SM8610 Nippon_Precision_Circuits America, SM8610 Datasheet - Page 7

• Manufacturer Part Number: SM8610
• Manufacturer: Nippon_Precision_Circuits America

Laser Diode Drive Current Mid-value Set Function
The laser diode drive current mid-value can be adjusted by changing the resistance R
LDISET and GND pins. The laser diode drive current mid-value base value I
equation, is set to the LDIOUT output current when the PDVIN voltage is in balance state (147 to 193mV).
Note that the actual LDIOUT current may change due to feedback gain, and laser diode/photo diode variations.
APC Loop Gain Setting
The APC (Auto Power Control) loop gain can be adjusted by changing the external gain set resistance (R
connected between the RG1 and RG2 pins. The PDVIN voltage-to-laser drive current open-loop gain is given
approximately by the following equation.
APC Loop Cutoff Frequency Setting
The APC loop cutoff frequency fc is determined by the external resistance R
nected between RG1 and RG2.
If C
G
is connected between RG2 and VCC, the cutoff frequency is given as follows.
I
LDSET
Gm
= I
f
f
C1
C2
PDVIN
LDSET
=
=
2√
= 9.1 × 10
SM8610CV
× 1000 =
2πR
2πR
1
1
G
C
G
C
G
G
−5
800[V]
R
[Hz]
[Hz]
R
G
LD
[S]
R
G
: Resistance connected between RG1 and RG2 [Ω]
NIPPON PRECISION CIRCUITS INC.—7
[A]
G
∆LDIOUT current /∆PDVIN voltage ratio [S]
LDSET
and the capacitance C
R
LD
LD
: LDISET connected resistance [Ω]
, given by the following
connected between the
G
, con-
G
)