AMC7891_15 Datasheet, PDF (26/41 Pages) Texas Instruments – Analog Monitor and Control Circuit with 10-Bit, Multi-Channel ADC and Four DACs, Temperature Sensor, and 12 GPIOs

AMC7891
SBAS518A – AUGUST 2011 – REVISED DECEMBER 2011
adc_rate[1:0]
00
01
10
11
t_ACQ
(µs)
0.375
2.375
6.375
14.375
Table 3. ADC Conversion Rate
t_CONV
(µs)
1.625
1.625
1.625
1.625
NAP
ENABLED
No
Yes
Yes
Yes
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THROUGHPUT
(Single-Channel Auto Mode)
500 kSPS (default)
250 kSPS
125 kSPS
62.5 kSPS
HANDSHAKING WITH THE HOST
The DAV pin and adc_ready bit (AMC_config register, bit 7) provide handshaking with the host. The DAV pin is
an open-drain, active low output. If used, an external 10 kΩ pull-up resistor to GPIOV_DD is required. If unused,
the pin can be connected to DGND. Pin and bit status depend on the conversion mode (direct or auto), as shown
in Figure 29.
In direct mode, after the ADCn_data registers of all the selected channels in register adc_enable are updated,
adc_ready is set immediately to '1' and the DAV pin is active (low) to signify that new data is available.
The adc_ready bit is reset to '0' and the DAV pin goes back to inactive (high) either by reading any of the
ADCn_data registers or when a new ADC conversion is started by issuing a trigger by adc_trig. The update
takes place immediately after the read command frame indicating the read operation or trigger event.
In auto-mode, after the adcn_data[9:0] values are updated, a pulse of 1μs (low) appears on the DAV pin to
signify that new data is available. However, the adc_trig bit is inactive and always set to ‘0’.
a ) Direct Mode
CS
adc_trig
set to “1”
1^st internal
trigger
Read Data
Command Frame
SDI
Read
Instruction
adc_trig
set to “1”
2^nd internal
trigger
Read Data
Command Frame
Read
Instruction
DAV
b) Auto Mode
1^st CONVERSION of the
channels specified in the ADC
Channel Register
CS
adc_trig
set to “1”
1^st internal
trigger
SDI
1µs
DAV
2^nd CONVERSION of the
channels specified in the ADC
Channel Register
1^st CONVERSION of the
channels specified in the ADC
Channel Register
2^nd CONVERSION
Figure 29. ADC Handshaking
3^rd CONVERSION
26
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