> 3.2.1 | Minimizing Power Losses

> When designing the power supply for your application please pay specific attention to power losses. Ensure that the input voltage VBATT+ never drops below 3.2V on the TC65 board, not even in a transmit burst where current consumption can rise to typical peaks of 2A. It should be noted that TC65 switches off when exceeding these limits. Any voltage drops that may occur in a transmit burst should not exceed 400mV.
> The measurement network monitors outburst and inburst values. The drop is the difference of both values. The maximum drop (Dmax) since the last start of the module will be saved. In IDLE and SLEEP mode, the module switches off if the minimum battery voltage (Vbattmin) is reached.
> Example:
> V Imin = 3.2V
> Dmax = 0.4V
> V battmin = VImin + Dmax
> V battmin = 3.2V + 0.4V = 3.6V
> The best approach to reducing voltage drops is to use a board-to-board connection as recommended, and a low impedance power source. The resistance of the power supply lines on the host board and of a battery pack should also be considered.
> Note: If the application design requires an adapter cable between both board-to-board connec tors, use a flex cable as short as possible in order to minimize power losses.
> Example: If the length of the flex cable reaches the maximum length of 100mm, this connection may cause, for example, a resistance of 30mΩ in the BATT+ line and 30mΩ in the GND line. As a result, a 2A transmit burst would add up to a total voltage drop of 120mV. Plus, if a battery pack is involved, further losses may occur due to the resistance across the battery lines and the internal resistance of the battery including its protection circuit.
> Figure 3: Power supply limits during transmit burst