MAXIM Integrated Products, represented in Australia by Arrow Electronics , has released the MAX7033 300MHz to 450MHz superheterodyne ASK receiver.
The receiver has a sensitivity of -114dBm, user-selectable centre frequency image rejection of better than 42dB, and the option of running from either a 3V or 5V supply. It has a one-step AGC circuit that drops the LNA gain by 35dB when the RF input signal is greater than -62dBm. An AGC feature locks the AGC in its current state and prevents it from switching in the middle of a data stream. The receiver uses a 10.7MHz IF filter with received signal strength indicator (RSSI) and has an on-chip, phase-locked loop, voltage-controlled oscillator (VCO), and analogue baseband data-recovery circuitry.
The MAX7033 consists of a low-noise amplifier (LNA), a fully differential image-rejection mixer, a 10.7MHz IF limiting amplifier stage with received signal strength indicator (RSSI), and analogue baseband recovery circuitry. A self-contained PLL requires no external components. The PLL block contains a phase detector, charge pump/integrated loop filter, VCO, synchronous 32x or 64x clock divider, and crystal oscillator.
The receiver is designed for power-sensitive applications such as keyless entry systems, car alarms, home-security systems, remote controls, and garage-door openers. The part draws less than 1.6μA in shutdown mode and 5.2mA in receive mode. The centre frequency of the differential image rejection mixer can be set to 315MHz, 375MHz, or 433MHz. Depending on the components selected, it can receive data rates up to 66kbps (NRZ coded) and transitions from shutdown to valid data out in less than 250μs. In power-cycled applications, this quick transition minimises the time the system needs to be in receive mode. The MAX7033 comes in a 28-pin SSOP and operates from -40°C to +105°C.