Datasheet

TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038G − JANUARY 1989 − REVISED FEBRUARY 2008
9
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
DEAD TIME
vs
TIMING CAPACITANCE
Figure 4
sµ
100401040
C
T
− Timing Capacitance − nF
100
40
10
4
1
0.4
0.1
Dead Time −
V
CC
= 15 V
R
T
≥ 5 kΩ
T
A
= 25°C
TIMING RESISTANCE
vs
FREQUENCY
Figure 5
Ω
100 1 k 10 k 100 k 1 M
f − Frequency − Hz
R
T
− Timing Resistance − k
100
40
10
4
1
V
CC
= 15 V
T
A
= 25°C
C
T
= 22 nF
C
T
= 47 nF
C
T
= 100 nF
C
T
= 10 nF
C
T
= 4.7 nF
C
T
= 2.2 nF
C
T
= 1 nF
open-loop laboratory test fixture
In the open-loop laboratory test fixture (see Figure 6), high peak currents associated with loads necessitate
careful grounding techniques. Timing and bypass capacitors should be connected close to the GND terminal
in a single-point ground. The transistor and 5-kΩ potentiometer sample the oscillator waveform and apply an
adjustable ramp to the ISENSE terminal.
2N2222
4.7 kΩ
1 kΩ
Error Amplifier
Adjust
4.7 kΩ
5 kΩ
ISENSE
Adjust
R
T
100 kΩ
COMP
VFB
ISENSE
RT/CT
REF
OUTPUT
GND
V
CC
0.1 µF
0.1 µF
REF
V
CC
OUTPUT
GND
1 kΩ, 1 W
A
C
T
TL284x
TL384x
DUT
Figure 6. Open-Loop Laboratory Test Fixture