Mitsubishi M66512P Laser-diode driver Datasheet

MITSUBISHI
MITSUBISHI
〈DIGITAL
〈DIGITAL
ASSP〉
ASSP〉
M66512P/FP
M66512P/FP
LASER-DIODE DRIVER
LASER-DIODE DRIVER
FEATURES
• Two kinds of outputs for monitoring laser power built in.
(comparator output and analog output)
• Pin provided for forced OFF of current circuit.
• High speed switching (40 Mbit/s)
• Large drive current (120mA max.)
• 5V single power supply
PIN CONFIGURATION (TOP VIEW)
VCC1
CURRENT SETTING INPUT 1 VL1
CURRENT SETTING LOAD OUTPUT 1 1RC
CURRENT SETTING INPUT 2 VL2
CURRENT SETTING LOAD OUTPUT 2 2RC
LASER CURRENT
FORCED OFF INPUT VOFF
CURRENT SETTING LOAD OUTPUT 3RC
GND1
MONITORING LOAD INPUT 1 1RM
MONITORING LOAD INPUT 2 2RM
1
2
3
4
5
6
7
8
9
10
M66512P/FP
DESCRIPTION
The M66512 is a semiconductor laser-diode driver for driving
a specific type* of semiconductor laser, in which the anode of
a semiconductor laser diode is connected in stem structure to
the cathode of a monitoring photodiode.
The amplitude of laser drive current is set by applying a voltage from an external source. the M66512 is capable of driving laser diodes on a maximum current of 120 mA.
It operates on a 5-V single power supply and switches laser
drive current at a rate of 40 Mbit/s.
*: The N type of Mitsubishi’s semiconductor lasers.
20
19
18
17
16
15
14
13
12
11
LASER CURRENT
RO LOAD OUTPUT
NC
LD LASER DIODE OUTPUT
GND2
PD MONITORING DIODE INPUT
DATA DATA INPUT
VCC2
MONITORING
CO COMPARATOR OUTPUT
ANALOG
MO MONITORING
OUTPUT
NC
Outline 20P4
20P2N-A
APPLICATION
Laser beam printers
NC: No Connection
BLOCK DIAGRAM
1RM 9
2RM 10
MONITORING
OUTPUT
MO
COMPARATOR
OUTPUT
CO
12
13
Linear amp
Comparator
(Vref=1.4V)
PD
16
LD
18
RO
20
Current switching circuit
Differential
amp
15 DATA
DATA INPUT
IL=IL1+IL2+IL3
VL1 2
1RC 3
VL2 4
Constant current
source(IL1)
Max.60mA
2RC 5
Constant current
source(IL2)
Max.30mA
3RC 7
Constant current
source(IL3)
Max.30mA
6 VOFF
LASER CURRENT
FORCED OFF
1 VCC1
14 VCC2
VL1, 1RC : Laser current (IL1) setting pin
VL2, 2RC : Laser current (IL2) setting pin
3RC : Laser current (IL3) setting pin
8 GND1
17 GND2
VCC1, GND1 : Power supply pin for analog circuits in IC
VCC2, GND2 : Power supply pin for digital circuits in IC
1
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
FUNCTION
The M66512 is a semiconductor laser-diode driver for driving
a specific type (Mitsubishi’s N type) of laser, in which the anode of a semiconductor laser diode is connected in stem
structure to the cathode of a monitoring photodiode.
The amplitude of laser drive current is set by applying a constant voltage from an external source. For that purpose, the
M66512 has two voltage applying pins, which they are independent each other, This mechanism makes it possible to set
a drive current with great accuracy.
As the IC is equipped with a pin to provide a forced OFF of
current circuit, it is possible to prevent a large current flowing
through laser diodes at the moment of power ON.
Regarding the detection of laser power, a monitor current
generated by a monitoring photodiode, which is incorporated
in laser unit, is drawn and converted into changes in voltage
by means of an external resistor, in order to output as an analog signal. Simultaneously, the converted voltage is compared with the internal reference voltage, thence the result is
output in TTL level as logic information.
PIN DESCRIPTIONS
Pin
1RC
VL2
2RC
3RC
Name
Laser connection pin
Monitoring diode connection pin
Voltage input pin for IL1 setting
Load resistor connection pin for IL1 setting
Voltage input pin for IL2 setting
Load resistor connection pin for IL2 setting
Load resistor connection pin for IL3 setting
DATA
1RM,
2RM
MO
CO
VOFF
RO
VCC1
Switching data input pin
Load resistor connection pins for monitoring
function
Analog output pin for monitoring function
Comparator output pin for monitoring function
Laser current forced OFF input pin
Load resistor connection pin for laser current
Power supply pin 1
VCC2
Power supply pin 2
GND1
GND2
GND pin 1
GND pin 2
LD
PD
VL1
2
Functions
Connect to cathode on semiconductor laser diode.
