msm7557 Oki Semiconductor, msm7557 Datasheet - Page 6

• Manufacturer Part Number: msm7557
• Description: Single Chip Msk Modem With Compandor For Cordless Telephone
• Manufacturer: Oki Semiconductor

¡ Semiconductor
(Continued)
Name
CMPI
CE3N
CE3P
RAIO
GND
DYN
RVO
CSH
TAO
CE1
CE2
RAI
SG
Compressor circuit input.
A 0.47 mF capacitor should be connected between CMPI and TVIO.
Dynamic range control input.
For an application of which V
modem transmit carrier level, typical input signal level, limiter clamp level and compandor
standard input level are up about 8dB to improve S/N ratio.
For an application of which V
To make easier interface with the RF part, one solution is to put digital "0" on DYN pin for both Base
Built-in analog signal ground. The DC voltage is half of V
To make this voltage source impedance lower and to ensure the device performance, it is necessary to
put a bypass capacitor of more than 1mF between SG and V
Ground pin, (0V).
Transmit analog signal output.
According to control data on ME and TVE, TAO is set as follows.
Receive voice signal output.
RVO pin state is defined by RVE control.
Capacitor connection pins to remove DC offset of the expander.
A 1 mF capacitor between SG pin and each pin should be connected.
Capacitor connection pins for the expander attack time and recovery time.
When DYN is digital "0" level, a 0.22 mF capacitor should be connected between CE3N and CE3P.
And when DYN is digital "1" level, a 0.47 mF capacitor should be connected between them.
Receive side amplifier input (RAI) and output (RAIO).
Second order RC-active filter is needed like TVIO and TVI.
Refer to TVIO and TVI pin description.
Capacitor connection pin to remove DC offset of the modem shaper circuit.
A 1 mF capacitor should be connected between GND pin and CSH.
station and Handset.
RVE
ME
0
0
1
0
1
Output disable (potential = SG)
Output enable
DD
DD
is always higher than 4.5 V (Base station), by setting DYN = "1",
is lower than 4.5 V (Hand-set) DYN shall be digital "0".
TVE
0
1
X
RVO
No signal output (potential = SG)
Voice signal output
MSK modulator output
Description
DD
DD
.
in close physical proximity to the device.
TAO
X : Don't care
MSM7557
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