ST10F269-T3 STMicroelectronics, ST10F269-T3 Datasheet - Page 135

• Manufacturer Part Number: ST10F269-T3
• Manufacturer: STMicroelectronics

Specifications of ST10F269-T3

• Cpu Family: ST10
• Device Core Size: 16b
• Frequency (max): 32MHz
• Interface Type: ASC/I2C/SSC
• Program Memory Type: Flash
• Program Memory Size: 256KB
• Total Internal Ram Size: 12KB
• # I/os (max): 111
• Number Of Timers - General Purpose: 4
• Operating Supply Voltage (typ): 5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• On-chip Adc: 16-chx10-bit
• Instruction Set Architecture: CISC/RISC
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 144
• Package Type: TQFP
• Lead Free Status / Rohs Status: Supplier Unconfirmed

21.3.2 - Conversion Timing Control
When
capacitances of the converter are loaded via the
respective analog input pin to the current analog
input voltage. The time to load the capacitances is
referred to as the sample time t
sampled voltage is converted to a digital value in
10 successive steps, which correspond to the
10-bit resolution of the ADC. The next 4 steps are
used for equalizing internal levels (and are kept for
exact timing matching with the 10-bit A/D
converter module implemented in the ST10F168).
The current that has to be drawn from the sources
for sampling and changing charges depends on
the time that each respective step takes, because
the capacitors must reach their final voltage level
within the given time, at least with a certain
approximation. The maximum current, however,
that a source can deliver, depends on its internal
resistance.
The sample time t
time t
programmed relatively to the ST10F269-T3 CPU
Table 33 : ADC Sampling and Conversion Timing
A complete conversion will take 14 t
time includes the conversion itself, the sample time and the time required to transfer the digital value to
the result register.
ADCON.15/14
ADCTC
c
00
01
10
11
a
(= 14 t
conversion
CC
Reserved, do not use
TCL = 1/2 x f
S
+ 2 t
(= 2 t
TCL x 24
TCL x 96
TCL x 48
Conversion Clock t
is
SC
SC
) and the conversion
XTAL
started,
+ 4 TCL) can be
CC
s
. Next the
At f
+ 2 t
first
CPU
Reserved
0.375µs
0.75 µs
CC
1.5 µs
SC
= 32MHz
+ 4 TCL (fastest conversion rate = 6.06µs at 32MHz). This
the
clock. This allows adjusting the A/D converter of
the ST10F269-T3 to the properties of the system:
Fast
programming the respective times to their
absolute possible minimum. This is preferable for
scanning high frequency signals. The internal
resistance of analog source and analog supply
must be sufficiently low, however.
High Internal Resistance can be achieved by
programming the respective times to a higher
value, or the possible maximum. This is preferable
when using analog sources and supply with a high
internal resistance in order to keep the current as
low as possible. However the conversion rate in
this case may be considerably lower.
The conversion times are programmed via the
upper four bit of register ADCON. Bit field ADCTC
(conversion time control) selects the basic
conversion clock t
converting. The sample time t
conversion time and is selected by bit field
ADSTC (sample time control). The table below
lists the possible combinations. The timings refer
to the unit TCL, where f
ADCON.13/12
ADSTC
00
01
10
11
Conversion
CC
t
t
t
CC
CC
CC
t
, used for the 14 steps of
SC
t
CC
can
CPU
x 2
x 4
x 8
Sample Clock t
=
= 1/2TCL.
S
be
is a multiple of this
and ADCTC = 00
At f
ST10F269-T3
achieved
CPU
0.375µs
0.75µs
1.50µs
3.00µs
SC
= 32MHz
135/162
by