APPLICATION CIRCUIT
+5 V
RTRIP1
C
RT
1.0 µF
R
RT2
42 kΩ
R
RT1
715 k
Ω
C
AX
= 2.2 nF
RFA = 50
Ω
TIP
U2
BAT1
U3
RING
RFB = 50
Ω
D4
RTRIP2
U1
Le79R101
A(TIP)
HPA
HPB
B(RING)
RD
RSGH
RSGL
VTX
VCC
VNEG
R
D
66 kΩ
R
SGH
short
R
SGL
open
V
TX
-5 V
D3
C
HP
18 nF
R
T1
125 k
Ω
R
RX
R
T2
C
T
125 k
Ω
250 kΩ
RSN
R
DC1
50 kΩ
RDC
R
DCR1
R
DC2
50 kΩ
C
DC
820 nF
C
DCR
10 nF
R
DCR2
15 kΩ
V
RX
CBX = 2.2 nF
RYOUT1
RYOUT2
RYE
RYOUT1
RYOUT2
RYE
RDCR
15 kΩ
D1
BAT1
0.1 µF
D2
BAT2
0.1 µF
BGND
VBAT2
VBAT1
C1
C2
C3
D1
D2
E1
DET
VRING
RREF
AGND/
DGND
C1
C2
C3
D1
D2
E1
DET
See note below.
BATTERY
GROUND
Assumptions:
1. Vring is 0.65 Vrms for 65 Vrms
ringing
2. 25 mA I
LOOP
3. 75 mA Ringing Current Limit
4. 5.2 KΩ High Battery Loop Threshold
5. 1200
Ω
Ringing Loop Threshold
6. 600
Ω
Two-wire Impedance, 600
Ω
Z
L
7. G
42L
= 1
8. -95 V BAT1, -24 V BAT2
DIGITAL
GROUND
ANALOG
GROUND
Note:
The input should be sinusoidal with less than
±
1 V peak amplitude.
U2, U3 - TECCOR BATTRAX P1001SC protector or TISP61089AD from Power Innovation. For battery voltages below 80 V, see Le79R79 for
alternate protection.
D3, D4: 1A, 100 V
Le79R101 Data Sheet
19
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
