Datasheet

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POWER SUPPLY SEQUENCING POWER DOWN

ADS5500

SBAS303F – DECEMBER 2003 – REVISED FEBRUARY 2007

Table 4. Recommended Amplifiers to Drive the Input of the ADS5500

INPUT SIGNAL FREQUENCY RECOMMENDED AMPLIFIER TYPE OF AMPLIFIER USE WITH TRANSFORMER?

DC to 20 MHz THS4503 Differential In/Out Amp No

DC to 50 MHz OPA847 Operational Amp Yes

DC to 100 MHz THS4509 Differential In/Out Amp NO

OPA695 Operational Amp Yes

10 MHz to 120 MHz THS3201 Operational Amp Yes

THS3202 Operational Amp Yes

Over 100 MHz THS90016 RF Gain Block Yes

Figure 43. Converting a Single-Ended Input Signal to a Differential Signal Using an RF Transformer

Figure 44. Using the THS4503 With the ADS5500

The preferred power-up sequence is to ramp AV

The device enters power-down in one of two ways:

first, followed by DRV

, including a simultaneous either by reducing the clock speed or by setting the

ramp of AV

and DRV

. In the case that DRV

PDN bit through the serial programming interface.

ramps up first in the system, care must be taken to Using the reduced clock speed, power-down may be

ensure that AV

ramps up within 10 ms. initiated for clock frequencies below 2 Msps. The

exact frequency at which the power down occurs

varies from device to device.

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