RENESAS M66515FP

M66515FP
Laser Diode Driver/Controller
REJ03F0084-0100Z
Rev.1.0
Sep.22.2003
Description
The M66515 is a laser diode driver/controller that performs drive and controls the laser power control of a type of
semiconductor laser diode the anode of which is connected, with the cathode of a photodiode for monitoring, to a stem
in which the semiconductor laser diode anode and monitoring photo diode cathode are connected to the stem.
This IC has a sink-type laser driving current output pin, and can drive a laser diode with a bias current of up to a
maximum 30 mA and with switched currents of up to 120 mA, switched at rates of up to 40 Mbps.
The IC incorporates a sample hold circuit, so that a self-APC (Automatic Power Control) system, which does not
require external laser power control, can be realized.
Features
•
•
•
•
•
Internal sample-and-hold circuit for self-APC configuration
High-speed switching (40 Mbps)
High driving currents (150 mA max)
Settable bias current (30 mA max)
Single 5 V power supply
Applications
• Equipment employing semiconductor laser diodes
Function Overview
The M66515 is a laser diode driver/controller which drives and controls the laser power of a semiconductor laser diode
(LD) the anode of which is connected, with the cathode of a photodiode (PD) for monitoring, to a stem (among
Mitsubishi lasers, N type models).
LD driving and laser power control are executed by connecting an external capacitance to the CH pin and applying a
reference voltage to the Vr pin.
The PD current occurring when a LD emits light flows through a resistance connected across 1RM and 2RM, resulting
in a potential difference (VM). This VM is compared with the voltage applied to the Vr pin, and when VM<Vr, a constant
current source from the CH pin flows to charge the external capacitor. When VM>Vr, a constant current sink from the
CH pin causes the charge on the external capacitor to be discharged.
This operation is performed when the S/H input is "L" (sample); when the S /H input is in the "H" state, the CH pin is in
the high-impedance state (hold), regardless of VM, Vr and the DATA input state.
The LD driving current consists of a switched current ISW, which is controlled by the DATA input, and IB, a LD bias
current which is independent of the DATA input state.
Rev.1.00, Sep.22.2003, page 1 of 11
M66515FP
Pin Configuration (top view)
Description of Pin
Pin name
Name
Function
LD
PD
RS
Laser current output
Monitor diode input
Switching current setting load
output
Connected to the semiconductor LD cathode
Connected to the monitor PD anode
Connects the load resistance to set the current for switching (ISW ) to GND
RB
Bias current setting load
output
Connects the load resistance to set the bias current (IB) to GND. If IB is not
used, this pin should be left open.
VB
Bias current setting voltage
input
DATA
1RM, 2RM
Switching data input
Load input for monitoring
The bias current value (IB) can be set by applying a voltage to this pin. If IB
is not used, this pin should be left open.
At "L", the current ISW+IB flows to the LD; at "H", the current to the LD is IB
Connect a load resistance to convert the monitor PD current to a voltage
across 1RM and 2RM
ENB
RO
S/H
Laser current enable input
Laser current load output
Sample hold control input
When "H", all current source circuits are turned off
Connect a laser current load resistance between this pin and VCC
When "L", sample (APC) operation is performed; when "H", hold
(switching) is performed
CH
Hold capacitor load
input/output
Connect a hold capacitor between this pin and GND. This pin is connected
within the M66515 to the sample hold circuit output and ISW current source
input.
Vref
Vr
Reference voltage output
Reference voltage input
TEST
VCC1
Test pin
Power supply pin 1
Output pin for the M66515 internal reference voltage (1.2 V typ)
A reference voltage is applied to cause operation of the comparator within
the sample hold circuit. When using the reference voltage within the
M66515, this pin should be connected to the Vref pin.
