PJ34118
Voice Switched Speakerphone Circuit
1-20
2003/10.rev.A
he PJ34118 Voice Switched Speakerphone Circuit
incorporates the necessary amplifiers, attenuators, level
detectors, and control algorithm to form the heart of a
high quality hands-free speakerphone system. Included are a
microphone amplifier with adjustable gain and MUTE
control, Transmit and Receive attenuators which operate in a
complementary manner, level detectors at both input and
output of both attenuators, and background noise monitors for
both the transmit and receive channels. A Dial Tone Detector
prevents the dial being attenuated by the Receive background
noise monitor circuit. Also included are two line drive
amplifiers which can be used to form a hybrid network in
conjunction with an external coupling transformer. A high-
pass filter can be used to filter out 60Hz noise in the receive
channel, or for other filtering functions .A Chip Disable pin
permits powering down the entire circuit to conserve power
on long loops where loop current is at a minimum.
The PJ34118 may be operated from a power supply, or it can
be powered from the telephone line, requiring typically
5.0mA. The PJ34118 can be interfaced directly to Tip and
Ring (through a coupling transformer) for stand-alone
operation, or it can be used in conjunction with a handset
speech network and/or other features of a featurephone.
Improved attenuator gain range: 52dB between transmit
and receive.
Low voltage operation for line-powered applications
(3.0-6.5V)
4-point signal sensing for improved sensitivity
Background noise monitors for both transmit and receive
paths
Microphone amplifier gain set by external resistors-mute
function included
Chip disable for active/standby operation
On board filter pinned-out for user defined function
Dial tone detector to inhibit receive idle mode during dial
tone presence
Standard 28-pin plastic DIP package and SOP package
available
Compatible with PJ34119 speaker amplifier
T
DIP-28 SOP-28
SIMPLIFIED BLOCK DIAGRAM
FEATURES
Pin:1.Fo 11.Mci
21.Rxi
2.Fi 12.Mut
22.Rxo
3.Cd 13.Vlc
23.Tli2
4.Vcc 14.Ct 24.Tlol
5.Hto+ 15.VB 25.Rlol
6.Hto- 16.Cpt 26.Rlil
7.Hti 17.Tli2
27.Cpr
8.Txo 18.Tlo2
28.Gnd
9.Txi 19.Rlo2
10.Mco 20.Rli2
Device
Operating Temperature
Package
PJ34118CD DIP-28
PJ34118CS
-20+85
SOP-28
ORDERING INFORMATION
PJ34118
Voice Switched Speakerphone Circuit
2-20
2003/10.rev.A
Parameter Value
Units
Supply voltage (pin 4)
-1.0, +7.0
Vdc
Voltage at CD (pin 3), MUT (pin 12)
-1.0,Vcc +1.0
Vdc
Voltage at VLC (pin 13)
-1.0Vcc +0.5
Vdc
Voltage at TXI (pin 9),RXI (pin 21),FI(pin 2)
-0.5, Vcc +0.5
Vdc
Storage temperature range
-65 to +150
Parameter Min.
Typ.
Max.
Units
Supply voltage (pin 4) (see Text)
3.5
-
6.5
Vdc
CD input (pin 3), MUT input (pin 12)
0
-
Vcc
Vdc
I
VB
current (pin 15)
-
-
500
A
VLC (pin 13)
0.3xV
B
- V
B
Vdc
Attenuator input signal voltage (pin 9,21)
0
-
350
mVrms
Microphone amplifier, Hybrid amplifier gain
0
-
40
dB
Load current @RXO, TXO (pins 8,22)
@MCO (pin 10)
@HTO-, HTO+ (pin 6,5)
0
0
0
-
-
-
2.0
1.0
5.0
mA
Ambient operating temperature range
-20
-
+60
Parameter Symbol
Min.
Typ.
Max.
