Texas Instruments TMS320F2802 - Manual (Page 65)

ADCINA[7:0]
ADCINB[7:0]
ADCLO
ADCREFIN
ADC External Current Bias Resistor ADCRESEXT
ADCREFP
V
DD1A18
V
DD2A18
V
SS1AGND
V
SS2AGND
V
DDAIO
V
SSAIO
V
DDA2
V
SSA2
ADC Reference Positive Output
ADCREFM ADC Reference Medium Output
ADC Analog Power
ADC Analog and Reference I/O Power
Analog input 0-3 V with respect to ADCLO
Connect to Analog Ground
ADCREFP and ADCREFM should not
be loaded by external circuitry
ADC 16-Channel Analog Inputs
Connect to 1.500, 1.024, or 2.048-V precision source
(D)
ADC Analog Power Pin (1.8 V)
ADC Analog Power Pin (1.8 V)
ADC Analog I/O Ground Pin
ADC Analog Power Pin (3.3 V)
ADC Analog Ground Pin
ADC Analog Ground Pin
ADC Analog Ground Pin
ADC Analog Power Pin (3.3 V)
22 k
2.2 F μ
(A)
2.2 F μ
(A)
TMS320F2809, TMS320F2808, TMS320F2806
TMS320F2802, TMS320F2801, TMS320C2802
TMS320C2801, TMS320F28016, TMS320F28015
www.ti.com SPRS230N – OCTOBER 2003 – REVISED MAY 2012
A. TAIYO YUDEN LMK212BJ225MG-T or equivalent
B. External decoupling capacitors are recommended on all power pins.
C. Analog inputs must be driven from an operational amplifier that does not degrade the ADC performance.
D. External voltage on ADCREFIN is enabled by changing bits 15:14 in the ADC Reference Select register depending on
the voltage used on this pin. TI recommends TI part REF3020 or equivalent for 2.048-V generation. Overall gain
accuracy will be determined by accuracy of this voltage source.
Figure 4-9. ADC Pin Connections With External Reference
NOTE
The temperature rating of any recommended component must match the rating of the end
product.
4.6.1 ADC Connections if the ADC Is Not Used
It is recommended to keep the connections for the analog power pins, even if the ADC is not used.
Following is a summary of how the ADC pins should be connected, if the ADC is not used in an
application:
• V
DD1A18
/V
DD2A18
– Connect to V
DD
• V
DDA2
, V
DDAIO
– Connect to V
DDIO
• V
SS1AGND
/V
SS2AGND
, V
SSA2
, V
SSAIO
– Connect to V
SS
• ADCLO – Connect to V
SS
• ADCREFIN – Connect to V
SS
• ADCREFP/ADCREFM – Connect a 100-nF cap to V
SS
• ADCRESEXT – Connect a 20-k Ω resistor (very loose tolerance) to V
SS
.
• ADCINAn, ADCINBn - Connect to V
SS
When the ADC is not used, be sure that the clock to the ADC module is not turned on to realize power
savings.
When the ADC module is used in an application, unused ADC input pins should be connected to analog
ground (V
SS1AGND
/V
SS2AGND
)
Copyright © 2003–2012, Texas Instruments Incorporated Peripherals 65
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