Altera MAX II - Manual (Page 16)

2–8 Development Kit Version 1.1.0 Altera Corporation
MAX II Development Kit Getting Started User Guide July 2005
Demo Designs
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This test is meant to verify the data provided in the MAX II
Device Data Sheet, not to replace it. All MAX II devices will have
some fluctuation in power-up timing. Designers should ensure
that systems relying on a MAX II device to perform power up
functions are using the MAX II device in accordance with the
specifications given in the Data Sheet.
Before performing a test to verify the power-up time of a MAX II device
under a certain load, you should set the V
CCINT
supply to 2.5 V or 3.3 V,
depending on what it will be in the final system. The shunt on J9 controls
this value. If the shunt is present on J9, the MAX II device’s V
CCINT
is
2.5 V; if the shunt is not present on J9, the V
CCINT
value is 3.3 V.
The MAX II device data sheet specifies that a MAX II device will be
functional less than 300
μs after minimum V
CC
level is reached. In
actuality, configuration starts at a voltage below minimum V
CC
. A MAX II
device on a board where the V
CC
rise time is greater than 1 ms will be fully
powered-up and configured before the supply reaches minimum V
CC
.
The Power-up demo allows users to investigate the power-up time in two
different ways. The first is a race against the MAX II device that helps
define what “Instant-on” means. The second is a much more detailed
investigation of the power-up time that requires an oscilloscope, but
provides a thorough understanding of how a MAX II device powers up
under different loads.
On Board Circuit
The circuit on the board consists of a power regulator that provides the
V
CCINT
voltage. The power regulator can be set to 2.5 V or 3.3 V by adding
or removing a shunt on J9. (If the shunt is in place, V
CCINT
= 2.5 V; if the
shunt is not in place, V
CCINT
= 3.3 V.) The load on the regulator can be
increased by a variable resistor (POT1). Four test points are also provided
on the board: V
CCINT
, V
CCIO
, GND, and a MAX II User I/O pin. These four
test points are labeled Active I/O Test Points and are located near the
prototyping area on the board. Refer to the MAX II Development Board
Data Sheet if you cannot locate the test points on your board. These test
points allow for oscilloscope probes to be attached so the outputs can be
thoroughly examined.