The interface module is fitted with a dual MOSFET switch. This provides two outputs that can be configured as Pulse Width Modulated (PWM) outputs or used as DC switches to switch external loads.
The MOSFET can switch loads at up to 30V. Although the MOSFET is rated for 3A, because of the power dissipation of the package the maximum load current is 2.5A if only one PWM output is used or 1.75A if both outputs are used.
The device U21, fitted to the underside of the PCB, and the surrounding area of the board becomes very hot when high load currents are used.
As a PWM output, the interfaces can be driven by the DC-DC PrimeCell (PL160). The DC-DC PrimeCell has feedback inputs that negate the drive outputs when LOW. These inputs can be used to implement a current limit with external circuitry.
Table 3.4 shows the assignment of the PWM interface signals to the logic module signals on the EXPIM connector.
|PWM1_DRIVE||IM_BBANK37||PWM1 switch control signal|
|PWM2_DRIVE||IM_BBANK38||PWM2 switch control signal|
Figure 3.4 shows the pin numbering of the PWM connectors.
Table 3.5 shows the signal assignment.