SLRS066D January   2014  – March 2016 TPL7407L


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
    8. 6.8 Thermal Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
    4. 7.4 Device Functional Modes
      1. 7.4.1 Inductive Load Drive
      2. 7.4.2 Resistive Load Drive
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Inductive Load Driver
        1. Design Requirements
        2. Detailed Design Procedure
          1. TTL and other Logic Inputs
          2. Input RC Snubber
          3. High-impedance Input Drivers
          4. Drive Current
          5. Output Low Voltage
        3. Application Curves
      2. 8.2.2 Unipolar Stepper Motschematic to correct Zener diode connection or Driver
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
      3. 8.2.3 Multi-Purpose Sink Driver
        1. Design Requirements
        2. Detailed Design Procedure
        3. Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
      1. 10.3.1 Improving Package Thermal Performance
  11. 11Device and Documentation Support
    1. 11.1 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information



10 Layout

10.1 Layout Guidelines

Thin traces can be used on the input due to the low current logic that is typically used to drive TPL7407L. Care must be taken to separate the input channels as much as possible, as to eliminate cross-talk. Thick traces are recommended for the output, in order to drive whatever high currents that may be needed. Wire thickness can be determined by the trace material's current density and desired drive current.

Since all of the channels currents return to a common ground, it is best to size that trace width to be very wide. Some applications require up to 2 A.

Since the COM pin will only draw up to 25 µA thick traces are not necessary.

10.2 Layout Example

TPL7407L layout.gif Figure 13. Package Layout

10.3 Thermal Considerations

The number of coils driven is dependent on the coil current and on-chip power dissipation. The number of coils driven can be determined by Figure 3, Figure 4, Figure 5, Figure 6, Figure 7, or Figure 8.

For a more accurate determination of number of coils possible, use the below equation to calculate TPL7407L on-chip power dissipation PD:

Equation 2. TPL7407L eq1_lrs059.gif
N is the number of channels active together.
VOLi is the OUTi pin voltage for the load current ILi. This is the same as VCE(SAT)

In order to guarantee reliability of TPL7407L and the system, the on-chip power dissipation must be lower than or equal to the maximum allowable power dissipation (PD(MAX)) dictated by below equation Equation 3.

Equation 3. TPL7407L eq2_lrs059.gif
TJ(MAX) is the target maximum junction temperature.
TA is the operating ambient temperature.
θJA is the package junction to ambient thermal resistance.

It is recommended to limit TPL7407L IC’s die junction temperature to less than 125°C. The IC junction temperature is directly proportional to the on-chip power dissipation.

10.3.1 Improving Package Thermal Performance

θJA value depends on the PC board layout. An external heat sink and/or a cooling mechanism, like a cold air fan, can help reduce θJA and thus improve device thermal capabilities. Refer to TI’s design support web page at for a general guidance on improving device thermal performance.