unicore UM980 - Power-On and Power-Off; Grounding and Heat Dissipation

UM980 User Manual
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3.3 Power-on and Power-off
VCC
 The VCC initial level when power-on should be less than 0.4 V.
 The VCC ramp when power-on should be monotonic, without plateaus.
 The voltages of undershoot and ringing should be within 5% VCC.
 Power-on time interval: The time interval between the power-off (VCC < 0.4 V) to
the next power-on must be larger than 500 ms.
V_BCKP
 The V_BCKP initial level when power-on should be less than 0.4 V.
 The V_BCKP ramp when power-on should be monotonic, without plateaus.
 The voltages of undershoot and ringing should be within 5% V_BCKP.
 Power-on time interval: The time interval between the power-off (V_BCKP < 0.4 V)
to the next power-on must be larger than 500 ms.
3.4 Grounding and Heat Dissipation
Figure 3-3 Grounding and Heat Dissipation Pad (Bottom View)
The 48 pads in the rectangle in Figure 3-3 are for grounding and heat dissipation. In the
PCB design, the pads should be connected to a large sized ground to strengthen the
heat dissipation.
Grounding and
heat dissipation pad