AD9705-EB datasheet(38/52 Pages) AD

38 / 52 page

AD9704/AD9705/AD9706/AD9707

Rev. 0 | Page 38 of 52

305070

fCLOCK (MSPS)

0.2

0.6

0.4

0.8

1.0

1.2

1.4

Figure 87. ICLKVDD vs. fCLOCK (Differential Clock Mode) @ CLKVDD = 1.8 V

Sleep and Power-Down Operation (Pin Mode)

The AD970x has a sleep mode that turns off the output current

and reduces the total power consumed by the device. This mode

is activated by applying a Logic 1 to the SLEEP/CSB pin. The

SLEEP/CSB pin logic threshold is equal to 0.5 × AVDD. This

digital input also contains an active pull-down circuit.

The AD970x takes less than 50 ns to power down and approxi-

mately 5 μs to power back up.

Sleep and Power-Down Operation (SPI Mode)

The AD970x offers three power-down functions that can be

controlled through the SPI. These power-down modes can be

used to minimize the power dissipation of the device. The

power-down functions are controlled through SPI Register 0x00,

Bit 1 to Bit 3. Table 25 summarizes the power-down functions

that can be controlled through the SPI. The power-down mode

can be enabled by writing a Logic 1 to the corresponding bit in

Table 25. Power-Down Mode Selection

Power-Down

Mode

(Reg. 0x00)

Bit #

Functional Description

Clock Off

Turn off clock

Sleep

Turn off output current

Power Down

Turn off output current and

internal voltage reference

SELF-CALIBRATION

The AD970x has a self-calibration feature that improves the

DNL of the device. Performing a self-calibration on the device

improves device performance in low frequency applications.

The device performance in applications where the analog

output frequencies are above 1 MHz are generally influenced

more by dynamic device behavior than by DNL, and in these

cases, self-calibration is unlikely to provide any benefits for

single-tones, as shown in Figure 88. Figure 89 shows that self-

calibration is helpful up to 20 MHz for two-tone IMD spaced

10 kHz apart.

00.2

0.4

0.6

fOUT (MHz)

0.8

CALIBRATED

UNCALIBRATED

Figure 88. AD9707 SFDR vs. fOUT @ 175 MSPS and IOUTFS = 2 mA

LOWER

fOUT (MHz)

CALIBRATED

UNCALIBRATED

Figure 89. IMD vs. fOUT @ 175 MSPS and IOUTFS = 2 mA

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