Z86D990 Datasheet, PDF (38/102 Pages) Zilog, Inc. – Low-Voltage Micro controllers with ADC

Z86D990/Z86D991 OTP and Z86L99X ROM
Low-Voltage Microcontrollers with ADC
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Though the ADC functions for smaller input voltage range (V_Ref+–V_Ref-), the noise
and offsets remain constant over the specified electrical range. The errors of the
converter increase due to small input signals.
For fast access to the output of the ADC, the current data is available in the ADC
result register (r8, bank00).
To reduce the interference between the digital part and the analog part, separate
AV_SS and AV_DD pins are available on the packages where the ADC can be used.
Note: In the smaller packages, which do not support the ADC, the
user must keep the converter not active in order to not have
power dissipated in the ADC block. By default, ADC is off.
Active Glitch Filter
The Z86D99/Z86L99 family incorporates an active power/glitch filter that can be
used to improve the quality of the power supply when the device is operating in
noisy environments. The chips use three separate power buses:
• pad ring power bus (all the output drivers plus the crystal/RC oscillator) called
V_{DD_padring}
• core power bus (all digital circuitry) called V_{DD_CORE}
• analog power bus (all analog circuitry) called AV_DD
Depending on the pin availability, one or more of the power buses are connected
together.
The active power filter can be used in the packages that have the V_DD separate.
Figure 16 shows the internal schematic.
PS003807-1002
PRELIMINARY