UC3842T STMICROELECTRONICS [STMicroelectronics], UC3842T Datasheet - Page 5

• Manufacturer Part Number: UC3842T
• Description: HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

High peak currents associated with capacitive loads
necessitate careful grounding techniques. Timing
and bypass capacitors should be connected close
Figure 2: Timing Resistor vs. Oscillator Fre-
(K )
Figure 1: Open Loop Test Circuit.
RT
0.8
50
20
10
5
2
1
ERROR AMP.
10K
V
T
ADJUST
A
i
=15V
=25˚C
4.7K
4.7K
20K
quency
C
T
30K
=5nF
C
T
=10nF
1K
50K
ADJUST
2N2222
D95IN343
I
100K
SENSE
100K
C
5K
T
=2nF
200K 300K
COMP
I
R
SENSE
R
T
T
V
/C
500K
FB
T
D95IN333
f
1
2
3
4
OSC
V
REF
(KHz)
D.U.T.
8
C
T
to pin 5 in a single point ground. The transistor and
5 K potentiometer are used to sample the oscillator
waveform and apply an adjustable ramp to pin 3.
Figure 3: Output Dead-Time vs. Oscillator Fre-
50
30
20
10
%
5
3
2
1
U3842T - UC3843T - UC3844T - UC3845T
7
6
5
10K
V
OUTPUT
GROUND
i
0.1 F
C
20K
T
=200pF
quency
C
T
30K
=500pF
0.1 F
C
T
50K
=1nF
100K
C
A
T
=10nF
1K
1W
C
200K 300K
T
=100pF
C
T
=5nF
C
T
V
T
=2nF
V
V
OUTPUT
GROUND
i
A
500K fOSC(KHz)
=15V
=25˚C
REF
i
D95IN334
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