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MITSUBISHI DIGITAL ASSP MITSUBISHI DIGITAL ASSP
M66516FP M66516FP
LASER-DIODE DRIVER/CONTROLLER LASER-DIODE DRIVER/CONTROLLER
MONITORING LOAD 2RM INPUTS MO MONITORING ANALOG OUTPUT MONITORING COMPARATOR OUTPUT
FEATURES * Built-in sample-hold circuit for APC function * High speed switching (20Mbps) * Large drive current (150mA max.) * Capable of setting bias current (30mA max.) * 5V single power supply APPLICATION Semiconductor laser-diode applied equipment
BLOCK DIAGRAM COMPARATOR OUTPUT
CO 12
MONITORING
MONITORING ANALOG OUTPUT MO 11
REFERENCE VOLTAGE OUTPUT Vref 19 REFERENCE VOLTAGE SOURCE
COMPARATOR Vr VL1 SWITCHING CURRENT VL2 SETTING INPUTS 1RC 2RC 18 2 4 3 5
LINEAR AMP
3RC 7
1 VCC 15
GND
SAMPLE-HOLD CIRCUIT
CURRENT SWITCHING CIRCUIT
8 20
DIFFERENTIAL AMP 9 1RM 10 2RM 13 S/H 14 CSH 21 PD 23 16 17 6
ENB LD DATA CD MONITORING SAMPLE-HOLD CONNECTION MONITORING OUTPUT TO DUTY CONTROL SWITCHING LASER CURRENT LASER INPUT DIODE INTPUT DATA INPUT ENABLE INPUT PIN FOR LOAD INPTUT CONTROL INPUT CURRENT LOAD SAMPLE-HOLD CAPACITOR

DESCRIPTION The M66516 is a semiconductor laser-diode driver/controller. Its functions are the driving and laser power control of a specific type (Mitsubishi's R type laser) of semiconductor laser diode, in which the cathode of a semiconductor laser diode is connected in stem structure to the anode of a monitoring photodiode. The IC has a laser drive current output pin of source type and is capable of driving a laser diode on a maximum bias current of 30mA and a maximum switching current of 120 mA, which is switched at a rate of 20Mbits/sec. Since the M66516 has a built in sample-hold circuit, it is possible to realize an internal APC system that requires no external device for laser power control. : Automatic Power Control
PIN CONFIGURATION (TOP VIEW)
VCC1
SWITCHING CURRENT SETTING INPUT 1 VL1 OUTPUT TO SWITCHING CURRENT SETTING LOAD 1RC 1 SWITCHING CURRENT VL2 SETTING INPUT 2 2RC OUTPUT TO SWITCHING CURRENT SETTING LOAD ENB 2 LASER CURRENT 3RC ENABLE INPUT OUTPUT TO BIAS GND1 CURRENT SETTING LOAD

1RM
CO
1 2 3 4 5 6 7 8 9 10 11 12
24 23 22 21 20 19 18 17 16 15 14 13
RO LD
NC
OUTPUT TO LASER CURRENT LOAD LASER CURRENT OUTPUT MONITORING DIODE INPUT
PD
GND2
Outline 24P2N-B
NC: No Connection
SWITCHING CURRENT SOURCE
BIAS CURRENT SOURCE
M66516FP
Vref REFERENCE VOLTAGE OUTPUT Vr REFERENCE VOLTAGE INPUT DATA SWITCHING DATA INPUT
CD VCC2
DUTY CONTROL INPUT CONNECTION PIN FOR SAMPLE-HOLD CONTROL INPUT
S/H
CSH SAMPLE-HOLD CAPACITOR
RO 24

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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
PIN DESCRIPTIONS
