UPD78F0988AGC-8BS Renesas Electronics America, UPD78F0988AGC-8BS Datasheet - Page 210

• Manufacturer Part Number: UPD78F0988AGC-8BS
• Manufacturer: Renesas Electronics America

Specifications of UPD78F0988AGC-8BS

• Lead Free Status / Rohs Status: Supplier Unconfirmed

11.4 Operation of A/D Converter
11.4.1 Basic operation of A/D converter
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Caution The first A/D conversion value immediately after starting the A/D conversion operation may not
<1> Select one channel for A/D conversion using analog input channel specification register 0 (ADS0).
<2> The voltage input to the selected analog input channel is sampled by the sample & hold circuit.
<3> When the voltage has been sampled for a specific time, the sample & hold circuit enters the hold status,
<4> Bit 9 of the successive approximation register (SAR) is set. The voltage tap of the series resistor string is
<5> The voltage differential between the voltage tap of the series resistor string and the analog input is compared
<6> Next, bit 8 of the SAR is automatically set, and the next voltage differential is compared. Here the voltage
<7> In this way, all the bits of the SAR, including bit 0, are compared.
<8> When all the 10 bits of the SAR have been compared, the SAR holds the valid digital results, which are then
and holds the input analog voltage until A/D conversion is completed.
set to (1/2) AV
by the voltage comparator. If the analog input is higher than (1/2) AV
If it is less than (1/2) AV
tap of the series resistor string is selected as follows, according to the value of bit 9 to which the result of
the first comparison has already been set.
• Bit 9 = 1: (3/4) AV
• Bit 9 = 0: (1/4) AV
This voltage tap and analog input voltage are compared, and bit 8 of the SAR is manipulated as follows,
according to the result of the comparison.
• Analog input voltage
• Analog input voltage
transferred and latched to A/D conversion result register 0 (ADCR0).
At the same time, an A/D conversion end interrupt request (INTAD0) can be generated.
satisfy ratings.
REF
by the tap selector.
REF
REF
REF
voltage tap: Bit 8 = 1
voltage tap: Bit 8 = 0
, the MSB is reset.
CHAPTER 11 A/D CONVERTER
User’s Manual U13029EJ7V1UD
REF
, the MSB of the SAR remains set.