PA4220 PROTEC [Protek Devices], PA4220 Datasheet - Page 5

• Manufacturer Part Number: PA4220
• Description: Pop-Up and Shutdown Noise Suppressor
• Manufacturer: PROTEC [Protek Devices]

THEORY OF OPERATION
STARTUP
During Startup, the Power supply ramps from 0V to V
critical that this rise time be around 50ms for the PA4220 to
perform well. This sudden rise in V
Capacitor to charge and thereby the pop up noise.
The PA4220 senses this sudden change in voltage and
clamps the output line to a low impedance state and
suppresses the Pop noise.
The capacitor at the R
line can be kept in low impedance state during startup after
which the switch is released and normal operation is started.
95027.Rev 0.0 12/10 PATENT PENDING; CONFIDENTIAL; COVERED BY NON DISCLOSURE AGREEMENT.
NOT FOR USE IN LIFE SUPPORT SYSTEMS
Figure 2: Startup Pop-Noise Reduction with PA4220 (32 Ω load )
Figure 1: Startup Pop-Noise without PA4220 (32 Ω load )
ANALOG PRODUCTS DIVISION
561 E. Elliot Road #175 Chandler, AZ 85225 Tel: [phone]. Fax: [phone]
CS
pin determines the time for which the
CC
causes the DC Blocking
CC
www.protekanalog.com
. It is
SHUTDOWN
During Shutdown, the reverse process happens. As the power
supply reaches the threshold on its way down, the PA4220
turns the internal switches ON and hence clamping the output
stage to low impedance state suppressing the shutdown
noise. This operation is governed by the charge stored in the
capacitor connected to V
Pop-Up and Shutdown Noise Suppressor
Figure 3: Shutdown Noise without PA4220 (32 Ω load )
Figure 4: Shutdown Noise with PA4220 (32 Ω load )
CAP
pin.
PA4220