m66515fp Renesas Electronics Corporation., m66515fp Datasheet - Page 4

• Manufacturer Part Number: m66515fp
• Description: Laser Diode Driver/controller
• Manufacturer: Renesas Electronics Corporation.

M66515FP
5. RO pin
The RO pin is connected to the laser driving current load resistance; current essentially equal to I
The load resistance is connected between this pin and V
reduced.
However, the circuit operation requires that the voltage at this pin be 2.5 V or above. Hence if the maximum value of
I
For example, if V
resistance R
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 (V
a constant current source which charges the external capacitor. If V
discharges the external capacitor. This operation is performed when the S /H input is "L" (sample); when the S/H input
is "H", the C
Function table
Input
ENB
H
L
L
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 C
state is the direction flowing out from the M66515 (the negative direction).
Rev.1.00, Sep.22.2003, page 4 of 11
SW
is I
SW
(max), then the maximum value RO(max) of the load resistance RO is as follows.
S
H
S/H
X
H
L
such that the maximum value of I
pin is kept in the high-impedance state (hold), regardless of V
CC
(min)=4.75 V and I
Vm, Vr
X
X
V
V
M
M
< Vr
> Vr
M
). This V
SW
Switched state
SW1
OFF
OFF
ON
OFF
M
(max)=120 mA, then RO(max)=18.8 . In other words, when setting the
is compared with the voltage applied to the pin V
SW
is 120 mA, RO should be 18.8
SW2
OFF
OFF
OFF
ON
CC
; by this means the Power dissipation within the IC is
Tr1
ON
OFF
OFF
OFF
M
>V
r
, pin C
M
, V
H
Output
Fixed at "L"
High-impedance state (hold)
Constant current source (sample)
Constant current sink (sample)
r
is a constant current sink which
, and the DATA input state.
or lower.
r
, and if V
SW
flows from this pin.
M
H
<V
pin in the hold
r
, pin C
H
is