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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > LED Drivers

Microchip Technology MCP1643T-I/MS

Name: MCP1643T-I/MS
Brand: Microchip Technology
SKU: MCP1643T-I/MS
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MCP1643T-I/MS

Manufacturer:: Microchip Technology

Category:: LED Drivers

Package:: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)

Datasheet:: MCP1643T-I/MS.pdf

Description:: IC LED DRV RGLTR PWM 550MA 8MSOP

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Product details

Overview

MCP1643T-I/MS from Microchip Technology is a synchronous step-up DC-DC converter optimized for constant-current LED driving from single/dual-cell alkaline or NiMH/NiCd batteries. It delivers up to 550 mA LED load current with 1 MHz fixed-frequency PWM operation, 120 mV feedback reference voltage, and true output disconnect during shutdown - enabling compact, high-efficiency flashlight and motion-sensing wall lamp designs.

For engineers reviewing the MCP1643T-I/MS datasheet, MCP1643T-I/MS pinout, MCP1643T-I/MS application, or MCP1643T-I/MS equivalent, key selection considerations include low 0.65V start-up voltage, integrated N/P-channel synchronous switches (R_DS(ON) = 0.2 Ω / 0.4 Ω), overvoltage protection clamping V_OUT at 5.0V, thermal shutdown at +150°C, and MSOP-8 package compatibility with space-constrained portable lighting PCBs.

Technical Context

The MCP1643T-I/MS implements peak-current-mode control with adaptive slope compensation and an internal 120 mV error amplifier reference to regulate LED current via external R_SET. Its dual-switch architecture integrates a 0.2 Ω N-channel boost switch and 0.4 Ω P-channel synchronous rectifier, eliminating external diode losses and enabling >90% efficiency at 100–300 mA loads.

Startup logic enables operation from 0.65V input (25 mA LED), sustaining regulation down to 0.5V after startup. Overvoltage protection monitors V_OUT and halts switching if >5.0V - critical when LEDs open-circuit - while true load disconnect during EN = GND removes the input-to-output DC path, limiting shutdown current to 1.2 µA.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	0.5 V to 5.0 V - supports direct operation from depleted single-cell alkaline (0.5 V) and two-cell NiMH (2.4 V), no UVLO circuitry required
Output Current Capability	Up to 550 mA - set by external R_SET; limited by 1.6 A typical peak input current and thermal design
Switching Frequency	1.0 MHz (±15%) - enables use of small 4.7 µH inductors and reduces EMI filtering requirements
Feedback Reference Voltage	120 mV (105–135 mV) - minimizes power loss in R_SET (e.g., 12 mW at 100 mA), improving system efficiency
Overvoltage Protection Threshold	5.0 V - protects IC and downstream components if LED opens or load disconnects
Shutdown Quiescent Current	1.2 µA - preserves battery life in standby mode; true load disconnect isolates V_IN from V_OUT
Thermal Shutdown	+150°C (with +25°C hysteresis) - self-recovering protection prevents damage during sustained overload or poor heatsinking

Pinout & Package

Package: MSOP-8 (3.0 mm × 4.9 mm, 0.65 mm pitch) with exposed thermal pad (EP) requiring external connection to SGND/PGND plane for thermal performance.

Pin/Terminal	Circuit Role	Design Meaning
EN	Enable control input	Logic-high (>75% VIN) enables regulation; logic-low (<20% VIN) triggers true load disconnect and 1.2 µA shutdown state
VFB	Current-sense feedback node	Regulates voltage across R_SET to 120 mV; connects to R_SET cathode and LED cathode - routing must avoid SW node coupling
NC	No-connect terminal	Internally unconnected; must be left floating or tied to GND per layout best practice (no electrical function)
VOUT	High-current output power pin	Delivers regulated LED current; requires 4.7–20 µF X7R/X5R ceramic capacitor close to pin for stability and PWM transient response
SW	Boost switch node	Connects to inductor; carries up to 1.6 A peak current; high dv/dt node - keep trace short and away from sensitive analog paths
PGND	Power ground return	Return path for N-channel switch current; must be connected directly to input capacitor negative and inductor ground
SGND	Signal ground reference	Return for VFB amplifier and bias circuitry; externally joined to PGND at single point near device to minimize noise injection
VIN	Main input supply	Accepts 0.5–5.0 V; requires ≥4.7 µF local ceramic decoupling capacitor placed adjacent to pin

Key Features

Feature	Design Value
Synchronous boost architecture	Integrated 0.2 Ω N-channel switch + 0.4 Ω P-channel rectifier eliminates Schottky losses, enabling >90% efficiency at 300 mA
Low-voltage start-up	0.65 V typical start-up (25 mA LED) allows operation from nearly-dead alkaline cells without external bias circuitry
True output load disconnect	EN = GND disables both switches and breaks input-to-output conduction path - prevents battery drain and enables fast restart
Internal soft-start	240 µs typical ramp time limits inrush current during enable, reducing stress on input capacitors and battery
Overvoltage & thermal protection	5.0 V OVP and +150°C thermal shutdown with +25°C hysteresis provide autonomous fault recovery without external components

