SA9903B
OUTPUT SIGNALS
SERIAL DATA OUT (DO)
The DO pin is the serial data output pin for the SA9903B. The
Serial Clock (SCK) determines the data output rate. Data is
only transferred during on active chip select (CS). This output
is tri-state when CS is low.
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SPI - INTERFACE
DESCRIPTION
A serial peripheral interface bus (SPI) is a synchronous bus
used for data transfers between a micro controller and the
SA9903B. The pins DO (Serial Data Out), DI (Serial Data In),
CS (Chip Select), and SCK (Serial Clock) are used in the bus
implementation. The SA9903B is the slave device with the
micro controller the bus master. The CS input initiates and
terminates data transfers. A SCK signal (generated by the
micro controller) strobes data between the micro-controller
and the SCK pin of the SA9903B device. The DI and DO pins
are the serial data input and output pins for the SA9903B,
respectively.
MAINS VOLTAGE SENSE ZERO CROSSOVER
(FMO)
The FMO output generates a signal, which follows the mains
voltage zero crossings, see figure 4. The micro controller may
use the FMO to extract mains timing.
ELECTROSTATIC DISCHARGE (ESD) PROTECTION
The SA9903B Integrated Circuit's inputs/outputs are protected
against ESD.
REGISTER ACCESS
The SA9903B contains four 24 bit registers. The content
represents active energy, reactive energy, mains voltage and
mains frequency. The register addresses are shown in the
following table:
ID
1
2
3
4
Register
Active
Reactive
Voltage
Frequency
Header
A5 A4 A3 A2 A1 A0
bits
1
1
1
1
1
1
1
1
0
0
0
0
X
X
X
X
X
X
X
X
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
1
POWER CONSUMPTION
The power consumption rating of the SA9903B integrated
circuit is less than 25mW.
Voltage
FM0
+5V (V
DD
)
0V (V
SS
)
Dr-01498
Figure 4: Mains voltage zero corssover pin FMO
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