dsp56853 Freescale Semiconductor, Inc, dsp56853 Datasheet - Page 27

• Manufacturer Part Number: dsp56853
• Description: 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

4.3 Supply Voltage Sequencing and Separation Cautions
Figure 4-2
Notes: 1. V
V
supply (1.8V) from the voltage generated by the 3.3V V
rising faster than V
V
Typically this situation is avoided by using external discrete diodes in series between supplies, as shown
in
approximately 2.1, causing V
operation, the difference between supplies will typically be 0.8V and conduction through the diode chain
reduces to essentially leakage current. During supply sequencing, the following general relationship
should be adhered to:
V
In practice, V
Freescale Semiconductor
DD
DD
DDIO
Figure
should not be allowed to rise early (1). This is usually avoided by running the regulator for the V
should not rise so late that a large voltage difference is allowed between the two supplies (2).
2. V
> V
3.3V
1.8V
DD
DDIO
4-3. The series diodes forward bias when the difference between V
DD
shows two situations to avoid in sequencing the V
0
rising before V
DDA
, V
> (V
Figure 4-2 Supply Voltage Sequencing and Separation Cautions
DDA
is typically connected directly to V
DDIO
DDIO
rising much faster than V
.
- 2.1V)
DDIO
1
, V
DD
DDA
to rise as V
56853 Technical Data, Rev. 6
DD
DDIO
2
ramps up. When the V
DDIO
DDIO
with some filtering.
supply, see
DD
and V
Supply Voltage Sequencing and Separation Cautions
Supplies Stable
DDIO,
Figure
DD
V
DDA
4-3. This keeps V
regulator begins proper
DDIO
supplies.
and V
V
DDIO,
V
Time
DD
DD
V
DDA
DD
reaches
from
DD
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