Mitsubishi M66510P, M66510FP Datasheet

MITSUBISHI 〈DIGITAL ASSP〉

MITSUBISHI 〈DIGIT AL ASSP〉

DESCRIPTION

The M66510 is a semiconductor laser diode driver that drives a semiconductor laser of the type whose cathode and the anode of monitor photodiode are connected to the stem. Laser driving current of up to 120mA can be set by applying constant voltage from outside to drive the laser diode. It operates from a 5V single power supply , allowing switching of laser driving current at a speed of 20M bits/sec. *: Our semiconductor laser is of R type.

FEATURES

• Built-in two outputs for monitoring laser power (comparator output and analog output)

• With laser driving current forced off pin

• High-speed switching (20M bits/s)

• High driving current (120mA max.)

• 5V single power supply

APPLICATION

Laser beam printer

M66510P/FP

LASER-DIODE DRIVER

PIN CONFIGURATION (TOP VIEW)

CC1

CURRENT SETTING

INPUT 1

CURRENT SETTING

LOAD OUTPUT 1

CURRENT SETTING

INPUT 2

CURRENT SETTING

LOAD OUTPUT 2

LASER CURRENT

FORCED OFF INPUT

CURRENT SETTING

LOAD OUTPUT 3

GND1

MONITOR

LOAD INPUT 1

MONITOR

LOAD INPUT 2

→

VL1

←

1RC

→

VL2

←

2RC

→

OFF

←

3RC

7 8

→

1RM

→

2RM

Outline 20P4K

20 19 18

M66510P/FP

17 16 15 14 13 12 11

M66510P/FP

→ → →

← ←

→ → ←

LASER CURRENT

1RO

LOAD OUTPUT 1 LASER CURRENT

2RO

LOAD OUTPUT 2 LASER DIODE

OUTPUT

GND2

MONITOR DIODE

INPUT

DATA

DATA INPUT

CC2

MONITOR COMPARATOR

OUTPUT MONITOR ANALOG

OUTPUT DUTY

CONTROL INPUT

BLOCK DIAGRAM

CURRENT SETTING INPUT 1

CURRENT SETTING INPUT 2

CC1

CC2

MONITOR OUTPUT

LINEAR

AMPLIFIER

2 31RC

4V 52RC

73RC

14V

DIFFERENTIAL AMPLIFIER

17GND2

8GND1

1RM102RM

VL1, 1RC: LASER CURRENT (IL1) SETTING PIN V

, 2RC: LASER CURRENT (IL2) SETTING PIN

3RC: LASER CURRENT (I

MONITOR

DIODE INPUT

COMPARATOR OUTPUT

CURRENT SWITCHING CIRCUIT

18 LD

LASER DIODE OUTPUT

) SETTING PIN

COMPARATOR

ref

= 1.2V)

CONSTANT CURRENT

SOURCE (I

CONSTANT CURRENT

SOURCE (I

CONSTANT CURRENT

SOURCE (I

L = IL1 + IL2 + IL3

CC1

V V

CC2

1RO

Max. 60mA

Max. 30mA

)

DUTY

CONTROL INPUT

, GND1: IC INTERNAL ANALOG POWER SUPPLY PIN , GND2: IC INTERNAL DIGITAL POWER SUPPLY PIN

DATA

DATA INPUT

2RO

LASER CURRENT

FORCED OFF

OFF

MITSUBISHI 〈DIGITAL ASSP〉

M66510P/FP

LASER-DIODE DRIVER

FUNCTION

The 66510 is a semiconductor laser diode driver that drives a semiconductor laser of the type (our R type) whose cathode and the anode of monitor photodiode are connected to the stem. Using the R type laser allows direct fixing the laser on a device for easy installation, thus improving its radiation efficiency. Laser driving current is set by applying voltage from outside. The M66510 is equipped with two independent voltage applying pins to provide higher accuracy of setting the current value.

PIN DESCRIPTIONS

Pin name LD PD VL1 1RC

VL2 2RC

3RC

DATA 1RM,

2RM MO CO VOFF 1RO

2RO

VCC1

VCC2

GND1 GND2

Laser connecting pin Monitor diode connecting pin Voltage input pin for IL1 setting Load resistor connecting pin for IL1

setting Voltage input pin for IL2 setting Load resistor connecting pin for IL2

setting Load resistor connecting pin for IL3

setting Switching data input pin Monitor load resistor connecting pin

Monitor analog output pin Monitor comparator output pin Laser current forced off input pin Load resistor connecting pin for laser

current IL1 Load resistor connecting pin for laser

current IL2/IL3 Duty compensating capacitor

connecting pin Power supply pin 1

Power supply pin 2

GND pin 1 GND pin 2

Name

Connects the anode of semiconductor laser diode. Connects the cathode of monitor photodiode. Voltage input for setting the output current (IL1) of current source 1. Connects IL1 setting load resistor between the pin and GND.