Connect to cathode on monitoring photodiode.
Voltage input to set output current (IL1) of current source 1.
Connect load resistor between this pin and GND for IL1 setting.
Voltage input to set output current (IL2) of current source 2.
Connect load resistor between this pin and GND for IL2 setting.
Connect load resistor between this pin and GND for IL3 setting.
Leave this pin open if IL3 is not used.
Laser turns on and off by “L” and “H”, respectively.
Connect resistor between pins 1RM and 2RM for conversion of
current generated by monitoring photodiode into changes in voltage.
Analog output for monitoring laser power
Comparator output for monitoring laser power
If this is “L”, all current supply circuits are turned off.
Connect load resistor between RO and VCC for laser current.
Power supply for internal analog circuits. Connect to positive power
source (+5V)
Power supply for internal digital circuits. Connect to positive power
source (+5V)
GND for internal analog circuits
GND for internal digital circuits
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
OPERATION
1. Setting for Laser Drive Current
The M66512 has 3 built-in constant current sources, IL1, IL2,
and IL3. Each output current can be controlled independently.
The following (1) to (3) describe the method for how to set
IL1,IL2, and IL3.
(1) IL1 setting method
The value of IL1 is determined by the voltage on the VL1
pin and the resistor (RC1) connected between the 1RC
pin and GND. The following equation is used for approximation.
VL1[V]
IL1 [mA] = 12 ×
RC1 [kΩ]
provided that 0≤VL1≤VCC–1.8V and IL1(max.) =60mA
(2) IL2 setting method
The value of IL2 is determined by the voltage on the VL2
pin and the resistor (RC2) connected between the 2RC
pin and GND. The following equation is used for approximation.
VL2[V]
IL2[mA] = 6 ×
RC2 [kΩ]
provided that 0≤VL2≤VCC–1.8V and IL2(max.) =30mA
(3) IL3 setting method
The value of IL3 is determined by the internal reference
voltage (Vref) and the resistor (RC3) connected between
the 3RC pin and GND. The following equation is used for
approximation.
IL3[mA] = 10 × Vref[V]
RC3 [kΩ]
provided that Vref =1.4V (typ.) and IL3(max.) =30mA
Note: Each of the above equations is a typical on for obtaining IL1–IL3. In practice values vary by a few percent due to some reasons such as differences of
ICs from lot to lot and variations in operation temperatures.
(1) A current equal to the PD current generated by laser light
flows through the resistor (RM) connected between 1RM
and 2RM. Then, a potential difference (VM) proportional to
the output of laser light occurs at RM.
(2) The VM is output at the MO pin as an analog signal
through a buffer amp. At the same time, VM is compared
with the internal reference voltage Vref(1.4V typ.) by the
comparator, thence the result of the comparison is output
at the CO pin in TTL level.
LD
_
PD
+
MO output
Buffer amp
+
VM
_
RM
CO output
Comparator
Vref
Condition
VM<Vref
VM>Vref
CO output
“L”
“H”
A Schematic Diagram of Monitor Circuits
2. Switching Operation
The laser turns on if DATA =“L”. The laser drive current at that
moment is IL1 +IL2 + IL3.
If DATA = “H” the laser is turned off, and the laser drive current is almost zero irrespective of the values of IL1 to IL3.
3. Use of the VOFF Input
When DATA = “H” the current flowing through the laser is zero
so the laser is turned off, but the internal current sources are
in operation.
When VOFF = “L” in contrast, the internal current sources are
turned off. Accordingly, it is possible to prevent an excessive
current from flowing through the laser by, for example, fixing
the VOFF input to “L” until V CC, after turned on, reaches
3.5V(typ.). (See the section dealing with internal reset.)
4. Laser Power Monitoring Operation
At the MO and CO pins, the M66512 outputs data obtained
by the monitoring photodiode (PD) contained in the laser, in
the sequence explained below.
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MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
5. RO Pin
The RO pin is used to connect a load resistor (RO) for the
current sources (IL1, IL2, and IL3). The load resistor is connected between the RO pin and VCC in order to reduce the
power dissipated in the IC.
