TMS470R1B768_08 Datasheet, PDF (42/49 Pages) Texas Instruments – 16/32-Bit RISC Flash Microcontroller

TMS470R1B768
SPNS108B – AUGUST 2005 – REVISED MAY 2008 ......................................................................................................................................................... www.ti.com
MULTI-BUFFERED A-TO-D CONVERTER (MibADC)
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
Monotonic
Output conversion code
10 bits (1024 values)
Assured
00h to 3FFh [00 for V_AI ≤ AD_REFLO; 3FFh for V_AI ≥ AD_REFHI]
Table 10. MibADC Recommended Operating Conditions⁽¹⁾
AD_REFHI
AD_REFLO
V_AI
I_AIC
A-to-D high-voltage reference source
A-to-D low-voltage reference source
Analog input voltage
Analog input clamp current⁽²⁾
(V_AI < V_SSAD – 0.3 or V_AI > V_CCAD + 0.3)
MIN
V_SSAD
V_SSAD
V_SSAD – 0.3
–2
MAX
V_CCAD
V_CCAD
V_CCAD + 0.3
2
(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.
UNIT
V
V
V
mA
Table 11. Operating Characteristics Over Full Ranges of Recommended Operating Conditions⁽¹⁾⁽²⁾
R_I
C_I
I_AIL
I_ADREFHI
CR
E_DNL
E_INL
E _TOT
PARAMETER
Analog input resistance
Analog input capacitance
Analog input leakage current
AD_REFHI input current
Conversion range over which specified
accuracy is maintained
Differential nonlinearity error
Integral nonlinearity error
Total error/absolute accuracy
DESCRIPTION/CONDITIONS
See Figure 18.
See Figure 18.
Conversion
Sampling
See Figure 18.
AD_REFHI = 3.6 V, AD_REFLO = V_SSAD
AD_REFHI - AD_REFLO
Difference between the actual step width
and the ideal value. See Figure 19.
Maximum deviation from the best straight
line through the MibADC. MibADC
transfer characteristics, excluding the
quantization error. See Figure 20.
Maximum value of the difference
between an analog value and the ideal
midstep value. See Figure 21.
MIN
TYP
MAX UNIT
250
500 Ω
10 pF
30 pF
–1
1 µA
5 mA
3
3.6 V
±1.5 LSB
±2.0 LSB
±2 LSB
(1) V_CCAD = AD_REFHI
(2) 1 LSB = (AD_REFHI – AD_REFLO)/2¹⁰ for the MibADC
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