Pin used for testing at time of shipment of the M66515; should be left open
Power supply for the internal analog system; connect to a positive power
supply (+5 V)
VCC2
Power supply pin 2
Power supply for the internal digital system; connect to a positive power
supply (+5 V)
GND1
GND pin 1
GND for internal analog system
GND2
GND pin 2
GND for internal digital system
Rev.1.00, Sep.22.2003, page 2 of 11
M66515FP
Block Diagram
Explanation of operation
1. Laser driving current values
The values of the laser driving currents ISW and IB can be approximated as follows, if VC is the voltage of the hold
capacitor connected to the CH pin.
(1) ISW (switched current)
Here 0≤VC≤VCC-1.8 V, ISW (max) =120 mA, and RS is the value of the resistance connected between the RS pin and
GND
(2) IB (bias current)
Here 0≤VB≤VCC-2.7 V, IB (max) =30 mA, and RB is the value of the resistance connected between the RB pin and GND
2. Switching operation
When DATA="L", the LD driving current is ISW+IB; when DATA="H", the LD driving current is IB.
3. ENB input
Whereas the laser driving current is controlled by DATA input by controlling the driving current applied to the laser
with the current source in the M66515 turned on, control by ENB turns the current source operation on and off.
When ENB="L" the current source is turned on, and when ENB="H" the current source is turned off.
When ENB="H", the CH pin is forced to "L" level, and the charge on the capacitor connected to the CH pin is forcibly
discharged.
4. Internal reset operation
The M66515 incorporates a reset circuit to prevent the flow of excessive current to the laser when power is turned on;
when VCC<3.5 V (typ), the internal current source is turned off and the CH pin is forced to "L" level.
Rev.1.00, Sep.22.2003, page 3 of 11
M66515FP
5. RO pin
The RO pin is connected to the laser driving current load resistance; current essentially equal to ISW flows from this pin.
The load resistance is connected between this pin and VCC; by this means the Power dissipation within the IC is
reduced.
However, the circuit operation requires that the voltage at this pin be 2.5 V or above. Hence if the maximum value of
ISW is ISW(max), then the maximum value RO(max) of the load resistance RO is as follows.
For example, if VCC(min)=4.75 V and ISW(max)=120 mA, then RO(max)=18.8 Ω. In other words, when setting the
resistance RS such that the maximum value of ISW is 120 mA, RO should be 18.8 Ω or lower.
6. Sample-and-hold circuit
(1) Summary of circuit operation
The following is a summary of operation of the sample hold circuit within the M66515.
A PD current arising upon LD light emission flows through the resistance connected between 1RM and 2RM, giving
rise to a potential difference (VM). This VM is compared with the voltage applied to the pin Vr, and if VM<Vr, pin CH is
a constant current source which charges the external capacitor. If VM>Vr, pin CH is a constant current sink which
discharges the external capacitor. This operation is performed when the S /H input is "L" (sample); when the S/H input
is "H", the CH pin is kept in the high-impedance state (hold), regardless of VM, Vr, and the DATA input state.
Function table
Input
Switched state
ENB
S/H
Vm, Vr
SW1
SW2
H
L
L
X
H
L
X
X
VM < Vr
VM > Vr
OFF
OFF
ON
OFF
OFF
OFF
OFF
ON
Tr1
Output
ON
OFF
OFF
OFF
Fixed at "L"
High-impedance state (hold)
Constant current source (sample)
Constant current sink (sample)
X: arbitrary
(2) APC operation timing chart
An example of an APC operation timing chart for a given sample hold control signal is shown below.
In this example, a case is shown in which it is assumed that the direction of the leakage current of the CH pin in the hold
state is the direction flowing out from the M66515 (the negative direction).
Rev.1.00, Sep.22.2003, page 4 of 11
M66515FP
7. VCC and GND pins
The VCC1 and VCC2 pins and the GND1 and GND2 pins are related to the power supply. The internal circuitry
connected to these pins is as follows.
VCC1, GND1: Connected to analog circuitry
VCC2, GND2: Connected to digital circuitry
The following should be taken into account in designing the actual wiring.
(1) Wiring widths should be as broad as possible, and drawn-out lengths of wiring should be avoided.
(2) The electrolytic capacitor for voltage stability should be positioned close to VCC1 and GND1.