Pin LD PD VL1 1RC VL2 2RC 3RC DATA 1RM, 2RM Name Laser current output Monitoring diode input Switching current setting input 1 Output to switching current setting load 1 Switching current setting input 2 Output to switching current setting load 2 Output to bias current setting load Switching data input Monitoring load input Monitoring analog output Description Connect to anode 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 a load resistor between this pin and GND for IL2 setting. Connect a load resistor between this pin and GND for setting IB (bias current). Leave this pin open if IB is not used. If this pin is "L," a current of IL1 + IL2 + IB flows through laser diode; if "H," current IB flows. Connect a load resistor between pins 1RM and 2RM for conversion of current generated by monitoring photodiode into changes in voltage. If DATA = "L" the potential difference generated on monitoring load resistor from photodiode monitoring current is output as a voltage referenced to GND. If DATA = "H" the output at this pin is fixed at "H" saturation level. The potential difference generated on monitoring load resistor from photodiode monitoring current is compared with the voltage on pin Vr. The result of the comparison is output in TTL level. This pin acts as comparator output pin only when S/H = "H" and DATA = "L." In other states, this output pin is fixed to "H." If this pin is "H," all current supply circuits are turned off. Connect a laser current load resistor between this pin and Vcc. Connect a capacitor between this pin and GND for duty correction of light intensity switching waveforms. If duty correction is not required, leave this pin open. In internal APC mode, if this pin is "L," sampling (APC) occurs, if "H," holding (switching). In external APC mode, connect this pin to Vcc. Connect a capacitor for sample-hold function between this pin and GND. Internal reference voltage (1.2V typ.) output pin of M66516 A reference voltage is applied to this pin to operate the comparator and the sample-hold circuit. Connect this pin to the Vref pin if the internal reference voltage of the M66516 is used. Power supply for internal analog circuits. Connect to a positive power source (+5V). Power supply for internal digital circuits. Connect to a positive power source (+5V). GND for internal analog circuits. GND for internal digital circuits.
MO
CO
Monitoring comparator output Laser current enable input Laser current load output Duty control input Sample-hold control input Connection pin for sample-hold capacitor Reference voltage output Reference voltage input
ENB RO CD S/H CSH Vref
Vr VCC1 VCC2 GND1 GND2
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
OPERATION 1. Settings for Laser Drive Currents The M66516 has built-in current sources for switching, IL1 and IL2, and a bias current source, IB. Each output current can be controlled independently. Approximate equations used for determining the current output from each of these current sources are as follows. (1) IL1 IL1 is determined by the voltage on the VL1 pin and the resistor (RC 1) connected between the 1RC pin and GND. The following equation is used for approximation. VL1 [V] IL1 [mA] = 12 x RC1 [k] (2) IL2 IL2 is determined by the voltage on the VL2 pin and the resistor (RC 2) connected between the 2RC pin and GND. The following equation is used for approximation. VL2 [V] IL2 [mA] = 12 x RC2 [k] (3) IB IB is determined by the internal reference voltage (Vref) and the resistor (RC 3) connected between the 3RC pin and GND. The following equation is used for approximation.
