DWC ADC 12b5M SAR, TSMC180 IP Databook
April 2012
Synopsys, Inc.
28-30
The following figure shows the configuration for differential inputs, with the negative and
positive references connected to ground internally in order to save package pins.
In the case of single ended inputs, the unused negative input should be connected to
agndref.
The connection of
agndref
to the ground supply and of
vrefp
to the positive supply should be
made as close as possible to the pad, in order to minimize the IR drop.
Figure 16 - IO ring case 3
– Separate Analog IO ring.
Vrefp
and
agndref
are connected to
the supply and ground pad, respectively and the inputs are differential.
It is possible to mix single-ended and differential inputs.
The ADC core contains a number of analog and digital signals that are not used in normal
operation (the ones marked as “Test” in the
Pin Description
section).
However these
signals are important to perform the test activities. Therefore, under test mode it is
necessary to have direct access from chip pinout to ALL analog and digital signals of
this ADC core cell.
Analog VDD
Power Cut
PVDD1
PANA
vinp18
PANA
vinn18
vinn0
IO Rings
Power Cut
PANA
PANA
avdd
SAR
ADC
vrefp
vinp18
vinn18
vinn0
agnd
agndref
in case not
used
dvdd
dgnd
Digital Core VDD
Digital Core Ground
All digital
inputs
From Digital
Core
!
PANA
!
!
IR droop is critical
b11..0
To Digital Core
eoc
sob
Analog GND
PGND1
dvdd_ldo
dvdd_ldo
......
PVDD1
