Bose PACKLITE A1 Manual page 44

AC Power Input Filter Section (continued)
D100 [B/C3] rectifies the AC signal, which is filtered by C107 [C4] and C108 [B4].
N100 [C3] and N101 [B3] provide in-rush current protection when connected to the AC line.
MOV1 [C4] and MOV2 [B4] are for surge protection.
SG101 through 104 [B/C2] provide an ESD discharge path to the AC mains around the higher
impedance of the coils.
S100 [B3] is a manufacturing option to control use for 120 or 230 VAC. The StartUp signal must
be over 9 volts for the converter circuitry to start.
4. Converter Section Circuitry
Note: Refer to the SMPS/Amplifier PCB Schematic Diagram, sheet 2 of 3 for the following.
The information inside the brackets [ ] is the schematic grid location on the sheet.
The DC to DC converter is a transformer isolated but unregulated switching power supply.
Output voltages are generated by the secondary windings, and consist of:
• Vss/Vdd: +/-5VDC regulated
• +/-18VDC for the limiter board (+/-16.5 to 29 VDC)
• Amp Vd / Amp Vs - Amplifier rail voltages: +/-40VDC (+/- 30to 45.5)
• Vdrive: 10V above Vs, regulated, for internal use
R200 [C1] and C200 [B1] set up a 100 kHz oscillating frequency for the half bridge driver IC200
[C1] which controls Q200 [C2] and Q201 [B2] to provide the high current switching.
N201 [A3] forms a resistive divider with R290 [B2], and turns on Q290 [A3] if the temperature at
the converter rises above 130 degrees C. Q290 turns the half bridge driver off.
N200 [D4] protects the rectifying diodes on the amplifeir DC rails from overheating by bringing
Enable low if the temperature goes too high, shutting off the amplifier section.
R206 [C2] in parallel with R207 [B2], and R213 [C2] in parallel with R214 [B2] improve current
sensing. If the DC current in the FETs goes above ten amps, Q205 [D2] and Q210 [D2] will shut
down Q200 [C2], or Q206 [A2] and Q207 [A2] will shut down Q201 [B2].
5. Amplifier Section
Note: Refer to the SMPS/Amplifier PCB Schematic Diagram, sheet 3 of 3 for the following.
Refer to the Appendix for pinout diagrams and block diagrams for the amplifier chipset consist-
ing of ICCI (reference designator IC3) and ICEdrive1 (IC1 and IC2).
The PackLite A1 amplifier is designed to provide 30 dB of gain, and drive 250 W into a 4 ohm
TM
load. It is a dual amp used in a bridged configuration. The pcb has the capability of being
configured for two channel use, but is not used for two separate channels in this product.
THEORY OF OPERATION
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