Datasheet

DS21352/DS21552
85 of 137
Figure 16-1 EXTERNAL ANALOG CONNECTIONS
Table 16-2 TRANSMIT TRANSFORMER SELECTION
DEVICE TRANSFORMER RESISTOR Rt
DS21552 1.15 : 1
1.36 : 1
0 ohms Ideal, 2.2 ohms max
4.7 ohms Ideal
DS21352 2 : 1 0 ohms
See separate application note on line interface design criteria for full details.
NOTES:
1. Resistor values are +/-1%.
2. The Rt resistors are used to protect the device from over–voltage.
3. See the Separate Application Note for details on how to construct a protected interface.
4. Normally a TTL level clock is applied MCLK and the XTAL pin is left as an NC. Optionally a crystal can be applied across
the MCLK and XTALD pins.
Table 16-3 TRANSFORMER SPECIFICATIONS
SPECIFICATION RECOMMENDED VALUE
Turns Ratio DS21352 1:1(receive) and1:2(transmit) 5%
Turns Ratio DS21552 1:1(receive) and1:1.15 or1:1.36(transmit) 5%
Primary Inductance
600mH minimum
Leakage Inductance
1.0mH maximum
Intertwining Capacitance 40 pF maximum
DC Resistance 1.2 Ohms maximum
RTIP
RRING
TTIP
TRING
T1 Receive
Line
T1 Transmit
Line
DS21352 / 552
0.47uF
(non-
polarized)
DVDD
DVSS
0.1uF
RVDD
RVSS
0.1uF
TVDD
TVSS
0.1uF
VDD
50 50
0.1uF
Rt
Rt
0.01uF
1.544MHz
XTALD
MCLK
NC
1 : 1
N : 1
(see table below)