Units
POWER SUPPLY
Vcc supply current (Vcc=6.5V, CD=0.8V)
(Vcc=6.5V,CD=2.0V)
Icc -
-
5.5
600
8.0
800
mA
A
CD input resistance (Vcc=V
CD
=6.5V)
CD input voltage - High
- Low
R
CD
V
CDH
V
CDL
50
2.0
0
90
-
-
-
Vcc
0.8
K
Vdc
Vdc
V
B
output voltage (Vcc=3.5V)
(Vcc=5.0V)
V
B
-
1.8
1.3
2.1
-
2.4
Vdc
V
B
output resistance (I
VB
=1.0mA) R
OVB
- 400 -
V
B
power supply rejection ratio (C
VB
=220F,f=1.0KHz) PSRR
- 54 - dB
ATTENUATORS (T
A
=+25)
Receive attenuator gain (f=1.0KHz, V
LC
=V
B
)
Rx model, RXI=150mVrms (Vcc=5.0V)
Rx model, RXI=150mVrms (Vcc=3.5V)
Gain change Vcc=3.5V versus Vcc=5.0V
AGC gain change Vcc=2.8V versus Vcc=5.0V*
Idle model, RXI=150mVrms
Range (Rx to Tx model)
G
RX
G
RX
G
RX1
G
RX2
G
RX1
G
RX3
+4.0
+4.0
-0.5
-
-22
49
+6.0
+6.0
0
-25
-20
52
+8.0
+8.0
+0.5
-15
-17
54
dB
Volume control range (Rx model, 0.3V
B
<V
LC
<V
B
) V
CR
27 35 - dB
RXO DC voltage (Rx model)
V
RXO
- VB - Vdc
RXO DC voltage (Rx to Tx model)
V
RXO
- 10
150 mV
RXO high voltage (Iout=-1.0mA RXI=V
B
+1.5V) V
RXOH
3.7 -
- Vdc
RXO low voltage (Iout=+1.0mA, RXI=V
B
-1.0,
Output measured with respect to V
B
)*
V
RXOL
- -1.5 -1.0 Vdc
RXI input resistance (RXI<350mVrms)
R
RXI
7.0 10 14 K
ABSOLUTE MAXIMUM RATINGS
RECOMMENDED OPERATING LIMITS
ELECTRICAL CHARACTERISTICS
(T
A
=+25,Vcc=5.0V, CD 0.8V, unless noted)
PJ34118
Voice Switched Speakerphone Circuit
3-20
2003/10.rev.A
Parameter Symbol
Min.
Typ.
Max.
Units
ATTENUATORS-continued (T
A
=+25)
Transmit attenuator gain (f=1.0KHz)
Tx model , TXI=150mVrms
Idle model, TXI=150mVrms
Range (Tx to Rx model)
G
TX
G
TXI
G
TXI
+4.0
-22
49
+6.0
-20
52
+8.0
-17
54
dB
TXO DC voltage (Tx model)
V
TXO
- V
B
- Vdc
TXO DC voltage (Tx to Rx model)
V
TXO
- 30
150 mV
TXO High voltage (Iout=-1.0mA TXI=V
B
+1.5V) V
TXOH
3.7 -
- Vdc
TXO Low voltage (Iout=+1.0mA TXI=V
B
-1.0V,
Output measured with respect to V
B
)*
V
TXOL
- -1.5 -1.0 Vdc
TXI input resistance (TXI<350mVrms)
R
TXI
7.0 10 14 K
Gain tracking (G
RX
+G
TX
,@Tx,Idle,Rx)* G
TR
- 0.1 - dB
*see text for explanation.
