M61880FP Ver la hoja de datos (PDF) - Renesas Electronics

Número de pieza

componentes Descripción

Fabricante

M61880FP

Laser Diode Driver/Controller

Renesas Electronics 

M61880FP

Comparator

Reference voltage input

RM resistance generation voltage

Control circuit

Sample-and-hold control input S/H

ENB

Charging constant-

current source

SW1

Output (CH pin)

SW2

Discharging constant-

current source

CH External capacitance

Tr1

Conceptual Diagram of Sample-and-Hold Circuit

Operation Function Table

Input

ENB

S/H

H

X

L

H

L

L

X: Don’t Care

DATA

X

X

H

L

VM, Vr

X

X

X

VM < Vr

VM > Vr

Switch State

SW1

SW2

OFF

OFF

OFF

OFF

OFF

OFF

ON

OFF

OFF

ON

Tr1

ON

OFF

OFF

OFF

OFF

Output (CH Pin)

Fixed at “L”

High-impedance state (hold)

High-impedance state (hold)

Current source (sample)

Current sink (sample)

(2) APC timing chart

An example of a timing chart of APC operation by means of the sample-and-hold control signals is shown below.

In this example, a case is shown in which the direction of the CH pin leakage current in the hold state is assumed to be

the direction of flow to the M61880 (forward direction).

Power supply

ENB input

S/H input

Sample

Hold

Sample

Hold

Sample Hold

DATA input

Laser drive

current

∆ILD

Example of Sample-and-Hold Type APC Circuit Operation Timing Chart

Rev.1.0, Sep.19.2003, page 5 of 20

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