Rainbow Electronics ISD5100 - Manual (Page 50)

ISD5100 – SERIES
- 50 -
A0, A1 (Address Pins)
These two pins are normally strapped for the desired address that the ISD5100 Series will have on the
I
2 C serial interface. If there are four of these devices on the bus, then each must be strapped
differently in order to allow the Master device to address them individually. The possible addresses
range from 80h to 87h, depending upon whether the device is being written to, or read from, by the
host. The ISD5100 Series have a 7-bit slave address of which only A0 and A1 are pin
programmable. The eighth bit (LSB) is the R/W bit. Thus, the address will be 1000 0xy0 or 1000
0xy1. (See the table in
section 7.3.1 on page 13.)
7.6.2. Analog I/O Pins
MIC+, MIC- (Microphone Input +/-)
The microphone input transfers the voice signal to the on-chip AGC preamplifier or directly to the ANA
OUT MUX, depending on the selected path. The direct path to the ANA OUT MUX has a gain of 6 dB
so a 208 mV p-p signal across the differential microphone inputs would give 416 mV p-p across the
ANA OUT pins. The AGC circuit has a range of 45 dB in order to deliver a nominal 694 mV p-p into
the storage array from a typical electret microphone output of 2 to 20 mV p-p. The input impedance is
typically 10kΩ.
ANA OUT+, ANA OUT- (Analog Output +/-)
This differential output is designed to go to the microphone input of the telephone chip set. It is de-
signed to drive a minimum of 5 kΩ between the “+” and “–” pins to a nominal voltage level of 694 mV
p-p. Both pins have DC bias of approximately 1.2 VDC. The AC signal is superimposed upon this
analog ground voltage. These pins can be used single-ended, getting only half the voltage. Do NOT
ground the unused pin.
+
Internal to the device
NOTE: f
CUTOFF
=
2 πRaC
COUP
1
FTHRU
C
COUP
=0.1 µF Ra=10k Ω
6 dB
MIC IN
10k Ω 0.1
1.5k Ω
Electret
Microphone
WM-54B
Panasonic
220 µF
1.5k Ω
1.5k Ω
AGC
MIC+
MIC-