COP888CF Datasheet, PDF (11/44 Pages) National Semiconductor (TI) – 8-Bit CMOS ROM Based Microcontrollers with 4k Memory and A/D Converter

A/D Converter Specifications (Continued)
Note 17: Pins G6 and RESET are designed with a high voltage input network for factory testing. These pins allow input voltages greater than V_CC and the pins will
have sink current to V_CC when biased at voltages greater than V_CC (the pins do not have source current when biased at a voltage below V_CC). The effective resis-
tance to V_CC is 750Ω (typical). These two pins will not latch up. The voltage at the pins must be limited to less than 14V.
Note 18: For V_IN(−)≥V_IN(+) the digital output code will be 0000 0000. Two on-chip diodes are tied to each analog input. The diodes will forward conduct for analog
input voltages below ground or above the V_CC supply. Be careful, during testing at low V_CC levels (4.5V), as high level analog inputs (5V) can cause this input diode
to conduct — especially at elevated temperatures, and cause errors for analog inputs near full-scale. The spec allows 50 mV forward bias of either diode. This means
that as long as the analog V_IN does not exceed the supply voltage by more than 50 mV, the output code will be correct. To achieve an absolute 0 V_DC to 5 V_DC input
voltage range will therefore require a minimum supply voltage of 4.950 V_DC over temperature variations, initial tolerance and loading. The voltage on any analog input
should be −0.3V to V_CC +0.3V.
DS009425-26
FIGURE 3. MICROWIRE/PLUS Timing
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