MITSUBISHI 〈DIGITAL ASSP〉 MITSUBISHI 〈DIGITAL ASSP〉 M66516FP M66516FP LASER-DIODE DRIVER/CONTROLLER LASER-DIODE DRIVER/CONTROLLER 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 → MONITORING LOAD 2RM → INPUTS MO ← MONITORING ANALOG OUTPUT MONITORING COMPARATOR OUTPUT CO ← 1 2 3 4 5 6 7 8 9 10 11 12 M66516FP 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 24 23 22 21 20 19 18 17 16 15 14 13 → RO → LD OUTPUT TO LASER CURRENT LOAD LASER CURRENT OUTPUT NC ← PD MONITORING DIODE INPUT GND2 VOLTAGE → Vref REFERENCE OUTPUT VOLTAGE ← Vr REFERENCE INPUT SWITCHING DATA ← DATA INPUT CD DUTY CONTROL INPUT VCC2 CONNECTION PIN FOR CSH SAMPLE-HOLD CAPACITOR ← S/H SAMPLE-HOLD CONTROL INPUT Outline 24P2N-B 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 NC: No Connection APPLICATION Semiconductor laser-diode applied equipment CO 12 MONITORING ANALOG OUTPUT MO 11 COMPARATOR LINEAR AMP MONITORING BLOCK DIAGRAM COMPARATOR OUTPUT Vr VL1 SWITCHING CURRENT VL2 SETTING INPUTS 1RC 2RC REFERENCE VOLTAGE OUTPUT Vref 19 RO 24 REFERENCE VOLTAGE SOURCE 18 2 4 3 5 SWITCHING CURRENT SOURCE BIAS CURRENT SOURCE 3RC 7 CURRENT SWITCHING CIRCUIT SAMPLE-HOLD CIRCUIT 1 VCC 15 8 GND 20 DIFFERENTIAL AMP 9 10 13 14 21 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 2RM 1RM S/H CSH PD 1 MITSUBISHI 〈DIGITAL ASSP〉 M66516FP LASER-DIODE DRIVER/CONTROLLER PIN DESCRIPTIONS Pin Name Laser current output Monitoring diode input Description Connect to anode on semiconductor laser diode. Connect to cathode on monitoring photodiode. VL1 Switching current setting input 1 Voltage input to set output current (IL1) of current source 1. 1RC Output to switching current setting load 1 Connect load resistor between this pin and GND for IL1 setting. VL2 Switching current setting input 2 Voltage input to set output current (IL2) of current source 2. 2RC Output to switching current setting load 2 Connect a load resistor between this pin and GND for IL2 setting. 3RC Output to bias current setting load Connect a load resistor between this pin and GND for setting IB (bias current). Leave this pin open if IB is not used. DATA Switching data input If this pin is “L,” a current of IL1 + IL2 + IB flows through laser diode; if “H,” current IB flows. 1RM, 2RM Monitoring load input Connect a load resistor between pins 1RM and 2RM for conversion of current generated by monitoring photodiode into changes in voltage. MO Monitoring analog output 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. CO Monitoring comparator output 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.” ENB Laser current enable input If this pin is “H,” all current supply circuits are turned off. RO Laser current load output Connect a laser current load resistor between this pin and Vcc. CD Duty control input 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. S/H Sample-hold control input 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. CSH Connection pin for sample-hold capacitor Connect a capacitor for sample-hold function between this pin and GND. Vref Reference voltage output Internal reference voltage (1.2V typ.) output pin of M66516 Vr Reference voltage input 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. LD PD VCC1 VCC2 GND1 GND2 2 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. 