High-Speed Current Mirror and Integrated FETs for DC-DC Controller

The DS3922 high-speed current mirror integrates high-voltage devices necessary for monitoring the burst mode receive power signal in avalanche photodiode (APD) biasing and OLT applications. The device has two small and one large gain current mirror outputs to monitor the APD current. An adjustable current clamp limits current through the APD. The clamp also features an external shutdown. An integrated FET is also provided that can be used to quickly clamp the high-voltage bias to ground in the case of high optical input power. Integrated low-voltage FET circuits can be used to create buck, boost, and inverting DC-DC converters for efficient laser bias and EML bias applications.

The DS3922 is available in a 24-pin TQFN package and operates over an extended -40°C to +95°C temperature range.

Applications

* 10G EPON * 10GPON OLT * Avalanche Photodiode (APD) Monitoring * EML Bias * GPON OLT

* Accurate Burst-Mode RSSI Measurement with Two Current Mirror Outputs Improves Dynamic Range

* -32dBm to -5dBm Optical Input Range

* ±0.5dB Accuracy

* Sampling Period as Short as 300ns

* Pin Discharge Option

* Low-Noise APD Bias with Shutdown Options Reduces Receiver Sensitivity

* 15V to 76V APD Bias

* External Capacitor Connection for Controlled RC Time Constant of APD Voltage Filter

* Current Clamp with Adjustable Limit and External Shutdown with Limit Status

* High-Voltage Switch FET for APD Fast Shutdown

* Supports Additional DC-DC Functions

* Low-Voltage Synchronous Buck FETs for Efficient DFB Bias

* Low-Voltage pMOSFET for Generating Negative Bias Voltage for EMLs

* Small Package Reduces Total Solution Size and Cost

* 3.5mm x 3.5mm, 24-Pin TQFN Package with Exposed Pad