KA3844B Fairchild Semiconductor, KA3844B Datasheet - Page 6

• Manufacturer Part Number: KA3844B
• Description: IC CONTROLLER PWM SMPS 8-DIP
• Manufacturer: Fairchild Semiconductor

Specifications of KA3844B

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 500kHz
• Duty Cycle: 50%
• Voltage - Supply: 11.5 V ~ 30 V
• Buck: No
• Boost: No
• Flyback: No
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: No
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Frequency-max: 500kHz
• Duty Cycle (max): 50 %
• Output Current: 1000 mA
• Mounting Style: Through Hole
• Switching Frequency: 500 KHz
• Supply Current: 17 mA
• Maximum Operating Temperature: + 70 C
• Fall Time: 35 ns
• Minimum Operating Temperature: 0 C
• Rise Time: 45 ns
• Synchronous Pin: No
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

KA3842B/KA3843B/KA3844B/KA3845B
Oscillator timing capacitor, C
charge time, the internal clock signal blanks the output to the low state. Selection of R
oscillator frequency and maximum duty cycle. Charge and discharge times are determined by the formulas:
t
Frequency, then, is: f=(t
6
t
c
ForRT
D
= 0.55 R
=
R
T
C
Figure 6. Oscillator Dead Time & Frequency
T
5K
T
I
n
C
0.0063R
--------------------------------------- -
T
0.0063R
,
f
=
-------------- -
R
(Deadtime vs C
1.8
T
C
T
T
T
c
–
–
+ t
2.7
4
d
)
T
-1
, is charged by V
Figure 5. Oscillator Waveforms and Maximum Duty Cycle
T
RT > 5k
Figure 8. Shutdown Techniques
REF
through R
T
and discharged by an internal current source. During the dis-
Figure 7. Timing Resistance vs Frequency
T
and C
T
therefore determines both