Datasheet

ADA4320-1
Rev. A | Page 13 of 16
RAMP PIN FEATURE OUTPUT TRANSFORMER
The RAMP pin (Pin 6) can be optionally used to control the
length of the burst on and off transients. By default, leaving the
RAMP pin unconnected results in a transient that is fully compliant
with DOCSIS 3.0. Adding capacitance to the RAMP pin slows
the dissipation even more.
Matching the 300 Ω differential output impedance to unbalanced
75 Ω requires a 4:1 impedance (2:1 turns) ratio transformer.
The transformer should have minimal insertion loss over the
5 MHz to 85 MHz band and have a maximum dc current rating
of at least 200 mA.
Characterization of the ADA4320-1 was performed using a
Coilcraft PWB-4-BL surface-mount wide-band RF transformer.
Alternate choices for the output transformer are the Toko
458PT-1565 and the Tyco Electronics (M/A-COM) ABACT0018.
GND
GND
VIN–
VIN+
GND
COMP
VOUT+
VOUT–
VOUT+
VOUT–
GND GND
VCC
VCC VCC
RAMP
TXEN
GND GND GND CLK DATEN
ADA4320-1
SDATA SLEEP
0.1µF
10µF
LPF
QPSK/QAM
BURST
MODULATOR
DAC
DIPLEXER
TO TUNER
OR SPLITTER
0.1µF
3-WIRE
(SPI-COMPATIBLE)
CONTROL
POWER-DOWN
CONTROL
TRANSMIT
ENABLE/DISABLE
CONTROL
+
5
V
100pF 0.1µF
100nH
2:1*
UPSTREAM
DOWNSTREAM
F-CONNECTOR
*COILCRAFT PWB-4-BL
ALTERNATES: TOKO 458PT-1565
TYCO MABACT0018
0
8707-025
1
8
13
20
Figure 24. Typical Application