ADSP2184 datasheet(26/31 Pages) AD

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ADSP-2184

–26–

REV. 0

OUTPUT DRIVE CURRENTS

Figure 20 shows typical I-V characteristics for the output drivers

of the ADSP-2184. The curves represent the current drive

capability of the output drivers as a function of output voltage.

SOURCE VOLTAGE – V

–20

–40

–60

VDD = 5.0V @ +25 C

VDD = 5.5V @ –40 C

VDD = 4.5V @ +85 C

VDD = 5.0V @ +25 C

VDD = 4.5V @ +85 C

VDD = 5.5V @ –40 C

VOL

VOH

Figure 20. Typical Drive Currents

POWER DISSIPATION

To determine total power dissipation in a specific application,

the following equation should be applied for each output:

× V

× f

C = load capacitance, f = output switching frequency.

Example

In an application where external data memory is used and no

other outputs are active, power dissipation is calculated as follows:

Assumptions

• External data memory is accessed every cycle with 50% of the

address pins switching.

• External data memory writes occur every other cycle with

50% of the data pins switching.

• Each address and data pin has a 10 pF total load at the pin.

• The application operates at VDD = 5.0 V and tCK = 25 ns.

Total Power Dissipation = PINT + (C

× V

× f)

PINT = internal power dissipation from Power vs. Frequency

graph (Figure 21).

× V

× f) is calculated for each output:

# of

Pins

VDD

Address,

DMS

× 10 pF × 52 V

× 40 MHz = 80 mW

Data Output,

WR 9

× 10 pF × 52 V

× 20 MHz = 45 mW

× 10 pF × 52 V

× 20 MHz = 5 mW

CLKOUT

× 10 pF × 52 V

× 40 MHz = 10 mW

140 mW

Total power dissipation for this example is PINT + 40 mW.

VALID FOR ALL TEMPERATURE GRADES.

1POWER REFLECTS DEVICE OPERATING WITH NO OUTPUT LOADS.

DD MEASUREMENT TAKEN WITH ALL INSTRUCTIONS EXECUTING FROM INTERNAL

MEMORY. 50% OF THE INSTRUCTIONS ARE MULTIFUNCTION (TYPES 1, 4, 5, 12, 13, 14)

30% ARE TYPE 2 AND TYPE 6, AND 20% ARE IDLE INSTRUCTIONS.

3IDLE REFERS TO ADSP-2184 STATE OF OPERATION DURING EXECUTION OF IDLE

INSTRUCTION. DEASSERTED PINS ARE DRIVEN TO EITHER VDD OR GND.

4TYPICAL POWER DISSIPATION AT 5.0V V

DD AND TA = 25 C EXCEPT WHERE SPECIFIED.

62.1mW

34.7mW

32.8mW

34.3mW

36.6mW

70.55mW

IDLE (16)

IDLE (128)

IDLE

POWER, IDLE

n MODES2

82.28mW

91.52mW

VDD = 5.5V

62.1mW

70.55mW

VDD = 5.0V

44.73mW

51.705mW

VDD = 4.5V

POWER, IDLE1, 2, 4

1/tCYC – MHz

33.33

175

400

275

250

225

200

375

350

300

325

330mW

250mW

180mW

300mW

225mW

2184 POWER, INTERNAL1, 2, 3

385mW

VDD = 5.5V

VDD = 5.0V

VDD = 4.5V

1/tCYC – MHz

33.33

1/tCYC – MHz

33.33

150

Figure 21. Power vs. Frequency

ADSP2184 Datasheet(PDF) 26 Page - Analog Devices

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