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 × RC1 [kΩ] (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 × RC2 [kΩ] (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 [kΩ] 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 × Monitor Function Table Buffer amp Input 2RM − + VM RM 1RM LD + − Differential amp + − PD Vr MO CO S/H L L H H Output DATA L H L H MO output Analog output “H” saturation Analog output “H” saturation CO output Fixed to “H” Fixed to “H” Comparator output Fixed to “H” Comparator A Schematic Diagram of Monitor Circuits 3 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.) (Ω) = 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 Ω. 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 8.3Ω 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 Vr RM resistor voltage difference Switching data VM SW1 Sample-hold control input Control circuit Output CSH DATA SW2 S/H External capacitor Comparator + logic Constant current source for discharging ENB Conceptual Diagram: Sample-Hold Circuit Function Table Input ENB H L L S/H × H L DATA × × H L L L ×: Don’t care 4 Switch condition VM, Vr × × × VM < Vr VM > Vr SW1 OFF OFF OFF ON OFF SW2 OFF OFF OFF OFF ON Output Fixed to “L” High impedance state (hold) High impedance state (hold) Constant current sourcing (sample) Constant current sinking (sample) 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. Vref 19 MO 11 CO 12 RO 24 Vr 18 External control voltage 1 2 VL1 1RC External control voltage 2 3 M66516FP 4 VL2 5 2RC 3RC 7 1RM 10 8 2RM 14 CSH 13 20 PD S/H 23 LD 16 CD 91pF DATA 17 ENB 6 RM 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. CO 12 Vr 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. RO 24 Vref 19 MO 11 18 2 VL1 1RC 3 M66516FP 4 VL2 2RC 3RC 5 7 9 1RM 10 2RM 14 CSH RM R1 C1 R2 13 21 S/H PD 23 16 LD CD 91pF 17 DATA 6 ENB 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.) 5 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, MO 11 CO 12 Vr VL1 1RC VL2 2RC 3RC 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. Vref 19 RO 24 18 2 3 M66516FP 4 5 7 10 2RM 9 1RM 14 CSH RM 13 S/H PD 21 23 LD CD 91pF DATA 17 ENB Control signal C1 Data stream Control signal C1: Capacitor for sample–hold function 6 16 6 MITSUBISHI 〈DIGITAL ASSP〉 M66516FP LASER-DIODE DRIVER/CONTROLLER ABSOLUTE MAXIMUM RATINGS (Ta = –20 ~ 75°C, unless otherwise noted) Symbol Parameter VCC Supply voltage VI Input voltage VO Output voltage IL1 IL2 IB Output current 1 Output current 2 Bias current Pd Power dissipation Tstg Storage temperature VL1, VL2, Vr DATE, ENB, S/H CO RO Conditions “H” Output “H” Output Measured being mounted Ta = 25°C (Note 1) Ratings –0.5 ~ +7.0 –0.3 ~ VCC –0.3 ~ +7.0 –0.3 ~ +5.5 –0.3 ~ +7.0 –90 –90 –45 Unit V 890 mW –60 ~ 150 °C V V mA mA mA SWITCHING CHARACTERISTICS (Ta = –20 ~ 75°C, 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 –20 Typ. 5.0 Max. 5.25 –60 –60 –30 75 Unit V mA mA mA °C Note 1: When Ta ≥ 25°C, derate by 7.1mW/°C 7 MITSUBISHI 〈DIGITAL ASSP〉 M66516FP LASER-DIODE DRIVER/CONTROLLER ELECTRICAL CHARACTERISTICS (Ta = –20 ~ 75°C, VCC = 5V±5%, unless otherwise noted) Symbol Test conditions Parameter VIH VIL VI VOH “H” Input voltage “L” Input voltage Maximum effective Input voltage “H” Output voltage DATA, ENB, S/H DATA, ENB, S/H VL1, VL2 CO VOL “L” Output voltage CO VOH VOL VLD VOS “H” Output voltage “L” Output voltage Ambient tempererature Output offset voltage CSH CSH LD MO ∆VM Output voltage fluctuation MO Temperature coefficient II DATA, ENB Input current VL1, VL2, Vr Vref Reference voltage output Vr Reference voltage input Temperature coefficient Limits Typ.