23.2.3 Full Bridge Mode

In Forward and Reverse Full Bridge modes, three outputs drive static values while the fourth is modulated by the input data signal. The mode selection may be toggled between forward and reverse by toggling the MODE[0] bit of the CWGxCON0 register while keeping the MODE[2:1] bits static, without disabling the CWG module. When connected, as shown in Figure 23-5, the outputs are appropriate for a full-bridge motor driver. Each CWG output signal has independent polarity control, so the circuit can be adapted to high-active and low-active drivers. A simplified block diagram for the Full Bridge modes is shown in Figure 23-6.

Figure 23-5. Example of Full-Bridge Application
Figure 23-6. Simplified CWG Block Diagram (Forward and Reverse Full Bridge Modes)

In Forward Full Bridge mode (MODE = ‘b010), CWGxA is driven to its Active state, CWGxB and CWGxC are driven to their Inactive state, and CWGxD is modulated by the input signal, as shown in Figure 23-7.

In Reverse Full Bridge mode (MODE = ‘b011), CWGxC is driven to its Active state, CWGxA and CWGxD are driven to their Inactive states, and CWGxB is modulated by the input signal, as shown in Figure 23-7.

In Full Bridge mode, the dead-band period is used when there is a switch from forward to reverse or vice versa. This dead-band control is described in the Dead-Band Control section, with additional details in the Rising Edge and Reverse Dead Band and Falling Edge and Forward Dead Band sections. Steering modes are not used with either of the Full Bridge modes.

Figure 23-7. Example of Full-Bridge Output
Note:
  1. A rising CWG data input creates a rising event on the modulated output.
  2. Output signals shown as active-high; all POLy bits are clear.