adc1020 austriamicrosystems, adc1020 Datasheet - Page 7

• Manufacturer Part Number: adc1020
• Description: Cmos 10-bit Pipelined A/d Converter
• Manufacturer: austriamicrosystems

Datasheet : ADC1020 – C35
OPERATING MODES
The modes of operation are summarized in the table bellow, and described in detail as follows.
Mode 0 - Power Down
In this mode all the circuitry is in power-down. The power dissipation is reduced to a minimum value.
Mode 1 - Normal Conversion
This is the normal conversion mode of the converter. The bias current is internally generated and the reference and the common mode voltages
are internally buffered. The external bandgap reference voltage VBG determines the values of the reference voltages.
Mode 2 through Mode 6 - Conversion Mode with different Bypassing options
These conversion modes allow different bypassing options for the bias current generator, the reference generation and the buffer of the common
mode voltages.
POWER SUPPLIES
The converter requires a single +3.3V power supply. The supplies for analog and digital are separated and may be connected together. However,
for maximum noise immunity it is recommended to wire them on chip to separated pins, especially when the block is embedded in a large digital
circuit. The supplies may then be connected together on PC-board level.
The proper use of blocking capacitors in the application is important!
REFERENCE VOLTAGES
If ONREF is set to high the converter needs a external bandgap reference VBG which defines the dynamic range of the input signal as described
in the technical data section. If ONREF is set to low the external voltage references VREFP and VREFN define the dynamic range of the input
signal.
A additional series resistor in the pad cell of VBG causes a wrong reference voltage generation in all modes with internal reference generation –
see footnotes in the technical data section.
For external reference generation an additional resistor in the pad cells of VREFP and VREFN causes a voltage drop. This results in a smaller
reference difference VREF.
The proper use of blocking capacitors in the application is important!
Revision C, 07.09.02
Mode
0
1
2
3
4
5
6
Description
Complete Power Down
Normal conversion with internally buffered VCM, VREF and
Ibias generation
Normal conversion with internal VREF and Ibias generation,
externally buffered VCM
Normal conversion with internal Ibias generation, external VCM
and VREF
Normal conversion with internally buffered VCM, VREF and
external Ibias
Normal conversion with internal VREF generation, external
VCM and Ibias
Normal conversion with external VCM, VREF and Ibias
ONADC
0
1
1
1
1
1
1
ONREF
X
1
1
0
1
1
0
ONCM
X
1
0
0
1
0
0
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SWIB
X
1
1
1
0
0
0