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TMS370Cx36
8-BIT MICROCONTROLLER
SPNS039B – JANUARY 1996 – REVISED FEBRUARY 1997
44
POST OFFICE BOX 1443
HOUSTON, TEXAS 77251–1443
ADC1 converter
The ADC1 converter has a separate power bus for its analog circuitry. These pins are referred to as V
CC3
and
V
SS3
. The purpose is to enhance ADC1 performance by preventing digital switching noise of the logic circuitry
that can be present on V
SS1
and V
CC1
from coupling into the ADC1 analog stage. All ADC1 specifications are
given with respect to V
SS3
unless otherwise noted.
Resolution
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Monotonic
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Output conversion mode
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Conversion time (excluding sample time)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8-bits (256 values)
Yes
00h to FFh (00 for V
I
≤
V
SS3
≤
; FF for V
I
≤
V
ref
)
164 t
c
recommended operating conditions
MIN
4.5
NOM
MAX
5.5
UNIT
VCC3
Analog supply voltage
5
V
VCC1–0.3
VSS1–0.3
2.5
VCC1+0.3
VSS1+0.3
VCC3 + 0.1
Vref
VSS3
Vref
Analog ground
Non-VCC3 reference
Analog input for conversion
Vref must be stable, within
±
1/2 LSB of the required resolution, during the entire conversion time.
V
VCC3
V
VSS3
V
operating characteristics over recommended ranges operating conditions
PARAMETER
MIN
MAX
±
1.5
±
0.9
UNIT
Absolute accuracy
Differential/integral linearity error§
VCC3 = 5.5 V
VCC3 = 5.5 V
Converting
Vref = 5.1 V
Vref = 5.1 V
LSB
LSB
ICC3
Analog supply current
2
mA
μ
A
μ
A
mA
k
k
Nonconverting
0 V
≤
VI
≤
5.5 V
5
II
Iref
Input current, AN0–AN7
2
Input charge current
1
Zref
Source impedance of V f
Source impedance of Vref
SYSCLK
≤
3 MHz
3 MHz < SYSCLK
≤
5 MHz
24
10
Absolute resolution = 20 mV. At Vref = 5 V, this is one LSB. As Vref decreases, LSB size decreases; therefore, the absolute accuracy and
differential/integral linearity errors in terms of LSBs increase.
§Excluding quantization error of 1/2 LSB