JAJSEC1C November 2019 – July 2020 ADS8686S
PRODUCTION DATA
The device enters hardware mode if the HW_RNGSEL[1:0] pins are set to either 01, 10, or 11 at the time of a full reset. In hardware mode, the device operates with restricted functionality. All device functionality is configured through the pin control. The logic levels of the following signals at a full reset configure the functionality of the ADS8686S: CRC, BURST, SEQEN, SER/BYTE/ PAR, DB9/BYESEL, DB8, and OSx. Table 7-5 provides a summary of the signals that are latched by the device on the release of a full reset. After the device is configured, a full reset through the RESET pin is required to exit the configuration and set up an alternate configuration. The data communication interface selected also dictates the functionality available in hardware mode. Table 7-6 provides a full list of the functionality available in hardware parallel, byte, or serial mode.
SIGNAL | LATCHED AT FULL RESET | READ AT RESET | READ WHEN BUSY | EDGE DRIVEN | ||||
---|---|---|---|---|---|---|---|---|
HW MODE |
SW MODE |
HW MODE |
SW MODE |
HW MODE |
SW MODE |
HW MODE |
SW MODE |
|
REFSEL | Yes | Yes | ||||||
SEQEN | Yes | |||||||
HW_RNGSELx
(range change) |
Yes | Yes | Yes | |||||
HW_RNGSELx
(HW or SW mode) |
Yes | Yes | ||||||
CRCEN | Yes | No | ||||||
OSx | Yes | No | ||||||
BURST | Yes | No | ||||||
CHSELx | Yes | Yes | ||||||
SER1W | Yes | Yes | ||||||
SER/BYTE/ PAR | Yes | Yes | ||||||
DB9/BYTESEL | Yes | Yes |
PIN NAME | OPERATION MODE | |||||
---|---|---|---|---|---|---|
SOFTWARE, HW_RNGSELx = 00 | HARDWARE, HW_RNGSELx ≠ 00 | |||||
SERIAL, SER/BYTE/ PAR = 1, DB9/BYTESEL = 0 | PARALLEL BYTE, SER/BYTE/ PAR = 1, DB9/BYTESEL = 1 | PARALLEL, SER/BYTE/ PAR = 0 | SERIAL, SER/BYTE/ PAR = 1, DB9/BYTESEL = 0 | PARALLEL BYTE, SER/BYTE/ PAR = 1, DB9/BYTESEL = 1 | PARALLEL, SER/BYTE/ PAR = 0 | |
CHSELx | No function, connect to DGND | No function, connect to DGND | No function, connect to DGND | CHSELx | CHSELx | CHSELx |
SCLK/ RD | SCLK | RD | RD | SCLK | RD | RD |
WR/BURST | Connect to DGND | WR | WR | BURST | BURST | BURST |
DB[15:13]/OS[0:2] | Connect to DGND | Connect to DGND | DB15 to DB13 | OSx | Connect to DGND | DB15 to DB13 |
DB12/SDOA | SDOA | Connect to DGND | DB12 | SDOA | Connect to DGND | DB12 |
DB11/SDOB | SDOB, leave floating for serial 1-wire mode | Connect to DGND | DB11 | SDOB | Connect to DGND | DB11 |
DB10/SDI | SDI | Connect to DGND | DB10 | Connect to DGND | Connect to DGND | DB10 |
DB9/BYTESEL | Connect to DGND | Connect to DVDD | DB9 | Connect to DGND | Connect to DVDD | DB9 |
DB8 to DB6, DB3 to DB0 |
Connect to DGND | DB8 to
DB6, DB3 to DB0 |
DB8 to
DB6, DB3 to DB0 |
Connect to DGND | DB8 to
DB6, DB3 to DB0 |
DB8 to
DB6, DB3 to DB0 |
DB5/CRCEN | Connect to DGND | DB5 | DB5 | CRCEN | DB5 | DB5 |
DB4/ SER1W | SER1W | DB4 | DB4 | SER1W | DB4 | DB4 |
HW_RNGSELx | Connect to DGND | Connect to DGND | Connect to DGND | Configure analog input range | Configure analog input range | Configure analog input range |
SEQEN | Connect to DGND | Connect to DGND | Connect to DGND | SEQEN | SEQEN | SEQEN |
REFSEL | REFSEL | REFSEL | REFSEL | REFSEL | REFSEL | REFSEL |
In hardware mode, the CHSELx and HW_RNGSELx control signals can change their state during device operation and have an immediate effect on the device configuration.
The CHSELx pins are read at reset to determine the first analog input channel pair to be acquired for conversion. In the sequencer mode of operation, the CHSELx pins configure the settings for the sequencer. See the Section 7.4.2.5 section for additional details. The CHSELx pin status must be kept constant during the ADC conversion process (that is, between the CONVST rising edge and the BUSY falling edge). The status of the CHSELx pins is read during this time to select the next channel pair for conversion or to modify the hardware sequencer setting.
The HW_RNGSELx signals program the analog input range. The selected input range is applied to all 16 analog input channels. A logic change on these pins has an immediate effect on the analog input range. Allow for a typical settling time of 120 µs, in addition to the normal acquisition time requirement after the range change. The recommended practice is to hardwire the range select pins according to the desired input range for the system signals.