Datasheet

Host
Processor
FS/CS
SDO
SDI
SCLK
CONVST
EOC/INT
4.7 Fm
VA REF+ AGND
Analog+5V
ADS8331/32
REF-
22mF
External
Reference
Input
AGND
IN
X
COM
Interface
Supply
+1.8V
DGND
VBD
AnalogInput
AGND
MUXOUT
ADCIN
4.7 Fm
ADS8331
ADS8332
SBAS363C –DECEMBER 2009–REVISED MAY 2012 www.ti.com
APPLICATION INFORMATION
TYPICAL CONFIGURATION EXAMPLE
Figure 50 illustrates a typical circuit configuration using the ADS8331/32.
Figure 50. Typical Circuit Configuration
POWER-ON SEQUENCE TIMING
During power-on of the ADS8331/32, the digital interface supply voltage (VBD) should not exceed the analog
supply voltage (VA). This condition is specified in the Power-Supply Requirements section of the Electrical
Characteristics tables. If the analog and digital interface supplies for the converter are not generated by a single
voltage source, it is recommended to power-on the analog supply and wait for it to reach its final value before the
digital interface supply is activated. Furthermore, the voltages applied to the analog input pins (IN
X
, ADCIN) and
digital input pins (RESET, FS/CS, SCLK, SDI, and CONVST) should not exceed the voltages on VA and VBD,
respectively, during the power-on sequence. This requirement prevents these input pins from powering the
ADS8331/32 through the ESD protection diodes/circuitry, and causing an increase in current consumption, until
both supplies are fully powered (see the Electrical Characteristics and Figure 34 for further details).
Communication with the ADS8331/32, such as initiating a conversion with CONVST or writing to the
Configuration register, should not occur for a minimum of 2μs after the analog and digital interface supplies have
finished the power-on sequence and reached the respective final values in the system. This time is required for
the internal POR to activate and place the digital core of the device into the default mode of operation. This
minimum delay time must also be adhered to whenever a reset condition occurs (see the Reset Function section
for additional information).
34 Copyright © 2009–2012, Texas Instruments Incorporated