Cirrus Logic CS5467 - Manual (Page 23)

CS5467
DS714F3 23
7. USING THE CS5467
7.1 Initialization
The CS5467 uses a power-on-reset circuit (POR) to
provide an internal reset until the analog voltage reach-
es 4.0 V. The RESET input pin can also be used by the
application circuit to reset the part.
After RESET is removed and the oscillator is stable, an
initialization program is executed to set the default reg-
ister values.
A Software Reset command is also provided to allow
the application to run the initialization program without
removing power or asserting RESET.
The application should avoid sending commands during
initialization. The DRDY bit in the Status register indi-
cates when the initialization program has completed.
7.2 Power-down States
The CS5467 has two power-down states, stand-by and
sleep. In the stand-by state, all circuitry except the volt-
age reference and crystal oscillator is powered off. In
sleep state, all circuitry except the instruction decoder is
powered off.
To return the device to the active state, send a Wake-
up/Halt command to the device. When returning from
stand-by mode, registers will retain their contents prior
to entering the stand-by state. When returning from
sleep mode, a complete initialization occurs.
7.3 Voltage Tamper Correction
The CSS5467 provides compensation for meter tam-
pering on voltage channels.
If the application detects that the voltage input has been
impaired it may choose to use the fixed internal RMS
voltage reference by setting the VFIX bit in the Modes
register. The value of this reference (VF
RMS
) is by de-
fault 0.707107 (full-scale RMS) but can be changed by
the application program. (See figure
9 )
Figure 9. Fixed RMS Voltage Selection