AD5590BBC datasheet(41/44 Pages) AD

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AD5590

Rev. 0 | Page 41 of 44

ADC Power vs. Throughput Rate

By operating the ADC in autoshutdown or autostandby mode,

the average power consumption of the ADC decreases at lower

throughput rates. Figure 73 shows how, as the throughput rate is

reduced, the ADC remains in its shutdown state longer and the

average power consumption over time drops accordingly.

For example, if the ADC is operated in a continuous sampling

mode with a throughput rate of 100 kSPS and an ASCLK of

20 MHz, with PM1 = 0 and PM0 = 1 (that is, the device is in

autoshutdown mode), the power consumption is calculated

as follows: the maximum power dissipation during normal

operation is 12.5 mW. If the power-up time from autoshutdown

is one dummy cycle, that is, 1 μs, and the remaining conversion

time is another cycle, that is, 1 μs, the ADC dissipates 12.5 mW

for 2 μs during each conversion cycle. For the remainder of the

conversion cycle, 8 μs, the ADC remains in shutdown mode. The

ADC dissipates 2.5 μW for the remaining 8 μs of the conversion

cycle. If the throughput rate is 100 kSPS, the cycle time is 10 μs

and the average power dissipated during each cycle is

502

μW

When operating the ADC in autostandby mode, PM1 = PM0 = 0

at 5 V, 100 kSPS, the ADC power dissipation is calculated as

follows: the maximum power dissipation is 12.5 mW at 5 V during

normal operation. The power-up time from autostandby is one

dummy cycle, 1 μs, and the remaining conversion time is another

dummy cycle, 1 μs. The ADC dissipates 12.5 mW for 2 μs during

each conversion cycle. For the remainder of the conversion cycle,

8 μs, the ADC remains in standby mode dissipating 460 μW for

8 μs. If the throughput rate is 100 kSPS, the cycle time is 10 μs

and the average power dissipated during each conversion cycle is

868

μW

Figure 73 shows the power vs. throughput rate when using the

autoshutdown mode and autostandby mode with 5 V supplies.

At the lower throughput rates, power consumption for the

autoshutdown mode is lower than that for the autostandby

mode, with the ADC dissipating less power when in shutdown

compared to standby. However, as the throughput rate is

increased, the ADC spends less time in power-down states;

thus, the difference in power dissipated is negligible between

modes.

0.01

0.1

100

150

200

250

300

350

THROUGHPUT (kSPS)

ADCVDD = 5V

AUTOSTANDBY

AUTOSHUTDOWN

Figure 73. Power vs. Throughput Rate in Autoshutdown

and Autostandby Mode

AD5590BBC Datasheet(PDF) 41 Page - Analog Devices

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