Is o la t e d Tra n s fo rm e r Drive r
fo r P CMCIA Ap p lic a t io n s
MAX845
TELEPHONE SUBSCRIBER LINE
ISOLATION
BARRIER
6.8V
D1
1k
2W
6
D2
1N5817
T1
1:2:1
1
V
CC
22k
22k
D1
IC2
TL431
5V @ 50mA
ISO OUTPUT
Q1
2N3906
0.1µF
C1
0.1µF
100k
IC1
100k
2M
ISO
GND
MAX845
4
8
3
SD
D2
FS
D3
1N5817
N.C.
100k
100k
680k
GND1
GND2
2
7
Q2
2N3904
Figure 7. 5V from Telephone-Subscriber Line
V
IN
ISOLATION
BARRIER
1CT:5CT
6
5V
24V UNREGULATED
10µF
V
CC
1
8
D1
D2
1N5817
IN
78L05
MAX845
GND
4
SD
OUT
GND1
GND2
7
R
I
L
OUT
1N5817
0k to 1k
4mA to 20mA
2
ISO
5V
3
6
7
49.9k
2
1
2
3
2
2N3904
MAX480
4
IL300
7
0.1V to 0.5V
6
2N3904
MAX480
4
3
4
6
10k
5
49.9k
24.9Ω
Figure 8. Typical 4mA/20mA Application Circuit
_______________________________________________________________________________________
9
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
