Datasheet
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MULTI-BUFFERED A-TO-D CONVERTER (MibADC)
TMS470R1B1M
16/32-Bit RISC Flash Microcontroller
SPNS109A – SEPTEMBER 2005 – REVISED AUGUST 2006
The multi-buffered A-to-D converter (MibADC) has a separate power bus for its analog circuitry that enhances
the A-to-D performance by preventing digital switching noise on the logic circuitry, which could be present on V
SS and V CC , from coupling into the A-to-D analog stage. All A-to-D specifications are given with respect to AD
REFLO unless otherwise noted.
Resolution 10 bits (1024 values)
Monotonic Assured
Output conversion code 00h to 3FFh [00 for V
AI
≤ AD
REFLO
; 3FF for V
AI
≥ AD
REFHI
]
Table 17. MibADC Recommended Operating Conditions
(1)
MIN MAX UNIT
AD
REFHI
A-to-D high-voltage reference source V
SSAD
V
CCAD
V
AD
REFLO
A-to-D low-voltage reference source V
SSAD
V
CCAD
V
V
AI
Analog input voltage V
SSAD
– 0.3 V
CCAD
+ 0.3 V
Analog input clamp current
(2)
I
AIC
–2 2 mA
(V
AI
< V
SSAD
– 0.3 or V
AI
> V
CCAD
+ 0.3)
(1) For V
CCAD
and V
SSAD
recommended operating conditions, see the "Device Recommended Operating Conditions" table.
(2) Input currents into any ADC input channel outside the specified limits could affect conversion results of other channels.
Table 18. Operating Characteristics over Full Ranges of Recommended Operating Conditions
(1) (2)
PARAMETER DESCRIPTION/CONDITIONS MIN TYP MAX UNIT
R
I
Analog input resistance See Figure 22 . 250 500 Ω
Conversion 10 pF
C
I
Analog input capacitance See Figure 22 .
Sampling 30 pF
I
AIL
Analog input leakage current See Figure 22 . –1 1 µA
I
ADREFHI
AD
REFHI
input current AD
REFHI
= 3.6 V, AD
REFLO
= V
SSAD
5 mA
Conversion range over which
CR AD
REFHI
- AD
REFLO
3 3.6 V
specified accuracy is maintained
Difference between the actual step width
E
DNL
Differential nonlinearity error ± 1.5 LSB
and the ideal value. See Figure 23 .
Maximum deviation from the best straight
line through the MibADC. MibADC transfer
E
INL
Integral nonlinearity error ± 2 LSB
characteristics, excluding the quantization
error. See Figure 24 .
Maximum value of the difference between
E
TOT
Total error/Absolute accuracy an analog value and the ideal midstep ± 2 LSB
value. See Figure 25 .
(1) V
CCAD
= AD
REFHI
(2) 1 LSB = (AD
REFHI
- AD
REFLO
)/2
10
for the MibADC
53
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