Data Center Control Solutions for Optical Systems and Modules

Applications

• Optical networking—100G/200G/400G and higher frequency modules

For more information on the ADuCM430, contact InfoOpticalNetwork@analog.com.

The LTC2688 is a 16-channel,12-/16-bit, ±15 V digital-to-analog converter (DAC) with an integrated precision reference. The LTC2688 is guaranteed monotonic and has built in rail-to-rail output buffers that can source or sink up to 20 mA. This SoftSpan^™ DAC offers five output ranges up to ±15 V. The range of each channel is independently programmable.

The internal 4.096 V precision reference sets the accuracy of the output voltage. An external reference can be used for additional range options. Three toggle pins support Input Register A and Input Register B toggle or sinusoidal dither at multiple frequencies. An analog multiplexer simplifies measurement of pin voltages, load currents, and junction temperature.

Programmable offset and gain registers improve the accuracy of the DAC outputs.

The serial peripheral interface (SPI) and MICROWIRE^™-compatible, 3-wire serial interface operates on logic levels as low as 1.71 V and clock rates up to 50 MHz.

APPLICATIONS

• Optical networking
• Instrumentation
• Data acquisition
• Automatic test equipment
• Process control and industrial automation

The AD4695/AD4696 are compact, high accuracy, low power, 16-channel, 16-bit, 500 kSPS/1 MSPS, multiplexed input precision, successive approximation register (SAR) analog-to-digital converters (ADCs) with Easy Drive features and extensive digital functionality.

The AD4695/AD4696 are optimal for use in space constrained, multichannel, precision data acquisition systems and monitoring circuits. The AD4695/AD4696 feature a true 16-bit SAR ADC core with no missing codes, a 16-channel, low crosstalk multiplexer, a flexible channel sequencer, overvoltage protection clamp circuits on each analog input, on-chip oversampling and decimation, threshold detection and alert indicators, and an autonomous conversion (autocycle) mode.

The AD4695/AD4696 Easy Drive features relax the drive requirements of the analog front end (AFE) and reference circuitry. Analog input high-Z mode and reference input high‑Z mode simplify system designs, reduce component count, and increase channel density by removing the need for dedicated high speed ADC drivers and reference buffers. The WLCSP option of the AD4695/AD4696 includes an internal reference buffer, which provides a true, buffered reference input.

Input overvoltage protection clamps on each analog input protect the AD4695/AD4696 from overvoltage events and prevent overvoltage events on one channel from degrading performance on other channels (see Figure 27 in the data sheet).

Advanced digital functionality makes the AD4695/AD4696 compatible with a variety of low power digital hosts. The low serial peripheral interface (SPI) clock rate requirements, on-chip customizable channel sequencers, and oversampling and decimation reduce the burden on the digital host system. Autocycle mode and threshold detection features enable low power, interrupt driven firmware design by performing conversions autonomously and generating alerts based on channel specific threshold limits.

The AD4695/AD4696 are available in a 5 mm × 5 mm 32-lead lead frame chip scale package (LFCSP) and a 2.96 mm × 2.96 mm 36-ball wafer level chip scale package (WLCSP) with operation specified from −40°C to +125°C.

APPLICATIONS

• Photodiode monitoring
• Medical instrumentation
• Vital signs monitoring
• Electronic test and measurement
• Automated test equipment
• Instrumentation and process control
• Battery-powered equipment

The LTC2672 is a family of five-channel, 12-/16-bit current source, digital-to-analog converters (DACs) that provide five high compliance, current source outputs with guaranteed 0.6 V dropout at 200 mA. There are eight current ranges that are programmable per channel with full-scale outputs of up to 300 mA. The channels can be paralleled to allow either ultrafine adjustments of large currents or combined outputs of up to 1.5 A. A dedicated supply pin is provided for each output channel. Each channel can be operated from 2.1 V to V_CC, and internal switches allow any output to be pulled to the optional negative supply. The LTC2672 includes a precision integrated 1.25 V reference (10 ppm/°C maximum (LFCSP) or 2.4 ppm/°C nominal (WLCSP)), with the option to use an external reference. The serial peripheral interface (SPI)-compatible, 3‑wire serial interface operates on logic levels as low as 1.71 V and at clock rates as high as 50 MHz.

