AD7858 Analog Devices, AD7858 Datasheet - Page 27

• Manufacturer Part Number: AD7858
• Description: 3 V to 5 V Single Supply, 200 kSPS, 8-Channel, 12-Bit, Serial Sampling ADC
• Manufacturer: Analog Devices

Specifications of AD7858

• Resolution (bits): 12bit
• # Chan: 8
• Sample Rate: 200kSPS
• Interface: Ser,SPI
• Analog Input Type: SE-Uni
• Ain Range: (Vref) p-p,Uni (Vref)
• Adc Architecture: SAR
• Pkg Type: DIP,SOIC

Interface Mode 2 Configuration
Figure 35 shows the flowchart for configuring the part in Inter-
face Mode 2. In this case the read and write operations take
place simultaneously via the serial port. Writing all 0s ensures
NOTES
1
2
WHEN USING THE SOFTWARE CONVERSION START AND TRANSFERRING DATA DURING CONVERSION THE USER MUST ENSURE THE CONTROL REGISTER
TWO SEPARATE WRITES ARE REQUIRED TO SET A NEW CHANNEL ADDRESS AND INITIATE A CONVERSION ON THAT NEW CHANNEL IN SOFTWARE AS
WRITE OPERATION EXTENDS BEYOND THE FALLING EDGE OF BUSY. THE FALLING EDGE OF BUSY RESETS THE CONVST BIT TO 0 AND ONLY AFTER THIS
TIME CAN IT BE REPROGRAMMED TO 1 TO START THE NEXT CONVERSION.
THE ACQUISITION TIME (2
RESULT OF THIS CONVERSION SHOULD BE DISCARDED AND THE NEXT CONVERSION ON THAT SAME CHANNEL WILL PROVIDE CORRECT RESULTS.
PREVIOUS CONVERSION RESULT ON DOUT
APPLY SYNC (IF REQUIRED), SCLK, READ
PIN, AND WRITE CHANNEL SELECTION
WAIT APPROX 200ns AFTER
CONVST RISING EDGE
t
CLKIN
) MUST ELAPSE BEFORE THE CONVERSION BEGINS. IF BOTH COMMANDS ARE ISSUED IN THE ONE WRITE THE
READ CURRENT CONVERSION RESULT
ON DOUT PIN, AND WRITE CHANNEL
APPLY SYNC (IF REQUIRED), SCLK,
WAIT FOR AUTOMATIC CALIBRATION
WAIT FOR BUSY SIGNAL TO GO LOW
POWER-ON, APPLY CLKIN SIGNAL,
YES
WAIT FOR BUSY BIT = 0
PULSE CONVST PIN
SELECTION
DATA DURING
CONVERSION
CONVERSION
INTERFACE
TRANSFER
SOFTWARE
INITIATE
SERIAL
START
MODE
OR
?
?
IN
?
NO
2
NO
YES
that no valid data is written to any of the registers. When using
the software conversion start and transferring data during con-
version Note 1 must be obeyed.
TO CONTROL REGISTER SETTING CHANNEL
APPLY SYNC (IF REQUIRED), SCLK, WRITE
WRITE TO CONTROL REGISTER SETTING
WAIT FOR BUSY SIGNAL TO GO LOW
CURRENT CONVERSION RESULT
ON DOUT PIN (SEE NOTE 2)
CONVST BIT TO 1, READ
WAIT FOR BUSY BIT = 0
DATA DURING
CONVERSION
TRANSFER
OR
?
NO
YES
TO CONTROL REGISTER SETTING CHANNEL,
APPLY SYNC (IF REQUIRED), SCLK, WRITE
AD7858/AD7858L
(SEE NOTE 1)
WRITE TO CONTROL REGISTER
READ PREVIOUS RESULT ON
DOUT PIN (SEE NOTES 1&2)
SETTING CONVST BIT TO 1,