CS6724 integrates three main functions in a single chip providing optimal solutions for various fiber module applications. The functional blocks include a 2.5G post-amplifier, a 2.5G burst or continuous mode LD driver, and an 8-bit MCU for configuring and controlling the module functions.

The post-amplifier receives AC coupled differential signal from pre-amplifier and performs the quantization amplifications. There are total four amplification stages excluding the output stage. The offset cancellation is built-in on chip. The LOS status is also configurable as a set peak level detection by the post-amplifier or combined with ADC detection on peak level.An on-chiop DC/DC boost converter control is included.

The LD driver performs the transmit function that receives the PECL differential signal TXINP/TXINN and convert to drive LD output driver. The LD driver is also controlled by burst-enable signal BENN/BENP. The polarity of control can be configured. The laser driver includes differential modulation outputs and DC bias control output. The setting of output power level is controlled through automatic power control loop and is configurable by MCU. The setting of output power extinction ratio level is controlled through automatic extinction ratio control loop and is configurable by MCU. The output can be connected to Laser diode either by AC or DC coupled. The transmit path can be enabled or disabled by TX_DIS signal.

The on-chip MCU is the flexibility and versatility of controlling and configurations of fiber module design. Almost all configurations and parameters of the PA and LD driver parameters can be controlled by MCU through software. The 12-bit ADC associated with MCU can be used to acquire various internal and external analog signals such on-chip temperature sensor and reference voltages. The MCU has 2K boot ROM and 2K SRAM for program storage which can meet various applications needs of SFP/SFF requirements. The boot ROM is uploads the user program from external serial EEPROM (with capacity of 2KB/4KB/8KB).  The I2C slave interface also serves as ISP/IAP interface as well as SFP/SFF DMI function.

CS6724 integrates essential building blocks for Fiber module design. The integration of MCU allows precision control to tailor various module applications and facilitates configuration and automatic calibration in the manufacturing process. Using CS6724, the module can achieve low cost and high performance and can be applied in FTTH, BPON, GEPON, and GPON.






Post Amplifier

¨     1.25GBPS – 2.5GBPS

¨     -3dB bandwidth 50KHz – 2GHz

¨     2mV sensitivity

¨     On-chip offset cancellation

¨     Programmable signal detect level and hysteresis

¨     Programmable LOS function and Power detection

§  SD control

§  Peak/ADC control

§  External Monitor/ADC control

¨     Programmable power down

¨     CML output

¨     DC/DC boost converter control

LD Driver

¨     Programmable bias current (up to 100mA)

¨     Programmable modulation current (up to 80mA)

¨     Digital automatic power control loop

§  Fast acquisition of laser power < 3 bursts

§  Programmable loop time constant

§  Update only at burst-off state

§  Loop monitoring by MCU

¨     Rise/Fall time < 100psec

¨     Burst or continuous mode compatible

¨     Programmable polarity and FAIL status

§  DCBIAS fail

§  MPD fail

§  APC fail

¨     Programmable power down and TX enable/disable function

¨     Laser power monitor and burst-on monitor

¨     Rogue LD detection and protection

Micro Controller (MCU)

¨     RISC CPU – 12.5MHz

§  2K Program ROM for Boot

§  2K Program SRAM for user program

§  Watchdog timer and Low voltage reset

¨     I2C master for EEPROM program upload and data storage

¨     I2C slave for host ISP/IAP and DMI

§  Two level password protection for A0/A2

§  Support software TX_DISABLE

§  Burst Counter

§  A0/A2 or B0/B2 configurable

¨     8-Channel 12-bit ADC

¨     10-bit R2R DAC

¨     On-chip temperature sensor


¨     Low power consumption (300mW)

¨     Single 3.3V supply with on-chip regulator

¨     Extended temperature range -40oC ~ +85oC

RoHS compliance package

More information
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