AX3842 Datasheet, PDF (7/12 Pages) List of Unclassifed Manufacturers – High Performance Current Mode Pwm Controlers

Page No. : 7/12
Application Information
Open Loop Test Circuit
Vref
4.7K
RT
HPN2222A
VREF
A
100K
COMP
1
8
7 ^Vcc
0.1uF
Error Amp.
Adjust _1K
I SENSE
Adjust _5K
VFB
2
I SENSE
3
RT/CT
AX3842
Output
6
Ground
0.1uF
1W
1K
4
5
4.7K
Vcc
Output
Ground
CT
High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and
bypass capacitors should be connected close to pin5 in a single point ground. The transistor and 5KΩ
potentiometerare used to samplethe oscillator waveform and apply an adjustable ramp to pin3.
Oscillator and Output Waveforms
Vcc
7
8
5V REG
PWM
1
3
2
RT
Clock
4
Oscillator
Id
6
Output
CT
5
GND
CT
Output
CT
Output
Large RT / Small CT
Small RT / Large CT
Error Amp Configuration
Under Voltage Lockout
2.5V
+
Zi
VFB 2
-
COMP 1
Zf
7 ^{ON/OFF Command}
Icc
1mA
Vi
To Rest Of IC
<17mA
AX3842
Von 16V
Voff 10V _<0.5mA
Vcc
Voff Von
AVANTICS - AX3842 Series
Specification No.: 050308-FE0008