Pin functions
N
1
2
Function
COMP
VFB
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 normally connected to the switching power supply
output through a resistor divider.
3
4
ISENSE
RT/CT
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.
5
6
GROUND
OUTPUT
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.
7
8
VCC
Vref
This pin is the positive supply of the integrated circuit.
This is the reference output. It provides charging current for capacitor CT through resistor RT .
Application information
2.5V
1mA
VFB
2
1
COMP
Figure 1. Error Amp Configuration
VCC
7
ON/OFF COMMAND TO S/R OF IC
ICC
MIK3842 MIK3843
MIK3844 MIK3845
13mA
8.4V
7.6V
16V
10V
VON
0.2mA
VOFF
VCC
VOFF VON
During UVLO, the Output is low
Figure 2. Undervoltage Lockout
ERROR
+
AMP
2R
2
_
VFB
1V
CURRENT
SENSE
COMPARATOR
COMP
1
5
R
IS
R
CURRENT
SENSE
RS
C
GND
1.0V
RS
Peak current is determined by IS max
Figure 3. Current Sense Circuit
BEIJING ESTEK ELECTRONICS CO.,LTD
3
ESTEK [ Estek Electronics Co. Ltd ]
