Advanced Analog Circuits
Data Sheet
AZ3842/3/4/5
CURRENT MODE PWM CONTROLLER
Electrical Characteristics (Continued)
Figure 4 is the basic test circuit for AZ384x. In testing, the high peak currents associated with capacitive loads necessitate
careful grounding techniques. Timing and bypass capacitors should be connected close to pin 5 in a single point ground. The
transistor and 5k potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3.
Typical Performance Characteristics
100k
30
10
50K
Dead Time (
µ
s)
CT
3
RT (
Ω
)
n
=1
CT
0n
=1
F
CT
10k
F
n
00
=1
1
5K
F
0.3
1
2.2
4.7
10
22
47
100
100
1k
10k
100k
1M
Timing Capacitor (nF)
Frequency (Hz)
Figure 5. Oscillator Dead Time vs. Timing Capacitor
1.0
Figure 6. Timing Resistor vs. Frequency
5.015
5.010
5.005
5.000
4.995
4.990
4.985
V
CC
=15V, I
O
=1mA
0.9
AZ3842
Reference Voltage (V)
Start Up Current (mA)
-20
0
20
40
60
80
o
0.8
0.7
0.6
0.5
0.4
4.980
-40
100
120
-40
-20
0
20
40
60
o
80
100
120
Ambient Temperature ( C)
Ambient Temperature ( C)
Figure 7. Reference Voltage vs. Ambient Temperature
Figure 8. Start-up Current vs. Ambient Temperature
March 2003
7
Rev: 1.0
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
