MC33215B Freescale Semiconductor, MC33215B Datasheet - Page 10

• Manufacturer Part Number: MC33215B
• Manufacturer: Freescale Semiconductor

Specifications of MC33215B

• Max Transmitter Gain: 58dB
• Receiver Gain (max): 27dB
• Operating Temp Range: -20C to 70C
• Package Type: SDIP
• Pin Count: 42
• Operating Current: 15mA
• Operating Temperature Classification: Commercial
• Mounting: Through Hole
• Lead Free Status / Rohs Status: Not Compliant

15 mA of current is available at V
taken, V
is drawn from V
the loudspeaker amplifier, the voltage at V
below VLN. Although the measurements for Figure 6 are
done with R
for other dc settings.
by the voltage at VLN minus 1.0 V. This means that the
voltage at V
necessary to limit the voltage at V
peripheral circuits, a zener from V
the supply of the loudspeaker VLS is also connected to V
it is advisable that V
to a high loudspeaker output power at moderate line
currents. More details on this can be found in the handsfree
operation paragraph.
HANDSET OPERATION
basic telephone functions for the handset microphone and
earpiece. It also enables DTMF transmission.
Handset Microphone Amplifier
to the circuit via the differential input HM1 and HM2. The
microphone signal is amplified by the HMIC amplifier and
modulates the line current by the injection of the signal into
the line driver. This transfer from the microphone inputs to the
line current is given as 15/(R
transmit voltage gain A
inputs to the line of:
gain calculates as 47 dB.
from the stabilized microphone supply point VMC of 1.75 V
properly biased with resistors R
the setmaker to use an electret microphone with poor supply
rejection to reduce total system costs. Since the transmit gain
A
of set impedance and line impedance, the transmit gain is set
HM
10
For instance, at a line current of 20 mA a maximum of
As can be seen from Figure 6, the voltage at V
The high efficiency of the V
During handset operation, the MC33215 performs the
The handset microphone is to be capacitively connected
With the typical application and Z
In case an electret microphone is used, it can be supplied
100
is fixed by the advised R
90
80
70
60
50
40
30
20
10
0
0
A
CC
HM
will be 1.7 V below VLN. When not all this current
CC
REG1
+
I
VCC
A. Maximum Available Current at V
is limited by the external zener at VLN. If it is
CC
20
V
V
/l
= 365 k, the results are also globally valid
, but for instance only 1.0 mA for biasing of
line
HM
line
CC
(%)
+
does not exceed 8.0 V.
HM
R
I
VCC(max) (mA)
40
SLP
from the handset microphone
15
SLP
I
line
SLP
CC
11
HM1
(mA)
= 220
CC
/11), which makes a total
Freescale Semiconductor, Inc.
power supply contributes
CC
line
x
to Gnd can be added. If
For More Information On This Product,
CC
and R
60
. If all this current is
Z
Z
= 600
line
line
in order to protect
and the constraints
Figure 6. Available Current at V
HM2
CC
)
x Z set
Go to: www.freescale.com
. This allows
will be 1.2 V
Z set
80
CC
the transmit
CC
is limited
MC33215
CC
100
,
by adjusting the sensitivity of the handset microphone by
adjusting the resistors R
adjust the gain by including series resistors towards the Pins
HM1 and HM2.
C
low pass filter can be created by putting capacitors in parallel
with the resistors R
handset microphone inputs loaded with a capacitively
coupled 200
loaded with a microphone powered by VMC. Although VMC
is a stablized supply voltage, it will contain some noise which
can be coupled to the handset microphone inputs, especially
when a microphone with a poor supply rejection is used. An
additional RC filter on VMC can improve the noise figure, see
also the base microphone section.
Handset Earpiece Amplifier
the RXO output. Here, the receive signal is available which is
amplified from the line via the sidetone network and the R
and EAR amplifiers. The sidetone network attenuates the
receive signal from the line via the resistor divider composed
of R
attenuation in the typical application by this network equals
24.6 dB. Then the signal from the sidetone network is
pre–amplified by the amplifier R
This amplifier also performs the AGC and MUTE functions,
see the related paragraphs. Finally, the signal is amplified by
the noninverting voltage amplifier EAR. The overall receive
gain A
With: A
the earpiece is close to 0 dB.
ratio R
confidence tone level during dialing which leaves R
chosen freely. A high pass filter is introduced by the coupling
capacitor C
HM1
A high pass filter is introduced by the coupling capacitors
The transmit noise is measured as –72 dBmp with the
The handset earpiece is to be capacitively connected to
For the typical application an overall gain from the line to
The receive gain can be adjusted by adjusting the resistor
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
SLB
A
0
A
and C
RX
RX
ST
RXI
RXO
from the line to the earpiece output then follows as:
and Z
CC
= Attenuation of the Sidetone Network
+
= Gain of the Pre–Amplifier R
RXI
HM2
over R
V
V
together with the input impedance of the input
. In a real life application, the inputs will be
RXO
20
line
bal
in combination with the input impedance. A
MOTOROLA ANALOG IC DEVICE DATA
, see also the sidetone section. The
HM1
+
GRX
B. Voltage Drop to V
and R
A
HM1
. However, R
ST
40
I
I
VCC
VCC(max)
I
line
x A
and R
HM2
at 98% of
x
(mA)
with a typical gain of 6.0 dB.
RXI
.
HM2
60
x
. It is not advised to
RXO
CC
x
1
I
I
VCC
VCC(max)
)
also sets the
at 50% of
80
R
R
RXO
GRX
V
V
CC
CC
GRX
to VLS
Open
to be
100
x