Low-noise supply protects expensive diodes

The MAX1932 is a high-accuracy, low-noise avalanche photodiode bias supply that uses accurate high-side current sensing to protect expensive diodes during avalanche breakdown.

The MAX1932 is a high-accuracy, low-noise avalanche photodiode (APD) bias supply that uses accurate high-side current sensing to protect expensive APD diodes during avalanche breakdown, thereby improving the reliability of optical networks and modules.

The MAX1932 employs a constant frequency voltage-mode PWM scheme to generate a low-noise output.

Output ripple can be reduced to less than 1mV by an optional in-loop R-C or L-C post-filtering circuit without sacrificing output accuracy.

Output voltage can be set from 4.5 to 90V while operating from a 3.3 or 5V input bus.

The MAX1932 integrates a high-accuracy reference and precision error amplifier.

Output voltage accuracy of 0.6% can be achieved over the 0 to +85C temperature range.

The avalanche breakdown of the APD is indicated through a logic signal, which can be used by external circuits to optimise bias point for highest gain.

The MAX1932 offers the flexibility of setting the output voltage through a conventional resistive feedback divider, an internal 8bit SPI-compatible DAC, or an external DAC.

The MAX1932ECG price starts at $3.10 (1000-up, FOB USA).

It is available in a small 4 x 4mm 12-pin, thin QFN package and is specified for the extended industrial temperature range (-40 to +85C).

An evaluation kit is available to speed designs.

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