RT0805&RT0805B
Single supply voltage ring slic: +3.3V to +5.0V
Integral high efficiency DC/DC converter.
Highly integrated with ringing generator.
Tip/Ring polarity reversal.
2 / 4 wire conversion
Constant current feed
High performance with low price
Excellent sound quality
On-Hook Transmission for caller line ID.
Designed for GSM network
Easy to use, with a minimum number of external components.
Related products
Features：
Applications：
Index：
Description：
The R-TONE RT0805 is a single Subscriber Line Interface Circuit (SLIC).
The combination of features and packaging offers extremely efficient use of board area, saving significant system size and cost, minimising time to market for Telephony Systems developers.
The RT0805 has been designed to work with loop lengths of typically 1.0km
The RT0805 has integral dc/dc converter and ringing generation thus providing all the line powering requirements from a single supply.24V(off-hook)and 48V(on-hook)and 75V(ringing).
The RT0805 requires a minimum of external components, making it ideal for low line count, short loop length applications, such as WLL Terminal (WLL), Fixed Cellular Terminals (FCT), Fixed Wireless Terminals (FWT) and Internet Telephony (VoIP).
The RT0805 has an integral DC/DC converter, which generates the battery voltage in the device. This means that only a single supply of between +3.3V to +5.0V is needed, unlike conventional SLICs which will also need a battery voltage of anything between 20V and60V ( 75V for ringing). This confers a significant cost, space and time to market benefit on the equipment designer.
Parameter
Symbol
Min
Max
Units
1
DC Supply Voltage
VCC
-0.3
5.5
V
2
Maximum Power Dissipation, Off Hook @ 25oC
PSLIC
1.2
W
3
Operating Temperature
TOP
0
70
OC
4
Storage Temperature
TS
-40
+100
OC
Characteristic
Sym
Min
Typ
Max
Units
Test Comments
Supply Current
ICC
40
50
mA
5V (on-hook)
3.3V(on-hook)
175
280
mA
5V (off-hook)
3.3V(off-hook)
during ring
180
220
mA
5V (during ring)
3.3V(during ring)
Constant current
Ibat
21
23
35
mA
Power Dissipation
Pd
30/850
mW
On/off hook (during 23mA Constant current)
Ringing voltage
Ving
130
VP-P
off-hook voltage
Vab
48
V
Supply current in power down
IPD
7
5
mA
mA
@ 5.0V
@ 3.3V
All DC Electrical Characteristics are over the Recommended Operating Conditions with VCC at +5.0V +1%,or +3.3V +1%, unless
otherwise stated.
2) Operating currents are dependent on the users application.
*Typical figures are at 25°C and are for design aid only. Not Guaranteed
Characteristic
Sym
Min
Typ
Max
Units
Test Comments
Two- Wire Impedance
Z0
600
Ω
Absolute Voltage Gain
T,R-VX
VR-T,R
-6
-6
0
0
6
6
dB
Relative Gain. Referenced to 1kHz
Gf
-0.5
+0.5
dB
Over frequency range 300 to
3400 Hz
Two-wire return loss
RL
30
dB
300-3400HZ，600R load
Four-wire return loss
THL
30
dB
300-3400HZ, 600R load
unbalanced to ground
60
dB
300-3400HZ，off-hook
common-mode rejection ratio
CMRR
45
55
dB
weighted noise
-75
dB
total harmonic distortion
THD
70
dB
300-3400HZ，off-hook
This applies to 3 phones with tone ringers or 2 phones with mechanical bells.
*Typical figures are at 25°C and are for design aid only.
Pin #
Name
Description
1
F/R
Forward/Reverse. A logic (L) will reverse the Tip and Ring voltage polarities.
2
25HZ
ringing frequency. to give the correct waveform with 20Hz to 25Hz ringing frequency.
3
RM
Ringing Mode. Sets bias conditions during ringing. Must be set to logic (H) during ringing. Logic (L) for other modes.
4
SHK
Switch Hook. Indicates an off-hook condition when at logic (H).
5
PD
Power Down DC/DC Converter. A logic (L) on this pin powers down the RT0805. DO NOT put logic (H) on this pin.
6
GNDPWR
DC/DC Ground. Ground input for the DC/DC converter.
7
+VPWR
DC/DC Supply. +5.0V or +3.3V input for the DC/DC converter.
8
Vbat
VBAT , connect a cap 33uf 100v.
9
VR
Audio In. Analog input signal from the Codec (which is output onTip and Ring). Connect via a 100nF capacitor
10
VX
Audio Out. This is the analog output signal (from Tip and Ring)
to the Codec. Connect via a 100nF capacitor.
11
NC
No Connection. Do not connect to this pin.
12
NC
No Connection. Do not connect to this pin.
13
RING (B)
Ring. Connects to the subscriber line Ring.
14
TIP (A)
Tip. Connects to the subscriber line Tip.
1 Ringing
The ringing signal is generated by switching the SLIC into ringing mode, by setting the RM pin high, and then toggling the F/R pin or 25Hz pin at the required frequency and cadence. The toggling of the F/R pin produces a balanced signal at Tip and Ring.
During ringing the integral DC/DC converter is switched produce a battery voltage of 75V.The slope of the edges on the ringing waveform is set internally to give the correct waveform with 20Hz to 25Hz ringing frequency.
2 Tip & Ring Polarity Reversal
If F/R is held at logic (H) (Forward) the d.c. voltage at Ring is negative with respect to Tip. If F/R is taken to logic (L) (Reverse) the voltage at Ring is positive with respect to Tip.
3 Switch Hook Detection
When an “off-hook” condition occurs during ringing, the ring-trip circuit on the RT0805 senses the loop current flowing and signals the off-hook condition on the SHK output. The SHK signal must be “de-bounced” (by the controlling processor) for 10ms to remove any spurious pulses.
Marking
Supply Voltage (V)
Constant current feed to line (mA)
Gain 2 Wire to VOUT
Gain VIN to 2Wire
Ringing voltage (Vp-p)
Supply Current, on-hook (mA)
Supply current, off-hook
(mA)
Ringing Load (REN)
Package
RT0805B
3.2~5.5
23~31
-6dB
6dB
120~135
50-35
310-270
3
SIL
