[Power Issue] Servo Motor Causes Arduino Reset When Powered from 5V Pin

[Customize5773]

Dear @embeddedlab786,

The servo motor (e.g. SG90) currently draws power directly from the Arduino UNO 5V pin. During operation—especially during rapid movement or obstacle scan—the Arduino intermittently resets or hangs.

1. Arduino resets randomly when servo is active
2. Ultrasonic sensor data becomes unstable or missing
3. IR sensors occasionally give false triggers

Servos can draw up to 500-800mA during peak load, far more than the Arduino’s onboard 5V regulator can safely supply. This causes a voltage drop, resulting in Brownouts, Unstable sensor readings, Logic-level failures.

✅ Recommended Power Setup

• Use a dedicated 5V regulator (e.g. AMS1117 or UBEC) to power the servo
• Ensure all components share a common GND
• Power the Arduino separately (e.g. via VIN from 7.4V battery pack)

[Customize5773]

Here’s a load chart comparing the AMS1117 linear regulator and the 5V UBEC (switching regulator) when powering an Arduino Uno, a continuously sweeping SG90 servo, and an HC-SR04 ultrasonic sensor, all running from a 2x18650 battery pack (~7.4V nominal, ~8.4V fully charged)

Parameter	AMS1117 5V Regulator	5V UBEC (3A Switching Regulator)
Type	Linear Regulator	Switching Regulator
Input Voltage Range	6.2–12V	5–26V
Output Voltage	5V (regulated)	5V (regulated)
Max Current Output	~800mA (safe practical)	3A
Idle Power Consumption	High (waste as heat)	Low (efficient conversion)
Heat Generation	High under load	Very low
Efficiency @ 7.4V in, ~300mA load	~67%	~90–95%
Performance with SG90 sweeping	Often unstable, may brown-out	Stable and reliable
Servo Behavior	Jittery, voltage dips	Smooth operation
Use Case Recommendation	Low-power, low-current only	Ideal for servo/motor loads
Thermal Management	Requires heat sink	None needed
Dropout Voltage	~1.1V	Very low

[Customize5773]

I try visualizing comparison chart data AMS1117 linear regulator and the 5V UBEC (switching regulator) in matplotlib.

Here’s the line chart visualizing the AMS1117 regulator's performance over time powering:

1. Arduino UNO
2. 1x SG90 servo (performing continuous sweeps)
3. 1x HC-SR04 ultrasonic sensor
4. Power source: 2x 18650 Li-ion (~7.4V nominal, ~8.4V fully charged)

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🔵 Blue Line: Output Voltage gradually drops as current increases due to the regulator’s limited capacity and thermal stress.
🔴 Red Dashed Line: Regulator Temperature rises significantly, nearing critical levels (>80°C) without a heatsink.

[Customize5773]

And, here's the line chart visualizing the 5V UBEC (switching regulator) performance over time powering:

1. Arduino UNO
2. 1x SG90 servo (performing continuous sweeps)
3. 1x HC-SR04 ultrasonic sensor
4. Power source: 2x 18650 Li-ion (~7.4V nominal, ~8.4V fully charged)

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🔵 Blue Line: Output Voltage stays perfectly flat at 5.00V, showing excellent voltage regulation.
🟢 Green Dashed Line: Regulator temperature gradually rises but stays within a safe, cool operating range (below 40°C).