KA3843 データシートの表示（PDF） - Estek Electronics Co. Ltd
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KA3843 Datasheet PDF : 7 Pages
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Pin functions
N Function
1 COMP
2 VFB
3
ISENSE
4 RT/CT
5 GROUND
6 OUTPUT
7 VCC
8
Vref
Description
This pin is the Error Amplifier output and is made for loop compensation.
This is the inverting input of the Error Amplifier. It is normall y connected to the switching power supply
output through a resistor divider.
A voltage proportional to inductor current is connected to this input. The PWM uses this information to
terminate the output switch conduction.
The oscillator frequency and maximum Output duty cycle are programmed by connecting resistor RT to Vref
and capacitor CT to ground.
This pin is the combined control circuitry and power ground.
This output directly drives the gate of a power MOSFET. Peak currents up to 1A are sourced and sink by
this pin.
This pin is the positive supply of the integrated circuit.
This is the reference output. It provides charging current for capacitor C T through resistor RT .
Application information
2.5V
1mA
VFB
2
COMP 1
Figure 1. Error Amp Configuration
VCC 7
ON/OFF COMMAND TO S/R OF IC
ICC
MIK3842 MIK3843
MIK3844 MIK3845
VON
16V 8.4V
VOFF
10V 7.6V
13mA
0.2mA
VCC
V V OFF
ON
During UVLO, the Output is low
Figure 2. Undervoltage Lockout
ERROR
+ AMP
2
VFB _
COMP 1
IS
2R
1V
R
CURRENT
SENSE
COMPARATOR
R
CURRENT 3
SENSE
RS
C
5
GND
Peak current is determined by
IS max
1.0V
RS
Figure 3. Current Sense Circuit
BEIJING ESTEK ELECTRONICS CO.,LTD
3
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