cs5460 Cirrus Logic, Inc., cs5460 Datasheet - Page 10

• Manufacturer Part Number: cs5460
• Description: Single Phase Bi-directional Power/energy Ic
• Manufacturer: Cirrus Logic, Inc.

2.2 Performing Measurements
The CS5460 performs measurements of instanta-
neous current, instantaneous voltage, instantaneous
power, energy, RMS current, and RMS voltage.
These measurements are output as 24-bit signed
and unsigned data formats as a percentage of full
scale. The flow of data to perform these calcula-
tions is shown in Figure 5. All of these measure-
ments begin when a start conversion command is
given. The energy and RMS registers are then up-
dated every N conversions (or 1 computation cy-
cle) where N is the content of the Cycle Count
register. After the computation cycle has finished,
the DRDY bit in the Status and Mask register is set.
The INT pin will also become active if the DRDY
bit is unmasked.
Table 1 provides an example detailing the output
linearity. A computation cycle is derived from the
master
(MCLK/K)/(1024*N). Instantaneous calculations
are performed at a 4000 Hz rate where as, I
10
clock
L
1
N
and
R
To Service
1
Figure 4. Typical Connection Diagram (One-Phase 3-Wire)
R
its
2
L
2
470 nF
* Refer to Input Current Protection
frequency
500
RMS
100 µF
500
is
,
R
S
RP
0.1 µF
I
V
so, DRDY is set only after computation cycles are
complete (i.e. there is no indicator flag to indicate
when the instantaneous conversions are read; how-
ever, if the Cycle Count register were set to 1, all
output calculations would be instantaneous and
DRDY would indicate when instantaneous calcula-
tions were finished).
*
Table 1. Specification with MCLK = 4.096 MHz, K = 1,
RMS
0.1 µF
CP
CP
Output word
Calibration)
10
16
15
12
11
Max Input
V
I
Linearity
9
*
*
, and energy, are performed at a 1 Hz rate. Al-
Range
VIN+
VIN-
IIN+
IIN-
VREFIN
VREFOUT
(After
VA+
14
VA-
13
CS5460
10
DGND
CPUCLK
PFMON
RESET
XOUT
EOUT
SCLK
4
EDIR
VD+
SDO
XIN
SDI
INT
CS
3
and N = 4000.
10 k
Energy
0.1% of
reading
17
2
1
24
19
7
23
6
5
20
22
21
1000:1
0.1 µF
See Analog Characteristics
2.5 MHz to
20 MHz
Interface
Optional
Source
Serial
Clock
5 k
Data
0.1% of
reading
24-bits
Vrms
2:1
CS5460
DS279PP5
0.1% of
reading
500:1
Irms