Philips Semiconductors
Data amplifier and laser supply circuit for CD
audio and video optical systems (ADALASLC)
Product specification
TZA1025
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Vi(mon)
monitor input voltage
N-substrate
P-substrate
Ii(mon)
monitor input current
tsw(on)(LASER) laser switch-on time
RSref
reference supply
rejection
Vclamp
ALPC clamp voltage
note 8
note 9
0.132
0.150
0.168
V
VDD − 0.168 VDD − 0.150 VDD − 0.132 V
−200
−
+200
nA
−
3
−
ms
−
−
5
%
−
−
0.5
V
Control inputs
Zi(pd)
Zi(pu)
VIL
VIH
pull-down input
impedance pin CDRW
pull-up input
impedance
pin PWRON
LOW-level input
voltage
pin CDRW
pin PWRON
HIGH-level input
voltage
pin CDRW
pin PWRON
−
200
−
kΩ
−
200
−
kΩ
−0.2
−
−0.2
−
2⁄3VDD
−
2⁄3VDD
−
1⁄3VDD
V
1⁄3VDD
V
VDD + 0.2
V
VDD + 0.2
V
Notes
1. Closed-loop output impedance (10 kΩ feedback resistor connected between pins RFEQO and RFFB).
2. GRF = (GRFEQO at fEQ) − (GRFEQO at 720 kHz).
3. Values to be used in equation (1).
4. An RF filter of 1 kΩ and 47 pF should be used on the RF output.
5. Vdrop = VDD(L) − Vo(LASER).
6. An external resistor can be used to reduce the maximum output current (and the gain) of the laser supply;
see equation (4).
7. The output impedance strongly depends on the drop voltage (Vdrop). The output impedance will approximately double
when the drop voltage doubles.
8.
RSref = -∆---∆---V----V--V----V---m---D---m---D---o--D----o--n-D-----n--
9. When a voltage dip at VDD(L) occurs it could cause peak currents on Io(LASER) coming out of the ALPC output.
To protect the laser against such peak currents a protection circuit will switch-off the laser current when Vdrop
becomes lower than Vclamp. When Vdrop > Vclamp the laser will switch-on automatically again.
1998 Oct 30
8