Vref [V] RC3 [k] 2. Laser Drive Current Switching Operation If DATA = "L," laser drive current is IL1 + IL2 + IB; if DATA = "H," IB. 3. Laser Power Monitoring Operation At the MO and CO pins, the M66516 outputs data obtained by the monitoring photodiode (PD) contained in laser, in the sequence explained below. (1) A current equal to the PD current generated from laser light flows through the resistor (RM) inserted between 1RM and 2RM. Thence a potential difference (VM) occurring on RM is converted by the internal differential amp. to a level from GND. (2) VM is output at the MO pin as an analog signal through a buffer amp. At the same time, the comparator compares VM with the voltage applied to the Vr pin, then the result of the comparison is output at the CO pin in TTL level. If VM < Vr, CO output = "L"; and if VM > Vr, CO output = "H." As the condition of the above operation, both the MO and CO output circuits should be in monitoring operation. See the table below. IB [mA] = 10 x
Buffer amp 2RM + VM 1RM LD PD Vr RM - Differential amp - + + - Comparator CO MO
Monitor Function Table
Input S/H L L H H DATA L H L H MO output Analog output "H" saturation Analog output "H" saturation Output CO output Fixed to "H" Fixed to "H" Comparator output Fixed to "H"
A Schematic Diagram of Monitor Circuits
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
4. RO Pin A load resistor for laser drive current is connected to the RO pin, through which a current almost equal to laser drive current flows in(when DATA = "H"). A load resistor is connected between the RO pin and Vcc to reduce power dissipated in the IC. Due to reasons related to the operation of circuits, the voltage at this pin should be 3.5V or higher. Consequently, the maximum resistance, RO (max.), of load resistor RO is: Vcc (min.) - 3.5 [V] RO (max.) () = ILD (max.) [A] where ILD (max.) is the maximum of laser drive current. If, for
example, Vcc (min.) = 4.75 V and ILD(max.) = 150 mA, RO (max.) = 8.3 . Accordingly, if the resistances of RC 1 to RC 3 is selected so as to gain a maximum laser drive current of 150mA, RO should be 8.3 at the maximum. 5. ENB Input If laser current is controlled by the DATA input, the current source circuit is in operation even with zero laser current. If ENB input = "H", all current source circuits go off including the bias current source. 6. APC Operation (1) Sample-hold circuit The following are a conceptual diagram and function table of the sample-hold circuit contained in the M66516.
Constant current source for charging
Reference voltage RM resistor voltage difference Switching data Sample-hold control input
Vr SW1 VM DATA S/H Comparator + logic SW2 External capacitor
Constant current source for discharging
Control circuit
Output CSH
ENB
Conceptual Diagram: Sample-Hold Circuit
Function Table
Input ENB H L L L
x: Don't care
Switch condition DATA x x H L VM, Vr x x x VM < Vr VM > Vr SW1 OFF OFF OFF ON OFF SW2 OFF OFF OFF OFF ON
S/H x H L L
Output Fixed to "L" High impedance state (hold) High impedance state (hold) Constant current sourcing (sample) Constant current sinking (sample)
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
(2) External voltage-applied APC circuit The following figure is an example of APC circuit configuration, in which voltages are applied from external sources to the VL1 and VL2 input pins of the M66516. In this example, the
S/H input pin is connected to Vcc and the CSH pin is open. The CO or MO output is used to monitor laser power for adjustment of external control voltage.
CO 12 Vr 18 External control voltage 1 VL1 1RC External control voltage 2 VL2 2RC 3RC 7 1RM 8 RM 10 2RM 2 3
MO 11
Vref 19
RO 24
M66516FP 4 5
14
CSH
13
S/H
20 PD
23 LD
16 CD 91pF
DATA
17
ENB
6
Data stream Control signal
(3) Peak-holding internal APC circuit The following figure is a configuration example of peak-holding internal APC circuit. In this example, the S/H input pin is connected to GND.
If laser power is lower than preset value, C1 is charged with the current from the CSH output pin through D1. The charge stored in C1 is discharged through R1 thereafter.
CO 12 Vr VL1 1RC VL2 2RC 3RC 18 2 3 4 5 7 9 1RM 10 2RM RM R1 C1
MO 11
Vref 19
RO 24
M66516FP
14 CSH
13 S/H PD
21
23 LD CD 91pF
16 DATA
17 ENB
6
R2
Data stream Control signal
C1, R1: Time constant components R2: Pull-down resistor (Used for establishing CSH line voltage in case that CSH is in high impedance condition.)
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
(4) Sample-hold type internal APC circuit The following figure is a configuration example of samplehold type internal APC circuit. In this example, a sample-hold control signal is applied to the S/H input pin. In a sampling state, if laser power is lower than preset value,
C1 is charged by current from the CSH output pin, while if it is higher than preset value, C1 is discharged. In a holding state, the CSH output is in high-impedance condition.
