SM320LF2407-EP Datasheet, PDF (36/112 Pages) Texas Instruments – 
DSP CONTROLLERS

SM320LF2407AĆEP
DSP CONTROLLERS
SGUS036B − JULY 2003 − REVISED OCTOBER 2003
enhanced analog-to-digital converter (ADC) module (continued)
The ADC module in the 240xA has been enhanced to provide flexible interface to event managers A and B. The
ADC interface is built around a fast, 10-bit ADC module with a total minimum conversion time of 375 ns
(S/H + conversion). The ADC module has 16 channels, configurable as two independent 8-channel modules
to service event managers A and B. The two independent 8-channel modules can be cascaded to form a
16-channel module. Although there are multiple input channels and two sequencers, there is only one converter
in the ADC module. Figure 5 shows the block diagram of the 240xA ADC module.
The two 8-channel modules have the capability to autosequence a series of conversions, each module has the
choice of selecting any one of the respective eight channels available through an analog MUX. In the cascaded
mode, the autosequencer functions as a single 16-channel sequencer. On each sequencer, once the
conversion is complete, the selected channel value is stored in its respective RESULT register. Autosequencing
allows the system to convert the same channel multiple times, allowing the user to perform oversampling
algorithms. This gives increased resolution over traditional single-sampled conversion results.
ADCIN00
Analog MUX
Result Registers
Result Reg 0
Result Reg 1
70A8h
ADCIN07
ADCIN08
10-Bit
ADC
Module
(375 ns MIN)
Result Reg 7
Result Reg 8
70AFh
70B0h
ADCIN15
Result Reg 15
70B7h
S/W
EVA
ADCSOC
SOC
ADC Control Registers
Sequencer 1
Sequencer 2
SOC
S/W
EVB
Figure 5. Block Diagram of the 240xA ADC Module
To obtain the specified accuracy of the ADC, proper board layout is very critical. To the best extent possible,
traces leading to the ADCINn pins should not run in close proximity to the digital signal paths. This is to minimize
switching noise on the digital lines from getting coupled to the ADC inputs. Furthermore, proper isolation
techniques must be used to isolate the ADC module power pins (such as V_CCA, V_REFHI, and V_SSA) from the
digital supply.
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