The MAX3505 programmable power amplifier is
designed for use in CATV upstream applications. The
MAX3505 drives 64dBmV (QPSK) into a 75Ω load when
driven with a 34dBmV nominal input signal. Both input
and output ports are differential, requiring that an external
balun be used at the output port. The variable gain
feature provides greater than 56dB of dynamic range,
which is controlled by an SPI? 3-wire interface. Gain
control is available in 0.5dB steps. The device operates
over a frequency range of 5MHz to 65MHz. The
MAX3505 is internally matched for use with a 1:1 balun.
This device operates from a single 5VDC supply and
draws 285mA during transmit (100% duty cycle,
64dBmV out). The bias current is automatically adjusted
based on the output level to increase efficiency.
Additionally, the device can be disabled between
bursts to minimize noise and save power while still
maintaining a match at the output port. In addition, a
shutdown mode is available to disable all circuitry and
reduce current consumption to 5μA (typ).
The MAX3505 is available in a 20-pin QFN package.
The device operates in the extended industrial temperature
range (-40°C to +85°C).
Applications
DOCSIS?/EuroDOCSIS? and DVB Cable
Modems
OpenCable? Set-Top Box
Telephony Over Cable
CATV Status Monitor