AK2570 Просмотр технического описания (PDF) - Asahi Kasei Microdevices

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AK2570

Feed Forward APC LSI for LD Module

Asahi Kasei Microdevices 

ASAHI KASEI

[AK2570]

AK2570 consists of these circuit blocks as below.

Circuit block

Oscillator

VREF

T-SENSE

AD1

AD2

DA1,

AMP1

DA2,

AMP2

DA3, ALMOUT,

Comparator, ALM

Timing Generator

EEPROM

Register

Control

Power on Reset

Functional description

This circuit generates the standard clock that settles the timing for the sequence of the

internal circuit in “Self-operation mode (Ordinary mode)”.

This circuit generates the reference voltage for the A to D converter, the D to A converter

and the T-SENSE.

This circuit is the thermo-sensor, outputs the voltage corresponding to the ambient

temperature, i.e. the temperature to voltage converter, and transfers this output voltage to

AD2. Also it integrates the offset adjustment circuit that cancels the distribution.

The A to D converter encodes the input voltage at VPDIN-pin (the signal from the

monitor PD) to the 8bits digital data. It is possible to read the encoded data of monitor PD

signal (the reference data for RDA3) held in RVPD register and to set the alarm threshold

level for the degraded LD in “Training mode”.

The A to D converter encodes the T-SENSE output signal to the 8bits digital data. In

“Self- operation mode”, the encoded data of the ambient temperature detected by the

T-SENSE is converted to the EEPROM address and utilized for reading the temperature

characteristic data of the LD retained in the EEPROM. In “Training mode”, it is possible

to read the encoded data of the detected temperature held in RTMP register.

This block consists of the D to A converter and the Op-amp and controls the Bias- or the

Modulation- current for the LD. DA1 decodes the 8bits digital data held in RDA1 register

to the compensation voltage for the temperature drift of the LD. Inputting the ‘H’ level

signal to SHUTDN-pin makes that DAOUT1-pin outputs ‘0V (min.)’.

This block consists of the D to A converter and the Op-amp and controls the Bias- or the

Modulation- current for the LD. DA2 decodes the 8bits digital data held in RDA2 register

to the compensation voltage for the temperature drift of the LD. Inputting the ‘H’ level

signal to SHUTDN-pin makes that DAOUT2-pin outputs ‘0V (min.)’.

This block outputs the ‘H’ level alarm signal from ALM-pin in the case that the

monitoring PD signal becomes lower than the alarm threshold level retained in the

EEPROM and held in RDA3 register, and this case is caused by the aging degradation.

This memory is the non-volatile memory, has the capacity ‘Address 9bits × Data 16bits’

and retains the data as below,

1. The temperature compensation data for the LD (transferred to RDA1 and RDA2 registers)

and the alarm threshold level data for the degraded LD (transferred to RDA3 register)

corresponding to the ambient temperature (the output from the T-SNESE and AD2).

2. The trimming data for the T-SENSE offset and the ALMOUT timing.

This circuit temporarily stores the ambient temperature data (in RTMP register), the

temperature compensation data for the LD (in RDA1 and RDA2 registers), the alarm

threshold level data (in RDA3 register) and so on.

This circuit controls the internal circuit, e.g. registers, with the serial interface.

At ‘Power ON’, this circuit initializes the data in all registers (see p.9) and sets AK2570 in

“Self-operation mode”.

<MS0115-E-00>

3

2001/10

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