SLVA504A February   2012  – July 2021 DRV8243-Q1 , DRV8244-Q1 , DRV8245-Q1 , DRV8800 , DRV8801 , DRV8802 , DRV8803 , DRV8804 , DRV8805 , DRV8806 , DRV8811 , DRV8812 , DRV8813 , DRV8814 , DRV8818 , DRV8821 , DRV8823 , DRV8824 , DRV8825 , DRV8828 , DRV8829 , DRV8830 , DRV8832 , DRV8832-Q1 , DRV8833 , DRV8834 , DRV8835 , DRV8836 , DRV8837 , DRV8840 , DRV8841 , DRV8842 , DRV8843 , DRV8844 , DRV8870 , DRV8871 , DRV8872

 

  1. 1Sources of Power Dissipation in an Integrated Driver
    1. 1.1 H-Bridge
      1. 1.1.1 H-Bridge Driver Using High-Side Recirculation
      2. 1.1.2 H-Bridge Driver Using Low-Side Recirculation
    2. 1.2 Half Bridge
      1. 1.2.1 Half Bridge Driver Using High-Side Recirculation
      2. 1.2.2 Half Bridge Driver Using Low-Side Recirculation
  2. 2Example Calculation
    1. 2.1 H-Bridge
      1. 2.1.1 High-Side Recirculation Example
      2. 2.1.2 Low-Side Recirculation Example
    2. 2.2 Half Bridge
      1. 2.2.1 Half-Bridge High-Side Recirculation Example
      2. 2.2.2 Half-Bridge Low-Side Recirculation Example
  3. 3References
  4. 4Revision History

2.1.1 High-Side Recirculation Example

Table 2-1 Power Dissipation for H-Bridge with High-side Recirculation
Region Time ratio within PWM cycle HS1 [W] LS1 [W] HS2 [W] LS2 [W]
1 50% = On-time × 20 KHz1 100 mΩ × 1A2 0 0 100 mΩ × 1A2
2 13.5 V/(13.5 V/μs) x 20 KHz 100 mΩ × 1A2 0 0 0.5 x 13.5 V x 1 A
3 100 ns x 10 KHz 100 mΩ × 1A2 0 1 V x 1 A 0
4 1 V/(13.5 V/μs) x 20 KHz 100 mΩ × 1A2 0 0.5 x 1 V x 1 A 0
5 (1 - 50%) = Off-time × 20 KHz1 100 mΩ × 1A2 0 100 mΩ × 1A2 0
6 1 V/(13.5 V/μs) x 20 KHz 100 mΩ × 1A2 0 0.5 x 1 V x 1 A 0
7 100 ns x 20 KHz 100 mΩ × 1A2 0 1 V x 1 A 0
8 13.5 V/(13.5 V/μs) x 20 KHz 100 mΩ × 1A2 0 0 0.5 x 13.5 V x 1 A

PHS1 = 100 mΩ × 1 A2 = 0.1 W

PLS1 = 0

PHS2 = [100 mΩ × 1 A2 x (1-0.5)] + [2 x 1 V x 1 A x 100 ns x 20 KHz] = 0.054 W

PLS2 = [ 100 mΩ × 1 A2x 0.5] + [13.5 x 1 A x 13.5 V/ (13.5 V/μs) x 20 KHz] = 0.32 W

It is not necessary to include PIVM and PLDO as their impact is usually minimal enough to be inconsequential. That being said, they can be calculated as:

PIVM = 13.5 V × 10 mA = 0.135 W and PLDO = 5 mA × (13.5 V - 5 V) = 0.0425 W

PTOT = PHS1 + PLS1 + PHS2 + PLS2 = 0.1 + 0 + 0.054 + 0.32 = 0.474 W

or PTOT = 0.474 W + PIVM + PLDO = 0.6515 W