ATTENUATOR CONTROL(T
A
=+25)
C
T
voltage (pin 14-V
B
)
Rx model (V
LC
=V
B
)
Idle model
Tx model
V
CT
-
-
-
+240
0
-240
-
-
-
mV
C
T
source current(switching to Rx mode)
I
CTR
-85 -60 -40 A
C
T
sink current(switching to Tx mode)
I
CTT
+40 +60 +85 A
C
T
slow idle current
I
CTS
- 0 - A
C
T
fast idle internal resistance
R
FI
1.5 2.0 3.6 K
V
LC
input current
I
VLC
- -60 - nA
Dial tone detector threshold
V
DT
10 15 20 mV
MICROPHONE AMPLIFIER(T
A
=+25,V
MUT
0.8V,A
VCL
=31dB unless otherwise noted)
Output offset (V
MCO
-V
B
, feedback R=180K) MCOvos
-50
0
+50
mVdc
Open loop gain (f<100Hz)
A
VOLM
70 80
- dB
Gain bandwidth
GBW
M
- 1.0 - MHz
Output High voltage(Iout=-1.0mA, Vcc=5.0V)
V
MCOH
3.7
-
- Vdc
Output Low voltage(Iout=+1.0mA)
V
MCOL
-
- 200
mVdc
Input bias current (@MCI)
I
BM
- -40 - nA
Muting (Gain) (f=1.0KHz, V
MUT
=2.0V)
(300Hz<f<10KHz)
GMT -55
-
-
-68
-
-
dB
MUT input resistance (Vcc=V
MUT
=6.5V) R
MUT
50 90 - K
MUT Input-High
V
MUTH
2.0
- Vcc Vdc
MUT Input-Low
V
MUTL
0 - 0.8 Vdc
Distorrion(300Hz<f<10KHz) THD
M
- 0.15 - %
HYBRID AMPLIFIERS(T
A
=+25)
HTO-offset(V
HTO-
-V
B
,Feedback R=51K) H
VOS
-20 0 +20 mVdc
HTO- to HTO+ offset (Feedback R=51K) HB
VOS
-30 0 +30 mVdc
Open loop gain(HTI to HTO-, f<100Hz)
A
VOLH
60 80 - dB
Gain bandwidth
GBW
H
- 1.0 - MHz
Closed loop gain(HTO- to HTO+)
A
VCLH
-0.35 0 +0.35 dB
Input bias current(@HTI)
I
BH
- -30 - nA
HTO- High voltage (Iout=-5.0mA)
V
HT-H
3.7 -
- Vdc
HTO- Low voltage (Iout=+5.0mA)
V
HT-L
- - 250
mVdc
HTO+ High voltage (Iout=-5.0mA)
V
HT+H
3.7 -
- Vdc
HTO+ Low voltage (Iout=+5.0mA)
V
HT+L
- - 450
mVdc
Distortion(300Hz<f<10KHz, see Figure 1)
THD
H
- 0.3 - %
ELECTRICAL CHARACTERISTICS
(TA=+25,Vcc=5.0V, CD =0.8V, unless noted)
PJ34118
Voice Switched Speakerphone Circuit
4-20
2003/10.rev.A
Parameter Symbol
Min.
Typ.
Max.
Units
LEVEL DETECTORS AND BACKGROUND NOISE MONITORS (T
A
=+25)
Transmit-Receive switch threshold
(Ratio of current at RLI1 + RLI2 to 20A
at TLI1 + TLI2 to switch from Tx to Rx)
I
TH
0.8 1.0 1.2
Source current at RLO1, RLO2, TLO1, TLO2
I
LSO
- -2.0 - mA
Sink current at RLO1, RLO2, TLO1, TLO2
I
LSK
- 4.0 - A
CPR, CPT output resistance (Iout=1.5mA)
R
CP
- 35 -
CPR, CPT leakage current
I
CPLK
- -0.2 - A
FILTER (T
A
=+25)
Voltage offset at FO (V
FO
-V
B
, 220K from V
B
to FI)
FO
VOS
-200 -90
0 mV
FO sink current
I
FO
150 260 400 A
FI bias current
I
FI
- -50 - nA
SYSTEM DISTORTION(T
A
=+25, f=1.0KHz)
Rx mode (from FI to RXO, FO connected to RXI)
THD
R
- 0.5 3.0 %
Tx mode (from MCI to HTO-/HTO+, includes Tx attenuator)
THD
T
- 0.8 3.0 %
1. All currents into a device pin are positive, those out of a pin are negative. Algebraic convention rather than magnitude is used
to define limits.