The resistance of the load resistor should be such that does
not generate a voltage equal to or lower than 2.5V at the RO
pin. Accordingly, a value that satisfies the following equation
should be chosen.
VCC–2.5[V]
RO (Ω) ≤
maximum load current flowing through RO [A]
Example: If VCC =5V and the maximum load current is 120
mA, RO is 20Ω or under.
6. Internal Reset Function
The M66512 has a reset circuit for the protection of laser from
an excessive current flowing at the moment of power on. The
reset circuit functions in the range VCC < 3.5V(typ.), letting all
current sources turn off.
7. VCC and GND Pins
Pins related to the power supply function are VCC1, VCC2,
GND1, and GND2. The role of these pins in terms of the internal circuits are as follows.
VCC1, GND1 : connected to analog circuits
VCC2, GND2 : connected to digital circuits
In practical wiring, the following should be noted.
(1) Secure as much a width as possible for conductors and
avoid lengthy wiring.
(2) Allocate electrolytic capacitors for stable voltage near
VCC1 and GND1.
(3) Allocate by-pass capacitors near VCC2 and GND2.
Notes on the Wiring for peripheral Components
Lay out peripheral components necessary for the M66512 to
operate in closest possible proximity to the M66512.
Calculation Method for Power Dissipation
The M66512’s approximated power dissipation, P, is determined by the following equation.
4
P=ICC × VCC +I(RO) × V(RO) + I(LD) × V(LD) + IOL(CO) × VOL(CO)
Where V(RO)
: voltage at RO pin
: voltage at LD pin
V(LD)
: load current at RO pin
I(RO)
I(LD)
: load current at LD pin
VOL(CO) : “L” output voltage at CO pin
IOL(CO) : “L” output voltage at CO pin
If, for example, VCC = 5.25V, V(RO) = V(LD) = 2.75V, I(RO) =
I(LD) = 120mA, IOL(CO) = 8mA, and VOL(CO) = 0.5V, power dissipation at times of turning on and off of laser will be as follows.
(1) Laser ON (DATA =“L” and ICC = 75mA)
PON = 75 × 5.25 + 0 + 120 × 2.75 + 8 × 0.5 = 727.8(mW)
(2) Laser OFF (DATA =“H” and ICC = 74mA)
POFF = 74 × 5.25 + 120 × 2.75 + 0 = 718.5(mW)
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
OPERATING WAVEFORMS
Laser output
P0
Laser output
IL1 : 0~60mA
IL2 : 0~30mA
IL3 : 0~30mA
Laser current IL
IL3
IL1
IL2
Drive current pulse
ABSOLUTE MAXIMUM RATINGS
Symbol
VCC
VI
VO
IL1
IL2
IL3
Pd
Tstg
Parameter
Supply voltage
VL1, VL2
Input voltage
DATA, VOFF
CO
Output voltage
RO
Output current 1
Output current 2
Output current 3
DIP
Power dissipation
SOP
Storage temperature
Conditions
Ratings
–0.5 ~ +7.0
–0.3 ~ VCC
–0.3 ~ + 7
–0.3 ~ + 5.5
–0.3 ~ + 7
90
45
45
1300
1200
–65 ~ 150
Output: “H”
For single integrated circuit; Ta=25˚C (Note 1)
IC Measured being mounted; Ta=25˚C (Note 2)
Unit
V
V
V
mA
mA
mA
mW
°C
Note 1: For operation above 25°C free-air temperature, derating of 10.4mW/°C is necessary.
2: For operation above 25°C free-air temperature, derating of 9.6mW/°C is necessary.
RECOMMENDED OPERATIONAL CONDITIONS
Symbol
VCC
IL1
IL2
IL3
Topr
Parameter
Supply voltage
Output current 1
Output current 2
Output current 3
Operational ambient temperature
Conditions
Min.
4.75
–20
Limits
Typ.
5
Max.
5.25
60
30
30
75
Unit
V
mA
mA
mA
˚C
5
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
ELECTRICAL CHARACTERISTICS (VCC = 5V ± 5%, Ta = –20 ~ 75˚C unless otherwise noted))
Symbol
Parameter
Test conditions
VIH
VIL
VI
VOH
“H” input voltage
“L” input voltage
Maximum effective input voltage
“H” output voltage
DATA, VOFF
DATA, VOFF
VL1, VL2
CO
VOL
“L” output voltage
CO
VLD
VOS
Operating voltage range
Output offset voltage
LD
MO
∆VM
Output voltage
fluctuation
MO
II
DATA, VOFF
VL1, VL2
Vref
Reference voltage
IL1
Output current 1 (Note 5)
LD
IL2
Output current 2 (Note 5)
LD
IL3
Output current 3 (Note 5)
LD
IOFF
OFF state output current
LD
ICC
Supply current
Limits
Typ.*
Temperature coefficient
Max.