CO 12 Vr 18 2 3 4 5 7 9 1RM RM 10 2RM
MO 11
Vref 19
RO 24
VL1 1RC VL2 2RC 3RC
M66516FP
14 CSH
13
S/H
PD
21
23
LD
CD 91pF
16
DATA
17
ENB
6
Control signal C1 Data stream Control signal C1: Capacitor for sample-hold function
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
ABSOLUTE MAXIMUM RATINGS (Ta = -20 ~ 75C, unless otherwise noted)
Symbol VCC VI VO IL1 IL2 IB Pd Tstg Supply voltage Input voltage Output voltage Output current 1 Output current 2 Bias current Power dissipation Storage temperature Measured being mounted Ta = 25C (Note 1) VL1, VL2, Vr DATE, ENB, S/H CO RO Parameter Conditions Ratings -0.5 ~ +7.0 -0.3 ~ VCC -0.3 ~ +7.0 -0.3 ~ +5.5 -0.3 ~ +7.0 -90 -90 -45 890 -60 ~ 150 Unit V V V mA mA mA mW C
"H" Output "H" Output
SWITCHING CHARACTERISTICS (Ta = -20 ~ 75C, unless otherwise noted)
Symbol VCC IL1 IL2 IB Topr Parameter Supply voltage Output current 1 Output current 2 Bias current Operational ambient temperature Conditions Limits Min. 4.75 Typ. 5.0 Max. 5.25 -60 -60 -30 75 Unit V mA mA mA C
-20
Note 1: When Ta 25C, derate by 7.1mW/C
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
ELECTRICAL CHARACTERISTICS (Ta = -20 ~ 75C, VCC = 5V5%, unless otherwise noted)
Symbol VIH VIL VI VOH VOL VOH VOL VLD VOS VM Parameter "H" Input voltage "L" Input voltage Maximum effective Input voltage "H" Output voltage "L" Output voltage "H" Output voltage "L" Output voltage Ambient tempererature Output offset voltage Output voltage fluctuation DATA, ENB, S/H DATA, ENB, S/H VL1, VL2 CO CO CSH CSH LD MO MO Temperature coefficient II Input current DATA, ENB VL1, VL2, Vr Vref Vr IL1 IL2 IB IOFF Icg Idg Ioz Reference voltage output Reference voltage input Output current 1 Output current 2 Bias current (5) LD (5) LD (5) LD LD CSH CSH CSH DATA = 0V ICC Supply current DATA = 4.5V Temperature coefficient Temperature coefficient VL1 = 3V, VL2 = 0V, VLD = 2V, RC1 = RC2 = 560, RC3 open VL1 = 0V, VL2 = 3V, VLD = 2V, RC1 = RC2 = 560, RC3 open RC3 = 360, VLD = 2V ENB = 0.8V, DATA = 2V ENB = 2V, DATA = 0.8V VO = 0.6 ~ 4.0V VO = 0.6 ~ 4.0V VO = 0 ~ VCC, Hold condition VCC = 5.25V, ENB = 0V, VL1 = VL2 = 3V, RC1 = RC2 = 560, RC3 = 360 output open Temperature coefficient Test conditions Min. 2.0 VCC - 1.8 2.7 Limits Typ.(2) Max. 0.8 VCC - 1.4 0.4 0.5 4.0 0.6 2.5 (3) (4) 30 20 0.05 20 -0.2 1 1.2 -1.5 -0.7 0.4 -62 0.037 -62 0.037 -31 -1 -20 -2.0 2.0 8 36 mA 54 2.0 IOH = -400A IOL = 4mA IOL = 8mA ENB = 0.8V, IOH = -2mA ENB = 0.8V, IOH = 2mA IMO = 20A IPD = -0.2 ~ 2.0mA IMO = 20A, RM = 1k IPD = -1.2mA VI = 2.7V VI = 0.4V VI = 0 ~ VCC IO = -10A Ta = -20 ~ 25C Ta = 25 ~ 75C Unit V V V V V V V V mV mV mV/C A mA A V mV/C V mA mA/C mA mA/C mA mA A mA mA A
OFF state output current Charge current Discharge current Output leak current
-0.66 0.66
Note 2: Typical values are gained under conditions of Vcc = 5V and Ta = 25C. Regarding parameters that Ta is specified as test condition, however, typical values are gained under the condition Vcc = 5V. 3: IMO: Output current at MO pin; IPD: Input current at PD pin 4: RM: Resistor inserted between 1RM and 2RM. 5: These parameters indicate the conversion characteristics of the input voltage and output current. In actual use, IL1, IL2, and IB shall be within the range specified as limits in the recommended operating conditions.