FIGURE 1.HYBRID AMPLIFIER DISTORTION TEST
TEMPERATURE CHARACTERISTICS
Parameter
Typical Value
@25
Typical Change
20 to +60
Vcc supply current (CD=0.8V)
5.0mA
-0.3%/
Vcc supply current (CD=2.0V)
400A -0.4%/
V
B
output voltage (Vcc=5.0V)
2.1V
+0.8%/
Attenuator gain (Max Gain)
+6.0dB
0.0008dB/
Attenuator gain (Max attenuation)
-46dB
0.004dB/
Attenuator input resistance (@ TXI, RXI)
10K +0.6%/
Dial tone detector threshold
15mV
+20V/
CT source, sink current
60A -0.15%/
Microelectphone, Hybrid amplifier offset
0 mV
4.0V/
Transmit-Receive switching threshold
1.0
0.02%/
Sink current at RLO1, RLO2, TLO1, TLO2
4.0A -10nA/
Closed loop gain (HTO- to HTO+)
0 dB
0.001%/
PJ34118
Voice Switched Speakerphone Circuit
5-20
2003/10.rev.A
PIN DESCRIPTION
Pin Name
Description
1
FO
Filter output. Output impedance is less than 50 ohms.
2
FI
Filter input. Input impedance is greater than 1.0Mohm.
3
CD
Chip Disable. A logic low(<0.8V) sets normal operation. A logic high(>2.0V) disables the IC
to conserve power. Input impedance is norminally 90K.
4
Vcc
A supply voltage of +2.8 to +6.5 volts is required, at
5.0mA. As Vcc falls from 3.5 to
2.8volts, an AGC circuit reduces the receive attenuator gain by
25dB(when in the receive
mode).
5
HTO+
Output of the second hybrid amplifier. The gain is internally set at 1.0 to provide a
differential output, in conjunction with HTO-, to the hybrid transformer.
6
HTO-
Output of the frist hybrid amplifier. The gain of the amp is set by external resistors.
7
HTI
Input and summing node for the first hybrid amplifier . DC level is
V
B.
8
TXO
Output of the transmit attenuator. DC level is approximately V
B.
9
TXI
Input to the transmit attenuator. Max. Signal level is 350mVrms . Input impedance is 10K.
10
MCO
Output of the microphone amplifier. The gain of the amplifier is set by external resistors.
11
MCI
Input and summing node of the microphone amplifier. DC level is
V
B.
12
MUT
Mute input. A logic low(<0.8V) sets normal operation. A logic high(>2.0V) mutes the
microphone amplifier without affecting the rest of the circuit. Input impedance is norminally
90K.
13
VLC
Volume control input. When VLC=V
B
, the receive attenuator is at maximum gain when in the
receive mode. When VLC=0.3V
B
, the receive gain is down 35dB. Does not affect the transmit
mode.
14 C
T
An RC at this pin sets the response time for the circuit to switch modes.
15 V
B
An output voltage
Vcc/2. This voltage is a system ac ground, and biases the volume control.
A filter cap is required
16
CPT
An RC at this pin sete the time constant for the transmit background monitor.
17
TLI2
Input to the transmit level detector on the mike/speaker side.
18
TLO2
Output of the transmit level detector on the mike/speaker side, and input to the transmit
background monitor.
19
RLO2
Output of the receive level deterctor on the mike/speaker side.
20
RLI2
Input to the receive level deterctor on the mike/speaker side.
21
RXI
Input to the receive attenuator and dial tone detector. Max input level is 350mV RMS. Input
impedance is
10K.
22
RXO
Output of the receive attenuator. DC level is approximately V
B
.
23
TLI1
Input to the transmit level detector on the line side.
24
TLO1
Output of the transmit level detector on the line side.
25
RLO1
Output of the receive level detector on the line side, and input to the receive background
monitor.
26
RLI1
Input to the receive level detector on the line side.
27
CPR
An RC at this pin sets the time constant for the receive background monitor.
28
GND
Ground pin for the entire IC.
Note:Pin numbers are identical for the DIP package and SOP package.
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