0.8
IOH=–400µA
IOL=4mA
IOL=8mA
VCC–1.8
2.7
VCC–1.4
0.4
0.5
VCC
VCC–2.5
Temperature coefficient
Input current
Min.
2
IMO=±20µA, IPD=0mA (Note 3)
IPD=0.2~2.0mA, IMO=±20µA
RM=1kΩ (Note 4)
RM=1kΩ, IPD=1.2mA
VI=2.7V
VI=0.4V
VI=0~VCC
VL2=3V, RC2=560Ω, VLD=2V
Temperature coefficient
RC3=360Ω, VLD=2V
VOFF=DATA=2V
VOFF=DATA=0.8V
VCC=5.25V, VOFF=4.5V, DATA
VL1=VL2=3.0V,
=0V
RC1=RC2=560Ω,
RC3=360Ω,
DATA
RO=LD=5.0V
=4.5V
V
V
mV
20
mV
20
–0.2
±1
Temperature coefficient
V
V
V
V
30
0.05
Ta=–20~25˚C
Ta=25~75˚C
VL1=3V, RC1=560Ω, VLD=2V
Unit
1.4
–0.8
–0.5
61
0.111
31
0.050
34
0.03
0.01
50
50
60
75
59
74
mV/˚C
µA
mA
µA
V
mV/˚C
mA
mA/˚C
mA
mA/˚C
mA
µA
µA
mA
Note 3. IMO: Output current at MO pin. IPD: Input current at PD pin
4. RM: Resistor connected between 1RM and 2RM pins
5. These parameters indicate the conversion characteristics of the input voltage and output current. In actual use, IL1 – IL3 shall be within the range
specified as limits in the recommended operating conditions.
* Typical values are gained under conditions of VCC =5V and Ta =25˚C. Regarding parameters that Ta is specified as test condition, however, typical
values are gained under the condition VCC = 5V.
SWITCHING CHARACTERISTICS (VCC = 5V, Ta = –25˚C)
Symbol
fOP
6
Parameter
Test pin
Input
Output
Test conditions
Operating frequency
tRP1
Circuit response time 1
VL1, VL2
Voltage
tRP2
Circuit response time 2
PD
Current
MO
Voltage
PD
Current
VOFF Voltage
VOFF Voltage
CO
Voltage
LD Current
LD Current
tRP3
Circuit response time 3
tON
tOFF
Circuit ON time
Circuit OFF time
LD
Current
ILD(L)=0mA, ILD(H)=60mA (Note 6)
ILD(L)=55mA, ILD(H)=65mA (Note 6)
IPD(L)=0mA, IPD(H)=2mA,
RM=1kΩ
(Note 7)
|∆IPD|=0.2mA, RM=1kΩ (Note 7)
|∆IPD|=1mA
(Note 7)
|∆IPD|=0.2mA
(Note 7)
ILD(H)=60mA, ILD(L)=0mA (Note 8)
ILD(H)=60mA, ILD(L)=0mA (Note 8)
Min.
Limits
Typ.
40
4.5
0.5
Max.
Unit
Mbps
7
2
7
10
1
7
0.5
3
0.5
3
10
2
5
2
µs
µs
µs
µs
µs
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
NOTE 6: MEASURING CIRCUIT
NOTE 7: MEASURING CIRCUIT
5V
5V
20Ω
Oscilloscope
(input)
VCC
50Ω
560Ω
560Ω
Oscilloscope
(input)
RO
VL1
RO
VL2
VL2
P.G.
tr=tf=6ns
Oscilloscope
(output)
VCC
VL1
20Ω
Current probe
PD
1RC
2RC
560Ω
LD
2RC
ILD
1RM DATA
P.G.
PD
IPD
1RM
RM
2RM
GND
Current probe
1RC DATA
560Ω
CO
tr=tf=6ns
Oscilloscope
(output)
2RM MO
GND
Other pins are opend
50Ω
Other pins are opend
TIMING CHART
VL1, VL2
TIMING CHART
VIH
50%
50%
IPD
50%
VIL
tRP1
tRP2,
tRP3
tRP1
ILD(H)
90%
ILD
10%
MO,CO
| IPD|
50%
|
tRP2,
tRP3
MO=10% MO=90%
CO=1.5V CO=1.5V
IPD|
IPD(H)
IPD(T)( ✽ )
IPD(L)
VOH
VOL
ILD(L)
( ✽ ): IPD gained at the moment CO output is inverted.
