
1-5
1—HARDWARE
ISD-SR3000
ISD
Figure 1-4:Connections for an External Crystal Oscillator
Keep stray capacitance and inductance, in the oscillator circuit, as low as possible. The crystal
resonator, and the external components, should be as close to the X1 and X2/CLKIN pins as
possible, to keep the trace lengths in the printed circuit to an absolute minimum.
You can use crystal oscillators with maximum load capacitance of 20pF, although the oscillation
frequency may differ from the crystal’s specified value.
The following table lists the components in the crystal oscillator circuit.
Table 1-2: Components of Crystal Oscillator Circuit
Component
Values
1.2.3
Power-down mode is useful during a power failure or in a power-saving model when the power
source for the processor is a backup battery or in battery-powered devices, while the processor
is in idle mode.
In power-down mode, the clock frequency of the ISD-SR3000 processor is reduced and some
of the processor modules are deactivated. As a result, the ISD-SR3000 consumes considerably
less power than in normal-power mode. Recognition is not active during power-down mode, so
the ISD-SR3000 must return to normal power mode to resume speech recognition.
POWER-DOWN MODE
Note
: In power-down mode all the chip select signals, CS0 to CS3, are set to 1. To guarantee that there
is no current flow from these signals to the Flash devices, the power supply to these devices must not be
disconnected
.
The ISD-SR3000 stores voicetags and all memory management information in Flash memory.
When Flash memory is used for memory management, power does not need to be maintained
to the processor to preserve stored voicetags.
To keep power consumption low during power-down mode, the RESET, MWCS, MWCLK and
MWDIN signals should be held above V
CC
– 0.5 V or below V
SS
+ 0.5 V.
Tolerance
Crystal Resonator
4.096MHz
Resistor R1
10M
5%
Capacitors C1, C2
33pF
20%
X1
X2
C1
R1
C2
ISD-SR3000
crystal