(3) The bypass capacitor should be positioned close to VCC2 and GND2.
Important Information Regarding Peripheral Element Wiring
Peripheral elements necessary for M66515 operation should be positioned as close to the M66515 as possible.
Method of Calculating Power dissipation
The M66515 Power dissipation P is essentially given by the following formula.
P = ICC × VCC + I(RO) × I(RO) + I(LD) × V(LD)
Here V(RO) is the RO pin voltage, V(LD) is the LD pin voltage, I(RO) is the RO pin load current, and I(LD) is the LD pin
load current.
For example, when VCC = 5.25 V, V(RO) = V(LD) = 2.5 V, and I(RO) = I(LD) = 150 mA, the Power dissipation when the laser
is turned on and off is as follows.
(1) When the laser is on (DATA = “L”, ICC = 75 mA):
PON = 75 × 5.25 + 0 + 150 × 2.5 = 768.8 (mW)
(2) When the laser is off (DATA = “H”, ICC = 74 mA):
POFF = 74 × 5.25 + 0 + 150 × 2.5 = 763.5 (mW)
Rev.1.00, Sep.22.2003, page 5 of 11
M66515FP
Absolute Maximum Ratings
(Unless otherwise noted, Ta = –20 to 70°C)
Symbol
Parameter
VCC
VO
ISW
IB
Pd
Power supply voltage
Input voltage
CH, Vr
DATA, ENB, S/H
Output voltage
RO
Switching current
Bias current
Power dissipation
Tstg
Storage temperature
VI
Conditions
Mounted on board, with
Ta=25°C (see note)
Value
Unit
−0.5 to +7.0
−0.3 to VCC
−0.3 to +7.0
−0.5 to +7.0
150
45
1200
V
V
V
V
mA
mA
mW
−60 to +150
°C
Note: When Ta ≥ 25°C, derating at 9.6 mW/°C should be performed.
Recommended Operating Conditions
(Unless otherwise noted, Ta = –20 to 70°C)
Symbol
VCC
ISW
IB
Topr
Parameter
Power supply voltage
Switching current
Bias current
Operating ambient temperature
Rev.1.00, Sep.22.2003, page 6 of 11
Limits
Unit
Min
Typ
Max
4.75
5.0
−20

5.25
120
30
70
V
mA
mA
°C
M66515FP
Electrical Characteristics
(Unless otherwise noted, VCC = 5 V ±5%, Ta = –20 to 70°C)
Symbol
Parameter
Measurement conditions
Limits
VIH
"H" input
voltage
DATA, ENB, S/H
VIL
"L" input voltage
DATA, ENB, S/H
Vr
Reference
voltage input
Vr
Vref
Reference
voltage output
Vref
IO = –10 µA
1.2
V
Temperature
coefficient
Ta = –20 to 25°C
–0.9
mV/°C
VLD
Operating
voltage range
LD
2.5
VI
Effective
voltage upper
limit
CH
VCC–
1.8
VOH
"H" output
voltage
CH
ENB = 0.8 V, IOH = –2 mA
VOL
"L" output
voltage
CH
ENB = 0.8 V, IOL = 2 mA
IL
Input current
DATA, ENB
VI = 2.7 V
VI = 0.4 V
–0.2
mA
CH
VI = 0 to VCC
±1
µA
Min
Unit
Typ
Max
2.0
V
0.4
Ta = 25 to 70°C
Measurement
circuit
0.8
V
2.0
V
1
–0.9
VCC
VCC–
1.4
V
V
4.0
V
1
0.6
V
1
20
µA
CH = 3.0 V, Rs = 360 Ω, VLD = 2 V
120
mA
Ta = 20 to 70°C
0.11
mA/°C
LD
VB = 1.2 V, RB = 360 Ω, VLD = 2 V
30
mA
2
Load charging
current
CH
ENB = 0.8 V, VO = 0.6 to 4.0 V
–0.66
–2.0
mA
3
Idg
Load discharge
current
CH
ENB = 0.8 V, VO = 0.6 to 4.0 V
0.66
2.0
mA
3
Ioz
Output current
in off state
CH
VO = 0 to VCC, Hold state
±5
µA
3
IOFF
Output current
when off
LD
µA
2
mA
4
Switching
current (see
note)
LD
IB
Bias current
(see note)
Icg
ISW
ICC
Temperature
coefficient
Power supply current
ENB = 0.8 V, DATA = 2.0 V
0.33
50
ENB = 2.0 V, DATA = 0.8 V
0.01
50
DATA =
0V
54
75
DATA =
4.5 V
52
74
VCC = 5.25 V, ENB = 0 V,
CH = 3.0 V, VB = 1.2 V,
RS = 300 Ω, RB = 360 Ω,
RO = LD = 5.0 V
2
*Typical values are for Ta = 25°C, VCC = 5 V.
