Electronic Design

Low-Power, Dual 8-Bit ADCs Regulate Their Own Operating Voltage

The MAX19505, MAX19506, and MAX19507 8-bit, dual-channel analog-to-digital converters (ADCs) from Maxim Integrated Products provide a 49.8-dBFS signal-to-noise ratio (SNR) and 69-dBc spurious-free dynamic range (SFDR) at 70 MHz (see the figure). Available in speed ranges from 65 to 130 Msamples/s, they target cellular basestations and point-to-point microwave receivers, set-top boxes, or ultrasound and medical imaging, as well as portable instrumentation and low-power data acquisition.

Since they’re intended for space-constrained applications, the chips dissipate modest power, specifically 43 mW for the 65-Msample/s version, 57 mW for 100 Msamples/s, and 74 mW for 130 Msamples/s. In addition, their built-in, self-sensing analog supply regulator allows them to operate from unregulated 1.8-V or 2.5- to 3.3-V rails. (That data, including the power consumption, is for the analog portion of the chip when operated at 1.8 V. The digital output drivers operate on an independent supply voltage).

Ease-of-design features include the ability to handle single-ended or differential clock inputs as well as an on-board clock divider. A wide 0.4- to 1.4-V input common-mode range enables them to deal with ac- or dc-coupled inputs without an external coupling capacitor. The ADCs also provide for various adjustments and feature selections through programmable registers (accessed through a three-wire serial-port interface). For instance, the impedance of the digital outputs is programmable 50 to 300 . Alternatively, that interface can be disabled, and the output mode, data format, and clock-divider mode can be set simply by pin-strapping.

The ADCs come in 7- by 7-mm, 48-pin thin quad flat no-lead (TQFN) packages. Pricing starts at $4.10, and 10-bit versions are also available.

MAXIM INTEGRATED PRODUCTS

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