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CS5460A-BS 参数 Datasheet PDF下载

CS5460A-BS图片预览
型号: CS5460A-BS
PDF下载: 下载PDF文件 查看货源
内容描述: 单相双向功率/电能IC [Single Phase Bi-Directional Power/Energy IC]
分类和应用:
文件页数/大小: 54 页 / 879 K
品牌: CIRRUS [ CIRRUS LOGIC ]
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CS5460A  
result from one of several result registers. The first  
8 SCLKs are used to clock in the command to de-  
termine which register is to be read. The last 24  
SCLKs are used to read the desired register. After  
reading the data, the serial port remains in the ac-  
tive state, and waits for a new command to be is-  
sued. (See Section 3 for more details on reading  
register data from the CS5460A).  
cycles data acquisition mode, the CS5460A will  
continue to perform A/D conversions on the volt-  
age/current channels, as well as all subsequent  
calculations, until:  
1) the ‘Power-Up/Halt’ command is received  
through the serial interface, or  
2) loss of power, or  
3) the RS bit in the Configuration Register is as-  
serted (‘software reset’), or  
2.2.3 Continuous Computation Cycles  
(C=1)  
4) the /RESET pin is asserted and then de-assert-  
ed (‘hardware reset’).  
When C = 1, the CS5460A will perform conversions  
in ‘continuous computation cycles’ data acquisition  
mode. Based on the information provided in the Cy-  
cle Count Register, computation cycles are repeat-  
edly performed on the voltage and current channels  
(after every N conversions). Computation cycles  
cannot be started/stopped on a ‘per-channel’ basis.  
After each computation cycle is completed, DRDY  
is set. Thirty-two SCLKs are then needed to read a  
register. The first 8 SCLKs are used to clock in the  
command to determine which results register is to  
be read. The last 24 SCLKs are used to read out the  
24-bit calculation result. While in this acquisition  
mode, the designer/programmer may choose to ac-  
quire (read) only those calculations required for  
their particular application, as DRDY repeatedly in-  
dicates the availability of new data. Note again that  
the MCU firmware must reset the DRDY bit to “0”  
before it can be asserted again.  
2.3 Basic Application Circuit  
Configurations  
Figure 6 shows the CS5460A connected to a ser-  
vice to measure power in a single-phase 2-wire  
system operating from a single power supply. Note  
that in this diagram the shunt resistor used to mon-  
itor the line current is connected on the “Line” (hot)  
side of the power mains. In most residential power  
metering applications, the power meter’s cur-  
rent-sense shunt resistor is intentionally placed on  
the ‘hot’ side of the power mains in order to help  
detect any attempt by the subscriber to steal pow-  
er. In this type of shunt-resistor configuration, note  
that the common-mode level of the CS5460A must  
be referenced to the hot side of the power line. This  
means that the common-mode potential of the  
CS5460A will typically oscillate to very high posi-  
tive voltage levels, as well as very high negative  
voltage levels, with respect to earth ground poten-  
tial. The designer must therefore be careful when  
attempting to interface the CS5460A’s digital out-  
put lines to an external digital interface (such as a  
LAN connection or other communication network).  
Such digital communication networks may require  
that the CMOS-level digital interface to the meter is  
referenced to an earth-ground. In such cases, the  
CS5460A’s digital serial interface pins must be iso-  
lated from the external digital interface, so that  
there is no conflict between the ground references  
of the meter and the external interface. The  
CS5460A and associate circuitry should be en-  
closed in a protective insulated case when used in  
this configuration, to avoid risk of harmful electric  
shock to humans/animals/etc.  
Referring again to Figure 3, note that within the  
Irms and Vrms data paths, prior to the square-root  
operation, the instantaneous voltage/current data  
2
is low-pass filtered by a Sinc filter. Then the data  
is decimated to every Nth sample. Because of the  
2
Sinc filter operation, the first output for each chan-  
nel will be invalid (i.e. all RMS calculations are in-  
valid in the ‘single computation cycle’ data  
acquisition mode and the first RMS calculation re-  
sults will be invalid in the ‘continuous computation  
cycles’ data acquisition mode). However, all ener-  
gy calculations will be valid since energy calcula-  
2
tions do not require this Sinc operation.  
If the ’Start Conversions’ command is issued to the  
CS5460A (see Section 4.1, Commands (Write  
Only)), and if the ‘C’ bit in this command is set to a  
value of ‘1’, the device will remain in its active state.  
Once commanded into continuous computation  
Figure 7 shows how the same single-phase  
two-wire system can be metered while achieving  
16