CS

SCLK

DOUT

DIN

1

16

InvalidData

CS

SCLK

DOUT

DIN

1

16

1

16

1

16

1

16

1

16

111111111111

NoWritetothe

ControlRegister

Command:SelectChannelAIN1,

STANDBY=0

NoWritetothe

ControlRegister

Command:EnterStandbyMode,

STANDBY=1

111111111111

InvalidData

InvalidData

ConversionResultfor

ChannelAIN1

WaitingforConfiguration

InStandbyMode

ConvertingforChannelAIN1

ConvertingforChannelAIN4

InStandbyMode

Command:ExitStandbyMode,

STANDBY=0

WaitingforConfiguration

Command:

SelectChannelAIN4

DeviceEnters

StandbyMode

DeviceExits

StandbyMode

DeviceStartstoExit

StandbyMode

¼

¼

¼

¼

ADS8028

www.ti.com

SBAS549B – MAY 2011 – REVISED MARCH 2012

It takes four serial transfer cycles for the ADS8028 to exit STANDBY mode and transmit the first valid conversion

data, as shown in Figure 38. The first cycle updates the STANDBY bit to '0'; the second cycle selects the

channels and operation mode; the third cycle converts the selected channel; and the result of this conversion can

be clocked out in the fourth cycle.

Figure 38. STANDBY Mode of Operation

Power-Down Mode

In power-down mode, all internal ADS8028 circuitry (including the internal reference) is powered down and the

Control Register is reset to the default values. The temperature sensor averaging feature is reset and disabled.

The ADS8028 can be placed into power-down mode by pulling the PD/RST pin to a logic low state for at least 90

ns. The PD/RST pin is asynchronous to the clock; thus, it can be triggered at any time regardless of the status of

other ADS8028 pins (including the analog input channels). When the device is in power-down mode, any activity

on the digital input pins (apart from the PD/RST pin) is ignored and the device does not take input-dependent

current from the analog input pins.

The ADS8028 powers up in default condition when the PD/RST pin is pulled back to a logic high level.

Conversions can begin when tPOWER_UP has elapsed.

Copyright © 2011–2012, Texas Instruments Incorporated

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