Applications

LED Flashlight Systems	Rechargeable Head Lamps
Use Scenario: Portable handheld illumination powered by two AA alkaline cells with momentary ON/OFF and variable-brightness PWM dimming. IC Role / Device Role / Timing Role: Constant-current LED driver regulating 350 mA through single white LED using R_SET, with EN pin accepting 400 Hz PWM for linear brightness control. Use Value: Enables >10-hour runtime from fresh alkalines and extends usable battery life down to 0.5 V input, reducing replacement frequency.	Use Scenario: Wearable headlamp with motion-activated illumination using NiMH rechargeable battery pack and ambient light sensing. IC Role / Device Role / Timing Role: Primary LED current regulator delivering 250 mA to red/yellow LED pair in series, with true load disconnect preserving battery during sleep mode. Use Value: 1.2 µA shutdown current extends weeks-long shelf life; 5.0 V OVP prevents overvoltage damage if LED string fails open.
Wall-Mounted Motion-Sensing Lamps	LED Backlight for Low-Power Displays
Use Scenario: Battery-powered indoor/outdoor wall lamp triggered by PIR sensor, requiring ultra-low quiescent current and reliable cold-temperature start-up. IC Role / Device Role / Timing Role: High-efficiency boost controller powering 2× red LEDs (series) from 1.2 V NiCd cell, leveraging 0.65 V start-up capability for operation below freezing. Use Value: Maintains full brightness down to –25°C ambient (per Figure 2-7), with thermal shutdown preventing failure during extended activation.	Use Scenario: Small-format industrial display backlight driven from coin-cell or single alkaline, requiring stable current and minimal board area. IC Role / Device Role / Timing Role: Compact constant-current source for parallel white LED strings, using MSOP-8 footprint and internal compensation to eliminate external RC networks. Use Value: Reduces BOM count by integrating compensation, soft-start, and OVP - cutting solution size by >40% vs. discrete boost+current-sense designs.

LED Flashlight Systems

Rechargeable Head Lamps

Use Scenario: Portable handheld illumination powered by two AA alkaline cells with momentary ON/OFF and variable-brightness PWM dimming.

IC Role / Device Role / Timing Role: Constant-current LED driver regulating 350 mA through single white LED using R_SET, with EN pin accepting 400 Hz PWM for linear brightness control.

Use Value: Enables >10-hour runtime from fresh alkalines and extends usable battery life down to 0.5 V input, reducing replacement frequency.

Use Scenario: Wearable headlamp with motion-activated illumination using NiMH rechargeable battery pack and ambient light sensing.

IC Role / Device Role / Timing Role: Primary LED current regulator delivering 250 mA to red/yellow LED pair in series, with true load disconnect preserving battery during sleep mode.

Use Value: 1.2 µA shutdown current extends weeks-long shelf life; 5.0 V OVP prevents overvoltage damage if LED string fails open.

Wall-Mounted Motion-Sensing Lamps

LED Backlight for Low-Power Displays

Use Scenario: Battery-powered indoor/outdoor wall lamp triggered by PIR sensor, requiring ultra-low quiescent current and reliable cold-temperature start-up.

IC Role / Device Role / Timing Role: High-efficiency boost controller powering 2× red LEDs (series) from 1.2 V NiCd cell, leveraging 0.65 V start-up capability for operation below freezing.

Use Value: Maintains full brightness down to –25°C ambient (per Figure 2-7), with thermal shutdown preventing failure during extended activation.

Use Scenario: Small-format industrial display backlight driven from coin-cell or single alkaline, requiring stable current and minimal board area.

IC Role / Device Role / Timing Role: Compact constant-current source for parallel white LED strings, using MSOP-8 footprint and internal compensation to eliminate external RC networks.

Use Value: Reduces BOM count by integrating compensation, soft-start, and OVP - cutting solution size by >40% vs. discrete boost+current-sense designs.

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED constant-current boost applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TPS61061DRVR	Fixed 500 mA current limit; no adjustable R_SET; 2.7–5.5 V input range; no true load disconnect	Best suited for fixed-output LED modules where current trimming isn't required and input voltage stays above 2.7 V	Select TPS61061DRVR only if system uses Li-ion or regulated 3.3 V supply and does not require sub-1 V start-up or battery-isolating shutdown
LT3466EDD-1#TRPBF	Adjustable current via R_SET; 2.5–16 V input; 1.2 MHz switching; includes LED cathode sensing but no OVP clamp	Targeted at higher-V_IN industrial LED drivers; lacks integrated OVP and true disconnect, requiring external protection	Choose LT3466EDD-1#TRPBF for 5–12 V input systems needing >550 mA, but add external Zener clamp and high-side switch for load isolation

Compared with TPS61061DRVR and LT3466EDD-1#TRPBF, the MCP1643T-I/MS uniquely combines sub-1 V start-up, true load disconnect, and 5.0 V OVP in an MSOP-8 package - making it the only option for battery-powered lighting requiring deep discharge utilization and autonomous fault protection without added components.

