The MAX3509 is a programmable power amplifier for use in CATV upstream applications. The device outputs up to 66dBmV QPSK through a 1:1 transformer. It features variable gain controlled by a 3-wire digital serial bus. Gain control is available in 1dB steps. The device operates over a 5MHz to 65MHz frequency range. The MAX3509 offers a transmit-disable mode, which places the device in a high-isolation state for use between bursts in TDMA systems. In this mode, all analog functions are shut down, minimizing output noise and power consumption. When entering and leaving transmit-disable mode, transients are kept to 25mV nominal at full gain. In addition, supply current is reduced to 7.8mA. An additional power-down mode is available. Shutdown mode disables all circuitry and reduces current consumption to less than 1A. The MAX3509 is available in a 20-pin TSSOP-EP package for the extended-industrial temperature range (-40C to +85C).