Solution of Micro Brushed DC Gear Motors in Smart Fingerprint Locks

As smart home technology continues to evolve, smart door locks — the first line of home security — are shifting toward full automation, high reliability, and low power consumption. Among various drive solutions, micro brushed DC gear motors have become the mainstream choice due to their compact size, cost-effectiveness, and ease of control. This article uses the GA12YN series motor as an example to explore its application design and performance in fingerprint lock systems.

1. Project Background and Core Functional Requirements

This case involves a household smart fingerprint lock that requires the motor to meet the following core functions:

• Drive the deadbolt: The motor rotates forward and backward to extend/retract the latch for quick locking and unlocking.

• Emergency unlocking during power loss: Supports external power input for unlocking when the internal battery is depleted.

• Real-time status monitoring: Paired with a Hall sensor or encoder for latch position feedback and jamming detection.

To meet these requirements, a compact, torque-efficient, and feedback-capable micro motor is essential.

2. Motor Selection: GA12YN Series Micro Brushed DC Gear Motor

Recommended Models:

• GA12YN20 / GA12YN30

• Rated Voltage: 5V / 6V

• No-load Speed:

  • GA12YN20: 285 rpm (@5V)

  • GA12YN30: 125 rpm (@6V)

• Stall Torque:

  • GA12YN20: 0.39 kgf·cm (@5V)

  • GA12YN30: 1.2 kgf·cm (@6V)

• Dimensions:

  • Motor diameter: 10mm, Gearbox length: 9mm

  • Motor body length: 20mm (N30) or 15mm (N20)

  • Weight: 12g (N20) / 13g (N30)

• Encoder-compatible: Supports encoder assembly for position and speed feedback

The GA12YN series adopts a planetary gearbox, with output torque covering 0.5–2 N·m, customizable for different lock designs and resistance levels.

N20 gear reduction motor with encoder dimension drawing :

N20 gear reduction motor dimension drawing:

N30 gear reduction motor dimension drawing:

3. Design Optimization and Performance Advantages

1. Enhanced Reliability & Lifespan

• Uses copper-graphite brushes, achieving up to 10,000–50,000 cycles;

• Supports stall detection and protection, automatically cutting power to avoid overheating or excessive wear.

2. Low Noise Performance

• Uses nylon gears with damping grease to reduce mechanical noise;

• Integrated PWM soft-start, reducing impact noise — overall system noise as low as 30dB, ideal for nighttime use.

3. Low Power Consumption

• Average consumption: 0.5–1W (powered at 3V), supports dual-battery system with 1–2 years of battery life;

• Simple control with an H-bridge driver (e.g., DRV8837) and PWM signals — no complex algorithm required.

4. Strong Environmental Adaptability

• Operates across a wide temperature range (-20℃ to 60℃);

• Optional preheating circuit available for extreme cold environments.

4. Typical Application Scenarios

1. Fully Automatic Push-Pull Locks

GA12YN30 drives the latch, completing unlocking within 0.5 seconds — fast and efficient.

2. Dual Motor Redundancy

Primary and backup motor switching enhances system fault tolerance and reliability.

3. Low-Noise Night Mode

Reduced-speed operation during nighttime balances noise control and energy savings.

5. Future Development Directions

• Smart Closed-loop Control: Detects jamming via current fluctuation and auto-retracts the latch;

• New Materials: Ceramic bearings and self-lubricating gear structures extend motor lifespan;

• Energy Recovery: Reuse door movement energy to assist in power supply, reducing battery load.

6. Conclusion

By integrating the GA12YN series micro brushed DC gear motor, fingerprint locks can achieve an ideal balance of automation, responsiveness, power efficiency, compact size, and cost control. Its mature design and wide adaptability make it a preferred drive solution for today’s smart lock applications.

For more custom motor solutions or technical support, feel free to contact us for datasheets and samples.