unicore UM621 Series - Power Supply Requirements

UM621 Series Hardware Reference Design
3
3 Power Supply Requirements
Main Supply (VCC)
The voltage range of VCC is 2.7 V ~ 3.6 V.
Notes:
 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.
 VCC power-on waveform: The time interval from 10% rising to 90% must be within
100 μs ~ 10 ms.
 Power-on time interval: The time interval between the power-off (VCC < 0.4 V) to
the next power-on is recommended to be larger than 500 ms.
Backup Supply (V_BCKP)
If the hot start function is needed, users should supply backup power to the module. The
voltage range of V_BCKP is 1.7 V ~ 3.6 V.
Notes:
 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.
 V_BCKP power-on waveform: The time interval from 10% rising to 90% must be
within 100 μs ~ 10 ms.
 Power-on time interval: The time interval between the power-off (V_BCKP < 0.4 V)
to the next power-on is recommended to be larger than 500 ms.
 The V_BCKP pin cannot be floating or connected to ground. When V_BCKP is not
used, it should be connected to VCC or connected to backup power.