M61880FP Ver la hoja de datos (PDF) - MITSUBISHI ELECTRIC

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Fabricante

M61880FP

Laser-diode driver / controller

MITSUBISHI ELECTRIC  

MITSUBISHI < DIGITAL ASSP >

M61880FP

Laser-diode driver / controller

FUNCTIONS

erating a potential difference (Vm). Vm is compared with the

The M61880 is a semiconductor laser-diode driver/controller. voltage applied to the Vr pin. If Vm < Vr , a constant current is

Its functions are the driving and laser power control of a spe- sourced through the CH pin so that the external capacitor is

cific type (Mitsubishi's N type laser) of semiconductor laser charged. If Vm > Vr , a constant current sinks through the CH

diode , in which the anode of a semiconductor laser diode pin to discharge the external capacitor.

(LD) is connected in stem structure to the cathode of a moni- The above operation occurs when the S/H input is "L" and

toring photodiode (PD).

DATA = "L" (sample).When the S/H input is "H" , the CH pin

The functions to drive LD and to control laser power are car- is maintained at high impedance state (hold) , irrespective of

ried out by connecting an external capacitor to the CH pin and the state of Vm , Vr , and DATA input.

applying a reference voltage to the Vr pin.

The LD drive current is made up of the switching current, lsw,

The PD current generated by LD illumination flows through which is controlled by the DATA input, and IB , which is the

the resistor connected between 1RM and 2RM , thereby gen- bias current to LD independent of the state of the DATA input.

PIN DESCRIPTIONS

Pin

Name

LD

Laser current output

PD

Monitoring diode input

Switching current

Rs

Set load output

Description

Connect to cathode on semiconductor laser diode.

Connect to anode on monitoring photodiode.

Connect a load resistor between this pin and GND for the setting of current (lsw)

to be switched.

RB

Bias current

Set load output

Connect a load resistor between this pin and GND for the setting of bias current

(IB). Leave this pin open if IB is not used.

Bias current setting

Bias current (IB) is set by applying a voltage at this pin. Leave this pin open if IB

VB

voltage input

is not used.

DATA

Switching data input

If this pin is "L" ,a current of Isw+IB flows through laser diode, if "H" , current

IB flows.

1RM,2RM

For monitoring

Load input

A load resistor is connected between pins 1RM and 2RM for conversion of

current generated by monitoring photodiode into changes in voltage.

( 2RM pin connects to GND in the IC.)

ENB

RO

Laser current enable input If this pin is "H" all current source circuits are turned off.

Laser current load output Connect a laser current load resistor between this pin and Vcc.

S/H

Sample hold control input If this pin is "L" ,sampling (APC) occurs, if "H" ,holding (switching).

CH

Holding capacitor load

input/output

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Vref

Reference voltage output Internal reference voltage (1.5Vtyp.) output pin of M61880.

A reference voltage is applied to this pin to operate the comparator in the

Vr

Reference voltage input sample-hold circuit. Connect this pin to the Vref pin if the internal reference

voltage of the M61880 is to be used.

Vcc1

Vcc2

Power supply pin 1

Power supply pin 2

Power supply to internal analog circuits. Connect to a positive power source(+5V).

Power supply to internal digital circuits. Connect to a positive power source(+5V).

GND1

GND2

GND pin 1

GND pin 2

GND for internal analog circuits.

GND for internal digital circuits.

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