(2) Output current 1 (5) LD IL2 Output current 2 (5) LD IB Bias current (5) LD IOFF OFF state output current LD Icg Idg Ioz Charge current Discharge current Output leak current CSH CSH CSH VCC – 1.8 2.7 IOH = –400µA IOL = 4mA IOL = 8mA ENB = 0.8V, IOH = –2mA ENB = 0.8V, IOH = 2mA VCC – 1.4 IMO = ±20µA (3) IPD = –0.2 ~ 2.0mA IMO = ±20µA, RM = 1kΩ (4) IPD = –1.2mA VI = 2.7V VI = 0.4V VI = 0 ~ VCC IO = –10µA Ta = –20 ~ 25°C Ta = 25 ~ 75°C VL1 = 3V, VL2 = 0V, VLD = 2V, RC1 = RC2 = 560Ω, RC3 open Temperature coefficient VL1 = 0V, VL2 = 3V, VLD = 2V, RC1 = RC2 = 560Ω, RC3 open Supply current DATA = 4.5V RC3 = 360Ω, 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 = 560Ω, RC3 = 360Ω output open V V V V V 0.6 2.5 30 V V V mV 20 mV 0.05 20 –0.2 ±1 1.2 –1.5 –0.7 mV/°C µA mA µA V mV/°C 2.0 –62 0.037 –62 0.037 –31 –0.66 0.66 Unit 0.4 0.5 4.0 Temperature coefficient DATA = 0V Max. 0.8 0.4 IL1 ICC Min. 2.0 –1 –20 –2.0 2.0 ±8 V mA mA/°C mA mA/°C mA mA µA mA mA µA 36 mA 54 Note 2: 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. 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. 8 MITSUBISHI 〈DIGITAL ASSP〉 M66516FP LASER-DIODE DRIVER/CONTROLLER SWITCHING CHARACTERISTICS (Ta = –25°C, VCC = 5V) Symbol fop Test pin Parameter Input Limits Test condition Output Min. Typ. 20 Operating frequency tRP1 Circuit response time 1 tRP2 Circuit response time 2 VL1, VL2 voltage Unit Max. Mbps ILD(L) = 0mA ILD(H) = –60mA(Note 6) 7 µs ILD(L) = –55mA ILD(H) = –65mA(Note 6) 2 µs IPD(L) = 0mA IPD(H) = –2mA RM = 1kΩ (Note 7) 10 µs |∆IPD| = 0.2mA RM = 1kΩ (Note 7) 3 µs LD current PD current MO voltage tRP3 Circuit response time 3 PD current CO voltage |∆IPD| = 1mA (Note 7) |∆IPD| = 0.2mA (Note 7) 10 2 µs tRP4 Circuit response time 4 DATA voltage CSH voltage IPD = 0mA, –2mA, RM = 1kΩ , Vr = 1.2V (Note 8) 8 µs tON tOFF Circuit ON time Circuit OFF time ENB voltage ENB voltage LD current LD current ILD(H) = –60mA(Note 9) ILD(H) = –60mA(Note 9) 5 2 µs µs NOTE 6: TEST CRICUTS NOTE 7: TEST CRICUTS VCC VCC Oscilloscope(input) 8.2Ω VCC VL1 P.G. tr=tf=6ns VL2 50Ω 560Ω 1RC Oscilloscope(output) 560Ω PD 560Ω 2RC 1RM Current probe DATA ENB 2RM GND RO VL2 ILD LD RM PD 8.2Ω Oscilloscope(input) VCC VL1 RO LD Current probe ILD 1RC 2RC PD DATA S/H 1RM CO MO 2RM GND 50Ω P.G. tr=tf=6ns Oscilloscope(output) Other pins are opened Other pins are opened TIMING CHARTS TIMING CHARTS VIH VL1 VL2 50% 50% IPD 50% ∆IPD 50% ∆IPD VIL t RP2, t RP3 t RP1 t RP1 ILD 90% 10% ILD(H) MO, CO ILD(L) MO =10%, CO =1.5V t RP2, t RP3 MO =90%, CO =1.5V IPD(H) IPD0(∗) IPD(L) VOH VOL (∗): IPD gained at the moment CH output is inverted. 9 MITSUBISHI 〈DIGITAL ASSP〉 M66516FP LASER-DIODE DRIVER/CONTROLLER NOTE 8: TEST CIRCUTS NOTE 9: TEST CIRCUTS VCC VCC 8.2Ω VCC VL1 VL2 ILD PD 560Ω 560Ω 1RC DATA Vr 560Ω ENB 2RC S/H 1RM RM CSH 2RM GND 1.2V 8.2Ω VCC Oscilloscope(input) RO 50Ω P.G. tr=tf=6ns Oscilloscope (input) 560Ω tr=tf=6ns Other pins are opened RO 1RC LD 2RC 1RM ILD 50Ω Oscilloscope (output) PD DATA 2RM ENB GND P.G. Oscilloscope(output) VL1 VL2 Current probe LD PD Other pins are opened TIMING CHARTS TIMING CHARTS 3V 3V ENB 1.5V DATA 0V t ON t RP4 3.0V VOH CSH 0.4V 10 1.5V 1.5V 0V t OFF ILD(H) 90% ILD(L) VOL 10% ILD(L)