UPSD3422 datasheet(248/293 Pages) STMICROELECTRONICS

248 / 293 page

PSD module

uPSD34xx

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READ and WRITE operations. When CSI is driven to logic '1,' none of these memories are

available for selection, regardless of the address activity from the 8032, reducing power

consumption. The state of the PLD and port I/O pins are not changed when CSI goes to

logic ’1’ (disabled).

28.5.55

PLD non-turbo mode

The power consumption and speed of the PLDs are controlled by the Turbo Bit (Bit 3) in the

csiop PMMR0 register. By setting this bit to logic '1,' the Turbo mode is turned off and both

PLDs consume only stand-by current when ALL PLD inputs have no transitions for an

extended time (65ns for 5V devices, 100ns for 3.3 V devices), significantly reducing current

consumption. The PLDs will latch their outputs and go to standby, drawing very little current.

When Turbo mode is off, PLD propagation delay time is increased as shown in the AC

specifications for the PSD Module. Since this additional propagation delay also effects the

DPLD, the response time of the memories on the PSD Module is also lengthened by that

same amount of time. If Turbo mode is off, the user should add an additional wait state to the

8032 BUSCON SFR register if the 8032 clock frequency is higher that a particular value.

Please refer to Table 38 on page 82 in the MCU Module section.

The default state of the Turbo Bit is logic '0,' meaning Turbo mode is on by default (after

power-up and reset conditions) until it is turned off by the 8032 writing to PMMR0.

28.5.56

PLD current consumption

Figure 96 on page 259 and Figure 97 on page 260 (5V and 3.3V devices respectively) show

the relationship between PLD current consumption and the composite frequency of all the

transitions on PLD inputs, indicating that a higher input frequency results in higher current

consumption.

Current consumption of the PLDs have a DC component and an AC component. Both need

to be considered when calculating current consumption for a specific PLD design. When

Turbo mode is on, there is a linear relationship between current and frequency, and there is

a substantial DC current component consumed by the PSD Module when there are no

transitions on PLD inputs (composite frequency is zero). The magnitude of this DC current

component is directly proportional to how many product terms are used in the equations of

both PLDs. PSDsoft Express generates a “fitter” report that specifies how many product

terms were used in a design out of a total of 186 available product terms. Figure 96 on

page 259 and Figure 97 on page 260 both give two examples, one with 100% of the 186

product terms used, and another with 25% of the 186 product terms used.

28.5.57

Turbo mode current consumption

To determine the AC current component of the specific PLD design with Turbo mode on, the

user will have to interpolate from the graph, given the number of product terms specified in

the fitter report, and the estimated composite frequency of PLD input signal transitions. For

the DC component (y-axis crossing), the user can calculate the number by multiplying the

number of product terms used (from fitter report) times the DC current per product term

specified in the DC specifications for the PSD Module. The total PLD current usage is the

sum of its AC and DC components.

28.5.58

Non-turbo mode current consumption

Notice in Figure 96 on page 259 and Figure 97 on page 260 that when Turbo mode is off,

the DC current consumption is “zero” (just standby current) when the composite frequency

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