs. | Select when board space allows larger passives and system already provides PWM signal generation. |
| TPS61160DRVR | 1.2MHz boost driver with integrated MOSFET (not bipolar); 26V OVP; supports I²C interface; no native single-wire mode. | Better suited for systems with I²C infrastructure; lacks MIC3291-18YML-TR's hardware-programmable startup level. | Choose for designs requiring remote brightness updates or multi-channel synchronization via bus protocol. |
Compared with MAX16832ATA+T and TPS61160DRVR, the MIC3291-18YML-TR uniquely combines single-wire digital control, integrated Schottky diode, and factory-presettable startup brightness-making it optimal for cost-sensitive, pin-constrained portable backlighting where minimal MCU intervention is required.
Availability
MIC3291-18YML-TR is available at Aetrix Electronics and suitable for mobile handsets, LCD backlighting, digital cameras, and portable media players requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for MIC3291-18YML-TR 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
Micrel Inc. was a U.S.-based semiconductor company specializing in analog, power management, and timing solutions before its acquisition by Microchip Technology in 2015.
The MIC3291 product line was designed specifically for compact, battery-powered white LED backlighting-emphasizing integration (internal Schottky), low quiescent current, and simplified digital control to reduce system-level complexity.
FAQ
What is the maximum number of white LEDs the MIC3291-18YML-TR can drive?
The MIC3291-18YML-TR supports up to four series-connected white LEDs, based on its 18V over-voltage protection threshold and typical forward voltage of ~4.5V per LED. Driving more than four LEDs risks exceeding the OVP limit and triggering shutdown. The actual count depends on LED VF variation and input voltage headroom-designers should verify worst-case VF sum against 18V minus diode and switch drops. MIC3291-18YML-TR datasheet Figure 1 confirms four-LED operation in typical application circuits.
How does the single-wire interface on the MIC3291-18YML-TR implement brightness control?
The MIC3291-18YML-TR uses pulse-width-defined logic transitions on the DC pin: two falling edges within 1µs–32µs width decrease brightness by one step in count-down mode; a 420–500µs LOW pulse switches to count-up mode. Startup brightness is preset by applying pulses during the 35–50µs tPROG_SETUP window after power-on. No external clock or data lines are needed-MIC3291-18YML-TR handles all timing internally, including rollover from Level 0 to 15.
What is the purpose of the NC pin on the MIC3291-18YML-TR MLF package?
Pin 5 on the MIC3291-18YML-TR's 8-pin MLF package is designated NC (No Connect)-it has no internal connection to the die and must remain electrically floating. It is not a test pin or thermal pad; routing traces or applying solder to this pin may cause mechanical stress or unintended coupling. MIC3291-18YML-TR layout guidelines specify leaving Pin 5 unconnected and avoiding copper pours beneath it to maintain signal integrity on adjacent SW and FB nodes.
Can the MIC3291-18YML-TR operate from a 2.5V input source?
Yes-the MIC3291-18YML-TR operates across 2.5V to 6.5V input, validated down to 2.5V per Absolute Maximum Ratings and Electrical Characteristics tables. At 2.5V, it sustains >80% efficiency driving three 20mA LEDs (see Typical Characteristics curves), though output headroom limits maximum LED string voltage to ~12V. UVLO activates below 2.1V (typ), ensuring clean startup. MIC3291-18YML-TR is thus suitable for deeply discharged Li-Ion or 3-cell NiMH systems.
Does the MIC3291-18YML-TR require an external Schottky diode?
No-the MIC3291-18YML-TR integrates a Schottky diode rated for 150mA forward current (VF = 0.8–1.0V) and 30V reverse blocking, eliminating the need for an external diode in standard 3–4 LED configurations. This integration reduces bill-of-materials count, PCB area, and forward conduction losses. MIC3291-18YML-TR's internal diode is explicitly cited in General Description, Features, and Pin Configuration sections as a key differentiator versus competing boost drivers.
MIC3291-18YML-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-VFDFN Exposed Pad, 8-MLF®
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 2.5V
- Voltage - Supply (Max):
- 6.5V
- Voltage - Output:
- -
- Current - Output / Channel:
- 1.2A (Switch)
- Frequency:
- 1.2MHz
- Dimming:
- -
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MLF® (2x2)
MIC3291-18YML-TR FAQ
1.How can I place an order for MIC3291-18YML-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for MIC3291-18YML-TR 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 MIC3291-18YML-TR reliable?
The price and inventory of MIC3291-18YML-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MIC3291-18YML-TR is usually 5 days.
3.What payment methods are accepted for MIC3291-18YML-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MIC3291-18YML-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MIC3291-18YML-TR?
MIC3291-18YML-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MIC3291-18YML-TR 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 MIC3291-18YML-TR?
For technical support, including MIC3291-18YML-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MIC3291-18YML-TR requirements.
6.How does Aetrix verify that MIC3291-18YML-TR is sourced from the original manufacturer or authorized distributors?
All MIC3291-18YML-TR 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 MIC3291-18YML-TR meets industry standards.
7.What is the process for return or replacement of MIC3291-18YML-TR?
All MIC3291-18YML-TR units undergo pre-shipment inspection (PSI). If there is an issue with MIC3291-18YML-TR, 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 MIC3291-18YML-TR part is unused and in its original packaging.
Return procedure for MIC3291-18YML-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MIC3291-18YML-TR Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
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BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
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