Voltage input for setting the output current (IL2) of current source 2. Connects IL2 setting load resistor between the pin and GND.

Connects IL3 setting load resistor between the pin and GND. If IL3 is not used, open the pin.

Turns on the laser in the “L” position, and off in the “H” position. Connects between 1RM and 2RM the load resistor for converting monitor

photodiode current into voltage. Analog output for monitoring laser power. Comparator output for monitoring laser power. Turns off all current source circuits in the “L” position. Connects load resistor for laser current IL1 between 1RO pin and VCC.

Connects load resistor for laser current IL2 and IL3 between 2RO pin and VCC.

Connects duty compensating capacitor of optical output switch waveforms between the pin and GND. If duty compensation is not required, open the pin.

Power supply for internal analog circuits. Connected to positive power supply (+5V).

Power supply for internal digital circuits. Connected to positive power supply (+5V).

GND for internal analog circuits. GND for internal digital circuits.

It is also equipped with a laser current forced off pin to prevent overcurrent from flowing into the laser diode at the power-ON time. For detection of laser power, the monitor current of monitor photodiode built in the laser is converted into voltage by an external resistor to generate an analog output, and simultaneously the result of comparison with the internal reference voltage is output as TTL-level logic information.

Function

MITSUBISHI 〈DIGITAL ASSP〉

M66510P/FP

LASER-DIODE DRIVER

DESCRIPTION OF OPERATION

1. Setting laser driving current

The M66510 is provided internally with three constant current sources IL1, IL2 and IL3, allowing setting of each independent output current. The methods of setting IL1 to IL3 are given below in (1) to (3).

(1) Method of setting IL1 IL1 is approximated by the VL1 pin input voltage and the resistor (RC1) connected between 1RC pin and GND as follows:

L1[V]

IL1[mA] = 12 ×

RC1[kΩ]

However, 0≤ VL1 ≤ VCC – 1.8V, IL1(max.) = 60mA (2) Method of setting I

IL2 is approximated by the VL2 pin input voltage and the resistor (RC2) connected between 2RC pin and GND as follows:

L2[V]

IL2[mA] = 6 ×

However, 0≤ V

L2 ≤ Vcc – 1.8V, IL2(max.) = 30mA

RC2[kΩ]

(3) Method of setting IL3 IL3 is approximated by the internal reference voltage (Vref) and the resistor (RC3) connected between 3RC pin and GND as follows:

ref[V]

IL3[mA] = 10 ×

RC3[kΩ]

However, Vref=1.2V (standard), IL3(max.) = 30mA

Note: The expressions for setting IL1 to IL3 are typical. Actually, the set values

fluctuate several % depending on IC lot dispersion or operating ambient temperature (See the ELECTRICAL CHARACTERISTICS).

(2) The VM is output as an analog output from the MO pin through the buffer amplifier and compared to the internal reference voltage Vref (1.2V standard) by the comparator. Then the result of comparison is output from the CO pin on the TTL level.

ref

–

Buffer amplifier

–

Comparator

CO output

“L”

“H”

CO output

+ MO output

–

Differential amplifier

Condition

VM < Vref VM > Vref

Monitor circuit schematic drawing

2. Switching operation

The laser is turned on when DATA= “L”. At this time, the laser driving current is I

L1 +IL2 +IL3.

The laser is turned off when DATA = “H”. At this time, the laser driving current becomes almost 0 regardless of IL1 to IL3.

3. Usage of VOFF input

The current which flows into the laser becomes 0 when DATA= “H”. And the laser is turned off but the internal current sources are active. Contrarily, the internal current sources are turned off when

OFF = “L”. It is therefore possible to prevent overcurrent from

V flowing into the laser by setting V

OFF input to “L” until VCC

reaches 3.5V (standard) at the power-ON time, for example (See 6. Internal reset).

4. Laser power monitor operation

The M66510 outputs the information on monitor photodiode (PD) built in the laser from the MO and CO pins in the flow given below.

(1) The current equal to the PD current produced through emission of the laser flows into the resistor (RM) connected between 1RM and 2RM. The potential difference (V

M) pro-

duced on RM is converted into a level from GND by the internal differential amplifier.

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