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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Digital to
Analog Converter – DAC
Voltage Reference Generator
32
Voltage Reference Generator
All devices include a bandgap circuit based internal voltage reference generator which can supply a
temperature stable reference voltage for use by the internal A/D converter and DAC.
Voltage Reference Generator Operation
The voltage reference circuit will be automatically enabled when either the A/D converter or DAC
is enabled. If both the A/D converter and DAC are disabled then the generator will be disabled thus
conserving power.
Internal Voltage Reference Enable/Disable Control
ADC
DAC
Voltage Reference
Disabled
Disabled
Disabled
Enabled
Disabled
Enabled
Disabled
Enabled
Enabled
Enabled
Enabled
Enabled
The internal Voltage Reference Generator output is pin VREF and can be used as a reference
source for other circuits if loaded lightly. A suitable capacitor should be connected to this pin to
enhance voltage stability. If the internal Voltage Reference Generator is enabled then the VREF pin
will act as an output pin and must be treated accordingly. However if the internal Voltage Reference
Generator is disabled, then the VREF pin will act as an input pin to enable an externally supplied
reference voltage to be provided if required.