SBAS843A september 2017 – july 2023 ADS8588H
PRODUCTION DATA
FRSTDATA is an active-high digital output signal that indicates if the conversion data output for the first analog input channel of the ADC (AIN_1P and AIN_1GND) is being read out in either of the interface modes. The FRSTDATA output pin comes out of tri-state when the CS input is pulled from a high to a low logic level. Table 7-5 indicates the functionality of the FRSTDATA output in different interface modes of the device.
DEVICE OPERATING CONDITION | FUNCTIONALITY OF THE FRSTDATA OUTPUT | |
---|---|---|
MODE | CONDITIONS | |
Parallel mode | PAR/SER/BYTE SEL = 0, DB15/BYTE SEL = X |
The first falling edge of the RD signal corresponding to the output result of channel 1 sets the FRSTDATA output to a logic high level. This setting indicates that the data output from channel 1 is being read on the parallel output bus (DB[15:0]). The FRSTDATA output goes low at the next falling edge of the RD signal and remains low until the conversion data output from all other channels is read. |
Parallel byte mode | PAR/SER/BYTE SEL = 1, DB15/BYTE SEL = 1 |
The first falling edge of the RD signal corresponding to one byte of the output of channel 1 sets the FRSTDATA output to a logic high level. This setting indicates that one byte of the data output from channel 1 is being read on the parallel output bus (DB[7:0]). The FRSTDATA output remains high at the next falling edge of the RD signal to read the second byte of the channel 1 output. This pin goes low on the third falling edge of the RD signal and remains low until the conversion data output from all other channels is read. |
Serial mode | PAR/SER/BYTE SEL = 1, DB15/BYTE SEL = 0 |
The FRSTDATA output goes to a logic high state on the falling edge of the CS signal when the MSB of the channel 1 conversion result is output on DOUTA at this instant. The FRSTDATA pin goes low at the 16th falling edge of the SCLK input, indicating that all 16 bits of the channel 1 output have been read. This pin remains low until the conversion data output from all other channels is read. |