Cirrus Logic CS5460A, Руководство пользователя

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CS5460A
14 DS284PP4
are expressed in two’s complement format. The
24-bit data words in the CS5460A output registers
represent values between 0 and 1 (for unsigned out-
put registers) or between -1 and +1 (for signed out-
put registers). A register value of 1 represents the
maximum possible value. Note that a value of 1.0
is never actually obtained in the registers of the
CS5460A. As an illustration, in any of the signed
output registers, the maximum register value is
[(2^23 - 1) / (2^23)] = 0.999999880791. After each
A/D conversion, the CRDY bit will be asserted in
the Status Register, and the INT pin will also be-
come active if the CRDY bit is unmasked (in the Mask Register). The assertion of the CRDY bit in-
dicates that new instantaneous 24-bit voltage and
current samples have been collected, and these two
samples have also been multiplied together to pro-
vide a corresponding instantaneous 24-bit power
sample .
Table 1 conveys the typical relationship between
the differential input voltage (across the “+” and
“-” input pins of the voltage channel input) and the
corresponding output code in the Instantaneous
Voltage Register. Note that this table is applicable
for the current channel if the current channel’s
PGA gain is set for the “10x” gain mode.
VOLTAGE
∆Σ
SINC2 +
x
V *
gn
x
V *
CURRENT
SINC4
+
x
I *
gn
x x
TBC *
DELAY
REG
DELAY
REG
FIR HPF
APF
Configuration Register *
PC[6:0] Bits
x
I *
RMS
N
V *
RMS
N
Σ
÷÷÷÷
4096
E to F
E *
E
E
out
dir
PULSE-RATE*
* DENOTES REGISTER NAME
∆Σ
HPF
APF
FIR
SINC2
I *
P*
N
SINC2
-
-
I
ACoff
*
I
DCoff
*
V
ACoff
*
V
DCoff
*
+
P
off
*
÷
N
÷ N
Figure 3. Data Flow.
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
Frequency (Hertz)
Ga
in
(d
B)
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Figure 4. Voltage Input Filter Characteristics
-2.5
-2
-1.5
-1
-0.5
0
0.5
0 200 400 600 800 1000 1200 1400 1600 1800 2000
Ga
in
(d
B
)
Frequency (Hertz)
Figure 5. Current Input Filter Characteristics