AMC7836 Datasheet, PDF (76/88 Pages) Texas Instruments – AMC7836 High-Density, 12-Bit Analog Monitor and Control Solution With Multichannel ADC, Bipolar DACs, Temperature Sensor, and GPIO Ports

AMC7836
SLAS986C – NOVEMBER 2014 – REVISED APRIL 2016
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Table 64. ADC Conversion Rate and Total Update Number of Clocks
ADC CONVERSION
RATE
00
01
10
11
ADC INPUT CHANNEL
Bipolar
Unipolar
Internal Temperature
Sensor
Bipolar
Unipolar
Internal Temperature
Sensor
Bipolar
Unipolar
Internal Temperature
Sensor
Bipolar
Unipolar
Internal Temperature
Sensor
ACQUISITION CLOCKS CONVERSION CLOCKS
124.5
13.5
32.5
13.5
—
—
124.5
13.5
78.5
13.5
—
—
124.5
13.5
124.5
13.5
—
—
262.5
13.5
262.5
13.5
—
—
t_S (ACQUISITION +
CONVERSION)
NUMBER OF CLOCKS
138
46
1025
138
92
1025
138
138
1025
276
276
1025
The minimum and maximum oscillator frequency specifications in conjunction with the number of clocks required
for the unipolar, bipolar and temperature sensor inputs should be applied to Equation 5 to calculate the total
update time range.
T_S
(B_CLK u # B_CH U_CLK u # U_CH T_CLK u # T_CH )
¦_OSC
where
• T_S is the total update time
• B_CLK is the total bipolar clocks
• #B_CH is the number of active bipolar inputs
• U_CLK is the total unipolar clocks
• #U_CH is the number of active unipolar inputs
• T_CKL is the total internal temperature-sensor clocks
• #T_CH is the number of active internal temperature sensor channels; either 1 or 0
• ƒ_OSC is the internal oscillator frequency
(5)
The following is an example of a complete calculation of the total update time range. In this example, the ADC
conversion rate is set to 00 and the following ADC input channels are used:
• Bipolar channels: ADC_1 through ADC_5 (5 active bipolar channels)
• Unipolar channels: LV_ADC16 through LV_ADC18 (3 active unipolar channels)
• Internal temperature sensor (1 active temperature channel)
Table 64 gives the total number of clocks required for each ADC input under the example conditions.
For the minimum specified oscillator frequency of 3.7 MHz, and with the ADC conversion rate set to 00, use
Equation 6 to calculate the total maximum update time for this example.
T_S
(138 u 5 46 u 3 1025 u 1) _{500.811 µs}
3.7 MHz
(6)
For the maximum specified oscillator frequency of 4.3 MHz, use Equation 7 to calculate the total minimum
update time for this example.
T_S
(138 u 5 46 u 3 1025 u 1) _{430.93 µs}
4.3 MHz
(7)
Therefore, the total update time range is 430.93 µs to 500.811 µs.
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