1. Overview & Functionality

️· Purpose: The HM2601 is a motor controller designed for fan speed control and protection. It's likely targeted at applications like computer fans, cooling systems, and similar devices.
️· Control Modes:
- Full Speed Mode: For high-temperature situations, the fan runs at maximum speed.
- Variable Speed Mode: Fan speed is controlled by an external voltage (VTH), allowing for dynamic speed adjustments.
- Minimum Speed Mode: Used in low-temperature environments to maintain a minimum fan speed (set by the SMIN input).
️· Protections:
- Lock Protection: If the motor is blocked, the controller shuts down and attempts a restart with a 4-second interval.
- Over Current Protection (OCP): Shuts down the output driver if the current exceeds a limit, and restarts after a 4-second interval.
- Input Under Voltage Lockout (UVLO): Disables the controller and resets the logic if the VREG6 voltage falls below 3.5V.
- Thermal Shutdown (TSD): Shuts down the PWM drive when the junction temperature reaches a limit (170°C) and restarts when it cools down (hysteresis of 15°C).
️· Soft Switching: Reduces motor electromagnetic noise by smoothing the current changes.
️· Typical application circuit: Fan motor connected to VCC & GND with a thermistor and resistor divider for VTH and SMIN.

2. Inputs & Outputs

️· VTH (Voltage Threshold): External voltage to control fan speed in variable speed mode.
️· SMIN (Minimum Speed Input): Sets the minimum fan speed. Pull up to VREG6 if unused.
️· FG (Frequency Output): Open-collector output for reflecting rotation count. Zero during lock protection.
️· HB (Hall Bias): Provides a 1.25V output for Hall sensor biasing.
️· MOTU/MOTV: Motor output pins (likely for positive/negative connection).
️· VREG6: Input Voltage.
️· F-GND: Ground

3. Electrical Characteristics (Key Values)

️· UVLO Voltage: 3.5V (Under Voltage Lockout)
️· TSD Operating Temperature: 170°C
️· TSD Hysteresis: 15°C
️· PWM Carrier Frequency: 21K-28K Hz
️· VPWM High Level Voltage: 3.48-3.84V
️· VPWM Low Level Voltage: 1.71-1.89V
️· FG Output Pin Low-Level Voltage: 0.1-0.2V

4. Application Notes (Important Considerations)

️· Power and Ground: Connect F-GND and VSS together.
️· Bypass Capacitor: Essential on VCC for stabilization and kickback absorption.
️· Hall Input: Requires a voltage with at least 20mV hysteresis (60mVp-p).
️· Motor Capacitor: Recommend adding a capacitor between MOTU and MOTV to reduce noise.

5. Package Information

️· Dimensions: Detailed dimensions are provided for both HTSSOP14 and TSSOP-20 packages. These are important for PCB layout.

Areas Where More Clarification is Needed

️· Pinout Diagram: A visual pinout diagram would be *extremely* helpful. It's hard to fully understand the connections without one.
️· Internal Block Diagram: A block diagram illustrating the internal components and their relationships would improve the understanding.
️· Detailed Protection Circuitry: More specifics about the OCP and TSD circuitry (e.g., trip levels, timing) would be valuable.
️· Soft Switch Implementation: How exactly is the soft switch implemented? Are there external components needed?
️· PWM Control: How does the PWM signal affect the speed? Is it a linear relationship?



Potential Questions & Responses

️· "What is the maximum current the motor can draw?" - The document doesn't specify a maximum motor current. This is a critical piece of information that needs to be obtained from the datasheet.
️· "Can I use this with a brushless DC (BLDC) motor?" - Potentially, but the document doesn's explicitly mention BLDC motors. Compatibility would depend on the motor's requirements.
️· "What is the voltage range for VREG6?" – The document doesn’t specify the exact range for VREG6.