KA3511DS Fairchild Semiconductor, KA3511DS Datasheet - Page 12

• Manufacturer Part Number: KA3511DS
• Description: IC PWM/SECONDARY COMBO 22-DIP
• Manufacturer: Fairchild Semiconductor

Specifications of KA3511DS

• Pwm Type: Current Mode
• Number Of Outputs: 3
• Frequency - Max: 10kHz
• Duty Cycle: 50%
• Voltage - Supply: 14 V ~ 30 V
• Buck: No
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: -25°C ~ 85°C
• Package / Case: 22-DIP (0.400", 10.16mm)
• Frequency-max: 10kHz
• Topology: Push-Pull
• Output Voltage: 40 V
• Output Current: 200 mA
• Switching Frequency: 10 KHz
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 25 C
• Fall Time: 50 ns
• Mounting Style: Through Hole
• Rise Time: 100 ns
• Synchronous Pin: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.5 OVP BLOCK
OVP function is simply realized by connecting Pin13, Pin14, Pin15 to each secondary output. R1,
2, 3, 4, 5, 6 are internal resistors of the IC. Each OVP level is determined by resistor ratio and the
typical values are 4.1V/6.2V/14.2V.
OVP Detecting voltage for +3.3V
OVP Detecting voltage for +5V
OVP Detecting voltage for +12V
Especially, pin16 (PT) is prepared for extra OVP input or another protection signal. That is, if you
want over voltage protection of extra output voltage, then you can make a function with two exter-
nal resistors.
OVP Detecting voltage for PT
In the case of OVP, system designer should know a fact that the main power can be dropped after
a little time because of system delay, even if PWM is triggered by OVP.
So when the OVP level is tested with a set, you should check the secondary outputs (+3.3V/+5V/
+12V) and PG (Pin11) simultaneously. you can know the each OVP level as checking each output
voltage in just time that PG (Pin11) is triggered from high to low.
V
V
V
OVP 3
OVP 1
OVP 2
V
+12V
PT
+3.3V
+5V
=
R
------------------------------ -
=
=
101
=
R
R
--------------------
R
--------------------
R
--------------------
+
102
5
3
R
R
1
R
+
+
R
+
4
6
102
R
2
R
R
6
4
2
V
V
V
12
V
D
B
C
A
=
=
=
=
R
------------------------------ -
R
--------------------
R
--------------------
R
--------------------
101
3
5
R
R
1
R
+
+
R
+
4
6
+
102
R
2
R
R
R
4
6
2
102
Vref
Vref
Vref
Vref
=
=
=
6.2V
14.2V
4.1V
Rev C, November 1999