TL284X_07 Datasheet, PDF (9/18 Pages) Texas Instruments – CURRENT-MODE PWM CONTROLLERS

TL284x, TL384x
CURRENT-MODE PWM CONTROLLERS
SLVS038F – JANUARY 1989 – REVISED FEBRUARY 2003
APPLICATION INFORMATION
DEAD TIME
vs
TIMING CAPACITANCE
100
VCC = 15 V
RT ≥ 5 kΩ
40 _{TA = 25°C}
10
TIMING RESISTANCE
vs
FREQUENCY
100
CT = 10 nF
CT = 4.7 nF
40
CT = 22 nF
CT = 1 nF
4
10 ^{CT = 22 nF}
CT = 47 nF
1
4
CT = 100 nF
0.4
VCC = 15 V
TA = 25°C
0.1
1
0
4
10
40
100
100
1k
10 k
100 k
1M
CT – Timing Capacitance – nF
f – Frequency – Hz
Figure 4
Figure 5
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.
REF
4.7 kΩ
2N2222
1 kΩ
Error Amplifier
Adjust
100 kΩ
4.7 kΩ
5 kΩ
ISENSE
Adjust
RT
COMP
DUT
REF
VFB
TL284x
VCC
TL384x
ISENSE
OUTPUT
RT/CT
GND
A
VCC
0.1 µF
0.1 µF
1 kΩ, 1 W
OUTPUT
GND
CT
Figure 6. Open-Loop Laboratory Test Fixture
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