8

Specifications ispLSI 2064V

Power Consumption

Power consumption in the ispLSI 2064V device depends

on two primary factors: the speed at which the device is

operating and the number of Product Terms used.

Figure 3 shows the relationship between power and

operating speed.

Figure 3. Typical Device Power Consumption vs fmax

0127/2064

ICC can be estimated for the ispLSI 2064V using the following equation:

ICC(mA) = 10 + (# of PTs * 0.556) + (# of nets * Max freq * 0.0053)

Where:

# of PTs = Number of Product Terms used in design

# of nets = Number of Signals used in device

Max freq = Highest Clock Frequency to the device (in MHz)

The ICC estimate is based on typical conditions (VCC = 3.3V, room temperature) and an assumption of two GLB loads

on average exists. These values are for estimates only. Since the value of ICC is sensitive to operating conditions

and the program in the device, the actual ICC should be verified.

Notes: Configuration of Four 16-bit Counters

Typical Current at 3.3V, 25

° C

80

100

120

0

25

50

75

100

ispLSI 2064V

110

90

70

Power-up Considerations

When Lattice 3.3-Volt 2000V devices are used in mixed

5V/3.3V applications, some consideration needs to be

given to the power-up sequence. When the I/O pins on

the 3.3V ispLSI devices are driven directly by 5V devices,

a low impedance path can exist on the 3.3V device

between its I/O and Vcc pins when the 3.3V supply is not

present. This low impedance path can cause current to

flow from the 5V device into the 3.3V ispLSI device. The

maximum current occurs when the signals on the I/O pins

are driven high by the 5V devices. If a large enough

current flows through the 3.3V I/O pins, latch-up can

occur and permanent device damage may result.

This latch-up condition occurs only during the power-up

sequence when the 5V supply comes up before the 3.3V

supply. The Lattice 3.3V ispLSI devices are guaranteed

to withstand 5V interface signals within the device oper-

ating Vcc range of 3.0V to 3.6V.

The recommended power-up options are as follows:

Option 1: Ensure that the 3.3V supply is powered-up and

stable before the 5V supply is powered up.

Option 2: Ensure that the 5V device outputs are driven to

a high impedance or logic low state during power-up.