The MAX1007 is a multifunctional integrated circuit designed for high-performance mobile radios. It includes one 8-bit analog-to-digital converter (ADC), and two 7-bit and two 6-bit digital-to-analog converters (DACs) for functions including radio-frequency (RF) power sensing and antenna-diversity selection.
The ADC provides for power sense, receive-signal strength intensity (RSSI) measurements and system supervision. In the power-sense mode, the ADC converts the power-sensing circuitry signal (representing either the transmitted (Tx) or received (Rx) RF power) into a digital code, ensuring optimum Tx power setting and Rx signal analysis. An additional direct input to the ADC provides for system-supervision measurements, such as power-supply voltages, battery voltage, and temperature.
Four DAC blocks typically control DC levels in radios. As part of the Maxim PWT1900 chip set, the two 7-bit DACs control the gain settings and the two 6-bit DACs control the varactor diodes to tune a TCXO and bias a GaAs amplifier. Each DAC register and output can be updated independently, providing maximum flexibility.
For antenna diversity, a magnitude-comparison circuit captures and compares two peak signals. A latched logic-comparator output reveals which signal has the largest magnitude. The MAX1007 also includes an on-board voltage reference for the ADC and DACs.
The MAX1007 offers a high level of signal integrity with minimal power dissipation. Single-supply operation ranges from +2.85V to +3.6V. To further save power, there are two shutdown modes: standby and total shutdown. Standby is a partial shutdown that keeps the bandgap reference and the 2.4V reference generator active. Total shutdown disables all circuit blocks except the serial interface, reducing supply current to less than 1µA.
The MAX1007 is available in a 24-pin SSOP and is specified for commercial and extended temperature ranges.
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