Tone Ringer. XR-T8205 Datasheet
The XR-TB205 Tone Ringer is primarily intended as a re-
placement for the mechanical telephone bell. The device
can be powered directly from telephone AC ringing voltage
or from a separate DC supply. An adjustable trigger level
is provided with an external resistor.
The XR-TB205 is designed for nominal 15 volt operation
and is available in an 8 pin D IL package.
FUNCTIONAL BLOCK DIAGRAM
Low Supply Current
Operates Directly From Telephone Line
Provides Single or Dual Tone Frequencies to Simulate
Operates from 15 to 30 Volts
Pin-to-Pin Compatible with MITEL ML8205
Alarm or Other Alerting Devices
Power Line Indicator
ABSOLUTE MAXIMUM RATINGS
-65°C to +150°C
DoC to 70°C
-.3 V <; V,N <; VDD +.3 V
DoC to 70°C
DoC to 70°C
The XR-T8205 Tone Ringer consists of two oscillator cir-
cuits, a dial reject filter and an amplifier to drive high impe-
dance audio transformer or plezo·eleetric transducers.
The power supply control circuit provides the hysteresis re-
quired to ensure positive triggering of the device and to pre-
vent transient triggering due to dial pulsing.
As the power supply voltage to the XR-T8205 is increased
up to the supply initiation voltage (VSll. oscillation begins.
The low frequency oscillator oscillates at a rate of FL con-
trolled by an external resistor and capacitor, connected
between Pins 3 and 4. The output of F L is internally con-
nected to the switching threshold cicuitry of the high fre-
Test Conditions: VOO = 17 V TA = 25°C, unless specified otherwise.
MIN. TYP. MAX.
Operating Supply Voltage
10 Operating Current
Supply Initiation Current
IT Trigger Current
Vo Output Voltage
t.fo Oscillator Frequency
No Load, RT = 6.8 kll
No Load, VOO = 21 V
0 2 4 6 8 10 12 14 16 18 K~l
Figure 1. SupplV Initiation Current (IS) VS RT
PIN AND FUNCTION DESCRIPTION
Power supply inputs - the device is designed to operate
from 15 to 30 volts.
This pin is provided to adjust power supply initiation
Rl, Cl low frequency oscillator external components.
Oscillation rate is determined using the relation FL ==
1/( 1.234 R l Cll where R is the value of the resistor con-
nected between Pin 3 and 4, and C is the value of the
capacitor connected between Pin 3 to Ground.
CH, RH High frequency oscillator external components.
When the output of the rate oscillator is high, the high
frequency oscillator oscillates at its normal rate, descri-
bes by the relation FH == 1/(1.515 RHCHI where R is the
value of the resistor connected between Pins 6 and 7, and
C is the value of the capacitor connected between Pin 6 to
Ground. When the output of
rate oscillator is low,
high frequency oscillator oscillation changes to FH =
The output amplifier of the XR-T8205 is capable of driving
a wide range of load impedances, when driven from a low
source impedance power supply.
Figure 2. Ring and Rate Oscillator Relationship