Note that throughout this data sheet, multifunction pins, such as CS/LD, are referred to by the entire pin name or by a single function of the pin.

APPLICATIONS

• Tunable lasers
• Semiconductor optical amplifier biasing
• Resistive heaters
• Current mode biasing

The ADL5303 is a monolithic logarithmic detector optimized for the measurement of low frequency signal power in fiber optic systems and offers a large dynamic range in a versatile and easily used form. Wide measurement range and accuracy are achieved using proprietary design and precise laser trimming. The ADL5303 requires only a single positive supply, V_PS, of 5 V. When using low supply voltages, the log slope can be altered to fit the available span. Low quiescent current and chip disable facilitate use in battery-operated applications.

The input current, I_PD, flows in the collector of an optimally scaled NPN transistor, connected in a feedback path around a low offset JFET amplifier. The current summing input node operates at a constant voltage, independent of current, with a default value of 0.5 V; this may be adjusted over a wide range. An adaptive biasing scheme is provided for reducing photo-diode dark current at very low light input levels. The VPDB pin applies approximately 0.1 V reverse bias across the photodiode for I_PD = 100 pA, rising linearly to 2.0 V of reverse bias at I_PD = 10 mA to improve response time at higher power levels. The input pin INPT is flanked by the VSUM guard pins that track the voltage at the summing node. Connecting the exposed pad of the device to the VSUM pins provides a continuous guard to minimize leakage into the INPT pin.

The default value of the logarithmic slope at the VLOG output is set by an internal 5 kΩ resistor. Logarithmic slope can be lowered with an external shunt resistor or increased using the buffer and a pair of external feedback resistors. The addition of a capacitor at the VLOG pin provides a simple low-pass filter. The intermediate voltage, V_LOG, is buffered in an output stage that can swing to within about 100 mV of ground and the positive supply, V_PS, and provides a peak current drive capacity of ±20 mA. An on-board 2 V reference is provided to facilitate the repositioning of the intercept. The incremental bandwidth of a translinear logarithmic amplifier inherently diminishes for small input currents. At I_PD =1 nA, the bandwidth of the ADL5303 is approximately 2 kHz increasing in proportion to I_PD up to a maximum value of 10 MHz.

APPLICATIONS

• High accuracy optical power measurement
• Wide range baseband log compression
• Versatile detector for APC loops

The ADA4355 is a complete, high performance, current input μModule^®. For space savings, the ADA4355 includes all the required active and passive components to realize a complete current to bits data acquisition solution, supporting a small form factor, optical modules as well as multichannel systems.

The high speed transimpedance amplifier (TIA) of the device supports 10 ns pulse widths, allowing high spatial resolution for Time of Flight (ToF) measurements. Additionally, the ADA4355 includes three TIA gain (T_Z) settings to maximize dynamic range. An internal, selectable, analog low-pass filter (LPF) can limit the device bandwidth with a corner frequency of 100 MHz to minimize broadband noise while also serving as an antialiasing filter for the 125 MSPS ADC. For lower bandwidth signals, or wider signal pulses (for example, 20 μs or wider), the filter can be set to a corner frequency of 1.0 MHz to provide additional noise reduction.

The 14-bit ADC converts the amplified voltage signal at a rate of up to 125 MSPS and outputs the digitized signals through two serial, low voltage differential signaling (LVDS) data lanes, operating at rates of up to 1 Gbps per lane. The data clock output (DCO) operates at frequencies of up to 500 MHz and supports double data rate (DDR) operation.

The ADA4355 exhibits fast overdrive recovery from a large input current signal and is available in a 12.00 mm × 6.00 mm CSP_BGA package with a −40°C to +85°C operating temperature range.

APPLICATIONS

• Current to voltage conversion
• Chemical analyzers
• Mass spectroscopy
• Time of Flight
• Fiber optic sensing
• OTDR
• Optical amplifiers
• Reconfigurable optical add and drop multiplexers (ROADM)