Altera Stratix - 1.5-V Regulator Application Examples; Synchronous Switching Regulator Example

Altera Corporation 14–19
January 2005 Stratix Device Handbook, Volume 2
Designing with 1.5-V Devices
1.5-V Regulator
Application
Examples
The following sections show the process used to select a voltage regulator
for three sample designs. The regulator selection is based on the amount
of power that the Cyclone device consumes. There are 14 variables to
consider when selecting a voltage regulator. The following variables
apply to Cyclone device power consumption:
■ f
MAX
■ Output and bidirectional pins
■ Average toggle rate for I/O pins (tog
IO
)
■ Average toggle rate for logic elements (LEs) (tog
LC
)
■ User-mode I
CC
consumption
■ Maximum power-up I
CCINT
requirement
■ Utilization
■ V
CCIO
supply level
■ V
CCINT
supply level
The following variables apply to the voltage regulator:
■ Output voltage precision requirement
■ Supply voltage on the board
■ Voltage supply output current
■ Variance of board supply
■ Efficiency
Different designs have different power consumptions based on the
variables listed. Once you calculate the Cyclone device’s power
consumption, you must consider how much current the Cyclone device
needs. You can use the Cyclone power calculator (available at
www.altera.com) or the PowerGauge
TM
tool in the Quartus II software to
determine the current needs. Also check the maximum power-up current
requirement listed in the Power Consumption section of the Cyclone
FPGA Family Data Sheet because the power-up current requirement may
exceed the user-mode current consumption for a specific design.
Once you determine the minimum current the Cyclone device requires,
you must select a voltage regulator that can generate the desired output
current with the voltage and current supply that is available on the board
using the variables listed in this section. An example is shown to illustrate
the voltage regulator selection process.