Infinity PS212W Service Manual page 31

PS212W subwoofer
Pin Description
PIN NAME
1 SW Switching Node
2 BST Boost Pin (Boot–strap capacitor input)
3 R Current Limit OFF time set pin
CL
Toff = 10
4 RTN Ground pin
5 FB Feedback input from Regulated Output
6 R /SD On time set pin
ON
Ton = 1.25 x 10
Output from the internal high voltage series pass
7 V
CC
regulator. Regulated at 7.0V.
8 V Input voltage
IN
Typical Application Circuit and Block Diagram
DESCRIPTION
-5 − 6
/ (0.285 + (FB / 6.35 x 10
-10
R / V
ON IN
APPLICATION INFORMATION
Power switching node. Connect to the output
inductor, re-circulating diode, and bootstrap
capacitor.
An external capacitor is required between the BST
and the SW pins. A 0.01µF ceramic capacitor is
recommended. An internal diode charges the
capacitor from V
CC
A resistor between this pin and RTN sets the
x R )) off-time when current limit is detected. The off-time
CL
is preset to 35µs if FB = 0V.
Ground for the entire circuit.
This pin is connected to the inverting input of the
internal regulation comparator. The regulation
threshold is 2.5V.
A resistor between this pin and V
on time as a function of V
recommended on time is 400ns at the maximum
input voltage. This pin can be used for remote
shutdown.
If an auxiliary voltage is available to raise the
voltage on this pin, above the regulation setpoint
(7V), the internal series pass regulator will
shutdown, reducing the IC power dissipation. Do not
exceed 14V. This voltage provides gate drive power
for the internal Buck switch. An internal diode is
provided between this pin and the BST pin. A local
0.1µF decoupling capacitor is recommended. Series
pass regulator is current limited to 10mA.
Recommended operating range: 9.5V to 95V.
30
F.
.
sets the switch
IN
. The minimum
IN
20097901