Optical Transceiver

Optical transceivers are commonly used for high speed data communications and they normally conform to industry standard form factors. This results in designers often needing to incorporate multiple power supply rails into a small predetermined physical space.

Efficiency and power dissipation become very important and the latest optical transceiver chipsets demand supplies with low output noise performance and excellent transient response.

Optical Transceiver (QSFP-DD)

QSFP-DD is a module and cage/connector system similar to current QSFP, but with an additional row of contacts providing for an eight lane electrical interface. It provides solutions up to 200 Gbps or 400 Gbps aggregate and uses PAM4 (4-level Pulse Amplitude Modulation) as well as NRZ modulation.

Typically QSFP-DD designs include an additional Digital Signal Processor (DSP) for PAM4 and they also require a negative voltage rail for the PAM4 EML (a laser source plus electro-absorptive modulator)

Block diagram Requirements Recommended ICs Features
Line Switch
For 3.3V input

Specifications
IOUT: 6A

Other points

  • Adjustable Slew Rate
- -
Power on Reset
To monitor 3.3V rail

Specifications
Detect voltage: 2.7V

Other points

  • Small
  • High accurate
XC6127

High accurate voltage detector

  • Small
  • High accurate

VIN: 0.7V ~ 6.0V
Detect voltage: 1.5V ~ 5.5V

TOSA (Transmitter Optical SubAssembly)

TX CDR (Transmitter Clock Data Recovery)

EML Driver (Electro-absorption Modulator Laser Driver)

EML (Electro-absorption Modulator Laser)

Specifications
VOUT: -1.2V ~ -3.3V
IOUT: 50mA ~ 300mA

Other points

  • Small
  • Low noise
  • High efficiency
XCL303

Inductor built-in Negative Output Voltage DC/DC

  • Suitable negative voltage supply for Laser Driver and EA
  • Low ripple, good for Laser stability
  • Small, Low noise

VIN: 2.7V ~ 5.5V
VOUT: -1.2V ~ -6.0V
IOUT max: 300mA @ VOUT=-3.3V, VIN=3.3V

Specifications
VOUT: 0.9V ~ 2.5V
IOUT: 100mA ~ 300mA

Other points

  • Small
  • Low noise
  • High efficiency
XCL223 / XCL219

Inductor built-in HiSAT-COT step-down DC/DC

  • Small and low height package (XCL223, h=0.75mm max.)
  • High speed transient response, Low noise

VIN: 2.5V ~ 5.5V
VOUT: 0.8V ~ 3.6V
IOUT max: 700mA (XCL223) / 1A (XCL219)

TEC (Thermo Electric Cooler)

Specifications
VOUT: 3.3V ~ 5.0V
IOUT: 100mA ~ 300mA

Other points

  • Small
  • High efficiency
XCL102

Inductor built-in step-up DC/DC

  • When> 3.3V is required to suppress laser temperature drift
  • Small, Low ripple

VIN: 0.6V ~ 5.5V
VOUT: 1.6V ~ 3.6V
IOUT max: 500mA @ VOUT=5.0V, VIN=3.3V

DSP(Digital Signal Processor)

PAM4(Pulse Amplitude Modulation)

PHY(PHYsical layer)

Specifications
VOUT: 0.6V ~ 1.2V
IOUT: 3A ~ 6A

Other points

  • High accurate
  • High speed transient response
XC9266

6A high speed transient response HiSAT-COT step-down DC/DC

  • For DSP core, low voltage
  • High speed transient response HiSAT-COT control
  • For low height of module (h=1.0mm)

VIN: 2.5V ~ 5.5V
VOUT: 0.6V ~ 3.6V
IOUT max: 6A

ROSA(Receiver Optical Sub Assembly)

Specifications
VOUT: 3.3V ~ 5.0V
IOUT: 100mA ~ 300mA

Other points

  • Small
  • Low noise
  • High efficiency
XCL102

Inductor built-in step-up DC/DC

  • Small, low ripple

VIN: 0.6V ~ 5.5V
VOUT: 1.6V ~ 3.6V
IOUT max: 500mA @ VOUT=5.0V, VIN=3.3V

Optical Transceiver (QSFP-100G)

QSFP stands for four-lane Quad Small Form-factor Pluggable system. The QSFP28 variant allows speeds up to 100 Gbit/s and the closely related QSFP56 doubles the top speed to 200 Gbit/s.

