KA3511DS Fairchild Semiconductor, KA3511DS Datasheet - Page 16

• 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

6.9 POWER GOOD SIGNAL GENERATOR
Power good signal generator curcuits generate “ON & OFF” signal depending on the status of out-
put voltage to prevent the malfunctions of following systems like microprocessor and etc. from
unstable outputs at power on & off. At power on, it produces PG “High” signal after some delay
(about 250ms) for stabilizing outputs.
At power off, it produces PG “Low” signal without delay by sensing the status of power source for
protecting following systems. V
mended values of R11, R12 are external components.
COMP3 creates PG “Low” without delay when +5V output falls to less than 4.3V to prevent some
malfunction at transient status, thus it improves system stability.
When remote On/Off signal is high, it generates PG “Low” signal without delay. It means that PG
becomes “Low” before main power is grounded.
PG delay time (Td) is determined by capacitor value, threshold voltage of COMP3 and the charg-
ing current and its equation is as following.
Td
=
Figure 11. PG Signal Generator Block
V
CC
----------- -
Ichg
DET
V
detection point can be calculated by following equation. recom-
=
PG
------------------------ -
1.25V
Ichg
Vth
16
1
=
+
2.2 F
----------------------------- -
R11
---------- -
R12
18 A
= 17.2V
2V
250ms
Rev C, November 1999