MSC7116 Freescale Semiconductor / Motorola, MSC7116 Datasheet - Page 42

• Manufacturer Part Number: MSC7116
• Description: Low-Cost 16-bit DSP with DDR Controller and 10/100 Mbps Ethernet MAC
• Manufacturer: Freescale Semiconductor / Motorola

Hardware Design Considerations
3.2
This section outlines the MSC7116 power considerations: power supply, power sequencing, power planes, decoupling, power
supply filtering, and power consumption. It also presents a recommended power supply design and options for low-power
consumption. For information on AC/DC electrical specifications and thermal characteristics, refer to Section 2.
3.2.1
The MSC7116 requires four input voltages, as shown in Table 32.
You should supply the MSC7116 core voltage via a variable switching supply or regulator to allow for compatibility with
possible core voltage changes on future silicon revisions. The core voltage is supplied with 1.2 V (+5% and –10%) across V
and
the DDR memory controller block. The memory voltage is supplied with 2.5 V across V
is supplied across V
(Stub Series Terminated Logic for 2.5 Volts (STTL_2)) for memory voltage supply requirements.
3.2.2
One consequence of multiple power supplies is that the voltage rails ramp up at different rates when power is initially applied.
The rates depend on the power supply, the type of load on each power supply, and the way different voltages are derived. It is
extremely important to observe the power up and power down sequences at the board level to avoid latch-up, forward biasing
of ESD devices, and excessive currents, which all lead to severe device damage.
Note:
42
GND
There are five possible power-up/power-down sequence cases. The first four cases listed in the following sections are
recommended for new designs. The fifth case is not recommended for new designs and must be carefully evaluated
for current spike risks based on actual information for the specific application.
and the I/O section is supplied with 3.3 V (± 10%) across V
Core
Memory
Reference
I/O
Power Supply Design Considerations
Power Supply
Power Sequencing
REF
Voltage
and
GND
and must be between 0.49 × V
MSC7116 Data Sheet, Rev. 13
Table 32. MSC7116 Voltages
Symbol
V
V
V
V
DDM
DDIO
DDM
DDC
REF
DDIO
and 0.51 × V
and
GND.
DDM
The memory and reference voltages supply
. Refer to the JEDEC standard JESD8
DDM
and
GND
Freescale Semiconductor
. The reference voltage
Value
1.25 V
1.2 V
2.5 V
3.3 V
DDC