Availability

MCP1643T-I/MS is available at Aetrix Electronics and suitable for LED flashlight systems, rechargeable head lamps, wall-mounted motion-sensing lamps, and low-power display backlights requiring stable component supply across production lifecycles.

Supply support for MCP1643T-I/MS 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

Microchip Technology is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and power management ICs for embedded control applications.

The MCP1643 product line was designed specifically for portable LED lighting powered by primary or rechargeable chemistries - prioritizing ultra-low start-up voltage, high efficiency at partial load, and autonomous protection features to reduce system-level design complexity.

FAQ

What is the minimum input voltage required for MCP1643T-I/MS to start regulating LED current?

The MCP1643T-I/MS starts regulating LED current at a typical input voltage of 0.65 V under 25 mA load conditions. After startup, it sustains regulation down to 0.5 V. This low start-up threshold enables operation from deeply discharged alkaline or NiMH cells - a key differentiator for long-runtime portable lighting. The MCP1643T-I/MS achieves this without external bias circuitry due to its dedicated low-voltage startup logic.

How does the MCP1643T-I/MS implement true output load disconnect during shutdown?

When EN is pulled low, the MCP1643T-I/MS turns off both its internal N-channel boost switch and P-channel synchronous rectifier, physically breaking the DC conduction path between VIN and VOUT. This eliminates leakage through the body diode of the P-channel switch - unlike conventional boost converters - resulting in only 1.2 µA shutdown current. The MCP1643T-I/MS thus isolates the battery from the LED load completely, preventing passive discharge and enabling rapid restart.

Can the MCP1643T-I/MS drive two white LEDs in series?

No, the MCP1643T-I/MS cannot reliably drive two white LEDs in series. With typical forward voltages of 2.7–3.2 V per white LED, two in series require 5.4–6.4 V, exceeding the MCP1643T-I/MS's 5.0 V overvoltage protection threshold and maximum output capability. The datasheet explicitly confirms that two white LEDs are not supported; however, two red/green/yellow LEDs (VF ≈ 1.8–2.4 V each) in series are fully supported within the 5.0 V limit.

What is the role of the NC pin on the MCP1643T-I/MS MSOP-8 package?

The NC (No Connect) pin on the MCP1643T-I/MS MSOP-8 package is internally unconnected and serves no electrical function. It must not be tied to any voltage or signal; Microchip recommends leaving it floating or connecting it to ground solely for mechanical stability or thermal relief - never for circuit operation. Routing traces to or from this pin may introduce noise coupling or violate layout guidelines defined in the datasheet.

How is LED current adjusted on the MCP1643T-I/MS, and what resistor tolerance is recommended?

LED current on the MCP1643T-I/MS is set by an external resistor (R_SET) connected between VFB and GND, using I_LED = 120 mV / R_SET. For production designs, ±1% tolerance metal-film or thin-film resistors are recommended to maintain tight current regulation, as the VFB reference itself has ±12.5% variation (105–135 mV). The MCP1643T-I/MS datasheet provides R_SET limits versus input voltage to ensure regulation across the full operating range.

MCP1643T-I/MS Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Type:: DC DC Regulator

Topology:: Step-Up (Boost)

Internal Switch(s):: Yes

Number of Outputs:: 1

Voltage - Supply (Min):: 0.5V

Voltage - Supply (Max):: 5V

Voltage - Output:: 5V

Current - Output / Channel:: 550mA

Frequency:: 1MHz

Dimming:: PWM

Applications:: Backlight

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-MSOP

MCP1643T-I/MS FAQ

1.How can I place an order for MCP1643T-I/MS through Aetrix?

Please submit a Request for Quotation (RFQ) for MCP1643T-I/MS 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 MCP1643T-I/MS reliable?

The price and inventory of MCP1643T-I/MS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MCP1643T-I/MS is usually 5 days.

3.What payment methods are accepted for MCP1643T-I/MS?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MCP1643T-I/MS transactions.

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4.How is shipping managed for MCP1643T-I/MS?

MCP1643T-I/MS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MCP1643T-I/MS 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 MCP1643T-I/MS?

For technical support, including MCP1643T-I/MS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MCP1643T-I/MS requirements.

6.How does Aetrix verify that MCP1643T-I/MS is sourced from the original manufacturer or authorized distributors?

All MCP1643T-I/MS 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 MCP1643T-I/MS meets industry standards.

7.What is the process for return or replacement of MCP1643T-I/MS?

All MCP1643T-I/MS units undergo pre-shipment inspection (PSI). If there is an issue with MCP1643T-I/MS, 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 MCP1643T-I/MS part is unused and in its original packaging.

Return procedure for MCP1643T-I/MS:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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