cxa2571n Sony Electronics, cxa2571n Datasheet - Page 14

• Manufacturer Part Number: cxa2571n
• Description: Rf Matrix Amplifier
• Manufacturer: Sony Electronics

• EQ
The boost gain can be adjusted by the BST pin
control voltage.
The control characteristics are shown in the graph
below.
• APC (Automatic Power Control)
When the laser diode is driven by a constant current, the optical power output has extremely large negative
temperature characteristics. Therefore, the current must be controlled to maintain the monitor photodiode
output at a constant level. This control is performed by the APC function.
In
Boost Gain [dB]
8dB
0dB
VC – 1.0
RFC
HPF
LPF
V
27
CC
VFC
Pin 25 voltage
fc
EQ CNT
Amp
VC
26
VC
Boost
BST
PD
VC
2
25
VC + 1.0
10k
LPF
55k
Vcut [V]
Out
– 14 –
10k
The diagram to the left shows the EQ internal block
diagram.
The EQ consists of a combination of HPF and LPF.
The HPF and LPF transmittance is the Bessel function.
The boost gain can be adjusted by adjusting the HPF
gain.
The boost frequency is adjusted by the RFC external
resistance value and the VFC control voltage value.
RFC resistance value: The cut-off frequency fo of each
VFC voltage:
10k
V
The cut-off frequency control characteristics are
shown in the graph below.
CC
1.5fo
0.5fo
56k
1.25V
fo
56k
fc [Hz]
VC – 1.0
1k
1
filter is adjusted by the Pin 27
external resistance value.
The VFC voltage can be varied
using this fo as the reference.
fo can be changed by the voltage
applied to Pin 26.
Pin 26 voltage
LD
VC
VC + 1.0
CXA2571N
Vcut [V]