Note: These quantities indicate the input voltage-output current conversion characteristic; ISW and IB should be used
within the range of the rated values under recommended operating conditions.
Rev.1.00, Sep.22.2003, page 7 of 11
M66515FP
Switching Characteristics
(Ta = 25°C, VCC = 5 V)
Symbol
Item
fOP
Operating
frequency
Circuit response
time 1
Measurement pin
Input
tRP1
tRP2
Circuit response
time 2
Output
Measurement
conditions
Limits
Min.
Unit
Typ.
Max.
40
CH voltage
PD current
LD current
CH voltage
Mbps
7
µs
2
µs
15
µs
|∆IPD| = 0.2 mA
RM = 1 kΩ
(Note 2)
8
µs
ILD(L) = 0 mA
ILD(H) = 60 mA (Note 1)
ILD(L) = 55 mA
ILD(H) = 65 mA (Note 1)
IPD(L) = 0 mA
IPD(H) = 2 mA
RM = 1 kΩ
(Note 2)
tRP3
Circuit response
time 3
S/H voltage
CH voltage
IPD = 0 mA, 2 mA
RM = 1 kΩ, Vr = 1.2 V
(Note 3)
1
µs
tON
Circuit turn-on
time
ENB voltage
LD current
ILD(H) = 60 mA (Note 4)
5
µs
tOFF
Circuit turn-off
time
ENB voltage
LD current
ILD(H) = 60 mA (Note 4)
2
µs
Note 1. Measurement circuit and Timing chart
Rev.1.00, Sep.22.2003, page 8 of 11
M66515FP
Note 2. Measurement circuit and Timing chart
Note 3. Measurement circuit and Timing chart
Rev.1.00, Sep.22.2003, page 9 of 11
M66515FP
Note 4. Measurement circuit and Timing chart
Application example
Rev.1.00, Sep.22.2003, page 10 of 11
Rev.1.00, Sep.22.2003, page 11 of 11
G
Z1
E
HE
1
20
EIAJ Package Code
SOP20-P-300-1.27
z
Detail G
e
D
JEDEC Code
—
y
b
x
Weight(g)
0.26
M
10
11
F
A
Detail F
A2
Lead Material
Cu Alloy
L1
MMP
c
A1
A
A1
A2
b
c
D
E
e
HE
L
L1
z
Z1
x
y
Symbol
e1
b2
e1
I2
b2
Dimension in Millimeters
Min
Nom
Max
—
2.1
—
0.1
0.2
0
1.8
—
—
0.5
0.35
0.4
0.2
0.18
0.25
12.6
12.7
12.5
5.3
5.4
5.2
1.27
—
—
7.8
8.1
7.5
0.8
0.6
0.4
—
1.25
—
—
0.585
—
—
—
0.735
—
—
0.25
—
0.1
—
—
0°
8°
—
—
0.76
—
7.62
—
1.27
—
—
Recommended Mount Pad
e
Plastic 20pin 300mil SOP
I2
20P2N-A
M66515FP
Package Dimensions
L
Sales Strategic Planning Div.
Nippon Bldg., 2-6-2, Ohte-machi, Chiyoda-ku, Tokyo 100-0004, Japan
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