SLLSFT3 November   2025 MC121-Q1

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings Auto
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 I2C Timing Requirements
    7. 5.7 Timing Diagrams
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Motor Control
        1. 6.3.1.1 Duty Input
        2. 6.3.1.2 Duty Curve
        3. 6.3.1.3 Motor Start, Speed Change, and Stop
        4. 6.3.1.4 Open-Loop (Duty Cycle) Control
        5. 6.3.1.5 Closed-Loop (Speed) Control
        6. 6.3.1.6 Commutation
          1. 6.3.1.6.1 Hall Sensor
            1. 6.3.1.6.1.1 Field Direction Definition
            2. 6.3.1.6.1.2 Internal Hall Latch Sensor Output
          2. 6.3.1.6.2 Hall Offset
          3. 6.3.1.6.3 Square Commutation
          4. 6.3.1.6.4 Soft Commutation
        7. 6.3.1.7 PWM Modulation Modes
      2. 6.3.2 Protections
        1. 6.3.2.1 Locked Rotor Protection
        2. 6.3.2.2 Current Limit
        3. 6.3.2.3 Overcurrent Protection (OCP)
        4. 6.3.2.4 VM Undervoltage Lockout (UVLO)
        5. 6.3.2.5 VM Over Voltage Protection (OVP)
        6. 6.3.2.6 Thermal Shutdown (TSD)
        7. 6.3.2.7 Integrated Supply (VM) Clamp
    4. 6.4 Device Functional Modes
      1. 6.4.1 Active Mode
      2. 6.4.2 Sleep and Standby Mode
      3. 6.4.3 Fault Mode
      4. 6.4.4 Test Mode and One-Time Programmable Memory
    5. 6.5 Programming
      1. 6.5.1 I2C Communication
        1. 6.5.1.1 I2C Read
        2. 6.5.1.2 I2C Write
  8. 7 Register Map
    1. 7.1 USR_OTP Registers
    2. 7.2 USR_TM Registers
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 External Components
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Bulk Capacitance
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History

封装选项

机械数据 (封装 | 引脚)
  • DYM|6
  • DEZ|6
散热焊盘机械数据 (封装 | 引脚)

8.1.1 External Components

This section presents recommended external components for the MC121-Q1 in a fan application.

Supply Components

Figure 8-1 shows typical components used on the supply connection in a fan module. The D1 diode in series with the power supply protects the MC121-Q1 in case of accidental reverse supply connection. A power supply decoupling capacitor is required for proper functioning of MC121-Q1 and a minimum value of 0.1 uF is recommended. The optional bulk capacitor, CBULK, placed near the VM pin helps to stabilize the VVM supply voltage during motor operation. A ceramic capacitor with low electrical series resistance (ESR) and a voltage rating twice the supply voltage is recommended to provide margin during transients. A capacitance value between 1 μF and 10 μF based on application is recommended.

MC121-Q1 Typical Fan Module External Components Figure 8-1 Typical Fan Module External Components

Motor systems requiring large motor currents and high rotor inertia can experience high currents flowing into the VM node from the H-bridge due to stored inductor energy during commutation. The additional charge in the CBULK capacitor increases the VVM supply voltage. Although the MC121-Q1 has overvoltage protection, adding protective clamp components on the supply rail can reduce the magnitude of voltage spikes. These components can also help protect against ESD strikes on the supply.

Figure 8-2 shows an example using a Zener diode or TVS diode (D2) on the VM node. The diode clamping voltage needs to be higher than the fan system maximum operating voltage and lower than the MC121-Q1 maximum operating voltage from the Recommended Operating Conditions table. An RC snubber on the supply also can protect the driver against voltage spikes and ESD (Figure 8-3). TI recommends using 1 μF for CSNUBBER and 2 Ω for RSNUBBER. Alternatively, an electrolyic capacitor can be used in parallel with CBULK.

MC121-Q1 Clamping Diode on VMFigure 8-2 Clamping Diode on VM
MC121-Q1 Snubber on VMFigure 8-3 Snubber on VM

PWM and FG/RD Pin Components

Figure 8-1 shows the minimal external components needed for fan module PWM control and speed/fault feedback. The FG/RD pin is an open drain output and requires an external pull-up resistor to provide an output signal at the proper voltage. The pull-up resistor value must be chosen to limit the current into the FG/RD pin to less than 5 mA when the open drain output asserts low. Adding resistors inline with the PWM input and FG/RD output can help protect the driver from ESD strikes on the connector wires, as shown in Figure 8-4. Clamping or TVS diodes on the FG/RD and PWM signals provides additional protection against ESD strikes as shown in Figure 8-5.

MC121-Q1 Resistors on PWM and FG/RDFigure 8-4 Resistors on PWM and FG/RD
MC121-Q1 Resistors and zener diodes on PWM and FG/RDFigure 8-5 Resistors and zener diodes on PWM and FG/RD

Some single phase fan modules require an open-collector interface for the FG/RD and PWM pins. Figure 8-6 and Figure 8-7 show examples for connecting components inside and outside of the fan module for the open-collector interface.

MC121-Q1 Open Collector on FG/RDFigure 8-6 Open Collector on FG/RD
MC121-Q1 Open Collector on PWM and FG/RDFigure 8-7 Open Collector on PWM and FG/RD

OTP and Test Mode Programming

The MC121-Q1 supports an I2C interface on the FG/RD and PWM pins in OTP (one-time programmable) mode. The OTP mode allows the designer to test various device settings and program the device OTP in production. Figure 8-8 shows an example of the external component connections for the MC121-Q1 for device programming. Additional details on OTP and test mode programming are in Section 6.4.4.

MC121-Q1 OTP Memory Programmer and Fan Module Figure 8-8 OTP Memory Programmer and Fan Module