AN-1091

APPLICATION NOTE

One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com

Configuring the AD7606/AD7607 for Slow Supply Ramp Conditions

by Claire Croke and Dominic Sloan

Rev. 0 | Page 1 of 2

INTRODUCTION

The AD7606/AD7606-6/AD7606-4/AD7607 are 16-/14-bit,

simultaneous sampling, analog-to-digital data acquisition

systems (DAS). The parts operate from a single 4.75 V to 5.25 V

supply and a 2.3 V to 5.25 V digital interface supply, V

DRIVE

This application note explains how to configure the AD7606/

AD7607 to heighten application immunity when the ramp rate

on the AV

and V

DRIVE

is very slow or the time between the

ramps on these supplies is long.

SLOW SUPPLY RAMP CONDITIONS

In multiboard systems where power supply circuitry is used to

power multiple boards or on a board where there is heavy

loading on the AV

and V

DRIVE

supply generation circuitry, very

long ramp rates may be seen at the AD7606/AD7607 AV

and

DRIVE

supply pins.

The AD7606/AD7607 mode of operation is controlled using pin

programmable inputs. In an application, the pin programmable

inputs can be hardwired to V

DRIVE

or AGND or can be driven by

general-purpose input/output (GPIO) pins. When the pin

programmable inputs are hardwired to V

DRIVE

, the logic state on

these pins on power-up is determined by the voltage on V

DRIVE

The

STBY

and RANGE pins are individually used to control the

standby power mode and the analog input range, respectively.

However, to heighten the immunity of the AD7606/AD7607 to

different supply ramp conditions, a combination of

STBY

and

RANGE pins is used to control the full shutdown mode after

supplies are established at the AD7606/AD7607.

CONFIGURING THE AD7606/AD7607 FOR SLOW

SUPPLY RAMP CONDITIONS

To increase immunity to long supply ramp conditions, the

AD7606/AD7607 should be placed into full shutdown mode

and then switched to normal mode after the supplies are

established at the AD7606/AD7607 pins.

To place the AD7606/AD7607 into full shutdown mode, the

STBY

and RANGE pins should be set low after the AV

and

DRIVE

supplies are established (see Figure 1 and Figure 2).

When the

STBY

and RANGE pins are both low after power-up,

or brought low after power-up, the AD7606/AD7607 are in full

shutdown mode.

To place the AD7606/AD7607 into normal mode, for the ±10 V

range, the

STBY

and RANGE pins are brought high (Figure 1).

For the ±5 V range, the

STBY

pin alone is brought high (see

Figure 2). At this point, the REGCAPA, REGCAPB, and REGCAP

pins power up to their correct potential as outlined in the AD7606

and AD7607

data sheets. If a

STBY

pulse is used to power up

the AD7606/AD7607, the duration of the pulse should be 500 ns

minimum.

Once fully powered up, the AD7606/AD7607 should see a

RESET rising edge to configure the AD7606/AD7607 for

normal operation. The time between coming out of full shut-

down and the RESET high edge is specified as t

WA K E-UP SHUTDOWN

as outlined in the AD7606 and AD7607 data sheets.

Figure 1

shows how to control the

STBY

and RANGE pins for

the ±10 V range. The

STBY

and RANGE pins return high to

take the AD7606/AD7607 out of full shutdown mode and into

normal mode and configure the AD7606/AD7607 for the ±10 V

range. In

Figure 2, the

STBY

pin alone is used to take the

AD7606/AD7607 out of full shutdown mode. The RANGE pin

can remain low to select the ±5 V range.

AVCC

VDRIVE

STBY

RANGE

RESET

09301-001

Figure 1. Placing the AD7606/AD7607 into Full Shutdown (±10 V Range)

AVCC

VDRIVE

STBY

RANGE

RESET

09301-002

Figure 2. Placing the AD7606/AD7607 into Full Shutdown (±5 V Range)

CONCLUSION

Implementing the above scheme after the AV

and V

DRIVE

supplies are established makes the AD7606/AD7607 immune to

slow supply ramp conditions and to delays between the AV

and V

DRIVE

supply ramps.