ISL5216_07 Datasheet, PDF (62/65 Pages) Intersil Corporation – Four-Channel Programmable Digital Downconverter

ISL5216
.
TABLE 55. BIT WEIGHTING FOR AGC LOOP FEEDBACK PATH
AGC
ACCUM
BIT
POSITION
GAIN
ERROR
INPUT
GAIN
ERROR
BIT
WEIGHT
AGC LOOP
FILTER GAIN
(MANTISSA)
AGC LOOP
FILTER
AGC LOOP FILTER GAIN
(EXPONENT)
GAIN
MULTIPLIER SHIFT SHIFT SHIFT SHIFT
(OUTPUT) = 0 = 4 = 8 = 15
AGC BIT WEIGHTS
TO
OUTPUT TO
LIMITS SECTION μP
31
2
2
2
2
0
0
30
2
2
2
2
3
E
E
29
2
2
2
2
2
E
E
28
2
2
2
2
1
E
E
27
15
=2
2
2
2
2
2
0
E
E
26
14
=1
1
2
2
2
1
-1
M
M
25
13
= 0.
0.
0.
2
2
2
0.
-2
M
M
24
12
=1
x
1
2
2
2
1
-3
M
M
23
11
=2
x
2
2
2
2
2
-4
M
M
22
10
=3
x
3
2
2
2
3
-5
M
M
21
9
=4
x
4
2
2
2
4
-6
M
M
20
8
=5
5
2
2
2
5
-7
M
M
19
7
=6
6
2
2
1
6
-8
M
M
18
6
=7
7
2
2
0.
7
-9
M
M
17
5
=8
8
2
2
1
8
-10
M
M
16
4
=9
9
2
2
2
9
-11
M
M
15
3
= 10
10
2
1
3
10
-12
M
14
2
= 11
11
2
0.
4
11
M
13
1
= 12
12
2
1
5
12
M
12
0
= 13
13
2
2
6
13
11
14
1
3
7
14
10
0.
4
8
G
9
1
5
9
G
8
2
6
10
G
7
3
7
11
G
6
4
8
12
G
5
5
9
13
G
4
6
10 14
G
3
7
11
G
G
2
8
12
G
G
1
9
13
G
G
0
10
14
G
G
AGC GAIN
RESOLUTION
(dB)
48
24
12
6
3
1.5
0.75
0.375
0.1875
0.09375
0.04688
0.02344
0.01172
0.00586
0.00293
0.00146
0.000732
0.000366
0.000183
0.0000916
0.0000458
0.0000229
0.0000114
0.00000572
0.00000286
Appendix A - Changes from HSP50216
The ISL5216 is pin and register compatible with the
HSP50216 facilitating an easy migration to the ISL5216 from
previous designs. Certain changes to hardware and possibly
software will be required to make this transition, however.
The listing below details the changes that should be
considered.
Pinout Changes
Thirteen previously no-connect pins have been assigned to
ISL5216 features. These are five JTAG pins (TDI, TDO,
TCLK, TMS, and TRST), four additional exponent bits (one
for each input bus: Am1, Bm1, Cm1 and Dm1), and four
additional channel-specific SYNCI inputs (SYNCI0, SYNCI1,
SYNCI2, and SYNCI3). All new input pins have weak pull-
ups/pull-downs to allow them to be left floating if not used.
In addition to the newly-assigned pins, some of the 3.3V
VCC lines of the HSP50216 have been changed to 2.5V on
the ISL5216. The ISL5216 now has VCC1 (2.5V core supply
pins) and VCC2 (3.3V for I/O pads).
See pin descriptions for additional information.
62
FN6013.3
July 13, 2007