ADS1605IPAPR datasheet(25/38 Pages) TI

25 / 38 page

ADS1605

ADS1606

SBAS274H − MARCH 2003 − REVISED MAY 2007

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32/f

CLK

128/f

CLK

DRDY

Figure 24. Example of Skipping Readback when FIFO Level = 4

64/f

CLK

DRDY

FIFO_LEV[2:0]

010 (Level = 4)

Change FIFO_LEV[2:0] here

100 (Level = 8)

32/f

CLK

Figure 25. Example of Synchronized Change of FIFO Level from 4 to 8

ANALOG POWER DISSIPATION

An external resistor connected between the RBIAS pin

and the analog ground sets the analog current level, as

shown in Figure 26. The current is inversely proportion-

al to the resistor value. Table 6 shows the recom-

mended values of RBIAS for different CLK frequencies.

Notice that the analog current can be reduced when us-

ing a slower frequency CLK input because the modula-

tor has more time to settle. Avoid adding any capaci-

tance in parallel to RBIAS , since this will interfere with

the internal circuitry used to set the biasing.

BIAS

RBIAS

AGND

ADS1606

ADS1605

Figure 26. External Resistor Used to Set Analog

Power Dissipation

Table 6. Recommended RBIAS Resistor Values for

Different CLK Frequencies

fCLK

DATA

RATE

RBIAS

TYPICAL POWER

DISSIPATION WITH REFEN

HIGH

16MHz

2MHz

60k

Ω

315mW

24MHz

3MHz

50k

Ω

400mW

32MHz

4MHz

45k

Ω

475mW

40MHz

5MHz

37k

Ω

570mW

POWER DOWN (PD)

When not in use, the ADS1605/6 can be powered down

by taking the PD pin low. All circuitry will be shutdown,

including the voltage reference. To minimize the digital

current during power down, stop the clock signal sup-

plied to the CLK input. There is an internal pull-up resis-

tor of 170k

Ω on the PD pin, but it is recommended that

this pin be connected to IOVDD if not used. If using the

ADS1606 with the FIFO enabled, issue a reset after ex-

iting power-down mode. Make sure to allow time for the

reference to start up after exiting power-down mode.

The internal reference typically requires 15ms. After the

reference has stabilized, allow at least 100 DRDY

cycles for the modulator and digital filter to settle before

retrieving data.

ADS1605IPAPR 数据表(PDF) 25 Page - Texas Instruments

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