Specifications

TC35 / TC37 Hardware Interface Description
TC35_37_HD_02_V03.10 - Released Page 24 of 92 21.12.2001
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 V
BATT+
never drops below 3.3 V on the TC35/TC37
board, not even during transmit bursts. Also, make sure that any voltage drops that may
occur during transmit bursts never exceed 400mV. It should be noted that TC35/TC37 will be
switched off in the event of exceeding these limits. For further details see Chapter 6.4.
Note: In order to minimize power losses, use a FFC cable as short as possible. The
resistance of the power supply lines on the host board and a battery pack should
also be considered.
Example: The ZIF-FFC-ZIF connection causes a resistance of 50m! in the VBATT+ line
and 50m! in the GND line, if the FFC reaches the maximum length of 200mm.
As a result, a 2A transmit burst would add up to a total voltage drop of 200mV.
Plus, if a battery pack is involved, further losses may occur due to the resistance
across the battery lines.
Figure 4: Power supply limits during transmit burst
Transmit
burst 2A
Transmit
burst 2A
min. 3.3V
max. 400mV
VBATT+