MAX11043 Datasheet, PDF (31/33 Pages) Maxim Integrated Products – 4-Channel, 16-Bit, Simultaneous-Sampling ADCs with PGA, Filter, and 8-/12-Bit Dual-Stage DAC

4-Channel, 16-Bit, Simultaneous-Sampling ADCs
with PGA, Filter, and 8-/12-Bit Dual-Stage DAC
A2, A3, and B2 Filter Coefficient
Format (52h, 54h, 56h)
Filter coefficients A2, A3, and B2 are stored as 16-bit
two’s complement values in the -4 to (4 - 2^-13) range.
The transfer function equation is as follows:
A2 = int (N x 2¹³)
where N is the decimal coefficient value.
The following are two examples of the transfer function
equation:
Example 1:
N = 2.381
A2 = int (2.381 x 2¹³)
A2 = int (19505.152)
A2 = 19505 = 4C31h (two’s complement)
Example 2:
N = -2.381
A2 = int (-2.381 x 2¹³)
A2 = int (-19505.152)
A2 = -19505 = B3CFh (two’s complement)
B3 Coefficient (56h)
BIT 15
B31
BIT 14
B30
BIT 13
RECT
BIT 7
X
BIT 6
X
BIT 5
X
B31:B30<15:14>: Filter coefficient B3.
11 = -1.
00 = 0.
01 = 1.
10 = 0.
BIT 12
X
BIT 4
X
BIT 11
X
BIT 10
X
BIT 9
X
BIT 8
X
BIT 3
X
BIT 2
X
BIT 1
X
X<13>: Don’t-care bit. Not used.
RECT<12>: Rectify bit.
0 = bipolar output.
1 = output rectified. All samples positive.
X<11:0>: Don’t-care bits. Not used.
BIT 0
X
Power Supplies, Layout, and
Bypassing Considerations
For best performance, use PCBs with ground planes.
Ensure that digital and analog signal lines are separat-
ed from each other. Do not run analog and digital lines
parallel to one another (especially clock lines), and do
not run digital lines underneath the MAX11043 pack-
age. Use a single-point analog ground (star ground
point) at AGND, separate from the logic ground.
Connect all other analog grounds and DGND to this
star ground point. Do not connect other digital system
grounds to this single-point analog ground. The ground
return to the power supply for this ground should be
low impedance and as short as possible for noise-free
operation. Bypass all supplies to ground with high
quality capacitors as close as possible to the device.
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