Simpler QSFP28 designs use non-return-to-zero (NRZ) modulation and normally an additional DSP and extra negative voltage rail is not required . QSFP56 uses PAM4 so an additional negative voltage rail for the PAM4 EML is often required.

Block diagram Requirements Recommended ICs Features
Line Switch
For 3.3V input

Specifications
IOUT: 3A

Other points

  • Adjustable Slew Rate
- -
Power on Reset
To monitor 3.3V rail

Specifications
Detect voltage: 2.7V

Other points

  • Small
  • High accurate
XC6127

High accurate voltage detector

  • Small
  • High accurate

VIN: 0.7V ~ 6.0V
Detect voltage: 1.5V ~ 5.5V

TOSA (Transmitter Optical SubAssembly)

TX CDR (Transmitter Clock Data Recovery)

EML Driver (Electro-absorption Modulator Laser Driver)

EML (Electro-absorption Modulator Laser)

Specifications
VOUT: -1.2V ~ -3.3V
IOUT: 50mA ~ 300mA

Other points

  • Small
  • Low noise
  • High efficiency
XCL303

Inductor built-in Negative Output Voltage DC/DC

  • Suitable negative voltage supply for Laser Driver and EA
  • Low ripple, good for Laser stability
  • Small, Low noise

VIN: 2.7V ~ 5.5V
VOUT: -1.2V ~ -6.0V
IOUT max: 300mA @ VOUT=-3.3V, VIN=3.3V

Specifications
VOUT: 0.9V ~ 2.5V
IOUT: 100mA ~ 300mA

Other points

  • Small
  • Low noise
  • High efficiency
XCL223 / XCL219

Inductor built-in HiSAT-COT step-down DC/DC

  • Small and low height package (XCL223, h=0.75mm max.)
  • High speed transient response, Low noise

VIN: 2.5V ~ 5.5V
VOUT: 0.8V ~ 3.6V
IOUT max: 700mA (XCL223) / 1A (XCL219)

TEC (Thermo Electric Cooler)

Specifications
VOUT: 3.3V ~ 5.0V
IOUT: 100mA ~ 300mA

Other points

  • Small
  • High efficiency
XCL102

Inductor built-in step-up DC/DC

  • Small, Low ripple

VIN: 0.6V ~ 5.5V
VOUT: 1.6V ~ 3.6V
IOUT max: 500mA @ VOUT=5.0V, VIN=3.3V

uPC(microcontroller)

Specifications
VOUT: 1.8V ~ 3.3V
IOUT: 100mA ~ 300mA

Other points

  • Small
  • High efficiency
XCL223

Inductor built-in HiSAT-COT step-down DC/DC

  • Small / Low height package (h=0.75mm max.)
  • High speed transient response, Low noise

VIN: 2.5V ~ 5.5V
VOUT: 0.8V ~ 3.6V
IOUT max: 700mA

RX CDR (Receiver Clock Data Recovery)

Specifications
VOUT: 1.8V ~ 3.3V
IOUT: 100mA ~ 300mA

Other points

  • High accurate
  • Low noise
XCL223 / XCL219

Inductor built-in HiSAT-COT step-down DC/DC

  • Ideal for preventing data errors with low ripple
  • Small / Low height package (XCL223, h=0.75mm max.)
  • High speed transient response, Low noise

VIN: 2.5V ~ 5.5V
VOUT: 0.8V ~ 3.6V
IOUT max: 700mA (XCL223) / 1A (XCL219)

ROSA (Receiver Optical Subassembly)

Specifications
VOUT: 3.3V ~ 5.0V
IOUT: 100mA ~ 300mA

Other points

  • High accurate
  • Low noise
XCL102

Inductor built-in step-up DC/DC

  • Small, Low ripple

VIN: 0.6V ~ 5.5V
VOUT: 1.6V ~ 3.6V
IOUT max: 500mA @ VOUT=5.0V, VIN=3.3V

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