These 10-bit, single-channel, ultra low power A/D converters are aimed at battery-powered devices and portable data acquisition systems, including remote sensors or pen digitizers with strict low power requirements. The AS1526 features an internal 2.5 V reference and consumes 4 mW (at 3 V). The AS1527 uses an external voltage reference and consumes 3 mW (at 3V) at the 73 kS/sec maximum sampling rate. Both parts operate from a 2.7 to 5.25 V single supply. Software power-down reduces current to 0.3 µA in shutdown mode for a total draw of 22 µA at sampling rates of 1 kS/sec (AS1527). Both devices contain an internal clock; however, they also support an external clock for increased flexibility. SPI, QSPI and a Microwire-compatible interface enable high-speed data access while minimizing board space.