Texas Instruments TMS320F2802 - Manual (Page 63)

Result Registers
EPWMSOCB
S/W
ADC Control Registers
70B7h
70B0h
70AFh
70A8h
Result Reg 15
Result Reg 8
Result Reg 7
Result Reg 1
Result Reg 0
12-Bit
ADC
Module
Analog
MUX
EPWMSOCA
S/W
GPIO/XINT2_
ADCSOC
ADCINA0
ADCINA7
ADCINB0
ADCINB7
System
Control Block
High-Speed
Prescaler
HSPCLK ADCENCLK
DSP
SYSCLKOUT
S/H
S/H
HALT
Sequencer 2 Sequencer 1 SOC SOC
TMS320F2809, TMS320F2808, TMS320F2806
TMS320F2802, TMS320F2801, TMS320C2802
TMS320C2801, TMS320F28016, TMS320F28015
www.ti.com SPRS230N – OCTOBER 2003 – REVISED MAY 2012
Figure 4-7. Block Diagram of the 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 ADCIN 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 (V
DD1A18
,
V
DD2A18
, V
DDA2
, V
DDAIO
) from the digital supply. Figure 4-8 and Figure 4-9 show the ADC pin connections
for the 280x devices.
NOTE
1. The ADC registers are accessed at the SYSCLKOUT rate. The internal timing of the
ADC module is controlled by the high-speed peripheral clock (HSPCLK).
2. The behavior of the ADC module based on the state of the ADCENCLK and HALT
signals is as follows:
– ADCENCLK: On reset, this signal will be low. While reset is active-low (XRS) the
clock to the register will still function. This is necessary to make sure all registers and
modes go into their default reset state. The analog module, however, will be in a low-
power inactive state. As soon as reset goes high, then the clock to the registers will
be disabled. When the user sets the ADCENCLK signal high, then the clocks to the
registers will be enabled and the analog module will be enabled. There will be a
certain time delay (ms range) before the ADC is stable and can be used.
– HALT: This mode only affects the analog module. It does not affect the registers. In
this mode, the ADC module goes into low-power mode. This mode also will stop the
clock to the CPU, which will stop the HSPCLK; therefore, the ADC register logic will
be turned off indirectly.
Copyright © 2003–2012, Texas Instruments Incorporated Peripherals 63
Submit Documentation Feedback
Product Folder Link(s): TMS320F2809 TMS320F2808 TMS320F2806 TMS320F2802 TMS320F2801 TMS320C2802
TMS320C2801 TMS320F28016 TMS320F28015