12
Hardware Design
UC-00-M47 EN R1.0
3.2
Grounding and Heat Dissipation
Figure 3-2 Grounding and Heat Dissipation Pad
The 55 pads in the rectangle in Figure 3-2 are for grounding and heat dissipation.
In the PCB design, they must connect to a large sized ground to strengthen the heat
dissipation.
3.3
Power-on and Power-off
VCC
The VCC initial level when power-on is less than 0.4 V and it has good
monotonicity. The voltages of undershoot and ringing are within 5% VCC.
VCC power-on waveform: The time interval from 10% rising to 90% must be within
100 μs to 1 ms.
Power-on time interval: The time interval between the VCC < 0.4 V (after power-off)
to the next power-on must be larger than 500 ms.
V_BCKP
The V_BCKP initial level when power-on is less than 0.4 V and it has good
monotonicity. The voltages of undershoot and ringing are within 5% V_BCKP.
V_BCKP power-on waveform: The time interval from 10% rising to 90% must be
within 100 μs to 1 ms.
Power-on time interval: The time interval between the V_BCKP < 0.4 V (after power-
off) to the next power-on must be larger than 500 ms.
Grounding and heat
dissipation pad
