To address the growing field of on-line, out-of-hospital healthcare a front-end ADC for portable electrocardiographic systems has been designed. The converter is realized as a first-order, 3-bit ΣΔ with an oversampling ratio of 512. Performance is optimized to adhere to the standard IEC60601-2-47, which governs ambulatory ECG equipment. The single ended design achieves a dynamic range of 16 bits for signal offsets up to ±1.25 V. Measured power consumption is 60 μW with supplies of 2.6 V analog and 2.2 V digital.