
V.22 bis Modem with AT Commands
CMX866
©
2008 CML Microsystems Plc
25
D/866/5
&Zn Sleep
States
Instructs the CMX866 to enter one of the following sleep states:
Syntax:
AT&Zn<CR>
Modifier Usage
n=0
'Zero-Power' state.
n=1
Powersave state.
The 'Zero-Power' state stops the crystal oscillator and removes power from the
V
BIAS
pin, for minimum power consumption. It takes about 30ms for the CMX866 to
become fully operational from the 'Zero-Power' state. However, the crystal
oscillator only takes about 1.4ms to become stable, so commands which do not
require the analogue parts of the DSP to be stable (V
BIAS
at ½V
DD
) can be given to
the on-chip µController after this time.
The Powersave state stops the internal clock distribution, but retains power to the
crystal oscillator and V
BIAS
circuit. Consequently, the CMX866 can become
operational from this state in about 10µs.
To enter either sleep state, the DTRN pin must already be inactive (high) and the
RD and RT pins inactive (low).