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
SWITCHING CHARACTERISTICS (Ta = -25C, VCC = 5V)
Symbol fop Parameter Operating frequency VL1, VL2 voltage ILD(L) = 0mA ILD(H) = -60mA(Note 6) LD current ILD(L) = -55mA ILD(H) = -65mA(Note 6) IPD(L) = 0mA IPD(H) = -2mA RM = 1k (Note 7) |IPD| = 0.2mA RM = 1k (Note 7) tRP3 tRP4 tON tOFF Circuit response time 3 Circuit response time 4 Circuit ON time Circuit OFF time PD current DATA voltage ENB voltage ENB voltage CO voltage CSH voltage LD current LD current |IPD| = 1mA (Note 7) |IPD| = 0.2mA (Note 7) IPD = 0mA, -2mA, RM = 1k , Vr = 1.2V (Note 8) ILD(H) = -60mA(Note 9) ILD(H) = -60mA(Note 9) 2 s s s s s s s Test pin Input Output Test condition Limits Min. Typ. 20 Max. Unit Mbps 7 s
tRP1
Circuit response time 1
10
tRP2
Circuit response time 2
PD current
MO voltage
3 10 2 8 5 2
NOTE 6: TEST CRICUTS
VCC Oscilloscope(input) VCC VL1 P.G. tr=tf=6ns VL2 50 560 1RC 2RC 1RM DATA ENB PD Current probe LD PD RO ILD Oscilloscope(output) 8.2
NOTE 7: TEST CRICUTS
VCC
VCC VL1 VL2 560 560 RO
8.2 Oscilloscope(input) Current probe ILD
1RC 2RC 1RM
PD DATA S/H CO
50
P.G. tr=tf=6ns
2RM GND Other pins are opened
RM
LD
MO 2RM GND
Oscilloscope(output)
Other pins are opened
TIMING CHARTS
VIH VL1 VL2 50% t RP1 ILD 10% 50% VIL t RP1 90% ILD(H)
TIMING CHARTS
IPD(H) IPD0() IPD(L)
IPD
50% t RP2, t RP3 MO =10%, CO =1.5V
50% t RP2, t RP3 MO =90%, CO =1.5V
IPD IPD
VOH
MO, CO
ILD(L)
VOL (): IPD gained at the moment CH output is inverted.
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MITSUBISHI DIGITAL ASSP
M66516FP
LASER-DIODE DRIVER/CONTROLLER
NOTE 8: TEST CIRCUTS
VCC
NOTE 9: TEST CIRCUTS
VCC
VCC VL1 VL2 560 RO ILD PD
8.2 Oscilloscope(input)
VCC VL1 VL2 560 1RC 2RC 1RM RO
8.2 ILD LD PD Current probe Oscilloscope (output)
1RC DATA Vr 560 ENB 2RC S/H 1RM RM CSH 2RM GND Other pins are opened
1.2V
50
P.G. tr=tf=6ns
Oscilloscope (input)
560
Oscilloscope(output)
P.G. tr=tf=6ns 50
DATA 2RM ENB GND
PD
LD
Other pins are opened
TIMING CHARTS
3V 1.5V DATA t RP4 3.0V CSH 0.4V VOL VOH 0V
TIMING CHARTS
3V ENB 1.5V t ON 90% ILD(L) 10% ILD(L) 1.5V 0V t OFF ILD(H)
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