NOTE 8: MEASURING CIRCUIT
TIMING CHART
5V
20Ω
Oscilloscope
(output)
VCC
VL1
RO
VOFF
VL2
560Ω
560Ω
Oscilloscope
(input)
1RC
1.5V
0V
Current probe
PD
tOFF
2RC
1RM DATA
VOFF
GND
tON
LD
ILD
90%
ILD
10%
2RM
P.G.
tr=tf=6ns 50Ω
3V
1.5V
ILD(H)
ILD(L)
Other pins are opend
7
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
APPLICATION EXAMPLE
Controller
M66512
RO
MO
CO
12
Linear
amp.
RM
1RM
2RM
RC1
VL1
1RC
RC2
VL2
2RC
RC3
3RC
8
9
10
2
3
4
13
PD
16
LD
18
20
RO
Comparator
(Vref=1.4V)
Differential
amp.
Consttant current
source(IL1)
Max.60mA
5
Consttant current
source(IL2)
Max.30mA
7
Consttant current
source(IL3)
Max.30mA
Current switching circuit
DATA STREAM
15
DATA
DATA INPUT
IL=IL1+IL2+IL3
6
CONTROL SIGNAL
VOFF
LASER CURRENT FORCED OFF
1 VCC1
14 VCC2
8 GND1
17 GND2
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
TYPICAL CHARACTERISTICS (VCC=5V, Ta=25˚C)
LASER CURRENT VS. RC3 RESISTANCE
LASER CURRENT VS. CURRENT SETTING VOLTAGE
50
IL1 +IL2
LASER CURRENT IL3 (mA)
LASER CURRENT IL1, IL2 (mA)
100
IL1(RC1=560Ω)
80
60
IL2(RC2=560Ω)
40
20
0
0
1
2
3
4
40
30
20
10
0
0.2
5
0.4
0.6
0.8
1.0
1.2
MO OUTPUT VS. MONITORING CURRENT
CO OUTPUT VS. MONITORING CURRENT
5
4
VMO
3
2
RM=1kΩ
1
0
0
1
2
3
4
MONITORING CURRENT IPD (mA)
5
MONITORING COMPARATOR OUTPUT VCO (V)
RC3 RESISTANCE (kΩ)
MONITORING ANALOG OUTPUT VMO (V)
CURRENT SETTING INPUT VOLTAGES VL1, VL2 (V)
5
4
3
2
RM=1kΩ
1
0
1.0
1.2
1.4
1.6
1.8
2.0
MONITORING CURRENT IPD (mA)
9
MITSUBISHI 〈DIGITAL ASSP〉
M66512P/FP
LASER-DIODE DRIVER
EVALUATION OF SWITCHING OPERATION WAVEFORMS
ML44114N
Connector
VCC=5V
Ta=25°C
RO
20Ω
0.1µF
VCC 1
1 VCC1
1RO 20
Light intensity
meter
(✽)
RLD
22µF
RD
GND 2
RC1
VL1 3
680Ω
VL2 4
RC2
VOFF 5
680Ω
GND 6
RC3
JP
CO 7
680Ω
MO 8
DATA 9
PD 10
100Ω
RM
3kΩ
2 VL1
NC 19
3 1RC
LD 18
4 VL2
(✽)
CLD
GND2 17
5 2RC
PD 16
6 VOFF
DATA 15
7 3RC
VCC2 14
8 GND1
CO 13
9 1RM
MO 12
10 2RM
NC 11
2Ω
50Ω
300pF
Oscilloscope
(laser light output)
0.1
µF
( ✽ ): Optimum values of RLD and CLD
may vary depending on the kind
of the laser in use and the pattern
of the printed board.
Oscilloscope (data input)
P.G. (Note 9)
50Ω
Evaluation Circuit
Note 9. tr=tf=6ns, VO=3VP-P, duty=50%
SWITCHING OPERATION WAVEFORMS
10Mbit/s (t : 50ns/div)
20Mbit/s (t : 20ns/div)
25Mbit/s (t : 20ns/div)
40Mbit/s (t : 10ns/div)
3V
DATA input
(2V/div)
Laser light output
(1mW/div)
0V
3mW
0mW
Note: The delay from the DATA input to the laser light output contains the delay occurring in measuring systems.
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