Z86C83 Datasheet, PDF (31/46 Pages) Zilog, Inc. – Z8 MCU MICROCONTROLLERS

Z86C83/C84
Z8^® MCU Microcontrollers
FUNCTIONAL DESCRIPTION (Continued)
Digital-to-Analog Converters
The Z86C84 has two Digital-to-Analog Converters
(DACs). Each DAC is an 8-bit resistor string, with a
programmable 0.25X, 0.5X, or 1X gain output buffer. The
DAC output voltage settles after the internal data is latched
into the DAC Data register. The top and bottom ends of the
resistor ladder are register-selected to be connected to
either the analog supply rails, AV_CC and A_GND, or two
externally-provided reference voltages, VDHI and VDLO.
External references are recommended to explicitly set the
DAC output limits. Since the gain stage cannot drive to the
supply rails, VDHI and VDLO must be within ranges shown
in the specifications. If either reference approaches the
analog supply rails, the output will be unable to span the
reference voltage range. The externally provided
reference voltages should not exceed the supply voltages.
The DAC outputs are latch-up protected and can drive
output loads (Figure 28).
Note: The AV_CC must be the same value as V_CC and A_GND
must be the same value as GND
8
Data
Bus
8
DACn
8
Data
Register
DACRn
Control
Register
(n = 1 or 2)
High
8-Bit
Resistor
Ladder
Low
AVCC
Analog
+
-
AGND
Programmable
Gain
* Bits 0, 1
Note:
* DACRn Control Register Bits
Figure 28. DAC Block Diagram
PAD
VDHI
DAC1
or
DAC2
PAD
PAD
VDLO
31
DS96DZ80203