MC1051 is a low dropout linear step-down constant current driver IC launched by Mass Chip, designed exclusively for DC low-voltage lighting equipment. It integrates a 60V withstand voltage, 50mΩ ultra-low on-resistance power MOSFET, eliminating the need for external power MOSFET and reducing overall BOM cost. The nominal VDD operating voltage ranges from 2.5V to 5.5V. An internal Zener diode clamps the supply to 5.7V under high input voltage, supporting 12/24/36/48/60V bus step-down applications. Output current is adjustable from 10mA to 2A via a high-precision sampling resistor connected to CS pin, with typical constant current accuracy within ±5%.

Independent DIM pin supports wide-frequency PWM input from 3KHz to 100KHz, delivering excellent dimming linearity without MCU compensation, minimum dimming depth below 1% with zero flicker & ripple-free performance. Staged built-in OTP over-temperature protection activates linear current derating at 130°C and full output cutoff at 150°C, preventing permanent damage to IC and LED beads caused by overheating. Widely adopted in residential lighting, display backlight, professional stage light fixtures.

MC1051 Full Product Introduction

MC1051 adopts standard ESOP8 SMD package with large exposed thermal pad connected to LED cathode for superior heat dissipation, maximum power dissipation reaches 1.8W. Quiescent supply current is only 160uA to minimize standby power consumption. Internal CS reference voltage is fixed at 200mV, LED output current formula: I_LED=200mV/Rcs. 1% tolerance metal film sampling resistor is recommended to reduce brightness deviation among mass-produced lighting products.

For 12~60V high voltage bus applications, series divider resistor shall be wired to VDD pin with 1~4.7uF filter capacitor placed nearby to suppress voltage spikes and high-temperature current ripples. For non-dimming projects, short DIM pin to VDD for full brightness constant output; apply 3~100KHz PWM square wave to DIM pin for 0~100% linear brightness adjustment. Built-in noise suppression circuit eliminates flickering and jumping issues caused by signal interference.

MC1051 Ordering Information

MC1051 Key Features & Product Advantages

● Supply voltage coverage 2.5V~6V, internal Zener clamp to 5.7V for high voltage input, compatible with 12V/24V/36V/48V/60V step-down lighting solutions

● Continuously adjustable output current 10mA~2000mA, compatible with low-current backlight to high-power stage lighting fixtures

● Integrated 60V withstand voltage & 50mΩ low Rds(on) MOSFET, removes external power tube to cut BOM & production cost

● PWM dimming frequency up to 100KHz, dimming depth below 1%, no MCU linearity correction required, flicker & ripple-free low-brightness performance

● Staged over-temperature protection logic: linear current derating at 130°C, full output shutdown at 150°C to avoid frequent light flashing damage to LED beads

● ±5% tight constant current tolerance, consistent brightness for mass lamp batches without LED sorting process

● 2000V HBM human-body ESD protection, low defective rate during SMT mass production

● ESOP8 package with exposed thermal pad, 1.8W max power rating, stable temperature under long-hour full-load operation

● Ultra-low quiescent current 160uA, ideal for battery-powered portable lighting devices

● Simplified peripheral circuit, only sampling resistor + VDD filter capacitor required for easy PCB layout & mass manufacturing

MC1051 Absolute Maximum Ratings

Warning: Continuous operation exceeding absolute maximum ratings will cause permanent IC damage and drastically shorten lighting service life.

Standard Electrical Characteristics (VDD=5V, TA=25°C)

MC1051 ESOP8 Pinout & Pin Function Definition

Pin Diagram:

MC1051 Internal Circuit Block Diagram

Internal Schematic Block:

This IC integrates bandgap reference, 200mV current detection module, PWM dimming logic, staged over-temperature protection circuit & 60V power MOS driver unit. Real-time voltage sampling on CS pin achieves closed-loop constant current regulation. DIM pin signal controls MOS turn-on/off; OTP module automatically reduces output current when temperature rises to protect IC & LED loads.

MC1051 Full Typical Application Schematic Collection

1. Standard 5V Low Voltage Input Circuit

For 2.5~5V low-voltage system, VDD directly connects to main bus without divider resistor, apply PWM signal to DIM pin for brightness adjustment.

2. 12V~60V High Voltage Step-Down Circuit

Series divider resistor R1 on VDD for high voltage bus, recommended resistance values: 12V=7K / 24V=19K / 36V=31K / 48V=43K / 60V=55K; match with 1~4.7uF filter capacitor.

3. Output Diode Series Voltage Sharing Circuit

Series diodes to share power dissipation when input-output voltage difference exceeds 0.4V to lower IC temperature. DIM pin needs no pull-down resistor with built-in anti-interference circuit to eliminate light flicker.

4. Non-Dimming Fixed Brightness Circuit

Short DIM pin directly to VDD for full constant LED output if dimming function is not required, simplest peripheral layout.

5. Dual Channel Color Tuning Circuit

Common anode multi-channel design, shared VDD divider resistor & filter capacitor placed close to IC to reduce current ripple.

6. Multi-IC Parallel High-Current Circuit

Parallel multiple MC1051 ICs to expand output current for high-power lighting products, shared VDD filter capacitor with matched divider resistance to minimize voltage drop.

Output Current Calculation Formula

The fixed 200mV reference voltage at CS pin defines LED driving current via below formula:

RCS = sampling resistor connected between CS pin and GND. Use 1% precision metal film resistor to reduce brightness inconsistency among mass production batches. Example: Target 1A output current, Rcs=0.2V/1A=200mΩ.

Efficiency & Power Loss Calculation:
Overall Efficiency = LED Forward Voltage / Input Bus Voltage
IC Power Dissipation = (Input Voltage - Total LED VF) × Output Current

PCB LAYOUT Design Notes

1. Mount 1~4.7uF ceramic filter capacitor as close as possible to VDD pin, connect capacitor GND to IC GND with short trace to suppress power-on voltage spikes & high-temperature current ripples;

2. Make sampling resistor RCS traces wide & short to eliminate constant current error caused by PCB parasitic resistance;

3. Pour large-area copper on ESOP8 exposed thermal pad to improve heat dissipation & lower IC operating temperature;

4. Separate DIM dimming signal traces from high-power power traces to avoid coupling interference & light flicker;

5. Tie DIM pin directly to VDD for non-dimming designs, floating DIM pin will cause abnormal brightness fluctuation.

Product Application Scenarios

● Smart LED Bulbs, Indoor Panel Ceiling Lights, Residential Flat Panel Lighting

● Monitor, Industrial Control Display, Household Appliance LED Backlight Modules

● LED Stage Lights, RGB Ambient Decorative Lights, High-Power Professional Stage Fixtures

● Portable Fill Lights, Battery-Powered LED Lighting Devices

● Low-Voltage DC Light Strips, Advertising Sign Decorative Lamps

Full Mass Chip Linear Constant Current Driver Solution Portfolio

All Mass Chip linear ICs feature zero EMI interference & built-in thermal protection, extending LED service life under long-hour operation with simple assembly & debugging. Select MC1051 for low-voltage indoor lighting; LAN series ICs for automotive high-voltage lamp applications.

MC1051 Cross-Compatible Parts & Competitive Advantages Comparison

MC1051 can direct drop-in replace DW8506, AMC7135, QX7135 and generic external MOS linear LED drivers, core competitive strengths listed below:

Frequently Asked Questions (FAQ)