PRELIMINARY ISD1700 SERIES
Publication Release Date: Nov 6, 2008
- 11 -
Revision 1.31
FUNCTIONS
[3]
PIN
PDIP /
TSOP
NAME
SOIC
SP- 13 6
SP-
: The negative Class D PWM provides a differential output with SP+
pin to directly drive an 8
Ω
speaker or typical buzzer. During power down
or not used, this pin is tri-stated. This output can be controlled by D8 of
APC register. The factory default is set at on state.
V
CCP
14 7
Power Supply for PWM Speaker Driver
: It is important to have a
separate path for each power signal including V
CCD
, V
CCA
and V
CCP
to
minimize the noise coupling. Decoupling capacitors to V
SSP1
and V
SSP2
should be as close to the device as possible. The V
CCP
supply and V
SSP
ground pins have large transient currents and need low impedance
returns to the system supply and ground, respectively.
SP+ 15 8
SP+:
The positive Class D PWM provides a differential output with the
SP- pin to directly drive an 8
Ω
speaker or typical buzzer. During power
down or not used, this pin is tri-stated. This output can be controlled by
D8 of APC register. The factory default is set at on state.
V
SSP1
16 9
Ground for Positive PWM Speaker Driver
: It is important to have a
separate path for each ground signal including V
SSA
, V
SSD
, V
SSP1
and V
SSP2
to minimize the noise coupling.
AUD /
AUX
17 10
Auxiliary Output
: Depending upon the D7 of APC register, this output is
either an AUD or AUX output. AUD is a single-ended current output,
whereas AUX is a single-ended voltage output. They can be used to drive
an external amplifier. The factory default is set to AUD. This output can be
powered down by D9 of APC register. The factory default is set to On
state. For AUD output, there is a ramp up at beginning and ramp down at
the end to reduce the pop.
AGC 18 11
Automatic Gain Control (AGC)
: The AGC adjusts the gain of the
preamplifier dynamically to compensate for the wide range of microphone
input levels. The AGC allows the full range of signals to be recorded with
minimal distortion. The AGC is designed to operate with a nominal
capacitor of 4.7 µF connected to this pin.
Connecting this pin to ground (V
SSA
) provides maximum gain to the
preamplifier circuitry. Conversely, connecting this pin to the power supply
(V
CCA
) provides minimum gain to the preamplifier circuitry.
VOL
19 12
Volume:
This control has 8 levels of volume adjustment. Each Low going
pulse decreases the volume by one level. Repeated pulses decrease
volume level from current setting to minimum then increase back to
maximum, and continue this pattern. During power-up or
RESET
, a
default setting is loaded from non-volatile configuration. The factory
default is set to maximum. This output can also be controlled by <D2:D0>
of APC register. This pin has an internal pull-up device
[1]
and an internal
debounce (T
Deb
)
[2]
for start and end allowing the use of a push button
switch.
R
OSC
20 13
Oscillator Resistor
: A resistor connected from R
OSC
pin to ground
determines the sample frequency of the device, which sets the duration.
Please refer to the Duration Section for details.
