IC MCU 8BIT OTP 4K 20 PDIP

ST62T20CB6

Manufacturer Part NumberST62T20CB6
DescriptionIC MCU 8BIT OTP 4K 20 PDIP
ManufacturerSTMicroelectronics
SeriesST6
ST62T20CB6 datasheet
 


Specifications of ST62T20CB6

Core ProcessorST6Core Size8-Bit
Speed8MHzPeripheralsLVD, POR, WDT
Number Of I /o12Program Memory Size4KB (4K x 8)
Program Memory TypeOTPRam Size64 x 8
Voltage - Supply (vcc/vdd)3 V ~ 6 VData ConvertersA/D 8x8b
Oscillator TypeInternalOperating Temperature-40°C ~ 85°C
Package / Case20-DIP (0.300", 7.62mm)Controller Family/seriesST6
No. Of I/o's12Ram Memory Size64Byte
Cpu Speed8MHzNo. Of Timers1
Rohs CompliantYesProcessor SeriesST62T2x
CoreST6Data Bus Width8 bit
Data Ram Size64 BMaximum Clock Frequency8 MHz
Number Of Programmable I/os12Number Of Timers2
Operating Supply Voltage3 V to 6 VMaximum Operating Temperature+ 85 C
Mounting StyleThrough HoleDevelopment Tools By SupplierST622XC-KIT/110, ST62GP-EMU2, ST62E2XC-EPB/110, ST62E6XC-EPB/US, STREALIZER-II
Minimum Operating Temperature- 40 COn-chip Adc8 bit
Lead Free Status / RoHS StatusLead free / RoHS CompliantEeprom Size-
Connectivity-Other names497-2098-5
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ST6208C/ST6209C/ST6210C/ST6220C
A/D CONVERTER (Cont’d)
8.3.4 Recommendations
The following six notes provide additional informa-
tion on using the A/D converter.
1.The A/D converter does not feature a sample
and hold circuit. The analog voltage to be meas-
ured should therefore be stable during the entire
conversion cycle. Voltage variation should not ex-
ceed ±1/2 LSB for optimum conversion accuracy.
A low pass filter may be used at the analog input
pins to reduce input voltage variation during con-
version.
2. When selected as an analog channel, the input
pin is internally connected to a capacitor C
typically 9pF. For maximum accuracy, this capaci-
tor must be fully charged at the beginning of con-
version. In the worst case, conversion starts one
instruction (6.5 µs) after the channel has been se-
lected. The impedance of the analog voltage
source (ASI) in worst case conditions, is calculat-
ed using the following formula:
6.5µs = 9 x C
x ASI
ad
(capacitor charged to over 99.9%), i.e. 30 kΩ in-
cluding a 50% guardband.
The ASI can be higher if C
has been charged for
ad
a longer period by adding instructions before the
start of conversion (adding more than 26 CPU cy-
cles is pointless).
3. Since the ADC is on the same chip as the micro-
processor, the user should not switch heavily load-
ed output signals during conversion, if high preci-
sion is required. Such switching will affect the sup-
ply voltages used as analog references.
4. Conversion accuracy depends on the quality of
the power supplies (V
and V
DD
take special care to ensure a well regulated refer-
ence voltage is present on the V
(power supply voltage variations must be less than
0.1V/ms). This implies, in particular, that a suitable
decoupling capacitor is used at the V
The converter resolution is given by:
V
V
DD
SS
------------------------------- -
256
The Input voltage (Ain) which is to be converted
must be constant for 1µs before conversion and
remain constant during conversion.
5. Conversion resolution can be improved if the
power supply voltage (V
) to the microcontroller
DD
is lowered.
6. In order to optimize the conversion resolution,
the user can configure the microcontroller in WAIT
mode, because this mode minimises noise distur-
54/104
1
bances and power supply variations due to output
switching. Nevertheless, the WAIT instruction
should be executed as soon as possible after the
beginning of the conversion, because execution of
the WAIT instruction may cause a small variation
of the V
iation is minimized at the beginning of the conver-
sion when the converter is less sensitive, rather
than at the end of conversion, when the least sig-
nificant bits are determined.
The best configuration, from an accuracy stand-
point, is WAIT mode with the Timer stopped. In
this case only the ADC peripheral and the oscilla-
tor are then still working. The MCU must be woken
of
ad
up from WAIT mode by the ADC interrupt at the
end of the conversion. The microcontroller can
also be woken up by the Timer interrupt, but this
means the Timer must be running and the result-
ing noise could affect conversion accuracy.
Caution: When an I/O pin is used as an analog in-
put, A/D conversion accuracy will be impaired if
negative current injections (V
adjacent I/O pins with analog input capability. Re-
fer to
Figure
– Use another I/O port located further away from
the analog pin, preferably not multiplexed on the
A/D converter
– Increase the input resistance R
current injections) and reduce R
conversion accuracy).
Figure 35. Leakage from Digital Inputs
). The user must
SS
and V
pins
DD
SS
pin.
DD
V
V
AIN
voltage. The negative effect of this var-
DD
< V
INJ
SS
35. To avoid this:
(to reduce the
IN J
ADC
Digital
Input
PBy/AINy
R
INJ
INJ
Leakage Current
if V
< V
INJ
SS
Analog
Input
PBx/AINx
R
ADC
) occur from
(to preserve
I/O Port
(Digital I/O)
A/D
Converter